NFPA 70, National Electrical Code [2020 ed.] 9781455922970, 1455922978

Citation preview

Ci.] NFP~ Copyright © 2019 National Fire Protection Association® One Batterymarch Park Quincy, Massachusetts 02169-7471 NFPA, NFPA 70, National Fire Pmtection Association, National Electrical Code, and NEC are registered trademarks of the

National Fire Protection Association.

IMPORTANT NOTICES AND DISCLAIMERS CO NCERNING NFPA ® STANDARDS NFPA® codes, standards, recommended practices, and guides ("NFPA Standards"), of which the document contained herein is one, are developed through a consensus standards development process approved by the American National Standards Institute. This process bri ngs together volunteers representing varied viewpoints and interests to achieve consensus on fire and other safety issues. While the NFPA adm inisters the process and establishes rules to promote fairness in the development of consensus, it does not independently test, evaluate, or verify the accuracy of any information or the soundness of any judgments contained in NFPA Standards. The NFPA disclaims liability for any personal injury, property, or other damages of any nature whatsoever, whether special, indirect, consequential or compensatory, directly or indirectly resulting from the publication, use of, or reliance on NFPA Stc--indards. The NFPA a lso makes no guaranty or warranty as to the accuracy or completeness of any information published herein. In issuing and making NFPA Standards available, the NFPA is not undertaking to render professional or other services for or on be half of any person or entity. Nor is the NFPA undertaking to perform any duty owed by any person or entity to someone else. Anyone usin g this document should rely on his or her own independent judgment or, as approp1iate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. The NFPA has no power, nor does it undertake, to police or enforce compliance with the contents ofNFPA Standards. Nor does the NFPA list, certify, test, or inspect products, designs, or installations for compliance with this document. Any certification or other statement of complian ce with the requirements of th is document shall not be atuibutable to the NFPA and is solely the responsibility of the certifier or maker of the statement.

~~~ ,.,,

See ALERT

ALERT: TI-llS STANDARD HAS BEEN MODIF1ED BY A TIA OR ERRATA Users of NFPA codes, standards, recomme nded practices, and guides ("NFPA Standards") should be aware that NFPA Standards may be amended from time to time through the issuance ofa Tentative Interim Amendment (TIA) or corrected by Errata. An official NFPA Standard at any point in time consists of the current edition of the document together with any TIAs and Errata then in effect. To determine whether an NFPA Standard has been amended through the issuance of TIAs or corrected by Errata, go to www.nfpa.org/ docinfo to choose from the list ofNFPA Standards or use the search feature to select the NFPA Standard number (e.g., NFPA 13) . The document information page provides up-to-date document-specific information as well as postings of all existing TIAs and Errata. It also includes the option to register for an "Alert" feature to receive an automatic email notification when new updates and other information are posted regarding the docume n t.

IMPORTANT NOTICES AND DISCLAIMERS CONCERNING NFPA® STANDARDS Updating of NFPA Standards Users ofNFPA codes, standards, recommended practices, and guides ("NFPA Standards") should be aware that these documents may be superseded at a ny time by the issuance of new editions or may be amended from time to time through the issuance of Tentative Interim Amendments or corrected by Errata. An official NFPA Standard at any point in time consists of the current edition of the document together with any Tentative Interim Amendments and any Errata then in effect. In order to determine whether a given document is the current edition and whether it has been amended through the issuance of Tentative Interim Amendments or corrected through the issuance of Errata, consult apprnpriate NFPA publications such as the National Fi re Codes® Subscription Service, visit the NFPA website at www.nfpa.org, or contact the NFPA at the address listed below.

Interpretations of NFPA Standards A statement, written or oral, that is not processed in accordance with Section 6 of the Regulations Governing the Development of NFPA Standards shall not be considered the official position of NFPA or any of its Committees and shall not be considered to be, nor be relied upon as, a Formal Interpretation .

Patents The NFPA does not take any position with respect to th e validity of an y patent rights referenced in, related to, or asserted in connection with an NFPA Standard. The users of NFPA Standards b ear the sole responsibility for determining the valid ity of a ny su ch patent rights, as well as the risk of infringem ent of su c h rights, and the NFPA disclaims liability for the infringe ment of any patent resulting from the u se of or reliance on NFPA Standards. NFPA adheres to the policy of the American National Standards Institute (ANSI) regarding the i nclusion of patents in American National Standards ("th e ANSI Patent Policy"), and hereby gives the following notice pursuant to that policy:

NOTICE: The u ser's attention is called to the possibility that compliance with an NFPA Standard m ay require u se of an invention covered by patent rights. NFPA takes no position as to the validity of a ny such patent rights or as to whether su ch patent rights constitute or include essential patent claims under the ANSI Patent Policy. If, in connection with the ANSI Patent Po licy, a patent holder has filed a statement of willingness to grant licenses under these rights on reasonable and nondiscriminatory terms and conditio ns to applicants desiring to obtain su ch a licen se, copies of such filed statements can be obtained, on request, from NFPA. For further information, contact the NFPA at the address listed below. Law and Regulations Users ofNFPA Standards should consult applicable federal, state, a nd local laws and regulations. NFPA does not, by the publication of its codes, standards, recommended practices, and guides, intend to urge action that is n ot in compliance with applicable laws, and these documents may not be con su-u ed as doing so.

Copyrights NFPA Standards a re copyrighted. They are made available for a wide variety of both public and private u ses. These include both use, b y reference, in laws and regulations, and u se in private self~regulation, standardizatio n, a nd the promotion of safe practices and methods. By making these documents available for use and adoption by public authorities and private u sers, the NFPA does not waive any rights in copyrig ht to these documents . Use of NFPA Standards for regulatory purposes should be accomplished through adoptio n by reference. The term "adoption by reference" means the citing of title, edition , and publishing information only. Any deletions, additions, and changes desired by th e adopting a uthority should be noted separately in the adopting insu-ument. In order to assist NFPA in following the u ses made of its documents, adopting authorities are requested to notify the NFPA (Attention: Secretary, Standards Council) in writing of su ch u se. For technical assistance and questions con cerning adoption of NFPA Standards, contact NFPA at the address b e low.

For Further Information All questions or other communications relating to NFPA Standards a nd all requests for information on NFPA procedures governing its codes and standards development process, including information o n the procedures for requesting Formal I nterpretations, for proposing Tentative Interim Amendments, and for proposin g revisions to NFPA standards dm·ing regular revision cycles, should be sen t to NFPA headquarters, addressed to the attention of the Secretary, Standards Council, NFPA, 1 Batterymarch Park, P.O. Box 9101, Quincy, MA 02269-9101 ; e mail: stds_admin@nfpa .org For more information about NFPA, visit the NFPA website at www.nfpa.org. All NFPA codes and standards can be viewed at no cost at www.nfpa.org/ docinfo.

Copyright© 2019 National Fire Protection Association®. All Rights Reserved.

NFPA 70®

National Electrical Code® 2020 Edition

This edition of NFPA 70, National Electrical Code, was prepared by the National Electrical Code Committee and acted on by NFPA at its June Association Technical Meeting held June 17-20, 2019, in San Antonio, TX. It was issued by the Standards Council o n August 5, 2019, with an effective date of August 25, 2019, and supersedes all previous editions. This Code was issued with Tentative Interim Amendments (TIAs) that impacted provisions in 210.52(C) (2), 240.67(C), 240.87(C), 725.1 21 (C), and Annex D3. For more information on TIAs, see www.nfpa .org/70 and Section 5 of the Regulations Governing the Development of NFPA Standards available at www.nfpa.org/ regs. This edition of NFPA 70was approved as an American National Standard on August 25, 2019. History and Development of the National Electrical Code®

The National Fire Protection Association has acted as sponsor of the NationalElect1ical Code since 1911. The original Code document was developed in 1897 as a result of the united efforts of vario us insurance, electrical, arch itectural, and all ied interests. In accordance with the Regulations Governing the Development of NFPA Standards, a National Elect1ical Code first draft report containing proposed a mendments to the 2017 National E.1.ectrical Code was published by NFPA in July 2018. This report recorded the actions of the various code-ma king panels and the correlating committee of th e National Elecu·ical Code Committee on each public input a nd first revision that had been made to revise the 2017 Code. The report was published at www.nfpa .org/70. Following the close of the public comment period, the code-making panels met, acted on each comme nt, and created some second revisions, which were reported to the correlating comm ittee. NFPA published the National Electrical Code second draft report in April 2019, which recorded the actions of the code-making panels and the cor relating committee o n each public comment on the National Electrical Code Com mittee first d raft report. The National Electrical Code first draft report and the National Electrical Code secon d draft report were presented to the 2019 June Association Technical Meeting for adoption. NFPA has a n Electrical Se ction that provides particular opportunity for NFPA members interested in elecu·ical safety to become better informed a nd to conu·i bute to the development of the National Electrical Code and other NFPA electrical standards. At the Electrical Section codes and standards review session held at the 2019 NFPA Conference and Expo, section members had t he opportunity to discuss and review the report of the National Electrical Code Committee prior to the adoption of this edition of the Code by the association at its 2019 June Tech nical Meeting. This 55th edition su persedes all other previous editions, supplemen ts, a nd printings dated 1897, 1899, 1901, 1903, 1904, 1905, 1907, 1909, 1911, 1913, 1915, 1918, 1920, 1923, 1925, 1926, 1928, 1930, 1931, 1933, 1935, 1937, 1940, 1942, 1943, 1947, 1949, 1951, 1953, 1954, 1955, 1956, 1957, 1958, 1959, 1962, 1965, 1968, 1971, 1975, 1978, 1981, 1984, 1987, 1990, 1993, 1996, 1999,2002, 2005,2008, 2011, 2014, and 2017. This Code is purely advisory as far as NFPA is concerned. It is made available for a wide variety of both public and private uses in the interest of life a nd property p rotection . These include both use in law a nd for regulatory purposes and use in private self~regulation and standa rdization activities suc h as insurance underwriting, building and facilities construction and management, a nd produ ct testing and ce rtification .

NFPA 70, National Elecu;cal Code, NFPA and National Fire Protection Association are registered trademarks of the National Fire Protection Association, Quincy, Massachusetts 02169.

NATIONAL ELECTRICAL CODE

Contents 90

I ntrod uctio n .... ..... .......... ..... .....

... ..... ..... ........ 70--

29

Chapter 1 General 100 Part I. Part II. Part III.

no Part I. Part II. Part III. Part IV. Part V.

De finitio ns.. ..... .......... .......... ............... ..... ..... ........ General . ..... ..... ..... .......... ..... ..... ..... ..... .......... ..... .... Over 1000 Volts, Nominal ............. ....................... H azardous (Classified) Locations (CMP-14) . ... Requireme n ts for Electrical I nscallations ....... .... General . ..... ..... ..... .......... ..... ..... .... ..... .......... ..... .... 1000 Volts, Nominal, or Less ..... ............... .......... Over 1000 Volts, Nominal ........ ......... .......... .. Tunnel Installations over 1000 Volts, Nominal . Manholes and Other Electrical Enclosures Intended for Personnel Entry... ........... ......

70-70-70-70-70-70-70-70-70--

32 32 41 42 46 46 50 52 55

70--

56

Chapter 2 Wiring and Protection Use and Ide n tification of Grounded Conductors ...... .. 210 Bra nch Circuits Part I. General Provisions Part II. Bra nch-Circuit Rati ngs Part III. Required Outlets .. 215 Feeders ... Bra nch-Circuit, Feeder, and Service Load 220 Calculations ... ..... .......... ................ . Part I. General ...... .............................. .......... ............... ... . Part II. Branch-Circui t Load Calculations .. ..... .......... ..... . Part III. Feeder and Service Load Calculations .... ..... ..... . Part IV. Optional Feeder and Service Load Calculations .......... ..... .......... .......... ..... .......... ....... . Part V. Fa rm Load Calculations ........... ..... .......... ............. 225 Omside Branch Circuits and Feeders .......... ..... .. Part I. General ...... ......................... ..... .......... ............... ... . Part II. Buildings or Olher Strucmres Supplied by a Feeder(s) or Branch Circuit(s) ......... ..... ............. Pan III. Over 1000 Volts. . ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... 230 Services .... ...... ..... ..... ..... ..... .......... ..... ..... .......... ..... Pan I. General . ..... ..... ..... .......... ..... ..... ..... ..... .......... ..... .... Part II. O verhead Service Conductors Part III. Underground Se,vice Conducwrs .... .................. Part IV. Service-En trance Conducwrs ...... Part V. Service Equipment - General Part VI. Service Equipment - Disconnecting Means..... Part VII . Se,vice Equipment - Overcurrent Protection .. Part VII I. Se,v ices Exceeding 1000 Volts, Nominal ............ 240 Overcurrent Protection .. .......... ............... ............ Part I. General . ..... ..... ..... .......... ..... ..... ..... ..... .......... ..... .... Part II. Location ........ ......................... ............... .......... ..... . Part III. Enclosures .............. .......... ............... ............... ..... . Part IV. DisconneCling and G u arding .............................. Part V. Plug Fuses, Fuseholders, a nd AdapLers .......... ... . Part VI. Canridge Fuses and Fuse holders ...... .......... .... . Part VII. C ircui t Breakers Part VII I. Supervised Industrial Installatio ns ............ ......... Part IX. O vercurrent Protection over 1000 Volts, Nominal .... ..... ............... ....... . 242 O vervoltage Protection ... ..... Part I. General. ..... ........ ... .............. . Part II. Surge-Protective Devices (SPDs), 1000 Volts o r Less.. ....... .............. . Part III. Surge Arresters, Over l 000 Volts .. 250 Grounding and Bonding .... ............ . Part I. General. ..... ..... ..... ..... ..... .............. . Part II. System Grounding ................ ........., ............... ..... .

Part Ill.

Grounding Electrode System a nd Grounding Electrode Conductor ..................... . .... ..... ........... Part IV. Enclosure, Raceway, and Service Cable Connections ................. .... ..... ............... Part V. Bonding ... ..................... .................. .. Part VI. Equipment Grounding a nd Equipment Grounding Conductors .... ....... Part VII. Methods of Equipment Grounding Conductor Connections ....... ............... Part VII I. Direct-Current Systems ...... ................ Pan IX. Instruments, Meters, and Relays ... ............ ..... ... . Part X. Grounding of Systems and Circuits of over IOOO Volts ......... .

300

70-2

58 60 60 65 68 71

70-70-70-70--

73 73 74 76

70-70-70-70--

79 81 82 82

70-70-70-70-70-70-7070707070707070707070707070-

85 86 88 88 89 90 91 93 93 95 96 97 97 101 104 104 104 104 105 107

Pan I. Pan II.

310 Pan I. Part II. Part III.

3ll Part I. Part II. Part II I. Part IV.

312

70- 108 70- 109 70- 109 70- 109 70- 110 70- 111 70- 111 70- 113

70- 125 70- 125 70- 129 70- 133 70- 135 70-- 136 70- 137

Chapter 3 Wiring Methods and Materials

200

70-70-70-70-70-70--

70- 120

Part I. Part II.

314

Part I. Part II. Part III. Part IV.

320 Part I. Part II. Part III.

322 Part I. Pan II. Pan III.

324 Pan I. Pan II. Part III.

326 Part I. Part II. Part III.

330 Part I. Part II. Part II I.

332 Part I. Part II.

Genera l Requ irements fo r Wiring Metl10ds and Materials . .... ............... ..... ............. ..... .. Gen era l Requirements ...... .......... . ..... ........ ..... Requirements for over 1000 Volts, Nom ina l .... Conductors fo r General Wiring .... General .... ..... ................. ....... .................... Construction Specifications lnscallation .. ..... ............... ..... .......... ..... ......... ...... ... Med ium Voltage Conducwrs and Cable ...... ...... General .... ..... ..... ..... ........ ...................... ..... ....... ... . Construction Specifications ..... ........... ..... ..... ...... lnscallation .. ............... Ampacities ...... ..... ........ ............ . Cabinets, Cutout Boxes, and Meter Socket Enclosures .. .... ............. Scope and lnscallation .. ............ ................. Construction Specifications O utlet, Device, Pull, and junction Boxes; Conduit Bodies; Fi ttings; and H andho le Enclosures ....... ..... .. Scope and General ......... ..... . Inscallation .. .... ............... ..... Construction Specifications ....... Pull a nd J unction Boxes, Conduit Bodies, and Hand hole Enclosures fo r Use o n System s over 1000 Volts, Nominal . ................................... ......... Armo red Cable: Type AC .... .......... ..... ............... ... General ......... ..... ...... ....... ....... .................... ....... ... . lnscallation .. ..... ............... ..... ..... ..... ....... ............. ... Construction Specifications ................ ..... ..... ...... Flat Cable Assemblies: Type FC ......................... .. General .... .......... ..... ........ ............................ ......... . lnscallation .. .................... ..... .......... ....... ................ Construction Specifications .......................... ..... . Flat Conducwr Cable: Type FCC ............... ..... General .............. ..... ................... ...... ........... ..... . I nscallation .. .. ... ....... ...... Construction Specifications ..... ..... Integrated Gas Spacer Cable: Type IGS Genera l .... .............. ................... ........... Inscallation .. Construction Specifications ..... .. Metal-Clad Cable: Type MC .... ........................... . General.... ... ........ ........... . lnscallation .. ............... Con stru ctio n Specificatio ns ..... ...... Mineral-Insulated, Mecal-Sh eath ed Cable : Type Ml ............. ........... ...................... ....... ...... . Genera l ............. ............... lnscallation ....... ...............

NATIONAL ELECTRJCAL CODE

707070707070707070707070-

140 140 149 151 151 151 156 165 165 165 167 168

70- 179 70- 179 70- 182

70707070-

182 182 183 189

70707070-70--

189 190 190 190 191 191 191 192 192 192 192 193 194 194 194 194 195 19.5 19.5 19.5 197

70-70-7070-70-70-70-707070707070707070-

70- 197 70- 197 70- 197

2020 Edition

CONTENTS

Part III.

334 Part I. Part II. Part III.

336 Part I. Part II. Part III.

337 Part I. Part II. Part III.

338 Part I. Part II. Part III. 340 Part I. Part II. Part III. 342 Part I. Part II. Part III. 344 Part I. Part II. Part III. 348 Part I. Part II.

350 Part I. Part II. Part III.

352 Part I. Part II. Part III.

353 Part I. Part II. Part III.

354 Part I. Part II. Part III.

355 Part I. Part II. Part III.

356 Part I. Part II. Part III.

358 Part I. Part II. Part III.

2020 Edition

Construction Specifications ................. . Nonmetallic-Sheathed Cable: Types NM and NMC .... . General ...... .... ..... .......... ..... ......... ..... ..... .... Installation ................ . ..... ..... ..... Construction Specifications........ ..... ..... Power and Control Tray Cable : Type T C . General . ..... ..... ..... ..... .... Insta llation .............. .......... ........... Construction Specifications ... .......... ..... Type P Cable ......... .......... ..... ......... Gene ral . ..... ..... ..... ..... .... ..... ..... ..... ..... ..... Installatio n .... .......... ... ........... ............... ...... Construction Specifications Service-Entrance Cable: Types SE and USE .. .. General . .......... ..... ..... Installation ......... ..... ..... Construction Specifications Underground Feeder and Branch-Circuit Cable: Type UF ............. .... .......... .... . General ...... .... .......... .... . .... Installation Construction Specifications ....... . Inte rmediate Metal Conduit: Type IMC ............ . General . .... ..... ..... ... . Installation .............. .............. ..... ............... . Construction Specifications ........ .......... Rig id Metal Conduit: Type RMC ........ ......... ...... . General .......................... ......................... ..... ........ . Installation ......... ............... ..... .......... .......... ..... ...... Construction Specifications ....................... ......... Flexible M.etal Conduit: Type FMC ................ ..... General . ..... ..... ..... ..... .... ..... ..... ... ... .... Installation .... ............... Liquidtig ht Flexible Metal Conduit: Type LFM C ... .................... .... .................... General .... .......... ..... Installation Construction Specifications Rigid Po lyvinyl Chloride Conduit: Type PVC ..... General...... ........................ .... Installation .... ..... ..... ..... Construction Specifications........ ......... .......... .... High De nsity Polyeth ylene Conduit: Type HOPE Conduit..... Gen e ral ..................... .... .......... ..... .... Installatio n ................................... Construction Specifications Nonmetallic Unde rground Conduit wid1 Conducto rs: Type N UCC . ................. Gen eral . .................. ............... ............... . Installatio n Con structio n Specificatio ns Reinforced T h ermosetting Resin Conduit: Type RTRC......... ........................ . General ................................... .... . Installation Constructio n Specifications Liquidtig ht Flex ible Nonmetallic Condui t: Type LFNC ........ . General. Installation Constructio n Specifications ................. . Electrical Metallic Tub ing: Type EMT ............... . General ................................................................ . Installatio n ......... ............... ............... .......... ........... Construction Specificatio ns ........ .................... ....

NATIONAL ELECTRJCAL CODE

70- 198 70707070707070707070707070707070-

198 198 I98 200 200 200 200 201 202 202 202 202 202 202 203 203

707070707070707070707070707070-

204 204 204 204 204 204 204 206 206 206 206 207 207 207 208

7070707070707070-

209 209 209 2 10 2 10 2 10 2 10 2 I2

70707070-

212 212 213 213

70707070-

213 213 214 214

70707070-

215 2 15 2 15 2 16

7070707070707070-

2 17 2 17 2 17 218 218 218 218 219

360 Part I. Part II. Part II I.

362 Part I. Part II. Part II I.

366 Part I. Part II. Part II I.

368 Part I. Part II. Part II I. Part IV.

370 Part I. Part II. Part II I.

372 Part I. Part II.

374 Pan !. Part!!. Pan III.

376 Part I. Part II. Part II I.

378 Part I. Part II. Part II I.

380 Part I. Part II.

382 Part I. Part II. Part II I. 384 Part I. Part II. Part II I.

386 Part I. Part II. Part II I.

388 Part I. Part! !. Part II I.

390 Pan !. Part!!.

392 Pan !. Part!!. Pan II I.

393 Part I. Part II.

Flexible Metallic Tubing: Type FMT ... ..... . Genera l .... . Installation ........... . ......... ... Construction Specifications .... ....... Electrical Nonmetallic Tubing: Type ENT ..... .. General.... . .... ..... ..... ............... . Installation ................. ..... ..... ..... .................... . Construction Specifications .... ....... ......... .......... . Aux iliary Gutters ......... .... ..... ..... ............... . General... ... ......................... ..... . Installation .... ............. ..... .......... .................... ..... .. . Construction Specifications .... ...... .......... .......... . Busways ........... .... .......... .................... ..... ............. . General Requirem e nts ...... ......................... ........ Installation Construction .. ...... .................... Require ments for Over 1000 Volts, Nominal Cablebus .... ............................ Genera l Installation . .... ... Construction Specifications ............... ..... .......... . Cellu lar Concrete Floor Raceways ........... . General.... . ... ..... .......... .... ..... ..... ............... . Installations. ..... .... ..... .......... .................... ............ Cellu lar Metal Floor Raceways... ............... .......... General .... ..... ..... ..... .......... ..... ..... ..... ..... ..... ..... ..... . Installation ............ .......... .......... .................... ........ Construction Specifications ...... ..... .......... ........... Metal Wireways .... .............................. ..... ......... ..... General .... .............................. ............... ............... . Installation ............ .......... ..... ...... ................... ........ Construction Specifications ........... .......... ........... Nonmetallic Wireways ..................... General .... ..... ......... Installation Construction Specifications .................... .......... . Multioutlet Assembly ........................... Genera l Installation ........... . .... ... Nonmetallic Extensions Genera l .... . ... ..... ......... . Installation.... ........ ... ..... .......... Construction Specifications (Concealable Nonmetallic Extensions Only) ...... .... ............ Strut-Type Channel Raceway ... ..... .................... ... General.... . ......... ..... .......... Installation .... ....... ...... ..... ..... ..... .................... . Construction Specifications .................... .......... . Surface Metal Raceways ...... ... .................... ... General... .... ............... .......... ......... ............... . Installation .... ....... ...... ..... ..... ..... .................... ..... .. . Construction Specifications ........... Surface Nonmetallic Raceways ......... ..... ............. Gen era l .................. . ..... ....... ....... . Installation ...... ........... .......... ..... ............... ..... ..... .. . Construction Specifications ..... ...... .......... ........... Underfloor Raceways... ..... ..... .................... ..... ..... General .... ..... ..... .. ... ..... ............... ..... ..... ........ .. ...... Installation ................. ................................... ..... ... Cable Trays ....................... ............ ........................ Gen eral ......... ............... ..... ..... ..... ..... ..... ............... . Installation ...................... .......... ........ ................. ... Construction Specifications ...... .......... ..... . Low-Voltage Su spended Ceiling Power Distributio n Systems ........ ... ..... .......... ........ Gen eral .... ..... ..... ..... ..... .......... ..... ..... ..... .......... ..... . Installation .................................................... ..... ...

707070707070707070707070707070707070707070707070707070707070707070707070707070707070-

219 219 220 220 220 220 221 222 222 222 222 223 224 224 224 225 225 226 226 226 227 227 227 227 228 228 228 229 229 229 229 230 230 230 230 23 1 23 1 231 23 1 232 232 232

7070707070707070707070707070707070707070-

233 233 233 233 234 234 234 234 235 235 235 235 236 236 236 236 237 237 237 243

70- 244 70- 244 70- 244

70-3

NATIONAL ELECTRICAL CODE

Part 394 Part Part Part 396 Part Part 398 Part Part Part 399

III. I. II. III. I. II. I. II. III.

Construction Specifications ... ..... ..... .... . Concealed Knob-and-Tube Wiring ............. ....... Gene ral .......... . Installation .... ..... .......... ............... ......... ............... . Construction Specifications ... .......... ..... .......... .... Messenger-Supported Wiring .. ............... Ge ne ral ...... ..... ..... Installation ..... ... ............... .......... ......... ............... . Open Wiring on Insu lators ......... ..... ..... .......... ... Gene ral ...... ..... Installation ......... ............... .................... .. Construction Specifications ... . Oll[door O verhead Conductors over IOOO Volts ... .............. ........ .

707070707070707070707070-

245 246 246 246 246 247 247 247 247 247 248 249

Part I. Part II. Part III.

402 404 Part I. Part II.

406 408 Part Part Part Part

I. II. III. IV.

409 Part I. Part II. Part III.

410 Part I. Part II. Part III.

Flexible Cords and Flex ible Cables ............... ...... General ........ . Construction Specifications Portable Cables Over 600 Volts, Nominal Fixture Wires .. .... . Switches ... .... . Installation Construction Specifications ... ..................... . Receptacles, Cord Co nnectors, and Attachment Plugs (Caps) ..... ............... ......... .......... ..... ....... Switchboards, Switchgear, and Panelboards . Ge ne ral . ..... ..... ..... .... ..... ..... ..... ..... Switchboards and Switchgear ..... .......... .......... Panel boards ... ..... ...... .... .......... .... ..... ..... ..... ..... ..... Construction Specifications ... ..... ..... ..... .......... .. Industrial Control Panels ..... .......... ............... ...... General . ..... ..... .... .... ..... ..... ..... ..... ..... ..... .... Installation .............. .......... .................... .......... . Co nstructio n Specifications .... ... .................... .. Luminaires, Lampho lders, and Lamps .......... General ...... ....... . L uminaire Locations .....................

Provisions at Luminaire Outlet Boxes, Canopies, and Pa ns .... Part IV. Lumina ire Supports ..... ............... ......... ......... . Part V. Groundin g . ........ ..... ..... ............... ..... . ... .............. . Part VI. Wiring of Luminaires .. ......... ..... .......... Part VII. Constructio n of Luminaires ... ..... ............... ........ . Part VII I. Installation of Lampholders ...... ..................... . Part IX. Lamps and Auxiliary Equipment ......... . Part X. Special Provisions for Flus h and Recessed L u.n1inaires .......... ..... .......... .... .............. .

Part XI.

L u.minaires .......... ..... .......... .... .............. .

7070707070707070-

250 250 259 260 260 263 263 266

70707070707070707070707070-

266 27 1 271 273 273 274 275 275 275 276 277 277 278

70707070707070-

279 279 280 280 282 282 282

Part I. Part II. Part III. Part IV. Part V. Part VI. Part VII.

426 Part I. Part II. Part Il l. Part IV. Part V. Part VI.

427 Part I. Part II. Part Ill. PartlV. PartV. Part VI. Part VII.

430 Part I. Part II. Part Ill. Part IV. Part V.

70- 282 70- 283

Part XI I.

70-4

Part X.

70- 249

Construction of Fl ush and Recessed

Special Provisions for Electric-Discharge Lighting Systems of 1000 Volts or Less ...... . Part XI II. Special Provisions for Electric-Discharge Lighting Systems of More T han 1000 Volts ... Part X IV. Lighting Track ... ................... . Part XV. Decorative Lighting and Similar Accessories. Part XVI. Special Provisions for H orticu ltural Lighting Equipment...... .................... . 411 Low-Voltage Lighting ..... . 422 Appliances Part I. General ............... . Part II. Installation .... . Part III. Disconnecting Means .............. . Part IV. Construction .... ..... ..... ..... .......... . Part V. Marking ........ .... ..... .......... ..... 424 Fixed Electric Space-Heating Equipment Part I. General ........... .... .

Part IV. Part V. Part VI. Part VII. Part VIII. Part IX.

425

Chapter 4 Equipment for General Use 400

Part II. Part Ill.

70- 283 70- 284 70- 285 70- 285 70707070707070707070-

285 286 286 286 287 289 290 29 1 291 291

Part VI. Part VII. Part VII I. Part IX. Part X. Part XI. Part XII. Part XIII. Part XIV.

440 Part I. Part II. Part Ill. Part IV. Part V. Part VI. Part VII.

Installation .. ..... .......... Control and Protection of Fixed Electric SpaceHeating Equipment . ..... ............ . Marking of Heating Equipment ... ..... ............... .. Electric Space-Heating Cables .. ............... . Duct Heaters ......... ................. ........ ..... . Resistance-Type Boilers ... ... ..... ..... ..... ............... .. Electrode-Type Boilers ..................... . Electric Radiant H eating Panels and Heating Panel Sets .... ..... .......... ........ ..... .......... Low-Voltage Fixed Electric Space-Heating Equipment .... .......... ... ....... Fixed Resistance and Electrode Industrial Process Heating Equipment .... .............. General.. ..... .................. ..... . Installation .. ................... ..... ..... ..... ............... Control and Protection of Fixed Industrial Process Heating Equipment .... ........ . Marking of Heating Equipme nt ... ................ . Fixed Industrial Process Duct H eaters Fixed Industrial Process Resistance-Type Boilers ....... .......... ... ........... ..... ..... ..... ............... .. Fixed Industrial Process Electrode-Type Boilers Fixed Outdoor Electric Deic ing and SnowMe lting Equipment ..... ......... ... ....... General .... ......... ..... ......................... ......... .......... . Installation .. ..... ........ .. Resistance Heating Elements ... ............... .......... . Impedance H eating ..... ............. ..... . Skin-Effect Heating ...... ..... ..... ..... ..... ............... .. Control and Protection ............ ..... Fixed Electric Heating Equipment for Pipelin es and Vessels .... .......... ....... ..... General .... ... In stallation .. Resistance Heating Ele ments ........ ........... . Impedance H eating .............. .................... Induction Heating ....... .......... .......... .... ............... Skin-Effect Heating ...... ..... .... ............... . Conu·ol and Protection ..... Motors, Motor C ircuits, and Contro llers .......... Gene ral.... .... ..... ......... ...... .... ..... . ......... .......... . Motor Circuit Conductors ...... .... ..... ............... .. Motor and Branch-Circuit O verload Protection Motor Branch-Circuit Short-Circuit and Ground-Fault Protection ......... .. Motor Feeder Short-Circuit and Ground-Fault Protection ... ... ....... ........... ..... ..... ..... ............... .. Motor Control Ci rcuits ............................. ... MolOr Controlle rs .. ...... ............. , ............... . MolOr Control Centers ............................. .. Disconnecting Means ........ ....... ... . ............. ....... Adjustable-Speed Drive Systems .............. ....... .. .. Over 1000 Volts, Nomina l. ....... ... . Protection of Live Parts - All Voltages... Grounding - All Voltages. ................. Tables .... ... ............... Air-Co nditioning and Refrigerating Equipme nt General .... .... ..... ..... ... ....... .......... D isconnecting Means ......... ...... ... ............... Branch-Circuit Short-Circuit and Ground-Fault Protection ....... ......... ..... . ... ..... ..... ..... ............... .. Branc h-Circuit Conductors .. .... .... ............... .... .. Controllers for Motor-Compressors ..... ...... ......... Motor-Compressor and Branch-Circuit O verload Protection ...... ..... Provisions for Room Air Conditioners .. ....... ......

NAT IONAL ELECTRJCAL CODE

70- 29 1 707070707070-

292 293 293 29.5 295 296

70- 297 70- 298 70- 299 70- 299 70- 299 70- 299 70- 30 1 70- 30 1 70- 30 1 70- 302 70707070707070-

303 303 303 303 304 304 305

707070707070707070707070-

305 305 306 306 306 307 307 307 308 308 313 315

70- 318 7070707070707070-

7070707070-

321 321 323 324 325 327 329 330 330 330 335 33.5 336

70- 337 70- 338 70- 339 70- 339 70- 340

2020 Edition

CONTENTS

445

450 Part I. Part II. Part III.

455 Part I. Part II. 460 Part I. Part II.

470 Part I. Part II.

480 490 Part I. Part II. Part III. Part IV. Part \I.

Generators ..... .......... .... . T ransformers and Tra nsforme r Vaults (Includi ng Secondary Ties)....... .... ..... ......... . General Provisions .......... . ... .......... ..... .... ..... ....... Specific Provisions Applicable to Diffe rent Types of Transformers . ..... ..... ..... .... ..... ......... . T ransformer Vaul ts ..... ..... ..... ..... ..... ..... ......... . Phase Converters General ............................... ............... .... .......... ... . Specific Provisions Applicable to Diffe rent Types of Phase Converters ..... ..... ..... ..... ..... Capacitors . ..... ..... ..... ... .... ..... ..... ..... .......... ... 1000 Volts, Nominal, and Under ... .......... .... Over 1000 Volts, Nominal .... ............... Resistors and Reactors 1000 Volts, Nominal, a nd Under .... ..... ..... ...... Over 1000 Volts, Nom inal Storage Batteries ..... .......... Equipment Over I 000 Vol ts, Nominal ....... .... .... General . ..... .... .................... Equipment - Sp ecific Provisions ... .... . Equipment - Switchgear and Industrial Control Assemblies ................. . Mobile and Portable Equipme nt ... .......... ..... ..... . Electrode-Type Boilers .... ....................

70- 340

Part VI.

70- 342 70- 342

Part VII.

70- 346 70- 348 70- 349

70- 349 70- 350 70- 350

70- 350 7070707070707070-

3.51 3.5 2 3.5 2 352 352 355 355 355

70- 357 70- 359 70- 360

Chapter 5 Special Occupancies 500 501 Part I. Part II. Part III.

502 Part I. Part II. Part III.

503 Part I. Part II. Part III.

504 505 506 510 511

513 514 515 516

Part Part Part Part

I. II. III. IV.

Part V.

517 Part I. Part II. Part III. Part IV. Part \I.

2020 Edition

H azardous (Classified) Locations, Classes I, II, and III, Divisions l a nd 2 ... .......... .... ..... ............. . Class I Locations ... .................... . Gene ral ...... .... .......... ..... Wiring ... ................................... ............... ..... ..... .... Equi pment .................. ......... ..... ........ . Class II Locations ............. ........ ............... Gen eral ................ ........ .... .......... Wiring... .. ............ .... ........ .............. . Equipment .. .......... ...... ... ...... ........ Class III Locations ................ ........................ ...... . Gen eral.... ....... ..... .......... Wi ring ............................. ... ..... ............... Equi pment . ................. Intri nsically Safe Systems ............... . Zone 0, 1, and 2 Locations .. Zone 20, 21, and 22 Locations fo r Combustible Dusts o r Ignitible Fibers/ Flyi ngs ......... ............... . Hazardous (Classifi ed) Locations - Specific ... . Commercial Garages, Repair an d Storage ......... Ai rcraft Ha ngars .. ............... ............... .......... ........ . Moto r Fuel Dispensi ng Facili ties ...... .......... ........ . Bu lk Storage Pla n ts .......... ............... ........... . Spray Applicatio n, Di ppi ng, Coating, and Printing Processes Using Flammable o r Combustible Materials .................. ..... ............... General ................ .... ........... .............. Open Containers............ ......... ......... . Spray Application Processes Spray Application Operations in Membrane Enclosures .... ..... ..... ..... ................... . Printing, Dippin g, and Coating Processes ......... H ealth Care Facilit ies General . ..... Wiring and Protection Essential Electrical System (EES) Inhalation Anesthetizing Locations ... ......... ....... X-Ray Installatio ns ... ........................

NATIONAL ELECTRJCAL CODE

70- 361 70- 368 70- 368

70- 368 70- 373

70- 377 70- 377 70- 378

70- 380

70- 383 70- 383

518 520

Part I. Part II. Part II I. Part IV. Part V. Part VI. Part VII.

522 Part I. Part II. Part II I.

525 Part Part Part Part

I. II. II I. IV.

530 Part I. Part II. Part II I. Part IV. Part\/. Part VI. 540 Part I. Part II.

70- 383 70- 384 70- 386 70- 388

Part III. Part IV. 545

70- 402 408 409

7070707070-

411 414 420

70- 423 70- 423 70- 424 70- 424 7070707070707070-

431 432 434 434 437 440 447 449

Part !. Part II. 547

550 Part I. Part II. Part III.

551 Part I. Part II. Part II I. Part IV. Part \I. Part VI.

552 Part I. Part II. Part II I. Part IV. Part \I.

Communications, Signali ng Systems, Data Systems, Fire Alarm Systems, and Systems Less Than 120 Volts, Nomi nal ........ ... ........ ...... Isolated Power Systems .... .......... ....... .... ............. . Assembly Occupancies ......... .......... T h eaters, Audience Areas of Motion Picture and Television Stud ios, Performance Areas, and Similar Locations ... .... ..... .............. . General.... . .... ..... ..... ............... . Fixed Stage Switch boa rds ..... .... ..... ..... .......... Fixed Stage Equipment Other T han Switch boards ........... .. ........ ..... . Portable Switchboards on Stage .. Portable Stage Equipment Other Than Switchboards ............. .............. ..... ....... . Dressing Rooms, D ressing Areas, and Makeup Areas. ... ............... .... .............. . Equ ip me nt Ground ing Conductor Control Systems for Permanent Amusement Attractions ........ ..... Genera l .... . ... ............... Control Circuits .. . ... .......... ......... Control Circuit Wiring Methods ... ......... ............ Carniva1s, Circuses, Fairs, and Sim ilar Events ... . General Requireme nts ...... .............. . Power Sources .. .... ..... .......... .................... . Wi ring Methods ..... .......... ............... ......... .......... . Equ ipment Grounding and Bonding . ............... . Motio n Pic ture and Television Studios and Similar Locations General............. ......................... .... ............ ~~ITT~ ··· ··············· ···-····· ········· ··········- ····· · Dressing Rooms ...... .......... ........... Viewing, Cutting, and Patching Tables .. ............. Cellu lose Nitrate Film Sto rage Vaul ts ............... .. Substations ... .... .............................. ..... . Motio n Picture Projection Rooms ............ ..... .. General .... ..... .... .. ....... ...... .......... .......... .............. . Equ ipment and Projectors of the Professional

~~ ························ ·········· ···················· ··········· ··· Nonprofess ional Projector s ........... ............ ......... . Audio Signal Processi ng, Amplification, and Reproduction Equipment .............................. ..... Manufactured Build ings a nd Re locatable Structures .......... ............... ............... ........... .......... General .... ..... .............................. .......... .......... ..... . Relocatable Structu res .......... ...... .............. ..... ..... Agricu ltural Build in gs ....... ................... Mob ile Homes, Manufactured Homes, and Mob ile Home Parks .................. ..... ...... General .... ..... .... ............... ..... .... ..... ..... ............... . Mobile and Manufactured H om es .. Services and Feeders ........ Recreatio nal Veh icles and Recreational Ve hicle Parks ......... .... .............................. Genera l Combination Electr ical Systems .. .... ............. Other Power Sources .. .... ....... ....... . Nominal 120-Volt o r 120/ 240-Vol t Systems .. ...... Factory Tests ............... ...... ... .............. Recreational Vehicle Pa rks . .... .............. Park Traile rs ....... . General .... . Low-Voltage Systems .... .... ...... ...... ...................... Combination Electrical Systems .. .... ............. Nominal 120-Volt or 120/ 240-Vol t Systems .. ...... Factory Tests ... .... ..... ..... ... .. .... .... ...... ....... .

70- 450 70- 451 70- 452

70- 453 70- 453 70- 454 70- 455 70- 457 70- 4.5 9 70- 460 70- 460 707070707070707070-

461 461 461 461 462 462 463 463 464

707070707070707070-

464 464 465 467 467 467 467 467 467

70- 467 70- 468 70- 468 70707070-

468 468 469 470

70707070-

472 472 473 479

70707070707070707070707070-

480 480 481 482 483 489 489 491 491 492 493 493 500

70-5

NATIONAL ELECTRICAL CODE

555

Part I. Part II. Part III. 590

Marinas, Boatyards, Floating Buildings, and Commercial and Noncommercial Docking Facilities ........ .. .... .............. . General .............. .. Marinas, Boatyards, and Docking Facilities ........ Floating Buildings ....... Temporary Installations .........

660

7070707070-

500 500 502 504 504

Chapter 6 Special Equipment 600 Part I. Part II. 604 605 610 Part I. Part II. Part III. Part IV. Part V. Part VI. Part VII. 620

Electric Signs and Outline Lighting ............ Ge neral ...... .......... .......... .......... .......... .......... ......... Field-Installed SkeleLOn Tubing, Outline Lighting, and Secondary Wiring ..... Manufactured Wiring Systems ....................... .. Office Furnishings ............................ ............... .. . Cranes and H oists .......... ..... ............................. .. Gene ral .............. .. Wiring ................................ Contact Conductors ...... ..

70707070707070D isconnecting Means ........................................ . 70O vercurrent Protection .. .. ...................... .. 70Control.................... .......... .. ................ .. 70Grounding and Bond ing ................................. .. 70-

Elevators, Dumbwaiters, Escalators, Moving Walks, Platform Lifts, and Stairway Chairlifts .... Part I. Ge neral .......... . Part II. Conductors ........... ........... ............... ......... .......... .. Part III. Wiring.................. .. ............ ........ .. Part IV. Installation of Conductors .................................. . Part V. Traveling Cables ....................................... . Part VI. Disconnecting Means and Control ...... . Part VII . Ove rcurre nt Protection .................................... .. Part VIII. Mac hine Rooms, Control Rooms, Machine ry Spaces, and Control Spaces ................. . Part IX. Grounding and Bond ing ................................... . Part X. Eme rge ncy and Standby Powe r Systems 625 Electric Vehicle Power Transfe r System Part I. Ge ne ral .............. .. ............ .. Part II. Equipment Construction ....................... Part III. Installation .................................... .. Part IV. Wire less Power Transfe r Equipment .. .. 626 Electrified Truck Parking Spaces ...................... . Part I. Ge ne ral................ .. ................ . Part II. Electrified Truck Parking Space Electrical Wiring Systems ............................ .......... ....... . Part Ill. Electrified Truck Parking Space Supply Equipme nt .......................................................... .. Part IV. Transport Re frigerated Units (TR Us) ........... ..... 630 Electric Welders ............................................... .. .. Pan I. General ...... ......................... .......... ....................... . Pan II. Arc Welders ..................................... ............... ..... . Part III. Res istance Welde rs ................ .. .................... . Part IV. ~ili~~~ ..... ...................... . 640 Audio Signal Processing, Amplification, and Reproduction Equipment ................ . Part I. General ......... Part II. Permanent Audio System Installations ............ .. Part III. Portable and Temporary Audio System Installations ........................... . 645 Information Tec hnology Equipment ................ .. 646 Modular Data Centers ........................ . Part I. Gene ral .............. .. Part II. Equipment .... .. Part III. Lighting ................ . Part IV. Workspace ................ ..... .... . 647 Sensitive Electronic Equipment ............. ........... .. 650 Pipe Organs .................. ........ ..

70-6

70- 508 70- 508

512 514 515 516 516 517 .519 520 520 52 1 52 1

7070707070707070-

52 1 52 1 523 525 527 528 528 530

70707070707070707070-

530 530 531 531 531 532 532 535 535 535

70- 536 70707070707070-

537 539 540 540 540 541 541

70- .542 70- 542 70- .544 707070707070707070-

545 546 549 549 552 552 553 553 554

Part I. Part II. Part II I. Part IV.

665 Part I. Part II.

668 669 670 675 Part I. Part II.

680 Part I. Part II. Part II I. Part IV. Part V. Part VI. Part VII. Part VIII.

X-Ray Equipment General .. .. Control .............. Transformers and Capacitors ... ............ ..... .. Guarding and Grounding.. .... ............ Induction and Dielectric Heating Equipment .. . Gen eral ................................................ Guarding, Gro unding, and Labeling ................ . Electrolytic Cells........ .. .......................... Electroplating .................. .. Industrial Machinery .......... .......... ............ Electrically Driven or Controlled Irrigation Machines ............ .......................... ................... General .. Center Pivot Irrigation Machines Swimming Pools, Fountains, and Sim ilar Installations ................ General .... Permanently Installed Pools .................. . Storable Pools, Storable Spas, Storable Hot Tubs, and Storable Immersion Pools Spas, Hot Tubs, and Permanently Installed Immersion Pools ...................... ............ . Fo unta.ins ........ ....... ................. ......... ...

Poo ls and Tubs for Therapeutic Use .................. Hydromassage Batl1tubs ... .. .............. Electrically Powered Pool Lifis .............. . 682 Natural and Artificially Made Bodies of Water .. Part I. General ................................ ..... ........................ .. Part II. Installation ................. . .......... .................. Part II I. Grounding and Bonding ................................ . .. Integrated Electrical Systems ...... ...... ...... .. 685 Part I. General.. .. ................ . Part II. Orderly Shutdown ... 690 Solar Photovoltaic ( PV) System s ..... Part I. General... .. ................ . Part II. Circuit Requirements .......................... Part II I. Disconnecting Means .............. .............. Part IV. Wiring Me tl10ds and Materials .. ....... ................ .. Part V. Grounding and Bonding ................................. .. Part VI. Marking...................... ........ ................. Part VII. Connection to Other Sources ..................... Part VII I. Ene rgy Storage Systems .. . .. ................. 691 Large-Scale Photovoltaic ( PV) Electric Supply Stations .............................. .. ................ ...... 692 Fuel Cell Systems ...... ................ .. ..... .................. .. Part I. General .......................................... ........... .......... . Part II. Circuit Require m e nts .......... ..... .... ....... ..... Part II I. Disconnecting Mean s ...................................... . Part IV. Wiring Me tl1ods ..... Part V. Grounding .......... .. Part VI. Marking ................ .. Part VII. Connectio n to Other Circuits .. .. .... ..... ...... . 694 Wind Electric Systems ............................ Part I. General ... Part II. Circuit Requirements .......................... Part II I. Disconnecting Means ............................ Part IV. Wiring Me tl1ods ............................ Part V. Grounding and Bonding ...................... .... . Pan VI. ~iling ................ ........................ _ ..... ............. Pan VII. Connec tion Lo Other Sources ............................ . 695 Fire Pumps ......................... ...................................

7070707070707070707070-

555 55.5 556 556 557 557 557 558 558 560 561

70- 562 70- 562 70- .564

70- 564 70- 564 70- 567 70- 573 707070707070707070707070707070707070707070-

574 576 578 578 579 579 579 580 580 .58 1 58 1 .582 582 582 583 587 588 590 592 592 592

707070707070707070707070707070707070-

593 594 594 594 595 595 595 595 595 596 596

597 597 599 599 599 599 600

Chapter 7 Special Conditions 700 Part I. Part II.

Eme rgency Systems ......................................... . 70- 605 General .......................................... ........... .......... . 70- 605 Circuit Wiring .......... ..... .............................. 70- 607

NAT IONAL ELECTRJCAL CODE

202 0 Edition

CONTENTS

Part III. Part IV. Part \I. Part VI. 701 Part I. Part II. Part III. Part IV. 702 Part I. Part II. 705 Part I. Part II. 706 Part I. Part II. Part III. Part IV. Part \I. Part VI. 708 Part I. Part II. Part III. Part IV. Part \I. 710 712 Part I. Part II. Part III. Part IV. Part \I. Part VI. Part VII. 720

725 Part I. Part II. Part III. Part IV. 727 728 750 760 Part I. Part II. Part III. Part IV. 770 Part I. Part II. Pan III. Pan !\/. Pan \I. Pan VI.

Sources of Power ..... ..... .... .......... ..... Emergency System Circuits for Lighting and Power ... .......... ..... .......... ..... .... ..... .......... ..... Control - Emerge ncy Lighting Circuits .... . Overcurrent Protection....... .......... ..... Legally Required Standby Systems .............. ....... General . ................................................ ..... ..... .... Circuit Wiring............ .......... .... ..... ..... .......... . Sources of Powe r ..... ..... .................... ............... ..... Overcurrent Protection ... ....................... ... .. Optional Standby Systems .......... ..... ..... .......... ..... General . ..... ..... ..... ..... .... ..... ..... .......... ..... Wiring ... ..... ..... ..... ..... ....... .. ..... .......... Interconnected Electric Power Production Sources ... ..... ..... ..... ... .... ..... ..... ... .. ..... ..... .. General........... .......... .............. ............... Microgrid Systems .. .. ............... . Energy Storage Systems .... ......... ..... ..... ..... ..... .. General ........... .......... Disconnecting Means ..... Installation Requirements .... Circuit Requirements ........ .......... Flow Battery Ene rgy Storage Systems .......... . Othe r En e rgy Storage Technologies ..... .............. Critical Operations Power Systems (CO PS) General . .... ..... .......... ..... ..... ..... .......... .... ..... ..... .... Circu it Wiring and Equipment ... ..... .......... .. Power Sources and Connection ..... ..... ................ Overcurrent Protection ....... .................... ..... ....... System Performance and Analysis .................... ... Stand-Alone Syst ems ............ .................... ..... ..... .. Direct Curre nt Microgrids .... .......... .......... ........... General . ..... ..... ..... ..... .... ..... ..... ... ... .... Circuit Requirements Disconnecting Means Wiring Methods . Marking ... .............. ...... Protection Systems over l000 Volts Circuits and Equipment Ope rating at Less T han 50\lolts ... ........ ................... .......... Class I, Class 2, a nd Class 3 Remote-Control, Signaling, and Power-Limited Circuits Gene ral . .... .................... .... .......... ... . Class I Circuits .......... .................... ....................... Class 2 and Class 3 Circu its ....................... .... . Listing Requ ire me nts ..... .................... Instrumentation Tray Cable: Type IT C .. ..... .... Fire-Resistive Cable Systems ............................... . Ene rgy Managem ent Systems ..... ...., ............... ... Fire Alarm Systems ..................... . Gen eral .................... ..... ................. . Non-Power-Lim ited Fire Alarm (NPLFA) Circ uits ..... .... ............. Power-Limited Fire Alarm (PLFA) Circuits . Listing Requirements Optical Fiber Cables General ..... . Cables Outside and Ente ring Buildings ............ Protection ............................................... ............ . Grounding Methods ............................. ............... Installation Methods Within Buildings .............. . Listing Requiremen ts ............... .........................

70- 608 7070707070707070707070-

6 10 6 10 6 11 6 12 612 613 613 614 615 615 616

70707070707070707070707070707070707070707070707070-

6 16 6 16 620 621 621 621 622 623 624 624 624 624 625 627 628 629 629 630 630 630 631 631 631 631 631

2020 Edition

70707070707070707070-

632 632 633 635 642 644 645 645 646 646

70707070707070707070-

647 649 652 656 656 656 657 657 659 661

General Requirements for Communications Systems .. .... ..... ..... ..... ..... .... ..... ..... ..... .... 70- 664

NATIONAL ELECTRJCAL CODE

Part III. Part IV. Part \I. 805 Part I. Part II. Part III. Part IV. Part \I. 810 Part I. Part II. Part III. Part IV. 820 Part I. Part II. Part III. Part IV. Part \I. Part VI. 830 Part I. Part II. Part III. Part IV. Part \I. Part VI. 840 Part I. Part II. Part III. Part IV. Part \I. Part VI.

70- 631

Chapter 8 Communications Systems 800

Part I. Part II.

Part VII.

General .... . Wires and Cables Outside and Entering Bui ldings .. ..... ......... ...... ..... ..... .... ..... ........ .. ..... Grounding Methods .. ...... ... ............... ................ Installation Methods Within Buildings .... Listing Requirements..... ... ............... Communications Circuits ......... ............ General .... . ..... ..... .......... Wires and Cables Outside and Entering Buildings .. .. .. .............. Protection ... ........ ..... .... ......................... ..... Installation Methods Within Buildings ... Listing Requirements ............................ Radio and Te levision Equipment ..... ..... .......... .... General .... ....... ...... . Receiving Equipment - Antenna Systems ... .. Amateur and Citizen Band T ransmitting and Receiving Stations - Antenna Systems .... Inte rior I nstallation - Transmitting Stations .... Community Antenna Television and Radio Distribution Systems ........ ............ ..... .......... Gene ral.... . ... ..... .......... .... ..... ........ ....... . Coaxial Cables Outside and Entering Buildings Protection ... ........ ..... .................... . Grounding Methods .. .......... .................... . Installation Methods Within Buildings .... Listing Requirements ........ .................... Network-Powered Broadband Communications Systems ..... ..... ....... ....... .... ............... ..... . General .... ..... .... ............... ..... .... ..... ..... ............... . Cables Outside and Entering Buildings ........... Protection ........... .... ......... ..... .... Grounding Methods .. . .................. Installation Methods Within Buildings ......... ..... . Listing Requirements ......... ....... ....... ..... Premises-Powered Broadband Commun ications Systems ... .. ... .... ...... ..... ..... .... ..... .. ...... . General Cables Outside and Entering Buildings ........... Protection ..... ...... ..... .......... ..... ..... Ground ing Methods .. ...... ... ...... ......... .... ........... . Installation Methods Within Buildings .... .... . Premises Powe ring of Communications Equipment over Communications Cables .... . Listing Requirements ...... .. ...... ........ .

70- 664 707070707070-

665 666 668 675 675 675

70707070707070-

676 676 678 679 680 680 681

70- 683 70- 683 70707070707070-

684 684 684 684 685 685 686

70707070707070-

686 686 687 688 690 690 691

707070707070-

691 691 692 692 693 693

70- 693 70- 693

Chapter 9 Tables

2 4

5

5A

8 9

10 ll (A)

Percent of Cross Section of Conduit and Tubin g for Conductors and Cables ......... .......... .. Raditts of Conduit and Tubing Bends ....... ......... Dimensio ns and Percent Area of Conduit and Tubing (Areas of Co nduit or Tubing for the Combinations of Wires Pe rmitted in Table I , Chapter 9) ........... ......................... .......... ........ ...... Dimensions of Insulated Co nducto rs and Fixture Wires ..... ..... ..... ..... ..... ... .... ..... .......... Compact Copper and Aluminum Building Wire Nominal Dime nsions** and Areas ....... Conductor Prop erties ...... ... ....... ..... Alternating-Current Resistan ce and Reactan ce for 600-Volt Cables, 3-Phase, 60 H z, 75°C (167°F) - Three Single Conductors in Conduit .................. ...... ..... ..... ........... ................... . Conductor Su·anding ....... ............ ........... ....... ...... Class 2 and Class 3 Alte rnating-Current Power Source Limitatio n s ........... ................... ........... ......

70- 695 70- 695

70- 696 70- 700 70- 704 70- 705

70- 706 70- 707 70- 707

70-7

NATIONAL ELECTRICAL CODE

12(A )

PLFA Alternating-Current Power Source Limitations ..... .......... ..... ......... ..... ..... ..... ...... .

70- 709

Informative Annex A: Product Safety Standards .......... 70- 710 Informative Annex B: Application Information for Ampacity Calculation .... .... ..... ..... ............... ..... .... 70- 7 16 Informative Annex C: Cond uit, Tubing, and Cable Tray Fill Tables for Cond uctors and Fixture Wires of the Same Size .... ..... ..... ..... ... .. ..... ..... ..... ..... ..... ..... ..... ..... .. 70- 729 Informative Annex D: Examples .......... ..... ..... ............... 70- 815 Informative Annex E: Types of Construction ......

Informative Annex G: Supervisory Control and Data Acquisition (SCADA) ........ ..... ... ............... ..

70- 833

Informative Annex H: Administration and Enforcement ..... .......... ..... .......... .......... .............. .......... .. 70- 834 Informative Annex I: Recommended Tightening Torque Tables from U L Standard 486A-486B

70- 840

Informative Annex _}: ADA Standards for Accessible Design .... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... .. ... ... 70- 842

Index ... ..... .......... ..... ..... ..... ..... ..... .......... ..... .......... ..... ...... 70- 845

70- 829

Informative Annex F: Avai lability and Reliability for Critical Operations Power Systems; and Development and Implementation of Functional Performance Tests (FPTs) for Critical Operations Power Systems ..... .. 70- 831

70-8

NAT IO NAL ELECTRJCAL CODE

2020 Edition

COMMITTEE PERSONNEL

NATIONAL ELECTRICAL CODE COMMITTEE These lists represent the membership at the time the Committee was balloted on the final text of this edition. Since that time, changes in the membership may have occurred. A key to classifications is found at the back of this document. Correlating Committee on National Electrical Code® Michael J. J ohnston, Chair National Electrical Contractors Association, MD [IM] Mark W. Earley, Secretmy (Nonvoting) National Fire Protection Associatio n, l'vlA Sarah D. Caldwell, Technical Cornrniuee Administrator ( Nonvoting) National Fire Protec tion Association, MA James E. Brunssen, Telco rdia Technolog ies (Ericsson) , NJ [UT] Rep. Alliance for Telecommunication s Industry Solutions Kevin L. Dressman , U.S. Departmen t of Energy, MD [U] Palmer L. Hickman, Electrical Training Alliance, MD [L] Rep. Inte rnational Brotherhood of Electrical Workers David L. Hittinger, Independent Electrical Contractors of Greater Cincinnati, OH [IM] Rep. Independent Electrical Contractors, Inc.

Richard A Holub, The Du Pont Company, Inc., DE [U] Rep. Ame rican Chemistry Council John R. Kovacik, UL LLC, IL [RT] Alan Manch e, Schneide r Electric, KY [Ml Roger D. McDaniel, Georgia Power Company, GA [UT] Rep. Electric Lig ht & Powe r Group/ EEi David A. Williams, Delta Charter Town ship, MI [El Rep. Inte rnational Association of Electrical In spectors Alternates

Lawrence S. Ayer, Biz Com Electric, Inc., OH [IM] (Alt. to David L. 1-!ittinger) Roland E. Deike, Jr., CenterPoint Energy, Inc., TX [UT] (Alt. to Roger D. McDaniel) James T. Dollard, Jr. , IBEW Local Union 98, PA [L] (Alt. to Palmer L. H ickman) Ernest ]. Gallo, Telcordia Techno logies (Ericsson ), NJ [UT] (Alt. to.James E. Brunssen )

Rob ert A. McCullough , Tuckerton , NJ [E] (Alt. to David A. Williams) Robert D. Osborne, UL LLC, NC [RT] (Alt. to j o hn R. Kovacik) Christine T. Porter, lntertek Testi ng Services, WA [RT] (Votin g Alt.) George A. Straniero, AFC Cable System s, Inc., NJ [M] (Voting Alt.) Nonvoting

Timothy J. Pope, Canad ia n Standards Association, Canada [SE] Rep. CSA/ Canadian Electrical Code Committee William R. Drake, Fairfield, CA [M] (Membe r Emeritus)

D. Harold Ware, Libra Electric Company, OK [IM] (Member Emeritus)

Mark W. Earley, NFPA Staff Liaiso n

2020 Ed ition

NATIONAL ELECTRJCAL CODE

70-9

NATIONAL ELECTRICAL CODE

Code-Making Panel No. I Articles 90, 100, 110, Chapter 9, Table 10, Annex A, Annex H, Annex I, and Annex J Kenneth P. Boyce, Chair UL LLC, IL [RT] Louis A Barrios, Shell Global Solutions, TX [U] Rep. American Chemistry Council Roland E. Deike, Jr. , CenterPoint Energy, Inc., TX [UT] Rep. Electric Light & Power Group/EEi

Donald R. Iverson, National Electrical Manufacturers Association, Ml[M] Rep. National Electrical Manufacturers Association James F. Pierce, I ntertek Testing Services, O R [RT]

Ernest]. Gallo, Telcordia Technologies (Ericsson), NJ [U] Rep. Alliance for Telecommunications Industry Solutions Palmer L. Hickman, Electrical Training Alliance, MD [L] Rep. International Brotherh ood of Electrical Workers

Harry J. Sassaman, Forest Electric Corporation, NJ [lM] Rep. National Electrical Contractors Association Kent A. Sayler, P2S Inc., CA [U] Rep. Institute of Electrical & Electronics Engineers, Inc. Mohinder P. Sood, City of Alexandria, VA [ E] Rep. International Association of Electrical Inspectors

David L. Rittinger, Independent Electrical ContraClors of Greater Cincinnati, OH [IM] Rep. Independent Electrical Contractors, Inc.

Alternates James E. Brunssen, Telcordia Technologies (Ericsson), NJ [U ] (AIL to ErnestJ. Gallo) Mark Christian, Electrical Training Alliance, TN [L] (AIL to Palmer L. Hickman) Jon Coulimore,.JC Electric, Inc., WA [ IM] (Alt. to David L. Hittinger) Timothy Garland, Keene State College, NH [U] (Voting Alt.) Larry Geyer, Quality Electric Inc., ID [ IM] (Alt to H arryJ. Sassaman) Joseph Marquardt, ExxonMobil ProduCLion Company, TX [U] (Alt to Louis A. Barrios) Roger D. McDaniel, Georgia Power Company, GA [UT] (AIL to Ro land E. Deike, .Jr·.)

Kenneth L. McKinney, Jr., UL LLC, NC [RT] (Alt. to Kenneth P. Boyce) Donald R. Offerdahl, lntertek Testing Services, ND [RT] (Alt. to J ames F. Pierce) Michael C. Stone, National Electrical Manufacturers Association, CA[M] (Alt. to Donald R. Iverson) Frank E. Tyler, The DuPont Company, Inc., DE [U] (Alt. lO Kent A. Sayler) Charles Valaer, City Of Glendale California, CA [E] (Alt. to Mohinder P. Sood)

Nonvoting Ark T sisserev, AES Engineering, Canada [SE] Rep. CSA/Canadian Electrical Code Committee

70--10

NAT IO NAL ELECTRJCAL CODE

2020 Edition

COMMITTEE PERSONNEL

Code-Making Panel No. 2 Articles 210,220, Annex D, Examples DI through D6 Mark R. Hilbert, Chair MR Hilbert Electrical Inspections & Training, NH [El Rep. lmernaLional Association of Electrical lnspecLOrs Mathher Abbassi, New Yo rk City Department Of Buildings, NY [E] Charles L. Boynton, The Du Pom Company, Inc., TX [U] Rep. American Chemistry Council

1l1omas L. Harman, University of Houston-Clear Lake, TX [SE] David W. Johnson, CenTex I EC, TX [IM] Rep. Independent Electrical Contractors, Inc.

Daniel Buuck, National Association of Home Builders (NAHB), DC [U] Rep. National Association of Home Builders Steve Campolo, Leviton Manufacturing Company, Inc ., NY [M] Thomas A. Domitrovich, Eato n Corporation , MO [Ml Rep. National Electrical Ma nufacwrers Association Nehad El-Sherif, SaskaLoon, SKCanada [U] Rep. lnstitme of Electrical & Electro nics Engineers, Inc.

Alan Manche, Schneider Electric, KY [Ml John McCamish, NECA IBEW Electrical Training Center, O R [L] Rep. International Brotherhood of Electrical Workers Christopher J. Pavese, Duke Energy, KY [UT] Rep. Electric Ligh t & Power Group/ EEi Frederick P. Reyes, U L LLC, NY [ RT] Michael Weaver, M&W EleCLric, OR [ IM] Rep. National Electrical Contractors Association

Alternates William B. Crist, Jr., IES Reside ntial Inc., TX [IM] (All. to David W. J ohnson) Andrew Kriegman , Leviton Manufacruring Company, Inc., NY [Ml (Alt. to Steve Campolo) Brett Larson, Schne ider Electric, IA [Ml (Alt. to Alan Manche) Cesar Lujan, National Association of H ome Builders (NAHB), DC [U]

(Alt. to Daniel Buuck) Roger D. McDaniel, Georgia Power Company, GA [UT] (Alt. to C hristoph er J. Pavese) Danielj. Naughton,JATC of Greater Boston, l\llA [L] (All. to.John McCamish )

Fred Neubauer, Neubauer Electric Inc., CA [IM] (AIL. to Michael Weaver) Robert D. Osbome, UL LLC, NC [RT] (Alt. to Fre derick P. Reyes) Femando E. Pacheco, MeLhanex Chile SA, TX [U] (Alt. to Charles L. Boynton) Brian E. Rock, Hubbell In corporated, CT [M] (Alt. to Thomas A. Domitrovich) Josephj. Wages, Jr., International Association of Electrical Inspectors, TX [El (Alt. to Ma rk R. Hilbert)

Nonvoting Douglas A. Lee, U.S. Con sumer Product Safety Commission, MD [CJ Rep. U.S. Co nsumer ProducL Safety Commissio n

2020 Edition

NATIONAL ELECTRJCAL CODE

Andrew M. Trotta, U.S. Consumer Product Safety Commissio n, MD [CJ Rep. U.S. Consume r ProducL Safhy Commissio n

70-11

NATIONAL ELECTRICAL CODE

Code-Making Panel No. 3 Articles 300,590, 720,725, 727, 728, 760, and Chapter 9, Tables ll(A) and (B), and Tables 12(A) and (B) Robert A.Jones, Chair Independent Electrical Contractors, Inc., TX [IM] Rep. Independent Electrical Contractors, Inc. Richard S. Anderson, RTKL Associates Inc., VA [M] Rep. Building Industry Consulting Services International Douglas P. Bassett, XFinity Ho me, FL [IM] Rep. Electronic Security Association

RandolphJ. Ivans, UL LLC, NY [RT] Chad M.Jones, Cisco Systems, OH [M] T. David Mills, T. David Mills Associates, LLC, GA [U] Rep. Institute of EleCLrical & Electron ics Engineers, Inc. StevenJ. Owen, Steven .). Owe n, Inc., AL [IM] Rep. Associated Builders & Contractors David A. Pace, Olin Corporation, AL [U] Rep. American Chemistry Council Charlesj. Palmieri, Town of Norwell, MA [El Rep. International Association of Electrical Inspectors John E. Sleights, Travele rs Insurance Company, CT [I] George Allan Zimmerman, CME Consulting, In c ., CA [SE] Rep. Ethernet Alliance

Larry G. Brewer, lntertek Testing Services, NC [ RT] Steven D. Burlison, Duke Ene rgy, FL [UT ] Rep. Electric Light & Power Group/ EEi Paulj. Casparro, Scranton ElectriciansJAT C, PA [L] Rep. Inte rnational Brotherhood of Electrical Workers Shane M. Clary, Bay Alarm Company, CA [M] Rep. Amomatic Fire Ala rm Association, Inc. Raymond W. Horner, Allied Tube & Conduit, IL [M] Rep. National Electrical Manufacturers Association

Alternates

Adam D. Corbin, Corbin Electrical Services, Inc., NJ [IM] (Alt. to Robert A.Jones) MichaelJ. Farrell Ill, Lucas Coumy Building Regulation, MI [L] (Alt. to PaulJ. Casparro) Joel Goergen, C isco Systems, Inc., CA [M] (AIL to Chad M.J o nes) Ward Judson, Pentair/ ERICO International Corporation, OH [M] (AIL to Richard S. Anderson) Kyle Krueger, National Electri cal Comractors- Milwaukee Chapter, WI [IM] (Voting Alt.) John Lupacchino, Gaylor Electric Incorporated, IN [IM] (Alt. to Steven J. Owen) Jack McNamara, Bosch Security Systems, NY [M] (Alt. to Shane M. Clary) Timothy J. Mikloiche, Town of West H artford, CT [E] (Alt. to Charles.). Palmieri)

Mark C. Ode, U L LLC, AZ [RT] (Alt. to Randolph J. Ivans) Christopher J. Pavese, Duke Energy, KY [UT ] (Alt. to Steven D. Burlison) Dmitriy V. Plotnikov, lntertek Testing Services, r-.{J [ RT] (Alt. to Larry G. Brewer) Rick D. Sheets, AT &T Digital Life, T X [IM] (Alt. to Douglas P. Bassett) George A. Straniero, AFC Cable Systems, Inc., NJ [M] (Alt. to Raymond W. Horner) William C. Szeto, McKinney, TX [U] (Alt. to T. David Mills) Rebecca S. T emplet, Shell Chemical, LA [U] (Alt. to David A. Pace)

Nonvoting Edward C. Lawry, Oregon, WI [E] (Member Emeritus)

70-12

NATIONAL ELECTRJCAL CODE

202 0 Edition

COMMITTEE PERSONNEL

Code-Making Panel No. 4 Articles 690, 692, 694, 705 James j. Rogers, Chair Towns of Oak Bluffs, Tisbury, West Tisbury, MA [El Rep. lmernaLional Association of Electrical lnspecLOrs William F. Brooks, Brooks Engineering, CA [U] Rep. Photovoltaic Industry Code Council Bill Brown , Schneider Electric, TN [M] Rep. National Electrical Manufacturers Association

Lee M. Kraemer, First Solar, O H [M] Rep. Large-Scale Solar Association Matthew Paiss, San J ose Fire Department, CA [L] Rep. Inte rnational Association of Fire Fighters

Thomas E. Buchal, lntertek Testi ng Services, NY [RT] James G . Cialdea , CE Power Enginee red Services, LLC, MA [IM] Rep. lnte rNatio nal Electrical Testing Associatio n Timothy M. Croushore, FirstEnergy Technologies, PA [UT] Rep. Electric Light & Power Group/ EEi Jason M. Fisher, Tesla Inc., VA [U] Rep. Solar Energy Industries Association Todd Fries, H elle rmannTyton, WI [M] Mark D. Gibbs, URSICH 2M Oak Ridge LLC (UCOR), TN [U] Rep. Institute of Electrical & Electro nics Engineers, Inc. Rebekah Wharton Hren, IPPNC LLC, NC [U] Rep. Sola r Ene rgy lmernational

lrozenell Pruitt, The Du Pont Company, I nc., TX [U] Rep. Am e rican Chemistry Council Duke W. Schamel, Electrical Service Solutions, Inc., CA [IM] Rep. Independent EleCLrical ComracLOrs, Inc. RonaldJ. Toomer, Toomer Electrical Company Inc., LA [IM] Rep. National Electrical Contractors Association Wendell R. Whistler, IBEW 1547, O R [L] Robert H. Wills, lnterg rid, LLC, NH [ U] Rep. American Wind Energy Association Timothy P. Zgon en a, UL LLC, IL [RT ]

Alternates John S. Berdner, Solarcowboyz, CA [U] (AIL to William F. Brooks) Ron Borowski, Eaton Corporation, WI [M] (Alt. to Bill Brown ) Ward I. Bower, Solar Ene rgy Industries Association, NM [U] (Alt. to J ason M. Fishe r ) Mark Gillespie, TMI Electric, OH [IM] (All. Lo Duke W. Scha me l) Antl1ony Granato, Ma nchester Fire Rescue EMS, CT [L] (AIL to Matthew Paiss) Howard Liu, lntertek Testing Services, NY [RT ] (Alt. to Tho mas E. Buchal) Brian Mehalic, Winston-Salem, NC [U] (AIL to Reb ekah Wharton H ren)

Harold C. Ohde, IBEW 134/ Electrical .JointApprenticeship Training & Trust, IL [L] (Ale. to Wendell R. Whistler) Isaac Opalinsky, S,111power Corporation, MD [M] (AIL. Lo Lee M. Kraemer) Rhonda Parkhurst, Ciry of Palo AlLO, CA [E] (Ale. to James.J. Rogers) Robert W. Preus, National Renewable En ergy Lab, CO [U] (Ale. to Robert H. Wills) Kent Whitfield, Underwriters Laboratories, CA [RT] (Ale. to Timod1y P. Zgonen a) Leo Zieman, Florida Power & Light (Nextera Energy), FL [UT] (Ale. to Timod1y M. Croushore)

Nonvoting Stephen W. Douglas, QPS Evaluation Services Inc., Canada [SE] Rep. CSA/ Canadian Electrical Code Committee

2020 Edition

NATIONAL ELECTRJCAL CODE

70-13

NATIONAL ELECTRICAL CODE

Code-Making Panel No. 5 Articles 200, 250 Nathan Philips, Chair Integrated Electronic Systems, O R [IM) Rep. National Electrical ContracLOrs Association Paul W. Abernathy, Encore Wire Corporation, TX [M ) Rep. The Aluminum Association, Inc. Joseph F. Andre, Steel Tube Institute, WA [M) Rep. Steel Tube Institute of North America Gary A. Beckstrand, Utah Electrical.JAT C, UT [L) Rep. Inte rnational Brotherhood of Electrical Workers Trevor N. Bowmer, Telcordia (Ericsson) , NJ [U ) Rep. Alliance fo r Telecommunications Industry Solutions David Brender, Copper Development Association, Inc., NY [M) Rep. Copper Development Association Inc. Paul Dobrowsky, Innovative Technology Services, NY [U) Rep. American Ch emistry Council David A. Gerstetter, UL LLC, IL [RT)

G. Scott Harding, F. B. Harding, Inc., MD [IM ) Rep. Independent Electrical Contractors, Inc. Joseph Harding, Power Tool Institute, O H [M) Daleep C. Mohla, DCM Electrical Consulting Services, Inc., TX [U] Rep. Institute of Electrical & Electron ics Enginee rs, Inc. Mike O'Meara, Arizona Public Service Company, AZ [UT) Rep. Electric Light & Power G roup/ EEi William A. Pancake, III, CAP Government, FL [E) Rep. Inte rnational Association of Electrical Inspectors Christine T. Porter, Inrenek Testing Services, WA [RT) Nick Sasso, State of Wyoming, WY [El Gregory J. Steinman, Thomas & Betts Corporation, TN [M) Rep. National Electrical Manufacturers Association Alternates

Larry Albert, Stanley Black And Decker, Nill [Ml (Alt. to.Joseph H arding) Derrick L. Atkins, Minneapolis Electrical J AT C, MN [L) (Alt. to Gary A. Beckstrand) Kenneth S. Crawford, Chemours Company, \VV [U) (AIL to Pau l Dobrowsky) Joseph P. DeGregoria, U L LLC, NY [RT) (AIL to David A. Gersteuer) Raymond Dunnigan , lntertek, NY [RT ) (Air. to Christine T. Porter) Ernestj. Gallo, Telcordia Technologies (Ericsson ), NJ [U) (Voting Air.) Bobby J. Gray, Hoydar/ Buck, Inc., WA [IM) (Alt. to Nathan Phil ips) Buster Grissett, Mississippi Power Company, MS [UT) (AIL to Mike O'Meara)

Raymond W. Homer, Allied Tube & Conduit, IL [Ml (Alt. to J oseph F. Andre) Ronald Lai, Burndy LLC, NH [M) (Alt. to Gregory.). Steinman) Karin Manfredi, AFC Cable Systems/ Atkore, MA [M) (Alt. to Paul W. Abernathy) Richard M. O'Brien, IAEI, NV [E) (Alt. to William A. Pancake, III ) DavidJ. Picatti, Picatti Bros. Inc., OBA Industrial Service & Electric, WA [IM) (Alt. to G. Scott H arding) Phil Simmons, Simmons Electrical Services, WA [M) (Alt. to David Brender)

Nonvoting

Robert A. Nelson, Canadian Standards Association, Canada [ RT)

70-14

NAT IONAL ELECTRJCAL CODE

2020 Edition

COMMITTEE PERSONNEL

Code-Making Panel No. 6 Articles310,311 , 320, 322,324, 326, 328, 330,332,334,336, 337, 338, 340, 382, 394, 396, 398, 399, 400, 402, Chapter 9, Tables 5 through 9, Annex B and Example D7 Susan Newm an Scearce, Chair City of Humboldt, TN, TN [El Rep. Inte rnational Association of Electrical Inspectors Todd Crisman, IBEW Local 22J ATC, NE [L] Rep. Inte rnational Brothe rhood of Electrical Workers Joseph W. Cross, Eastman Ch em ical Company, TN [U] Rep. American Chemistry Council Timothy Earl, GBH International, Ml [M] Rep. T he Vinyl Institute Christel K. Hunter, Cerro Wire, NV [M] Rep. The Aluminum Association, Inc. G erald W. Kent, Kent Electric & Plumbing Systems, TX [IM] Rep. Independent Elecu·ical Contractors, Inc. Charles David Mercier, Somhwire Company, GA [M] Rep. National Electrical Manufacture rs Association

Dennis A. Nielsen, Lawrence Be rkeley National Laboratory, CA [U] Rep. Institute of Electrical & Electronics Engineers, Inc. Michael Thomas Porcaro, National Grid, MA [UT] Rep. Electric Lig ht & Powe r Group/ EEi Kenneth Riedl, Im enek Testi ng Services, NY [RT] Rep. Inrenek Testin g Services Susan L. Stene, UL LLC, CA [RT] George A. Straniero, AFC Cable Systems, Inc., NJ [M] Rep. Copper Development Association Inc . Wesley L. Wheeler, National Electrical Conu·anors Association, MD [IM] Rep. National Electrical Contractors Associatio n Alternates

David Carroll, Flo rida Power And Light, FL [UT] (Air. to Michael Thomas Porcaro) Chris J. Fahrenth old, Facility Solmions Group, TX [IM] (AIL to Gerald W. Kent) Samuel B. Friedman, General Cable Corporation, RI [M] (Alt. to C harles David Me rcie r) H ermanj. Hall, Austin, T X [M] (Alt. to Timothy Earl) Samuel R. La Dart, City of Memphis, TN [L] (AIL LO Todd C risman )

2020 Edition

NATIONAL ELECTRJCAL CODE

Kelly Lamp, Idaho Chapter NECA, ID [IM] (A lt. to Wesley L. Wheeler) Borgia Noel, State of Wyoming Fire Marsh al's Office, WY [El (A ir. to Susan Newman Scearce) Kevin T. Porter, Encore Wire Corporatio n , TX [M] (AIL to Christel K. Humer ) Mario Xer ri, UL LLC, NY [ RT] (AIL to Su san L. Sten e) Joseph S. Zimnoch, The Oko nite Company, NJ [M] (Alt. Lo George A. Straniero)

70-15

NATIONAL ELECTRICAL CODE

Code-Making Panel No. 7 Articles 545, 547,550, 551, 552,553, 555, 604, 675, and Annex D, Examples D11 and D12 L. Keith Lofland, Chair Interna tio nal Associatio n of Electrical Inspectors (IAEI), TX [El Re p . Ime rnmio na l Associatio n of Electrical Inspectors Jorge L. Arocha, Flo rida Power & Ligh t, FL [UT ] Rep. Ed ison Electric Institute Joseph R. Chandler, Independe nt Electrical Contractors-Da llas, TX [ IM ] Rep. Indepe nde nt Electrical Contractors, Inc. Wade Elliott, U tili ty Services G rou p, Inc., WA [U] Rep. Natio nal Association of RV Parks & Campgro unds Robertj. Fick, Allia m Energy, WI [U] Rep. American Society of Agriculru ral & Biological Engineers Robert A. Garcia, Cavco Industries/ Fleetwood Hom es, Inc., AZ [M] Bruce A. Hopkins, Recreatio n Vehicle Industry Associatio n, VA [M l Ryan Hyer, Testing Eng ineers Internatio nal, UT [RT ] Thomas R. Lichtenstein, U L LLC, IL [ RT]

Doug Mulvaney, Kam pgrounds of Am erica, Inc., MT [U] Clifford Norto n , Bellingha m Marine Utilities, FL [ IM] Richard A. Pared es, IBEW Local 164 J AT C, NJ [L] Rep. Imernatio nal Brothe rhood of Electrical Workers Stephen G. Rood, Legran d Nor th Am erica, NY [ M] Rep. Natio n al Electrical Ma nufacturers Associatio n Dave Watson, Sou thwire, C A [M ] Rep. The Aluminum Associatio n , Inc. Wesley L. Wheeler, National Electrical Contractors Associatio n, MD [IM]

Rep. Natio n al Electrical Conu·actors Associatio n Michael L. Zieman, RADCO , CA [ M] Rep. Ma nufactured H ou sing Institute

Alternates Barry S. Bauman, Alliant Ene rgy, WI [ U] (Alt. to Robert]. Fick) William Bruce Bowman, Fox Systems, Inc., CA [ IM] (Alt. to J oseph R. Cha ndler) Byron Carroll, Carrol Woods Inc., NC [ U] (Alt. to Wade Elliott) Gerald D. Dix, H am p to n Roads J oint Appre n ticesh ip Training Committee, VA [ L] (Alt. to Richa rd A. Paredes) Dean C. Hunter, Minnesota Deparm1ent of Labo r & Indu stry, MN [ El (Alt. to L. Keith Lo fla nd)

70-16

Jeffrey Kre idler, Ka m pgrou nds of A merica Inc ., MT [U] (Alt. to Do ug Mu lva ney) Mark C. Ode, U L LLC, AZ [RT] (Alt. to Tho mas R. Lich te nstein) Kent Perkins, Recreation Vehicle Industry Association , VA [M] (Alt. to Bruce A. Hopkins) Paulj. Reis, A FC Cable Systems, Inc., MA [ M ] (Alt. to Dave Watson ) Matthew J. Samojeden, Hubbell In corporated, CT [M ] (AIL to Steph e n C . Rood)

NATIONAL ELECTRJCAL CODE

2020 Edition

COMMITTEE PERSONNEL

Code-Making Panel No. 8

Articles342,344,348,350,352,353,354, 355,356,358,360,362, 366,368,370,372,374,376,378,380,384,386, 388, 390, 392, Chapter 9, Tables 1 through 4, Example D13, and Annex C Larry D. Cogburn, Chair Cogburn Bros., Inc., FL [IM] Rep. National Elecu-ical Contractors Association Richard E. Loyd , R & N Associates, AZ [M] Rep. Steel Tube In stitute of North America Michael C. Martin, ExxonMobil Research & Engineering, TX [U] Rep. American Chemisuy Council Paul W. Myers, Nutrien , OH [U] Rep. Institute of Elecu-ical & Electron ics Engineers, Inc. Donald R. Offerdahl, ln tertek Testing Services, ND [RT ] Rhett A. Roe, !BEW Local Un ion 26JAT C, MD [L] Rep. Inte rnational Brotherhood of Electrical Workers Rodney J. West, Schneider Electric, O H [M] Rep. National Electrical Manufacturers Association

Doug Adams, MP Husky LLC, SC [M] Rep. Cable Bus Manufacture rs Association Richardj. Berman, UL LLC, IL [RT] David M. Campbell, AFC Cable Systems, Inc., MA [M] Rep. The Alumin um Association, Inc. Kenneth W. Hengst, 4C2 Electrical Specialists, TX [IM] Rep. Independent Elecu-ical Contractors, Inc. Pete Jackson, C ity of Bakersfield, Californ ia, CA [El Rep. Inte rnational Association of Electrical Inspectors David H. Kendall, Thomas & Betts Corporation, TN [M] Rep. The Vinyl Institute

Alternates Jay Burris, Wheatland Tube (Div. ofZekelman Indusu-ies), O H [Ml (Alt. LO Richard E. Loyd) Joel Uoey) Crider, AEP, O H [UT] (Voting Alt. ) Brian Deacy, Allied Tube Conduit Corporation , IL [M] (Alt. to David H. Kendall ) David A. Gerstetter , UL LLC, IL [RT] (AIL to Richard]. Berman)

J. Grant Hammett, Colorado State Elecu-ical Board, CO [El (Alt. to Pete J ackson) Gary K. Johnson, Dow Corning Corporation, LA [U] (Alt. LO Michael C. Martin)

Stephen P. Poholski, Newkirk Elecu-ic Associates, In c., MI [IM] (Al t. to Larry D. Cogburn ) Dan Rodriguez, !BEW Local Un ion 332, CA [L] (Alt. LO Rhen A. Roe) Frederic F. Small, Hubbe ll Incorporated, CT [M ] (Alt. to Rodney J. West) Dan Suriyamongkol, Advanced Cable Bus, SC [M] (Alt. to Doug Adams) Raul L. Vasquez, Independent Electrical Contractors, TX [IM] (Alt. to Kenneth W. He n gst) Dave Wats on, Somlnvire, GA [Ml (Al t. to David M. Campbell)

Nonvoting Stephen W. Douglas, QPS Evaluation Se1v ices Inc., Canada [SE] Rep. CSA/Canadia n Electrical Code Committee

2020 Ed ition

NATIONAL ELECTRJCAL CODE

70-17

NATIONAL ELECTRICAL CODE

Code-Making Panel No. 9 Articles 312,314,404,408,450, 490 David G. Hwnphrey, Chair County of Henrico, Virginia, VA [El Rep. Imernmional Association of Electrical Inspectors

Richard Anderson, Fluor Corporation, TX [U] Rep. Associated Bu ilders & Comractors Rodney D. Belisle, NECA-IBEW Electrical Training Trust, OR [L] Rep. Imernational Brotherhood of Electrical Workers

Timothy Schultheis, T.S.B Inc., Schultheis Electric, PA [IM] Rep. National Electrical Contractors Association Paul B. Sullivan, DuPont, SC [U] Rep. Institute of Electrical & Electronics Engineers, Inc.

Carmon A. Colvin, Bright Future Electric, LLC, A L [IM] Rep. Independent Electrical Contractors, Inc. Frederic P. Hartwell, H artwell Electrical Services, Inc., l\lJA [SE] Kevin R. Miller, Intertek Testing Services, WA [RT] Robert D. Osborne, UL LLC, NC [RT ] Bradford D. Rupp, Allied Moulded Products, Inc., OH [M] Rep. National Electrical Manufacwrers Association

Darrell M. Sumbera, Centerpoint Energy, TX [UT] Rep. Edison Electric Institute Ralph H. Young, Eastman Chemical Company, TN [U] Rep. American Chemistry Council

Alternates Jeffrey A. Fecteau, Underwriters Laboratories LLC, AZ [ RT] (AIL to Robert D. Osborne) Ken Filips, Bergelectric, O R [IM] (Air. to Carmon A. Colvin) Barry N. Hornberger, PECO Energy Company, PA [UT] (Alt. to Darrell M. Sumbera) Michael O'Connell, .Joint Apprentice & Training Committee of G reater Boston, MA [L] (Air. to Rodney D. Belisle)

70-18

Ronnie H. Ridgeway, Siemens Industry, In c., TX [M] (Alt. to Bradford D. Rupp) Pat Griffith Rose, City of Greensboro, NC [ El (Alt. to David G. Humphrey) Michael Simister, Imenek Testing Services, TX [RT] (Alt. to Kevin R. Miller)

NATIONAL ELECTRJCAL CODE

2020 Edition

COMMITTEE PERSONNEL

Code-Making Panel No. 10 Articles 215, 225, 230, 240, 242 Julian R. Burns, Chair Quality Power Solutions, Inc., NC [IM) Rep. Independent Electrical Co ntractors, Inc. Paul D. Barnhart, UL LLC, NC [ RT) Scott A. Blizard, American Electrical Testing Company, Inc., MA [IM) Rep. lnce rNational Electrical Testing Association

James T. Dollard, J r. , !BEW Local Union 98, PA [L) Rep. Inte rnational Brotherhood of Electrical Workers Ed Koepke, Nidec Motor Corporation, MO [M) Kenne th]. Rempe, Siemens Industry Inc., GA [Ml Rep. National Electrical Ma nufacture rs Association

VincentJ. Saporita, Eaton's Bussmann Business, MO [M) Roy K Sparks, Ill, Eli Lilly and Company, I N [U) Rep. American Chemistry Council

Steven E. Townsend, General Mowrs Company, Ml [U] Rep. Institute of Electrical & Electron ics Engineers, Inc. Christopher R. Vance, National Grid, NY [UT) Rep. Electric Light & Power Group/ EEi David A. Williams, Delta Charter Town ship, Ml [E) Rep. Inte rnational Association of Electrical In spectors Alternates

Anthony Dawes, DTE Energy, Ml [UT) (Alt. to C hristoph er R . Vance) James Dorsey, Douglas Cou n ty Electrical lnspecto1; CO [El (Alt. to David A. Williams) KevinJ. Lippert, Eato n Corporation, PA [Ml (Alt. to Vincent]. Saporita) Richard E. Lofton, II, !BEW Local Union 280, OR [L) (Alt. to J ames T. Dolla rd, J r.) Alan Manche, Schneide r Electric, KY [M) (Alt. to Kenneth]. Re mpe) David Morrissey, American Electrical Testing Company, Inc., MA [IM) (Alt. to Scott A. Blizard)

2020 Edition

NATIONAL ELECTRJCAL CODE

Nathan Philips, Integrated Electronic Systems, OR [IM) (Votin g Alt.) Steve A. Struble, Freeman's Electric Service, Inc., SD [IM) (A lt. to J u lian R. Burns) Peter R. Walsh, Teaticket Technical Associates, LLC, MA [U) (A lt. to Steven E. Townsend) Danish Zia, UL LLC, NY [RT) (Alt. to PaLLI D. Barnhart)

70--19

NATIONAL ELECTRICAL CODE

Code-Making Panel No. 11

Articles 409, 430, 440, 460, 470, and Annex D, Example D8 Dirk R. F. Mueller, Chair U L LLC, Germany [RT ] Rep. UL LLC Luis M. Bas, l ntertek Testing Services, FL [RT] John E. Cabaniss, Easmrnn Chemical Company, TN [U] Rep. American Chemistry Council Terry D. Cole, Ha mer Electric, Inc., WA [IM] Rep. Indep e ndent Electrical Contractors, Inc. Zivorad Cosic, ABB Inc., WI [M] Robert G. Fahey, City ofJ anesville, WI [El Rep. International Associat ion of Electrical Inspectors Paul E. Guidry, Fluo r Enterprises, Inc., TX [U] Rep. Associated Bu ilders & Contracto rs Stephen M. Jackson , Southern Company, GA [ UT] Rep. Electric Light & Power Group/ EEi

Arthur S. Ne ubauer, Arseal Technologies, GA [U] Rep. American Petroleum In stitute JebediahJ. Novak, Cedar Rapids ElectricalJATC, LA [L] Rep. Inte rnatio nal Brot he rhood of Electrical Workers Joe Schomaker, Eaton, MO [M ] Arthur J. Smith, III, Waldem ar S. Nelson & Company, Inc. , LA [U] Rep. In stitute of Electrical & Electronics Engineers, Inc . Keith Waters, Schneider Electric, KY [Ml Rep. National Electrical Manufacturers Association Ron Widup, Sh ermco Industries, TX [IM] Rep. lnterNatio nal Electrical Testing Association

Alternates Sethj. Carlton, UL LLC, IL [RT] (AIL to Dirk R. F. Mueller) Donald P. Deachin, DTE, MI [UT] (Alt. to Stephen M. J ackson) Eric Gesualdi, Shell Oil Company, T X [U] (Al t. to Arthur S. Neubauer) Charles A. Goetz, Siemens Industry, Inc., IL [M] (AIL to Ke ith Wate rs) Darryl Hill, Wichita ElectricalJAT C/IBEW 271, KS [L] (AIL toJ ebedia h J. Novak) Tim Hinson, Mille r Electric Company, FL [IM] (Vo ting Alt.)

70-20

Chester Kelly, Dupo nt Ch estnut Run Plaza, DE [U] (Alt. to J ohn E. Cabaniss) Tim LaLonde, Haskin Electric, Inc., WA [IM] (Alt. to Terry D. Cole) Charles Littlefield, Goochland County, VA [E] (Alt. to Robert G. Fah ey) VincentJ. Saporita, Eato n 's Bussmann Business, MO [M] (Alt. to J oe Schomaker) Steven E. Townsend, Gen eral Motors Compa ny, MI [ U] (Alt. to Arthur J. Smith, III) Bobby A. Walton, lnte rte k, TX [ RT] (Alt. to Luis M. Bas)

NAT IONAL ELECTRJCAL CODE

2020 Edition

COMMITTEE PERSONNEL

Code-Making Panel No. 12 Articles 610, 620,625, 626,630, 640, 645, 646, 647, 650, 660, 665, 668, 669, 670, 685 and Annex D, Examples D9 and D10 Scott Cline, Chair McMurtrey Electric, Inc., CA [IM] Rep. National Electrical Contractors Association

Joseph M. Bablo, UL LLC, IL [RT] Frank Anthony Belio, Inte rnational Union of Elevator Constructors, CA [L] J effrey W. Blain, Schindler Elevator Corporation, NJ [Ml Rep. National Elevator Industry Inc. Philip Clark, City of Southfield, Ml [E] Rep. Inte rnational Association of Electrical Inspectors Karl M. Cunningham, Alcoa, Corporation, PA [M] Rep. The Aluminum Associatio n, Inc. Joel Goergen, C isco Systems, Inc., CA [M] Jody B. Greenwood, Navy Crane Center, VA [U] J effrey L. Holmes, IBEW Local Unio n l J AT C, MO [L] Rep. International Brothe rhood of Electrical Wo rkers Robert E. Johnson, ITE Safety, MA [ U] Rep. Information Technology Industry Council

Mark S.Joiner, Office State Fire Marshal, LA [El Stanley Kaufman, CableSafe, lnc./ O FS, GA [M] Rep. Plastics Industry Association ( Plastics) Todd R. Konieczny, lnte rte k Testing Services, MA [RT] Rep. lnte rtek Testin g Se,v ices Todd F. Lottmann, Eaton•s Bussmann Business, PA [M ] Rep. National Electrical Manufacturers Association Karl Reighard, Delmarva Power and Lig ht, MD [UT] Rep. Edison Electric Institute Edward E. Rodriguez, Walke r Enginee ring, In c., TX [IM] Rep. Inde pe ndent Electrical Contractors, Inc. James E. Tarchinski, Gene ral Motors C ompany, MI [U] Rep. SAE Hybrid/ EV Technical Standards Committee Robert C. Turner, Inductotherm Corporation, PA [M]

Alternates Rocco DeLuca, Jr., City And County Of Broomfield, CO [El (AIL to Philip Clark) Jacob Haney, Ge ne ral Cable Corporation, IN [M] (AIL to Karl M. Cunningham) John D. (Do ug) Henderson, ThyssenKrupp Elevator Manufacturing Inc., TN [M] (Alt. toJ effreyW. Blain) John R. Kovacik, UL LLC, IL [RT] (Alt. to.Joseph M. Bablo) Richard (Tony) O'Brien, Cisco Systems, Inc., CA [Ml (Alt. to.Joel Goergen) Mike O'Meara, Arizona Public Ser vice Company, AZ [UT] (Alt. to Karl Reighard)

Joseph F. Prisco, IBM Corporation, MN [U ] (Alt. to Robert E. Johnson) P eter Sedor, I nte rtek, MA [ RT] (Alt. to Todd R. Konieczny) Richard R. Shawbell, Jr., Florida East Coast ElectricalJATC, FL [L ] (Alt. to J effrey L. Holmes) David B. Stump, Independent Electrica l Contractors, TX [IM] (Alt. to Edward E. Rodriguez) Emad Tabatabaei, lnductotherm Corpo ratio n , f\!J [M] (Alt. to Robert C. Turner ) Frank Tse, Leviton Manufacturing Company, In c., NY [M] (Alt. to Todd F. Lomnann)

Non voting Andre R. Cartal, Yardley, PA [E] (Member Emeriws)

2020 Ed ition

NATIONAL ELECTRJCAL CODE

70--21

NATIONAL ELECTRICAL CODE

Code-Making Panel No. 13 Articles 445, 455,480,695, 700, 701 , 702, 708, 750, Annex F and Annex G LindaJ. Little, Chair !BEW Local l ElectriciansJ ATC, MO [L] Martin D. Adams, Adams Electric, Inc., CO [IM] Rep. National Electrical Contractors Association Steve Baldwin, lntertek, CA [RT] Rep. lntertek Testing Services

John R. Kovacik, UL LLC, IL [ RT] Greg Marchand, Briggs & Stranon, WI [M] Rep. Portable Generator Manufacturers' Associmion Daniel R. Neeser, Eaton's Bussmann Division, MO [M]

Gregj. Ball, Tesla, CA [M] Krista McDonald Biason , HCA Architects and Engineers, MN [U] Rep. American Society for Healthcare Engineering Daniel J. Caron, Bard, Rao + Athan as Consulting Engineers, LLC, MA[SE] Richard D. Currin, Jr., North Carolina State University, NC [U] Rep. American Society of Agricultural & Biological Engineers Neil A. Czarnecki, Reliance Controls Corporation, WI [Ml Rep. National Electrical Manufacturers Association Steven F. Froemming, City of Franklin, WI [ E] Rep. International Associat ion of Electrical Inspectors Robert E. Jordan , Alabama Power Company, AL [UT ] Rep. Electric Ligh t & Power Group/ EEi

Shawn Paulsen, CSA Group, Canada [RT] Arnoldo L. Rodriguez, LyondellBasell Industries, TX [U] Rep. American Chemistry Council Michael L. Savage, Sr., Marion County Building Safety, FL [El Mario C. Spina, Verizon Wireless, OH [U] Rep. Institute of Electrical & Electronics Engineers, Inc. Kendall M. Waterman, D raka Cableteq, MA [M] Rep. Copper Development Association Inc. James R. Whlte, Shermco Industries, Inc., T X [IM] Rep. lnterNational Electrical Testing Association Timothy P. Windey, Cummins Power Generation, MN [M]

Alternates

Lawrence S. Ayer, Biz Com Electric, Inc., OH [IM] (Voting AIL) Barry S. Bauman, Allianc Energy, WI [U] (AIL to Richard D. Currin, J r.) Glenn Brown, GJL Engineering, PA [U] (AIL to Krista McDonald Biason) William P. Cantor, TPI Corporation, PA [U ] (AIL to Mario C. Spina) James S. Conrad, RSCC Wire & Cable, CT [M ] (Alt. to Kendall M. Waterman) Timothy Crnko, Eaton's Bussmann Business, MO [M] (Alt. to Danie l R. Neeser) James T. Dollard, Jr., !BEW Local Union 98, PA [L] (Alt. to Linda.). Linle) Laurie B. Florence, UL LLC, IL [RT] (Alt. to j ohn R. Kovacik) Travis Foster, Shell Oil Company, TX [U] (AIL to Arnoldo L. Rodriguez) Richard Garbark, BCE, MD [UT] (AIL to Robert E.Jordan)

70-22

Jan Gromadzki, Tesla, CA [M] (Alt. to Greg j. Ball) Jeff Jonas, Generac Power Systems, Inc., Wl [M] (Voting Alt.) Chad Kennedy, Schneider EleClric, SC [M] (Alt. to Neil A. Czarnecki) Raymond Richard Prucha, Bard, Rao + Anthanas Consulting Engineers, LLC, NY [SE] (Alt. to Danielj. Caron) Daniel Schlepp, Wacker Neuson, WI [M] (Alt. to Greg Marchand) Rich Scroggins, Cummins Power Generation, MN [M] (Alt. to Timothy P. Windey) Richard Tice, VEC, Inc., OH [IM] (AIL to Martin D. Adams) Anton Tomasin, City Of Roch ester Hills, MI [El (Alt. to Steven F. Froemming) Michael Wilson, CSA Group, Canada [RT] (Alt. to Shawn Paulsen)

NAT IO NAL ELECTRJCAL CODE

2020 Edition

COMMITTEE PERSONNEL

Code-Making Panel No. 14 Articles 500, 501,502,503, 504, 505, 506, 510, 511, 513, 5 14, 515, 516 Michael W. Smith, Chair Schaeffer Electric Compan y, MO [IM] Rep. National Electrical Comractors Association Donald W. Ankele, UL LLC, IL [RT ] StevenJ. Blais, Appleton Group, IL [Ml Rep. National Electrical Manufacturers Association

Corey Cahill, U.S. Coast Guard, DC [El Mark A. Chrysler, City of San Diego, CA [E] Rep. lme rnational Association of Electrical Inspectors William T. Fiske, lntertek Testing Services, NY [RT ] Mark Goodman, Mark Goodman Electrical Consu lting, CA [U] Rep. American Petrole um Institute William G. Lawrence,Jr., FM Global, I\IIA [I] L. Evans Massey, Baldor Electric Company, SC [Ml Rep. Instrume ntation, Systems, & Automation Society William E. McBride, CONAM Construction Company, AK [U] Rep. Institute of Electrical & Electro nics Engineers, Inc.

Jeremy Neagle, U.S. Bureau of Alcohol, Tobacco, Fi rearms & Explosives, MD [U] Thomas L. P ottschmidt, Indianapolis P ower & Light, IN [UT] Rep. Edison Electric Institute

Lowell Reith, Inte rstates Construction Services, In c., KS [IM] Rep. lndependem Electrical Contraetors, Inc. John L. Simmons, Florida East CoastJAT C, FL [L] Rep. lme rnational Brotherhood of Electrical Workers Fred K. Walker, U.S. Department Of The Air Force, FL [E] David B. Wechsler, Consultant, TX [U] Rep. American Ch emistry Council Mark C. Wirfs, R & W Engineering, Inc., OR [U] Rep. Grain Elevator and Processing Society

Alternates Miltail Bantic, l ntertek, TX [ RT ] (AIL to William T. Fiske) Dave Burns, Shell P&T: l nnovation/ R&D, TX [U] (AIL to Mark Goodma n ) Cory Co le, Hame r Electric, Inc., WA [IM] (Alt. to Lowell Reith) Thomas E. Dllltne, Long Island Joint Apprenticeship & Training Committee, NY [L] (AIL to.John L. Simm o ns) Andrew H ernandez, AstraZeneca Pharmaceuticals, DE [U] (Alt. to William E. Mc Bride) Richard A. Holub, The DuPont Company, In c., DE [U] (Alt. to David B. Wechsle r)

Paul T. Kelly, UL LLC, IL [ RT] (Alt. to Do nald W. Ankele) Haywood Kines, Prince William County Building Development, VA [El (Alt. to Ma rk A. Chrysler) Edmund R. Leubner, Eaton's Crouse-Hinds Business, NY [M] (Alt. to Steven J. Blais) Eddie Ramirez, FM Global, MA [I] (Alt. to William G. Lawrence, J r.) Ted H. Schnaare, Rosemount In corporated, MN [Ml (A lt. LO L. Evans Massey)

Nonvoting Michael E. Aaron, Wiss Ja nney Elstner Associates, Inc., IL [SE] Rep. TC on Airport Facilities

2020 Edition

NATIONAL ELECTRJCAL CODE

Timothy J. Pope, Canadian Standards Association, Ca nada [RT]

70-23

NATIONAL ELECTRICAL CODE

Code-Making Panel No. 15 Articles 517, 518,520,522,525,530,540 Lawrence E. Todd, Chair lntertek Testing Services, KY [RT] Chad E. Beebe, ASHE - AHA, WA [U] David A. Dagenais, Partners/ Wentworth-Douglass Hospital, NH [U ] Rep. NFPA Health Care Section Matthew B. Dozier, !Design Services, TN [ U] Rep. lnsticme of Electrical & Electronics Engineers, Inc. Joe L. DuPriest, City of St. Cloud, FL [ E] Rep. International Association of Elec crical lnspeccors KennethJ. Gilbert, Florida Power & Light Company, FL [UT] Rep. Electric Light & Power Group/ EEi Pamela Gwynn, UL LLC, NC [RT] Rep. UL LLC Mitchell K. Hefter, Signify, TX [ IM] Rep. Illuminating Engineering Society of North America Kim Jones, Funtastic Shows, OR [U] Rep. Outdoor Amuseme nt Business Association, Inc.

Edwin S. Kramer, Radio City Music Hall, NY [L] Rep. International Alliance of Theatrical Stage Employees Gary J. Krupa, U.S. Departme nt of Vete rans Affairs, NE [U] Kevin T. Porter, Encore Wire Corporation, TX [M] Rep. The Aluminum Association, Inc. Brian E. Rock, H ubbell Incorporated, CT [M ] Rep. National Electrical Manufacturers Association James C. Seabury III, Enterprise Electric, LLC, TN [IM] Rep. Indep endent Electrical Concractors, In c. Bruce D. Shelly, Shelly Electric Company, Inc., PA [IM] Rep. National Electrical Concractors Association Michael D. Skinner, CBS Smd io Cente1; CA [U] Rep. Alliance of Motion Picture and Television Producers Steven R. Terry, Electronic Theatre Controls Inc., NY [M] Rep. U.S. In stitute for Theacre Technology, Inc.

Alternates Michael A. Anthony, Standards Michigan, Ml [U] (Alt. to Matthew B. Dozier) Gary A. Beckstrand, Utah Electrical.JATC, UT [L] (Voting Alt. ) David M. Campbell, AFC Cable Systems, Inc., lvlA [M] (Alt. to Kevin T. Porter) Carmon A. Colvin, Bright Future Electric, LLC, A L [IM] (Alt. to J ames C. Seabury III ) Connor Wright Frazier, HCA Architects And Engineers, MN [U] (Alt. to Chad E. Beebe) Samuel B. Friedman, General Cable Corporation, RI [M] (Alt. to Brian E. Rock) EdwardJoseph, Underwriters Laboratories Inc., NY [RT] (Alt. to Pamela Gwynn) Jay Y. Kogoma, lntertek Testing Services, CA [RT] (Alt. to Lawrence E. Todd)

70--24

Frank Novitzki, U.S. Departme nt of Veterans Affairs, VA [U] (Alt. to Gary J. Krupa) Don Rabel, Mid-West Electric Company, TX [I M] (Alt. to Bruce D. Shelly) Douglas Rheinheimer, Paramount Picm res, CA [U] (Alt. to Michael D. Skinner) Alan M. Rowe, Inte rnational Alliance of Theatrical Stage Employees, CA [L] (Alt. to Edwin S. Kramer) Clinton Bret Stoddard, City of Rexburg, ID [El (Alt. to J oe L. Du Priest) Walter N. Vernon, IV, Mazzetti, CA [SE] (Voting Alt.) R. Duane Wilson, Geo rge C. lzenour Associates, Inc., NM [IM ] (Alt. lO Mitchell K. Hefte r )

NAT IONAL ELECTRJCAL CODE

2020 Edition

COMMITTEE PERSONNEL

Code-Making Panel No. 16 Articles 770, 800, 805, 810, 820, 830, 840 Thomas E. Moore, Chair City of Beachwood, O H [E] Rep. lmernational Association of Electrical Inspectors

G eorge Bish, Amazon/ Ring Protect Inc., NC [IM ] Rep. Satellite Broadcasting & Communications Association James E. Brunssen , Telcordia Technologies (Ericsson ), NJ [U] Rep. Alliance for Te lecommunications Industry Solutions Terry C. Coleman, Electrical Training Alliance, TN [L] Rep. Inte rnational Brotherhood of Electrical Workers Robert Davies, Davies Electric Company, CA [IM] Rep. National Electrical Comractors Association Fred C. Dawson, Chemours, Canada [U] Rep. American Chemistry Council Gerald Lee Dorna, Belden Wire & Cable Co., IN [M] Rep. Insulated Cable Engineers Associatio n, Inc. Robert W.Jensen, dbi-Telecommunicatio n Infrastrucmre Design, TX [M] Rep. Building Industry Consulting Services Internatio nal Steven C.Johnson, J o hnson Te lecom, LLC, TX [UT] Rep. Sociecy of Cable Telecommunicatio ns Engineers (SCTE)

Williamj. McCoy, Telco Sales, Inc., TX [U] Rep. Institute of Electrical & Electronics Engineers, Inc. Michael F. Murphy, lntertek Testing Services, MA [RT] 111omasJ. Parrish, Telgian Corporation, Ml [Ml Rep. Automatic Fire Alarm Association, Inc. Roy Pollack, Comcast Xfinicy Home, FL [UT] Rep. Electro nic Secu rity Association Luigi G. Prezioso, M. C. Dean, Inc., VA [IM] Rep . Independe nt Electrical Contractors, Inc. Rodger Reiswig,J ohnson Contro ls, FL [M] Rep. National EleCLrical Manufacmrers Association Masood Shariff, Commscope, "!J [M ] Rep. Telecommunicatio n s Industry Association Anthony T assone, UL LLC, NY [RT] Rep. UL LLC Leo Zieman, Florida Power & Light (Nextera Energy), FL [UT] Rep. Electric Light & Power Grou p / EEi Alternates

Rendell K. Bourg, National Fire Protection Compan y Inc., HI [M] (Alt. to Tho mas]. Parrish ) Trevor N. Bowmer, Telcordia (Ericsson ), NJ [U] (Alt. to .James E. Brunssen ) Larry Chan, City of New Orleans, LA [El (AIL to Thomas E. Moore) Timothy D. Cooke, Times Fiber Communicatio ns, Inc., VA [UT] (Alt. co Steven C. J o hnson ) RandolphJ. Ivans, U L LLC, NY [RT] (Alt. co Anthony Tasso ne) John A. Kacperski, P2S Engineering, Inc ., CA [M] (Alt. LO Robert \~1.Je n sen ) Stanley Kaufman, CableSafe, Inc ./ O FS, GA [M] (Alt. Lo Gerald Lee Do rna)

2020 Ed ition

NATIONAL ELECTRJCAL CODE

Eric Lawrence, Berk-Tek, A Nexans Compan y, PA [M ] (Alt. to Masood Sh ariff) Diana M. Lettkeman, Dish Network Service, LLC, CO [IM] (Alt. to George Bish ) Christopher Rawson, International Brotherhood of Electrical Workers-Technical Institute (IBEW), IL [L] (Alt. LO Terry C. Coleman ) David B. Schrembeck, DBS Communications, In c., OH [IM] (A lt. to Luigi G. Prezioso) Carl R. Wetterhan, Genera l Cable Industries, Inc., KY [M] (Alt. co Rodge r Re iswig)

70-25

NATIONAL ELECTRICAL CODE

Code-Making Panel No. 17 Articles 422, 424, 426, 427, 680, 682 Donald R. Cook, Chair Sh e lby County De pa rtm e nt of Develo pment Ser vices, AL [El Re p. Ime rnmio na l Associatio n of Electrical Inspectors Chester L. Sandberg, C L Sand berg & Associates, LLC, CA [ U) Rep. In stitute of Electrical & Electro nics Engineers, Inc . Kenneth M. Shell, nVent Therma l Ma nagem ent, CA [M) Rep. Coppe r Develo pm ent Associatio n Inc.

Thomas V. Blewitt, U L LLC, NY [RT ] Jerry Lee Daniel, Texas Depar tm e m of Licensing Regulatio n, TX [El E. P. Hamilton, Ill, E. P. Hamilto n & Associates, Inc., TX [Ml Rep. Associatio n of Pool & Spa Professio nals Emmanuel (Lee) DeWayne Jones, Georg ia Power Com pany, GA [ UT] Rep. Electric Ligh t & Power Gro up/ EEi Brian Myers, !BEW Local Unio n 98, PA [ L] Rep. Inte rnatio nal Brothe rhood of Electrical Wo rke rs Timothy R. O'Brien, Chula Vista Electric, CA [ IM ] Rep. Nationa l Electrical Contracto rs Association Dennis Michael Querry, Trinity River Au thority, TX [ IM) Re p. Indepe nde n t Electrical Contractors, Inc.

Kam Fai Siu, lntertek Testing Services, Ho n g Ko n g [RT) Rep. lntertek Testing Services Peter C. Swim, Whirl pool Corporatio n, Ml [ M) Rep. Air-Con d itioning, H eating, & Refrigeratio n Insti tllle Marcelo E. Valdes, G E Energy In dustrial Solutio ns, NC [M) Rep. Natio n al Electrical Ma nufacturers Associatio n Matt B. Williams, Associatio n of Ho rne Applia n ce Manufaccure rs (AHAM ), DC [M) Rep. Association of Ho rne Applian ce Ma nufactu re rs

Alternates Paul W. Abernathy, Encore Wire Corporatio n, TX [M ) (Alt. to Ke nneth M. Sh e ll ) Ryan Andrew, Alaska J oint Electrical Apprenticeship a nd Tra ining Trust, AK [L) (Alt. to Brian Mye rs) Bernie Donnie Bell, Gulf Power Com pany, FL [UT ) (Alt. to Emma nuel (Lee) DeWayne J o nes) Masud Chowdhury, Associatio n of Horne Applia nce Manufacturers (AHA M), VA [M ) (Alt. to Matt B. William s) Chris Faucette, State of North Carolina, NC [ El (Al t. to Do na ld R. Cook) Stephen R. Kuscsik, Unde rwri te rs Laboratories Inc., I L [RT) (Alt. to T h omas \I. Blewitt)

Armando M. Lozano, MSF Electric, Inc., TX [ IM) (Alt. to De nnis Michael Que rry) Stephen Macey, Watkins Manufacturing Corporatio n, CA [ M] (Alt. to E. P. H amilto n, 111 ) Bernard Poton, lntertek, TX [ RT] (Alt. to Kam Fai Siu) Larry Reichle, Texas Depanmem Of Licensing Regul mio n, TX [El (Alt. to J erry Lee Daniel) Svetlana Ulemek, Hubbel/ Burndy LLC, N H [M) (Alt. to Ma rcelo E. Valdes) Thomas H. Wood, Cecil B. Wood, Inc., IL [ IM] (Alt. to Timothy R. O ' Brie n )

Nonvoting Andrew M. Trotta, U.S. Co nsumer Produ ct Safety Commissio n, MD [Cl Rep. U.S. Co nsume r Product Safety Commissio n

70-26

Douglas A. Lee, U.S. Consume r Prod uct Safety Commissio n , MD [Cl Rep. U.S. Consumer Product Safety Commissio n

NATIO NAL ELECTRJCAL CODE

2020 Edition

COMMITTEE PERSONNEL

Code-Making Panel No. 18 Articles 393,406,410,411,600, 605 Bobby J. Gray, Chair Hoydar/ Buck, Inc., WA [IM] Rep. National Electrical Contractors Associatio n

Ron D. Alley, Northern New Mexico IEC, NM [ IM] Rep. Independent Electrical Contractors, Inc. Frederick L. Carpenter, Acui ty Brands Lighting, GA [M] Rep. National Electrical Manufacturers Association KurtJ. Clemente, Clark Nexsen, Inc., VA [U] Rep. Institute of Electrical & Electronics Engineers, Inc. Paul Costello, NECA and I BEW Local 90 JATC, CT [ L] Rep. Inte rnatio nal Broth erhood of Electrical Workers Hakim Hasan, lntertek, GA [RT] Jack E. Jamison, Jr., Mille r Eng ineering, Inc., WV [El Rep. Inte rnational Association of Electrical Inspectors

Charles S. Kurten, UL LLC, NY [RT] William Ross McCorcle, American Ele CLric Power, O K [UT] Rep. Electric Light & Power Group/ EEi

Michael S. O'Boyle, Philips Lightolier, lVlA [M ] Rep. American Lighting Association Wesley J. Wilkens, Persona, Inc., SD [M] Rep. Inte rnatio nal Sign Association Randall K Wright, RKW Consulting, PA [SE]

Alternates Donald Berlin, lnrermatic Inc., IL [M] (AIL to Michael S. O' Boyle) Juan M. Caamano, U L LLC, NY [RT] (Alt. to C harles S. Kurte n ) Mark Coshal, JES Commercial of San Anronio, TX [ IM] (Alt. to Ro n D. Alley) Gabriel A. Griffin, Clear Sign and Design Inc., CA [M] (Alt. to Wesley J. Wilkens) Richard Hollander, City of Tucson, AZ [ El (AIL to J ack E.Jamison,Jr.)

Robert Setaro, lntertek, GA [RT] (Alt. to Hakim Hasan ) Frank Tse, Leviton Manufacturing Compan y, In c., NY [Ml (Alt. to Fre d erick L. Carpenrer) Daniel Van Sickle, III, Electrical Training Alliance ofj acksonville, FL [L] (Alt. to Paul Costello ) Paul Yesbeck, ACU Sign Corporation, FL [IM] (Alt. to Bobby J. Gray)

Committee Scope: This Committee sh all have primary responsibi lity for documents on minim izing the risk of electricity as a source of electric shock and as a pote ntial ignition source of fires and explosions. It shall a lso be responsib le for text to minimize the propagation of fire and explosio ns due to electrical installations.

2020 Ed ition

NATIONAL ELECTRJCAL CODE

70--27

NATIONAL ELECTRICAL CODE

NFPA Electrical Engineering Division Technical Staff Gordon S. Frost, Divisio n Man ager Mark W. Earley, Chie f Electrical Engineer Sarah D. Caldwell, Technica l C o mmittee Adminisu-ator Kimberly H. Cervantes, Senio r Technical Conte nt Edito r Barry Chase, Senior Engineer

70--28

Mark Cloutier, Senio r Elecu-ical Engineer Christopher Coache, Senio r Electrical Eng ineer Erik Hohengasser, Technical Lead , Elecu-ical Richard J. Roux, Senio r Electrical Sp ecialist Jeffrey S. Sargent, Principal Elecu-ical Specialist

NAT IO NAL ELECTRJCAL CODE

2020 Edition

ARTICLE 90- INTRODUCTION

NFPA 70

National Electrical Code 2020 Edition

I!vfPORTANI' NOTE: This NFPA document is made available for use subject to important notices and legal disclaimers. These notices and disclaimers appear in all publications containing this document and may be found under the heading "Important Notices and Disclaimers Concerning NFPA Standards. " They can also be viewed at www.njpa.org/disclaimers or obtained on request from NFPA. UPDATES, ALERTS, AND FUTURE EDITIONS: New editions of NFPA codes, standards, recommended practices, and guides (i.e., NFPA Standards) are released on scheduled revision cycles. This edition may be superseded by a later one, or it may be amended outside of its scheduled revision cyde through the issuance of Tentative Interim Amendments (T/As). An official NFPA Standard at any point in time consists of the current edition of the document, together with all TIAs and Errata in effect. To verify that this document is the current edition or to determine if it has been amended by TIAs or Errata, please consult the National Fire Codes® Subscription Service or the "List of NFPA Codes & Standards" at www.nfpa.org/docinfo. In addition fQ IlAs and Errata, the document information pages also include the option t-0 sign up for alerts for individual documents and fQ be involved in the development ofthe next edition.

(C) Relation to Other International Standards. The requirements in this Code address the fundamental principles of protection for safety contained in Section 131 of Internatio na l Electrotechnical Commission Standard 60364-1, E/,ectrical Installations of Buildings. Informational Note: IEC 60364-1, Section 131, contains fimdamental principles of protection for safety that encompass protec• tion against elecu-ic shock, protection against thermal effects, protection against overcurrent, protection against fault currents, and protection against overvoltage. All of these potential hazards are addressed by the requirements in this Code.

90.2 Scope. (A) Covered. This Code covers the installation a nd removal of elecu·ical conductors, equipment, and raceways; signaling and communications condu ctors, equipme nt, and raceways; and optical fiber cables for the following: (1)

(2) (3) (4)

(5)

ARTICLE90 Introduction

90.2

(6)

Public and private prem ises, including buildings, so-u ctures, mobile homes. recreational vehicles, and floating buildings Yards, lots, parking lots, carnivals, and industrial substations Installations of conductors and equipment that connect to the supply of e lectricity Installations used by th e e lectric utility, such as office buildings, warehou ses, garages, machine shops, and recreational buildings, that are not an integral part of a generating plant, substation , or contro l center Installations supplyin g sho1·e power to ships and watercraft in marinas a n d boatyards, including monitoring of leakage current Installations u sed to export electric power from vehicles to premises wiring or for bidirectional current fl ow

(B) Not Covered. This Code does not cover the following: 90. I Purpose.

(1 )

(A) Practical Safeguarding. The purpose of this Code is the practical safeguarding o f persons and property from hazards arising from the use of electricity. This Code is not intended as a design specification or an instruction manual for untrained persons. (B) Adequacy. This Code contains prov1s1ons that are considered necessary for safety. Compliance therewith and proper main tenance result in an installation that is essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion of electrical use. Informational Note: Hazards often occur because of overloading of wiring systems by methods or usage not in conformity with this Code. This occurs because initial wiring did not provide for increases in the use of electricity. An initial adequate installation and reasonable provisions for system changes provide for future increases in the use of elecu-icity.

2020 Edition

NATIONAL ELECTRJCAL CODE

Installations in ships, watercraft other than fl oating buildings, railway rolling stock, aircraft, or autom otive vehicles other th an mobile homes and recreational vehicles Informational Note: Although the scope of this Code indicates that the Codi! does not cover installations in ships, portions of this Code are incorporated by reference into Title 46, Code of Federal Regulations, Parts 110-113.

(2)

(3)

(4)

Installations underground in mines and self-propelled mobile surface mining machinery and its attendant electrical trailing cable Installations of railways fo1· generation, transformation, transmission, energy storage, or d isu·ibution of power used exclu sively for operation of rolling stock or install ations used exclusively for si gnaling an d communications purposes Installations of commun ications equipment under the exclusive conu-ol of communications utilities located outdoors or in building spaces used exclusively for such installation s

70-29

90.2 (5)

ARTICLE 90- INTRODUCTION Installations under the exclusive control of an electric utility where such installations a . Consist of service drops or service laterals, and associated metering, or b. Are on property owned or leased by the electric utility for the purpose of communications, metering, generation, control, transformation, transmission, energy storage, or disu·ibution of electric energy, or c. Are located in legally established easements or rightsof-way, or d . Are located by othe1· written agreements e ither designated by or recognized b y public service commissions, utility commissions, or other regulatory agencies having jurisdiction for such installations. These written agreements shall be limited to installations for the purpose of communications, metering, generation, control, transformation, transmission, energy storage, or distribution of electl"ic energy where legally established easements or rights-of-way cannot be obtained . These installations shall be limited to federal lands, Native American 1·eservations through the U .S. Department of the Interior Bureau of Indian Affairs, military bases, lands controlled by port authorities and state agencies and departments, and lands owned b y railroads.

I nformational Note to (4) and (5): Examples of utilities may include those emilies that are typically designated or recognized by governmental law or regulation by public service/ utility commissions and that install, operate, and maintain el ectric supply (such as generation, transmission, or distribmion systems) or communications systems (such as telephone, CATV, l mernet, satellite, or data services) . Utilities may be subject Lo compliance with codes and standards covering their regulated activities as adopted under governmental law or regulation. Additional information can be found through consultation with the appropriate governmental bodies, such as state regulatory commissions, the Federal Energy Regu latory Commission, and the Federal Communications Commission.

(C) Special Permission. The authority having jurisdiction for enforcing this Code may grant exception for the installation of conductors and equipment that are not under the exclusive control of the e lectric utilities and are used to connect the electric utility supply system to the service conductors of the premises served, provided such installations are outside a building or strucntre, or terminate inside at a readily accessible location nearest the point of entrance of the service conductors.

90.3 Code Arrangement. This Code is divided into the introduction and nine chapters, as shown in Figure 90.3 . Chapters 1, 2, 3, and 4 apply generally. Chapters 5, 6, and 7 apply to special occupancies, special equipment, or other special conditions and may supplement or modify the requirements in Chapters 1 through 7. Chapter 8 covers commun ications systems and is not subject to the requirements of Chapters I through 7 except where the requirements ar e specifically referenced in Chapter 8. Chapter 9 consists of tables that are applicable as referenced. Informative annexes a re not part of the requirements of this Code but are included for informational purposes o nly.

70-30

Chapter 1 -

General

Chapter 2 - Wiring and Protection Chapter 3 - Wiring Methods and Materials Chapter 4 -

Applies generally to all electrical installations

Equipment for General Use

I Chapter 5 Supplements or modifies I Chapter 6 Chapters 1 through 7 { I Chapter 7 -

· • Systems I} IChapter 8 - Commu111cat1ons

I

Chapter 9 - Tables Informative Annex A through Informative Annex J

FIGURE 90.3

I} }

Special Occupancies Special Equipment Special Conditions

I I I

Chapter 8 is not subject to the requirements of Chapters 1 through 7 except where the requirements are specifically referenced in Chapter 8. Applicable as referenced Informational only; not mandatory

Code Arrangement.

90.4 Enforcement. This Code is intended to be suitable for mandatory application by governmental bodies that exercise legal jurisdiction over electrical installations, including signaling and communications systems, and for u se by insurance inspectors. The authority having jurisdiction for enforcement of the Corle has the respon sibility for making interpretations of the rules, for deciding on the approval of equipment and materials, and for granting the special permission contemplated in a number of the rules. By special permission, the authority having jurisdiction may waive specific requirements in this Corle or permit alternative methods where it is assured that equivalent objectives can be achieved by establishing and maintaining effective safety. This Code may require new products, consu·uctions, or materials that may not yet be available at the time the Code is adopted. In such event, the authority having jurisdiction may permit the use of the products, constructions, or materials that comply with the most recent previous edition of this Code adopted by the jurisdiction . 90.5 Mandatory Rules, Permissive Rules, and Explanatory Material. (A) Mandatory Rules. Mandatory rules of this Corle are those that identify actions that are specifically required or prohibited and are characterized by the use of the terms shall or shall not. (B) Permissive Rules. Permissive rules of this Corle are those that identify actions th at are allowed but not required, are normally used to describe options or alternative methods, and are characterized by the use of the terms shall be permitted or shall not be required.

NAT IO NAL ELECTRJCAL CODE

2020 Edition

ARTICLE 90- INTRODUCTION (C) Explanatory Material. Explanato1y material, su ch as references to o ther standards, references to related sectio ns of this Code, or information related to a Code rule, is included in t his Code in the form of informational notes. Such notes are informational o nly and are n ot enforceable as requirements of this

Code. Brackets containing section references to another NFPA document are for informational purposes only and are provided as a guide to indicate the source of the extracted text. These bracketed references immediately follow the extracted text.

90.9

additional spaces allow for futu re increases in electric power and communications circuits. Disu·ibution centers located in readily accessible locations provide convenience and safety of operation. (B) Number of Circuits in Enclosures. It is elsewh ere provided in this Code that the number of circuits confin ed in a single enclosure be varyingly restricted. Limiting th e number of circuits in a single enclosure minimizes the effects from a sh ort circuit or ground fault.

90.9 Units of Measurement.

Informational Note: The fo rmat and language used in this Code follows guidelines established by N FPA and published in the NEC Styli! Manual. Copies of this manual can be obrained from NFPA.

(A) Measurement System of Preference. For th e purpose of this Code, metric units of measurement are in accordance with the modernized metric system known as the International System of U nits (SI) .

(D) Informative Annexes. Nonmandatory inform ation relative to the use of the NEC is provided in informative annexes. Informative annexes are not part of the enforceable requirements of the NEC, but are included for information purposes only.

(B) Dual System of Units. SI units shall appear first, a nd inch pound units sh all immediate ly follow in parentheses. Con version from inch-pound units to SI units shall b e based on hard conversio n except as provided in 90.9 (C) .

90.6 Formal Interpretations. To promote uniformity of interpretation and application of this Code, formal interpretation procedures have b een established and a re found in the NFPA Regulations Govern ing Committee Projects.

(C) Permitted Uses of Soft Conversion. The cases g iven in 90.9(C) (1) through (C) ( 4) sh a ll not be required to use h ard conversion and shall be permitted to u se soft conversion.

90. 7 Examination of Equipment for Safety. For specific ite ms of equipment and mate1·ials referred to in this Code, examination s for safety made under standard conditio n s provide a b asis for approval where the record is made ge nerally available through promulgation by organizations prope rly equipped and qualified for experimental testing, inspections of the run of goods at factories, and service-value determination th rough field inspections. This avoids the necessity for repetition of examinations by different examiners, frequently with inadequate facilities for su ch work, a n d the confusion that would result from con flicting re ports on the suitability of devices and materials examined for a g iven purpose. It is the intent of this Code that factory-installed internal wi ring or the construction of equipment need not be inspected at the time of installation of the equipment, except to detect a lterations or damage, if t h e equipme nt has been listed by a qualified electrical testing laboratory that is recognized as having the facilities described in the preceding paragraph and th at requ ires suitability for installation in accordance with this Code. Suitability shall b e determined by application of requirements that are compatible with this Code. Informational Note No. 1: See requirements in 110.3. Informational Note No. 2: Listed is defined in Article 100. Informational Note No . 3: Informative Annex A conrains a list of product safety standards that are compatible with th is Code.

90.8 Wiring Planning. (A) Future Expansion and Convenience. Plans and specification s th at provide ample s pace in raceways, spare raceways, and

2020 Edition

NATIONAL ELECTRJCAL CODE

(1) Trade Sizes. Where th e actu a l measured size of a product is not the sam e as the nominal size, trade size designators shall be u sed rather than dimensions. Trade practices shall be followed in al I cases . (2) Extracted Material. Where material is extracted from another standard, the context of the orig inal m aterial shall not be compromised or violated. Any editing of th e extracted text sh all be confined to making the style con sisten t with that of the

NEC. (3) Industry Practice. Where in d ustry practice is to express units in inch-pound uni ts, the inclusion of SI units shall not be required. (4) Safety. Where a n egative im p act o n safety would result, soft conversion shall be u sed. (D) Compliance. Conversion fro m inch-pound uni ts to SI units shall b e permitted to be an approximate conversion. Compliance with the numbers shown in either the SI system or the inch -pound system shall constitu te compliance with this

Code. Informational Note No. l : Hard conve rsion is considered a change in d imensions o r properties of an item into new sizes that might o r might not be interchangeable with the sizes used in che original measuremenL Soft conversion is considered a direct mathematical conversion and involves a ch ange in d1e description of an existing measurement but n ot in the actual dimensio n. Informational Note No. 2: SI conversions are based on IEEE/ ASTM SI 10-1997, Standard for the Use of the Intemalional Syswm of Unils (SI): The Modern M etric System.

70-31

CHAPTER!

AITTICLE l 00- DEFINITIONS

Chapter 1 General ARTICLE 100 Definitions Scope. This article contains only those definitions essential to the application of this Code. It is not intended to include commonly defined general terms or commonly defined technical terms from related codes and standards. In general, only those terms that are used in two or more articles are defined in Article 100. Definitions are also found in XXX.2 sections of other articles. Part I of this article contains definitions intended to apply wherever the terms are used throughout this Code. Part II contains definitio ns applicable to installations and equipment operating at over 1000 volts, nominal. Part III contains definitions applicable to Hazardous (Classified) Locations.

Part I. General

Accessible (as applied to equipment). Capable of being reached for operation, renewal, and inspection. (CMP-1) Accessible (as applied to wiring methods). Capable of being removed or exposed without damaging the building structure or finish or not permanently closed in by the structure or finish of the building. (CMP-1) Accessible, Readily (Readily Accessible). Capable of being reached quickly for operation, renewal, or inspections without requiring those to whom ready access is requisite to take actions such as to use tools (other than keys), to climb o ver or under, to remove obstacles, or to resort to portable ladders, and so fo rth. (CMP-1) Informational Note: Use of keys is a common practice under controlled or supe rvised conditions and a common alte rnative to the ready access requirements under such supervised conditions as provided elsewh e re in the NEC.

Adjustable Speed Drive. Power conversion equipment that provides a means of adjusting the speed of an electric m o tor. (CMP-11 ) In formational Note: A variab le frequency drive is o ne type of electronic adjustable speed drive that controls the rotational speed of a n ac electric motor by controlling th e frequency and voltage of die electrical power supplied to th e motor.

Adjustable Speed Drive System. A combination of an adjustable speed drive, its associated motor(s), and auxiliary equipment. (CMP-11) Ampacity. The maximum cu rre nt, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its tempe rature rating. (CMP-6) Appliance. Utilization equipment, generally other than industrial , that is normally built in standa rdized size s or types and is installed or connected as a unit to perform one or more fi.mctions such as clothes washing, air-conditioning, food mixing, deep frying, and so forth . (CMP-17)

70-32

Approved. (CMP-1)

Acceptable to the authority having jurisdiction .

Arc-Fault Circuit Interrupter (AFCI). A device intended to provide protection from the effects of arc faults by recogn izing characteristics unique to arcing and by functioning to deenergize the circuit when an a rc fault is detected. (CMP-2) Askarel. A generic term for a group of nonflammable synthetic chlorinated hydrocarbo ns used as electrical insulating media . (CMP-9) In formational Note: Askare ls of various compositional types are used. Under arcing conditions, the gases produced, while con sistin g predominandy of no n combustible hyd rogen chlo ride, can include var ying amounts of combustible gases, depending on the askarel type.

Attachment Fitting. A device that, by insertion into a locking support and m ounting receptacle, establishes a connection between the conductors of th e attach ed utilizatio n equipment and the branch-circu it conductors con nected to the locking support and m o unting receptacle. (CMP-18) Informational Note: An attachment fitting is different from an attachment plug because no cord is associated with the fitting. An attachment fittin g in combination with a locking support and mounting receptacle secures the associated utilization equipment in place and suppor ts its weight.

Attachment Plug (Plug Cap) (Plug). A device that, by insertion in a receptacle, establishes a connection between the conductors of the attached flexible cord and the conductors connected permanently to the receptacle. (CMP-18) Authority Having Jurisdiction (AFq). An organization, office, or individual responsible for enforcing the requirements of a code or standard, or for approving equipment, materials, an installation, or a procedure . ( CMP-1) Informational Note: The phrase "auth o ri ty having jurisdiction," or its acronym AHJ , is u sed in NFPA documents in a broad ma nne r, since jurisdictions and approval agencies var y, as do d1eir responsibilities. Where public safety is primary, th e authority having j urisdiction may be a federal , state, local, o r 01.her regio nal department or individual such as a fire chief; fire marshal; chief of a fire prevention bureau, labor department, or h ealth department; building official; electrical inspector; o r othe rs having statutory authority. For insuran ce purposes, an insurance inspectio n department, ratin g bureau, or other insura nce company representative may be the aud1o ri ty h aving jurisdiction. In many circumstances, the p roperty owner o r his o r h e r desig nated agent assumes the role of the amh ority having jurisdictio n; at government installations, the commanding officer o r deparm1ental official may be the amhority havingjurisdiction.

Automatic. Performing a fun ction without the necessity of human intervention. (CMP-1) Bathroom. An area including a sink (basin) with one or more of the following: a toilet, a urinal, a tub, a shower, a bidet, or similar plumbing fi xtures. (CMP-2) Battery System. Interconnected battery subsystems consisting o f one or more storage batte ries a nd b attery c hargers, and can

NAT IO NAL ELECTRJCAL CODE

2020 Edition

ARf!CLE 100 include inverters, converters, and associated electrical equipment. (CMP-13)

Bonded (Bonding). Connected to establish electrical continuity and conductivity. (CMP-5) Bonding Conductor or Jumper. A reliable conductor to ensure the required electrical conductivity between meta l parts required to be electrically connected. (CMP-5) Bonding Jumper, Equipment. The connection between two or more portions of the equipment grounding conductor. (CMP-5) Bonding Jumper, Main. The connection between the grounded circuit conductor a nd the equipment grounding conductor, or the supply-side bonding jumper, or both, at the service . (CMP-5) Bonding Jumper, Supply-Side. A conductor installed on t he supply side of a service or within a service equipment enclosure(s), or for a separately derived system, that ensures the required electrical condu ctivity between metal parts required to be electrically connected. (CMP-5) Bonding Jumper, System. The connection between th e grounded c ircuit conductor and the supply-side bonding jumper, or the equipment grounding conductor, or both , at a separately derived system . (CMP-5) Branch Circuit. The circ uit conductors betwee n the final overcurrent device protecting the c ircuit and the outlet (s) . (CMP-2) Branch Circuit, Appliance. A bra nch circuit that supplies energy to one or more o utlets to which appliances are to be connected and that has no permanently connected luminaires that are not a part ofan appliance. (CMP-2) Branch Circuit, General-Purpose. A branch circuit that supplies two or more receptacles or outlets for lighting and appliances. (CMP-2) Branch Circuit, Individual. A branch c ircuit that supplies only one utilization equipment. (CMP-2) Branch Circuit, Multiwire. A branch circuit that consists of two or more ungrounded conductors that h ave a voltage between them, and a grounded conductor that has equal voltage bel:W'een it and each ungrounded conductor of the circuit and that is connected to the neuu·al or grounded conductor of the system. (CMP-2) Building. A su·ucture that stands alone or that is separated from adjoining structures by fire walls. (CMP-1) Cabinet. An enclosure that is designed for e ither surface mounting or flush mounting a nd is provided with a frame, mat, or trim in which a swingi ng door or doors are or can be hung. (CMP-9) Cable, Coaxial. A cylindrical assembly composed of a conductor centered inside a metallic tube or shield, separated by a dielectric materia l, and u sually covered by an insulating jacket. (CMP-16) Cable, Optical Fiber. A factory assembly or field assembly of one or more optical fibers having an overall covering. (CMP-16)

2020 Edition

NATIONAL ELECTRJCAL CODE

DEFINITIONS

CHAPTER I

Informational Note: A field-assembled optical fiber cable is an assembly of one or more optical fibers within a jacket. The jackeL, wiLhom optical fibers, is in srnlled in a manner similar Lo conduit or raceway. Once the j a cket is inscalled, the optical fibers are inserted into the jacket, completing the cable assembly.

Cable, Optical Fiber, Composite. A cable containing optical fibers and current-carrying electrical conductors. (CMP-16) Cable, Optical Fiber, Conductive. A factory assembly of one or more optical fibers having a n overall covering and containing non-current-carrying conductive member(s) such as metallic su·ength member(s), metallic vapor barrier(s), metallic armor, or me tallic sheath. (CMP-16) Cable, Optical Fiber, Nonconductive. A factory assembly of one or more optical fibers having an overall covering and containing no electrically conductive materials. (CMP-16) Cable Routing Assembly. A single channel o r connected multiple channels, as well as associated fittings, forming a su·uctura l syste m that is used to support and route communications wires and cables, optical fiber cables, data cables associated with information technology and communications equipment, Class 2, Class 3, and Type PLTC cables, a nd power-limited fire alarm cables in plenum, riser, and general-purpose applications. (CMP-16) Charge Controller. Equipment that conu·ols de voltage or de current, or both , and that is used to charge a battery or other energy storage device . (CMP-13) Circuit Breaker. A device des igned to open and close a circuit by nonautomatic mea ns and to open the circuit automatically on a predetermined overcurrent w ithout damage to itself when properly applied within its rating. (CMP-10) Informational Note: The automatic opening means can be integral, direct acting with the circu it breaker, or remote from the circuit breaker.

Adjustable (as applied to circuit breakers). A qualifying term indicating that the c ircuit breaker can be set to trip at various values of current, time, or both, within a predetermined range. Instantaneom Trip (as applied lo circuit breakers). A qualifying term indicating that no delay is purposely introduced in the tripping action of the c ircuit breaker. Inverse Time (as applied to circuit breakers). A qualifying term indicating that there is purposely introduced a delay in the tripping action of the circuit breaker, which delay decreases as the magnitude of the current increases. Nonadjustab/,e (as applied to circuit breakers). A qualifying term indicating that the circuit breaker does not have any adjustment to alter the value of the current at which it wi II trip or the time required for its operation. Setting (of circuit breakers). The value of current, time, or both, at which an adjustable c ircuit breaker is set to trip.

Circuit Integrity (Cl) Cable. Cable(s) used for remote-control, signaling, or power-limited system s that supply critical circuits to en sure survivability for continued circuit operation for a specified time under fire conditions. (CMP-3)

70-33

CHAPTER!

AITTICLE l 00- DEFINITIONS

Class 1 Circuit. The portion of the wiring system between the load side of the overcurrent device or power-li mited supply and the connected equipment. (CMP-3) In formational Note: See 725.4 l for voltage and power limitations of Class l circuits.

Class 2 Circuit. The portion of the wiring system between the load side of a Class 2 power source and the connected equipment. Due to its power limitations, a C lass 2 circuit considers safety from a fire initiation standpoint and provides acceptable protection from electric shock. (CMP-3) Class 3 Circuit. The portion of the wiring system between the load side of a Class 3 power source and the connected equipment. Due to its power limitations, a C lass 3 circuit considers safety from a fire initiation standpoint. Since higher levels of voltage and current than for Class 2 are permitted, additional safeguards are specified to provide protection from an electric shock hazard that could be encountered. (CMP-3) Clothes Closet. A nonhabitable room or space intended primarily for storage of garments and apparel. (CMP-1) Communications Equipment. The electronic equipment that performs the telecommun ications operations for the u·ansmission of audio, video, and data, and includes power equipment (e.g., de converters, inverters, and batteries), technical support equipment (e .g., computers), and conductors dedicated solely to the operation of the equipment. (CMP-16) Informational Note: As the telecommunications network transitions to a more data-centric network, computers, routers, servers, and their powering equipment, are becoming essential to the transmission of audio, video, and data and are finding increasing application in communications equipment installations.

Control Circuit. The circuit of a control apparanis or system that carries the elecu·ic signals directing the performance of the controller but does not carry the main power current. (CMP-11) Controller. A device or group of devices that serves to govern, in some predetermined manner, the elecu·ic power delivered to the apparatus to which it is connected. (CMP-1) Cooking U nit, Counter-Mounted. A cooking appliance designed for mounting in or on a counter and consisting of one or more heating elements, internal wiring, and built-in or mountable controls. (CMP-2) Coordination, Selective (Selective Coordination). Localization of an overcurrent condition to restrict outages to the circuit or equipment affected, accomplished by the selection and installation of overcurrent protective devices and their ratings or settings for the full range of available overcurrents, from overload to the available fault current, and for the foll range of overcurrent protective device opening times associated with those overcurrents. (CMP-10) Copper-Clad Aluminum Conductors. Conductors drawn from a copper-clad aluminum rod, ,vith the copper m etallurgically bonded to an aluminum core, where the copper forms a minimum of 10 percent of the cross-sectional area of a solid conductor or each strand of a stranded conductor. (CMP-6) Cutout Box. An enclosure designed for surface mounting that has swinging doors or covers secured directly to and telescoping ,vith the walls of the enclosure. (CMP-9) DC-to-DC Converter. A device that can provide an o utput de voltage and current at a higher or lower value than the input de voltage and current. (CMP-4)

Concealed. Rendered inaccessible by the structure or finish of the building. (CMP-1)

Dead Front. Without live parts exposed to a person on the operating side of the equipment. (CMP-9)

Informational Note: Wires in concealed raceways are considered concealed, even though they may become accessible by withdrawing them.

Demand Factor. The ratio of the maxi mum demand of a system, or part of a system, to the total connected load of a system or the part of the system under consideration . (CMP-2)

Conductor, Bare. A conductor having no covering or electrical insulation whatsoever. (CMP-6)

Device. A unit of an electrical system, other tha n a conductor, that carries or controls electric energy as its principal function . (CMP-1)

Conductor, Covered. A conductor encased within material of composition or thickness that is not recogn ized by this Code as e lectrical insulation . (CMP-6) Conductor, Insulated. A conductor encased within material of composition and thickness that is recognized by this Code as elecu·ical insulation . (CMP-6) Conduit Body. A separate portion of a conduit or tubing system that provides access through a removable cover(s) to the interior of the system at a junction of two or more sections of the system or at a terminal point of the system .

Boxes such as FS and FD or larger cast or sheet metal boxes are not classified as conduit bod ies. (CMP-9) Connector, Pressure (Solderless). A device that establishes a connection between two or more conductors or between one or more conductors and a terminal by means of mechan ical pressure and without the use of solder. (CMP-1) Continuous Load. A load where the maximum current is expected to continue for 3 hours or more. (CMP-2)

70-34

Disconnecting Means. A device, or grnup of devices, or other means by which the conductors of a circuit can be disconnected from their source of supply. (CMP-1) Dormitory Unit. A building or a space in a building in wh ich group sleeping accommodations are provided for more than 16 persons who are not members of the same fam ily in one room, or a series of closely associated rooms, under joint occupancy a nd single management, with or without meals, but ,vithout individual cooking facilities. (CMP 2) Duty, Continuous. Operation at a substantially constant load for an indefinitely long time. (CMP-1) Duty, Intermittent. Operation for a lternate intervals of (1) load a nd no load; or (2) load and rest; or (3) load, no load, and rest. (CMP-1) Duty, Periodic. Intermittent operation i n which the load conditio ns are regularly recu rrent. (CMP-1) Duty, Short-Time. Operation at a substantially constant load for a short and definite, specified time. (CMP-1)

NATIONAL ELECTRJCAL CODE

2020 Edition

ARf! CLE 100 Duty, Varying. Operation at loads, and for intervals of time, both of which may be subject to wide variation. (CMP-1) Dwelling, One-Family. A building that consists solely of one dwelling unit. (CMP-1) Dwelling, Two-Family. A building that consists solely of two dwelling units. (CMP-1)

DEFINITIONS

CHAPTER I

Enclosed. Surrounded by a case, housing, fence, or wall (s) that prevents persons from accidentally contacting energized parts. (CMP-1) Enclosure. The case or housing of apparatus, or the fence or walls su rrounding an installation to prevent personnel from accidentally con tacting energized parts or to protect th e equipment from physical damage. (CMP-1)

Dwelling, Multifamily. A building th at contains three or more dwelli ng units. (CMP-1)

Informational Note: See Table I 10.28 for examples of enclosure types.

Dwelling Unit. A single unit, providing complete and independent living faci lities for one or more persons, including permanent provisions for living, sleeping, cooking, and san itation . (CMP-2)

Energized. Electrically connected to, or is, a source of voltage. (CMP-1)

Effective Ground-Fault Current Path. An intentionally constructed, low-impedance e lectrically conductive path designed and intended to carry current under ground-fault conditions from the point of a ground fault on a wiring system to the electrical supply source and that facilitates the operation of the overcurrent protective device or ground-fault detectors . (CMP-5) Electric Power Production and Distribution Network. Power production, distribution, and utilization equipment and facilities, such as elecu·ic utility systems that are connected to premises wiring and are external to and not controlled by an interactive system. (CMP-13) Electric Sign. A fixed, stationary, or portable self-contained, electrically operated and/ or electrically illuminated utilization equipment with words or symbols designed to convey information or attract attention . (CMP-18) Electric Vehicle (EV). An automotive-type veh icle for on-ro ad use, such as passenger automobiles, buses, trucks, van s, neighborhood electric vehicles, electric motorcycles, and the like , primarily powered by an electric motor that draws current from a rechargeable storage battery, fuel cell, photovoltaic array, or othe r source of e lecu-ic current. Plug-in h ybrid e lectric vehicles (PHEV) are elecu·ic veh icles having a second source of motive power. Off~road, self~propelled electric mobile equipment, such as industrial trucks, hoists, lifts, transports, golf carts, airli ne ground support equipment, tractors, boats, and the like, are not considered e lectric vehicles. (CMP-12) Electrical Circuit Protective System A system consisting of compone n ts and materials intended for installation as protection for specific electrical wiring systems with respect to the disruption of electrical circuit integrity upon exterior fire exposure. (CMP-16) Electrical Datum Plane. A specified distance above a water level above which electrical equipment can be installed and electrical connections can be made . (CMP-7)

Equipment. A ge neral term, including fittin gs, devices, appliances, luminaires, apparatus, machinery, and the like used as a pa.rt of, or in connection with , an el ecu·ical installation. (CMP-1) Equipotential Plane. Accessible conductive parts bo nded together to reduce voltage gradients in a design ated area. (CMP-17) Exposed (as applied to live parts). Capable of being inadvertently touched or approached nearer than a safe dista nce by a person . (CMP-1) Informationa l Note: This term applies to parts that are not suitably guarded, isolated, or insulated.

Exposed (as applie d to wiring methods). On or attach ed to the surface or beh ind panels designed to allow access. (CMP-1) Externally Operable. Capable of being operated without exposing the operator to contact w ith live parts. (CMP-1) Fault Current. The current delivered at a point on the syste m during a short-circuit condition. (CMP-10) Fault Current, Available (Available Fault Current). The largest amount of curre nt capable of be ing delivered at a point o n the system during a short-circuit condition. (CMP-10) Informational Note: A shon-circuit can occur during abnormal conditions such as a fat~t between circu it conductors or a ground faulL See Informational Note Figure 100. 1.

Feeder. All circuit conductors between the service equipment, the source of a separately derived system, or oth er power supply source and the final bra n ch-circuit overcurrent device. (CMP-10) Festoon Lighting. A string of o u tdoor lights that is suspen ded between two points. (CMP-18) Field Evaluation Body (FEB). An organization or part of an organization that performs fi eld evaluations of elecu-ical or other equipment. [790, 20181 (CMP-1)

Electric-Discharge Lighting. Systems of illumination utilizing fluorescent lamps, high-intensity discharge (HID) lamps, or neon tubing. (CMP-18)

Informational Note: NFPA 790-2018, Standard for Compe!en.cy of Third-Party Field Evaluation Bodies, provides guide Ii nes for establishing the qualification and competency of a body performing field evaluations of electrical products and assembles with electrical components.

Electronically Actuated Fuse. An overcurrent protective device th at generally consists of a control module that provides current-sensing, electronically derived time-current characteristics, energy to initiate tripping, and an interrupting module that interrupts current when an overcurrent occurs. Such fuses may or may not operate in a current-limiting fash ion, depending on the type of control selected. (CMP- 10)

Field Labeled (as applied to evaluated products). Equip ment or materials to which h as been attached a label, symbol, or other identify ing m ark of a n FEB indicating the equi pment or materials were evaluated and found to comply with requirements as described in an accompanying field evaluation report. [790, 20181 (CMP-1)

2020 Edition

NATIONAL ELECTRJCAL CODE

70-35

CHAPTER!

AITTICLE l 00- DEFINITIONS

Grounded (Grounding). Connected (connecting) to ground or to a conductive body that extends the ground connection. (CMP-5)

Supply source: ac or de

Grounded, Solidly. Connected to ground without inserting any resistor or impedance device . (CMP-5) Grounded Conductor. A system o r c ircuit conductor that is intentionally grounded. (CMP-5) Available fault current Equipment

Equipment with a short-circuit current rating

I I

I I

: OCPD: Overcurrent protective device _ _,__ __.~' 1 with an interrupting rating

: 1

Available fault c u r r e n t ~

Informational Note: Although an equipment grounding conductor is grounded, it is not considered a grounded conductor.

Ground-Fault Circuit Interrupter (GFCI). A device intended for the protection of personnel that functions to de-energize a circu it or portion thereof within an established period of time when a ground-fault current exceeds the values established for a Class A device. (CMP-2) Informational Note: Class A ground-fault circuit interrupters trip when the ground-fault current is 6 mA or higher and do not trip when the ground-fault current is less than 4 mA. For funher information, see UL 943, Slandard for Ground-Faull Circuil fnlerruf!lers.

Load

Informational Note Figure 100.1

Available Fault Current.

Fitting. An accessory such as a locknut, bushing, or other part of a wiring system that is intended primarily to perform a mechanical rather than an electrical function . (CMP-1) Free Air (as applied to conductors). Open or ventilated environment that a llows for heat dissipation and air flow around an installed conductor. (CMP-6) Fuel Cell. An e lecu·ochem ical system that consumes fuel to produce an electric current. In such cells, the main chem ical reaction used for producing electric power is not combustion. H owever, there may be sources of combustion used within the overall cell system, such as reformers/fuel processors. (CMP-4)

Ground-Fault Current Path. An electrically conductive path from the point of a ground fault on a wiring system through normally non-current-carrying conductors, grounded conductors, equipment, or the earth to the electrical supply source. (CMP-5) Informational Note: Examples of ground-fault current paths are any combination of equipment grounding conductors, metallic raceways, metallic cable sheaths, electrical equipment, and any other eleClrically conductive material such as metal, water, and gas piping; steel framing members; stucco mesh; metal ducting; reinforcing steel; shields of communications cables; grounded conductors; and the earth itself.

Ground-Fault Protection of Equipment. A system intended to provide protection of equipment from damaging line-toground fault currents by operating to cause a disconnecting means to open all ungrounded conductors of the faulted circuit. This protection is provided at current levels less than those required to protect conductors from damage through the operation of a supply circuit overcurrent device. (CMP-5)

Fuel Cell System. The complete aggregate of equipment used to convert chemical fuel into usable elecu·icity and typically consisting of a reformer, stack, power inverter, and auxiliary equipment. (CMP-4)

Grounding Conductor, Equipment (EGC). A conductive path(s) that is part of an effective ground-fault current path and connects normally non-current-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both. (CMP-5)

Garage. A building or portion of a building in which one or more self-propelled vehicles can be kept for use, sale, storage, rental, repair, exhibition, or demonstration purposes. (CMP-1)

I nformational Note No. 1: It is recognized that the equipment grounding conductor also performs bonding.

Informational Note: For commercial garages, repair and storage, see Article 51 I.

Generating Capacity, Inverter. The sum of parallel-connected inverter maximum continuous output power at 40°C in watts or kilowatts. (CMP-4) Ground. The earth. (CMP-5) Ground Fault. An unintentional, e lectrically conductive connection benveen an ungrounded conductor of an electrical circuit and the normally non-current-carrying conductors, metallic enclosures, metallic raceways, metallic equipment, or earth. (CMP-5)

70-36

Informational Note No. 2: See 250.118 for a list of acceptable equipmem grounding conductors.

Grounding Electrode. A conducting object throug h which a direct connection to earth is established. (CMP-5) Grounding Electrode Conductor. A conductor used to connect the system grounded conductor or the equipment to a grounding elecu·ode or to a point on the grounding e lectrode system. (CMP-5) Guarded. Covered, shielded, fenced, enclosed, or otherwise protected by means of suitable covers, casings, barriers, rails, screens, mats, or platforms to remove the likelihood of

NATIONAL ELECTRJCAL CODE

2020 Edition

ARf!CLE 100- DEFINITIONS

CHAPTER I

approach o r contact b y person s or o bjects to a poin t of dan ger. (CMP-1)

The ind ustrial control panel does not include t he controlled equi p men t. ( CMP-11 )

Guest Room. An accommodation combini ng livin g, sleeping, sanitary, and storage fac ilities within a compartm ent. (CMP-2)

Information Technology Equipment (ITE). Equip m ent and syste ms rated 1000 volts or less, normally fou n d in offices or o ther business establish ments and sim ilar e nvironments classified as ordinary locations, tha t are used for creation and m anip ulation of data, voice, vide o , a nd similar signals that are not commu n ications equipment as defined in Part I of Article 100 a n d d o n ot pro cess commun ications circuits as defi ned in 805.2. (CMP-12)

Guest Suite. An accomm odation with two or more con tigu ous roo ms com p rising a compartment, wit h or without doo rs between su ch rooms, that provides living, sleeping, sanitary, and sto rage facilities. (CMP-2) Habitable Room. A room in a building for living, sleeping, eating, or cook ing, but exclud ing bathrooms, toilet room s, closets, hallways, storage or utility spaces, an d similar areas . (CMP-2) Handhole Enclosure. An e nclosure for use in u ndergrou nd systems, provided with a n o pen o r closed botto m , a nd sized to a llow personnel to reach into , but n ot en ter, for the purpose of installing, o perating, or maintaining equi p ment or wiring o r both . (CMP-9) Hermetic Refrigerant Motor-Compressor. A combinatio n consisting of a com p ressor a nd motor, both o f which a re enclosed in the same housing, with no exte rnal sh aft or shaft seals, with the motor operating in the refrigerant. (CMP-11) Hoistway. Any shafi:way, hatchway, well h ole, or oth er vertical opening or space in wh ich an e levator o r d u m bwaiter is designed to ope rate. (CMP-12)

Informational Note: For information on listing requiremencs for both information technology equ ipmenc and communications equipment, see UL 609.50-1-2014, Information Technology Equij>rnenl - Safety - Part 1: General Requirements or UL 62368-1-2014, Audio/Video Information and Communication Technology Equijnnenl Part 1: Safely Requi,wumls.

Information Technology Equipment Room. A room with in th e informatio n techno logy equi pment area th at contains th e information techno logy equipment. [75:3 .3 .14) (CMP-12) Innerduct. A nonmetallic raceway placed within a larger raceway. (CMP-16) Interactive Inverter. An inverter inte nded for use in paralle l with power source(s) such as an electric u tility to su pply commo n loads a n d capable of delivering power to the u tility. (CMP-13) Interactive System. An elecu-ic power production system that is operati ng in parallel wit h and capable of delivering energy to an electric p rimary source supply system. (CMP-4)

Hybrid System. A system comprised of m ultiple power sources . These power sou rces could in clude ph otovoltaic, wind, m icrohydro generators, e n gine-driven generators, and others, but d o not include e lectric power production and d istributio n network system s. Energy storage system s such as batteries, flywheels, or su pe rconducting magnetic sto rage equipment d o not constitute a powe r sou rce for th e purpose of this definitio n. The energy regenernted by a n overhauling (descen d ing) elevator does not constitute a powe r sou rce for the pu rpose of this definition. (CMP-4)

Interrupting Rating. The high est cu rren t at rated voltage th at a device is identified to interrupt under stan dard test cond itions. (CMP-10)

Identified (as applied to equipment). Recognizable as suitable for th e specific pu rpose , fu nction, u se, e nvi ron men t, application, a nd so forth , where described in a partic ula r Code requirement. (CMP-1)

Intersystem Bonding Termination. A d evice that provides a means for connecting intersystem bonding cond uctors for com m u n ications systems to the ground ing electrode system. (CMP-16)

Informational Note: Some examples of ways to determine suitab ility of equipment fo r a specific purpose, envi ronmenc, or application include investigations by a qualified testing laboratory (listing and labeling), an inspection agency, or other organizations concerned with product evaluation.

In Sight From (Within Sight From, Within Sight). Where t his Code specifies that o n e equip me n t shall be "in sigh t from ," "within sight from ," or "wit h in sigh t of," and so forth , another equip m ent, the specified e qui pment is to be visible and not more than 15 m (50 ft) d istant from the oth e r. (CMP-1) Industrial Control Panel. An assembly of two or more components consisting of one of th e following: ( l ) power circuit co mponents o nly, such as moto r controllers, ove rload relays, fosed d isconnect switches, and c ircui t b reakers; (2) control ci rcuit com ponents o nly, such as push buttons, pilot lights, selector switches, timers, switches, a nd conu·ol relays; (3) a combinatio n of power and con trol circuit components. T h ese compone n ts, with associated wiring a nd terminals, are m ounted on, or con tained within, an enclosu re or mou nted on a subpa nel.

2020 Edition

NATIONAL ELECTRJCAt. CODE

Informational Note: Equipment intended to in terrupt current at other than fault levels may have its interrupting rating implied in other ratings, such as horsepower or locked rotor current.

Inverter. Equipment that changes de to ac. (CMP-4) Inverter Input Circuit. Con d uctors con nected to th e de inp ut of an inverter. (CMP-13) Inverter Output Circuit. Conductors connected to the ac o u tpu t o f an inverter. (CMP-13) Inverter, Multimode. Equip ment h aving the capabilities of both the interactive inverter a n d the stand-alo ne inverter. (CMP-4) Island Mode. The operation al mode for stand-alo n e power production equipment or a n isolated microgrid, or for a multimode inverter or an interconnected microgrid th at is d isconnected from a n electric power produc tion a nd d istributio n network or other primary power sou rce. (CMP-4) Informational Note: Isolated m icrogrids are distin guished from interconnected microgrids, which are addressed in Article 705.

Isolated (as applied to location). Not readily accessible to persons u nless special means for access are used. (CMP-1)

70-37

CHAPTER !

AITTICLE l 00- DEFINITIONS

Kitchen. An area with a sink and permanent provisions for food preparation and cooking. (CMP-2) Labeled. Equipment or materials to which has been attached a label, symbol, or other identifying mark of an organization that is acceptable to the authority having jurisd iction and concerned with product evaluation, that maintains periodic inspection of production of labeled equipment or materials, and by whose labeling the manufacturer indicates compliance with appropriate standards or performance in a specified manner. (CMP-1) Informational Note: If a listed product is of such a size, shape, material, or surface texture t h at it is not possible to apply legibly th e complete label to the product, the co mplete label may appear on the smallest unit container in which the product is packaged.

Laundry Area. An area containing or desig ned to contain a laundry tray, clothes washer, o r clothes dryer. (CMP-2) Lig hting Outlet. An outlet intended for the direct connection ofa lampholder or lumina ire . (CMP-18) Lig hting Track (Track Lighting). A manufactured assembly designed to support and energize lum inaires that are capable of being readily repositioned on the u·ack. Its length can be altered by the addition or subtraction of sectio ns of track. (CMP-18) Listed. Equipment, materials, or services included in a list published by a n organization that is acceptable to the authority having jurisdiction and conce rned with evaluation of products or services, that maintains periodic inspection of production of listed equipment or materials or periodic evaluation of services, and whose listing states th at e ither the equipment, material, or service meets appropriate designated standards or has bee n tested and found suitable for a specified purpose. (CMP-1) Info rmatio nal Note: The means fo r identifyi ng listed equipment may vary fo r each o rganizatio n concerned with p roduct evaluation, some of which do not recognize equipment as listed unless it is a lso labeled. Use of the system employed by the listing organization a llows th e auth oricy h avingjurisdiction to identify a listed p roduct.

Live Parts. Energ ized conductive components. (CMP-1) Location, D amp . Locations protected from weather and not subject to saturation with water or other liquids but subject to moderate degrees of m o isture. (CMP-1) Informational Note: Examples of such locations include partially protected locations under canopies, marquees, roofed open porches, and like locations, and interio r locations subject to moderate degrees of moisture, such as some basements, some barns, and some cold-storage warehouses.

Location, D ry. A location not normally subject to dampness or wetness. A location classified as dry may be temporarily subject to dampness or wetness, as in the case of a building under construction . (CMP-1) Location, Wet. Installatio ns underground or in concrete slabs or masonry in direct con tact with the earth; in locatio ns subject to saturation with water or other liquids, suc h as ve hicle washin g areas; and in unprotected locations exposed to weather. (CMP-1) Luminaire. A complete lighting unit cons1sung of a lig ht source such as a lamp or lamps, together with the parts

70-38

designed to position the light source and connect it to the power supply. It may also include parts to p rotect the light source or the ballast or to distribute the light. A lampholder itself is not a luminaire . (CMP-18) Messenger o r Messenger Wire. A wire that is run along with or integral with a cable o r conductor to provid e mechanical support for the cable o r conductor. (CMP-6) Mo tor Con trol Center. An assembly o f o ne or more enclosed sections having a common power bus and princ ipally containing motor contro l units. (CMP-11) Multioutlet Assembly. A type of surface, flush , or freestanding raceway designed to ho ld conducto rs and receptacles, assembled in the fie ld or at the factory. (CMP-18) Neutral Conductor. The conductor connected to the neutral point of a system that is inte nded to cany current under normal condi tions. (CMP-5) Neutral Point. The common point on a wye-connection in a polyphase system or midpoint o n a sin gle-phase, 3-wire syste m , or midpo int of a sing le-phase portion of a ~phase delta system , or a midpoint ofa 3-wire, direct-current syste m. (CMP-5) Informational Note: At the neutral poim of the system, the vectoria l su m of th e nominal voltages from all other p hases within the system that utilize the neutral, with respect to th e neutral po int, is zero potential.

Nonautomatic. Requiring human interve ntio n to pe1form a function . (CMP-1) Nonlinear Load. A load where the wave sh ape of the steadystate current does not follow the ,vave shape of the appl ied voltage. (CMP-1) I nformational Note: Electron ic equipment, e lectronic/ electricdischarge lighting, adjustable-speed drive systems, and similar equipment may be nonlinear loads.

Outlet. A point on the wiring system at which cu rrent is taken to supply utilization equipme nt. (CMP-1) O utline Ligh ting. An arrangement of incandesce nt lamps, electric-discharge lighting, or other electrically powe red light sources to outline o r call attention to certa in fe atures such as the shape of a building or the decoratio n of a window. (CMP-18) Overcurren t. Any cu rre nt in excess of the rated curre nt o f equipment o r the ampacity of a conductor. It m ay result from overload, sh ort c ircu it, or ground fault. (CMP-10) Informational Note: A current in excess of rating may be accommodated by certain equipment and conductors for a given set of conditions. The refore, the rules for overcurrent protection are specific for panicular situations.

Overcurrent Protective Device, Branch-Circuit. A device capable of providing protection for service, feeder, and branch c ircuits and equipment over the full range of overcu rrents be tween its rated current and its inte rrnpting rating. Such devices are provided with interrupting ratings appropriate for the intended use but n o less than 5000 amperes. (CMP-10) Overcurren t Protective D evice, Supplementary. A device intended to provide limited overcurrent protection for specific applications and utilization equipment such as luminaires and applia nces. Th is lim ited protection is in addition to the protec-

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARf!CLE 100 tion provided in the required branch circuit by the branchcircuit overcurrent protective device. (CMP-10) Overload. Operation of equipment in excess of normal, follload rating, o r of a conductor in excess of its a mpacity that, when it persists for a sufficient length of time, would cause damage or dangerous overheating. A fault, such as a short circuit or ground fault, is not a n overlo ad. (CMP-10) Panelboard. A sing le panel or group of panel units designed for assembly in the form of a single panel, including buses and automatic overcurrent devices, and equipped with or without switches for the control of light, heat, or power circuits; designed to be placed in a cabinet or cutout box placed in or against a wall, partition, or other suppo rt; and accessible only from the front. (CMP-9) Photovoltaic (PV) System. The total components, circuits, and equipm ent up to and including the PV system disconnecting means that, in combination, conve rt solar energy into electric energy. (CMP-4) Pier. A strucntre extending over the water and supported on a fixed foundation (fixed pier), or on flotation (floating pier), that provides access to the water. (303:3 .3.1 7 ] (CMP-7) Pier, Fixed. Pier constructed on a permanent, fixed foundation , su ch as on piles, that permanently establishes the elevation of the structure deck with respect to land. [303:3.3 .1 7 .21 (CMP-7) Pier, Floating. Pier designed with inherent flotation capability that allows the structure to float on the water surface and rise a nd fall with water level changes. [303:3 .3.1 7.31 (CMP-7) Plenum. A compartment or chamber to which one or more air ducts are connected and that forms part of the air d istribution system. (CMP-3) Power Outlet. An enclosed assembly that may include receptacles, circuit breakers, foseholders, fused switches, buses, and ,van-hour meter mounting means; intended to supply and control power to mobile homes, recreational vehicles, park trailers, or boats or to serve as a means for d istributing power required to operate mobile or temporarily installed e quipme nt. (CMP-7) Power Production Equipment. Electrical generating equipment supplied by any source other than a utility service, up to the source system disconnecting means. (CMP-4) Informational Note: Examples of power p roduction equ ipment include such items as generators, solar photovoltaic systems, and fuel cell systems.

Power-Limited Tray Cable (PLTC). A factory assembly of two or more insulated condu ctors rated at 300 volts, with o r without associated bare or insulated equipment grounding conductors, under a nonmetallic jacket. (CMP-3) Premises Wiring (System). Interior and exterior wiring, including power, lighting, conu-ol, a nd sig nal circuit wiring together with all the ir asso ciated h a rdware, fittings, and wiring devices, both permanently and temporarily installed . This includes (a) wiring from the service po int or power source to the outlets or (b ) wiring from and including the power source to the outlets where there is no service point.

2020 Edition

NATIONAL ELECTRJCAL CODE

DEFINITIONS

CHAPTER I

Such wiring does not include wiring internal to appliances, 1uminaires, mo tors, conu·ollers, motor control centers, and similarequipment. (CMP-1 ) Informationa l Note: Power sources include, but are not limited to, interconnected or stand-alone batteries, solar photovoltaic systems, other distributed generation systems, or generators.

Prime Mover. The m achine that supplies the mecha nical horsepower to a generator. (CMP-13) Qualified Person. One who has ski lls and knowledge re lated to the construction a nd operation of the electrical equipment and installations and has received safety training to recognize and avoid the h azards involved. (CMP-1) Informational Note: Refer to NFPA 70£-2018, Standard for Electrical Safely in lhe Worl,J;lace, for electrical safety training requirements.

Raceway. An enclosed channe l designed expressly for holding wires, cables, or busbars, with additional fun ctions as permitte d in this Code. (CMP-8) Informational Note: A raceway is identified with in specific article definitions.

Raceway, Communications. An enclosed channel of n o nmetallic m aterials designed expressly for ho lding communications wires and cables; optical fiber cables; data cables associated with information technology a nd communications equipme nt; Class 2, Class 3, and Type PLTC cables; and power-limited fire alarm cables in ple num , riser, and general-purpose applications. (CMP-16) Rainproof. Constructed, protected, o r treated so as to prevent rain from interfering with the successfol operation of the apparanis under specified test conditions. (CM P-1) Raintight. Constructed or protected so that exposure to a beating rain will not result in the e ntrance of water unde r specified test conditions. (CMP-1) Receptacle. A contact device installed at the outlet for the connection of a n attachment plug, or for the d irect connectio n of elecu·ical u tilization equipment designed to m a te with the corresponding contact device. A single receptacle is a single contact device with no other contact device on the same yoke or strap. A multiple receptacle is two or mo re contact devices on the same yoke or strap. (CMP-18) Informational Note: A duplex receptacle is an example of a multiple receptacle that has two receptacles on the same yoke or strap.

Receptacle Outlet. An outlet where one or more receptacles are installed. (CMP-18) Reconditioned. Electromechanical system s, equipment, apparatus, or components th at are restored to operating cond itions. This process differs from n orm al servicing of equipment that remains within a facility, or replacement o f listed equipment o n a one-to-one basis. (CMP-10) Informational Note: The term reconditioned is frequently referred to as rebuill, nf urbished, or ,wwnufactwrd.

Remote-Control Circuit. An y electrical circuit that controls any other circuit thro u gh a relay or an equivalent device . (CMP-3)

70-39

CHAPTER !

AITTICLE l 00- DEFINITIONS

Retrofit Kit. A general term for a complete subassembly of parts and devices for field conversion of utilizatio n equipment. (CMP-18) Sealable Equipmen t. Equipment enclosed in a case or cabinet that is provided with a means of sealing or locking so that live parts cannot be made accessible without opening the enclosure. (CMP-1) Informational Note: The equ ip ment may or may not be operable without opening the e nclosure.

I nformational Note: T h e service point can be described as die point of demarcation between where the serving utility ends and the premises wiring begins. The serving utility generally specifies the location of th e service point based on th e conditions of service.

Short-Circuit Curren t Rating. The prospective symmetrical fau lt current at a nominal voltage to wh ich an apparatus or syste m is able to be connected without sustaining damage exceeding defined acceptance criteria. (CMP-10)

Separately Derived System. An electrical source, other than a service, having no direct connection(s) to circuit conductors of any o ther electrical source other than those established by grounding and bonding connections. (CMP-5)

Show Window. Any window, including windows above d oors, used or designed to be used for the display of goods or advertising material, whether it is fully or partly enclosed or entirely open at the rea r and whether o r n ot it h as a platfo r m ra ised higher than the street fl o or leve l. (CMP-2)

Service. The conductors and equipment connecting the serving utili ty to the wiring system of the premises served . (CMP-10)

Signaling Circuit. Any electr ical circuit that ene rgizes signaling equi pment. (CMP-3)

Service Cable. Service conductors made up in the form of a cable. (CMP-10) Service Conductors. The conductors from the service point to the service discon necting mea ns. (CMP-10) Service Conductors, Overhead. The overhead conductors between the service point and the first point of connection to the service-entrance conductors at th e building or other structure . (CMP-10) Service Conducto rs, Underground. The underground conductors between the service point a nd the first point of connection to the serv ice-entrance conductors in a terminal box, meter, or other enclosure, inside or outside the building wall. (CMP-10) Informational Note: Where th e re is no termina l box, meter, or oth er enclosure, the point of connection is conside red to be the point of e n tra nce of th e service conductors into the building.

Service Drop. The overhead conductors between the serving utility and the service point. (CMP-10) Service-Entrance Conductors, Overhead System. The service condu ctors between the terminals of the service equipment and a point usually outside the building, clear of building walls, where joined by tap or splice to the se rvice drop or overhead service conductors. (CMP-10) Service-Entrance Conductors, Underground System. The service conductors between the terminals o f the service eq uipment and the point of connection to the service lateral or u n derground service conductors. (CMP-10) Informational Note: Wh ere service equ ipment is located outside th e building walls, d1ere may be no service-entrance conductors o r they may be entire ly omside the bu ilding.

Service Equipment. The necessary equipment, consisting of a circuit breaker(s) or switch(es) and fuse(s) and their accessories, connected to the serv ing utility and intended to constitute the ma in control and disconnect of the serving utility. (CMP-10) Service Lateral. T he underground conductors between the utility electric supply system and the service point. (CMP-10) Service Point. The point of connection betv, een the facilities of the serving utility and the premises wiring. (CMP-10 )

Single-Pole Separable Connector. A device that is installed at the ends of portable, flexible, sing le-conductor cable that is used to establish connection or disconnection between two cables or one cable and a s ingle-pole, panel-mounted separable connector. (CMP-18) Special Permission. The written consent o f the authority having jurisdictio n. (CMP-1) Stand-Alone System. A syste m that is capable of supplying power independent of an electric power production and distribution network. (CMP-4) Structure. That which is built or consu·ucted, other than equ ipment. (CMP-1) Surge Arrester. A protective device for limiting surge voltages by d ischarging or bypassing surge current; it also prevents continued flow of follow current while remaining capable of repeating these functio ns. (CMP-10) Surge-Protective D evice (SPD). A protective device for limiti ng u·ansient voltages by d iverting or limiting surge current; it also prevents continued flow of follow current while rema ining capable of re peating these fonctions and is d esignated as follows: Type l: Permanently connecte d SPDs intended for installation between the secondary of the service transformer a nd the line side of the service disconnect ove1·current device. Type 2: Permanently connected SPDs intended for installation on the lo ad side of the service disconnect overcu rrent device, including SPDs located at the branch panel. Type 3: Point of utilization SPDs. Type 4: Component SPDs, includ ing discrete compo nents, as well as asse mblies. (CMP-10) Informational Note: Fo r furd1er informatio n o n Type I , Type 2, Type 3, and Type 4 SPDs, see UL 1449, Standard for Surge Prowclive Devices.

Switch, Bypass Isolation. A manual, nonautomatic, or autom atic o perated device used in conjunction with a transfer switch to provide a means of directly connecting load conductors to a power source and o f d isconnectin g the transfer switch. (CMP-13) Switch, General-Use. A switch inte nded for use in general distribution and bra nch circuits. It is rated in a mperes, and it is

70-40

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARf!CLE 100 capable of interrupting its rated current at its rated voltage . (CMP-9)

Switch, General-Use Snap. A form of general-use switch constructed so that it can be installed in device boxes or on box covers, or otherwise used in conjunction with wiring systems recognized by this Code. (CMP-9) Switch, Isolating. A switch intended for isolating an electrical circuit from the source of power. It has no interrupting rating, and it is intended to be operated only after the circuit has been opened by some other means. (CMP-9) Switch, Motor-Circuit. A switch rated in h orsepower that is capable of interrupting the maximum operating ove rload current of a motor of the same horsepower rating as the switch at the rated voltage . (CMP-11) Switch, Transfer. An auto matic o r nonautomatic device for transferring one or more load conductor connections from one power source to another. (CMP-13) Switchboard. A large sing le panel, frame, or assembly of panels on which are mounted on the face, back, or both, switches, overcurrent and other protective devices, buses, and usually instruments . These assemblies are generally accessible from the rear as well as from the front and are not intended to be installed in cabinets. (CMP-9) Switchgear. An assembly completely enclosed on all sides and top with sheet metal (except for ventilating open ings and inspection windows) and containing primary power circuit switching, interrupting devices, or both, with buses and connections. The assembly may include control and auxiliary devices. Access to the interior of the enclosure is provided b y doors, removable covers, or both. (CMP-9) Informational Note: All switchgear subject to NEC requiremenlS is metal enclosed. Switchgear rated below 1000 \I or less may be identified as "low-voltage power circuit breaker switchgear." Switchgear rated over 1000 \I may be identified as "metalenclosed switchgear" or "metal-clad switchgear." Switchgear is available in non-arc-resistant or arc-resistant constructions.

Thermal Protector (as applied to motors). A protective device for assembly as an integral part of a motor or motorcompressor that, when properly applied, protects the motor against dangerous overheating due to overload and failure to start. ( CMP-11 ) Informational Note: The thermal protector may consist of one or more sensing elemenlS integral with the motor or motorcompressor and an external control device.

Thermally Protected (as applied to motors). A motor or motor-compressor that is provided with a thermal protector. (CMP-11 )

Ungrounded. Not connected to ground or to a conductive body that extends the ground connection. (CMP-5) Uninterruptible Power Supply. A power supply used to provide alternating current power to a load for some period of time in the event ofa power fa ilure. (CMP-13) Informational Note: In addition, it may provide a more constant vo ltage and frequency supply to the load, reducing the efleclS of vo ltage and frequen cy variations.

DEFINITIONS

CHAPTER I

Utilization Equipment. Equipment that utilizes electric energy for electronic, electromechanical, chemical, h eating, lig hting, or similar purposes. (CMP-1) Voltage (of a circuit). The greatest root-mean-square (rms) (effective) d ifference of potential bet\veen any t\vo conductors of the circuit concerned. (CMP-1) Informational Note: Some systems, such as 3-phase 4-wire, single-phase 3-wire, and 3-wire direct current, may have various circuits of various voltages.

Voltage, Nominal. A nominal value assigned to a circuit or syste m for the purpose of conven iently designating its voltage class (e.g., 120/ 240 vol ts, 480Y/ 277 volts, 600 volts) . (CMP-1) Informational Note No. 1: The actual voltage at which a circuit operates can vary from the nominal within a range that permits satisfactory operation of equipment. Informationa l Note No. 2: See ANSI C84.l-2011, Vollage Ratings for t:kclric Power Syslems and t.quijmuml (60 Hz). Informational Note No. 3: Certain battery unilS may be considered to be rated at nominal 48 volts de, but may have a charging float voltage up to 58 volts. In de applications, 60 volts is used to cover the entire range of float voltages.

Voltage to Ground. For grounded circuits, the voltage between the g iven conductor and that point or conductor of the circuit that is grounded; for ungrounded circuits, the greatest voltage between the g iven conductor and any other conductor of the circuit. (CMP-1) Vl'atertight. Con structed so that m oistu re will not enter the enclosure unde r specified test conditions. (CMP-1) Weatherproof. Con su·ucted or protected so that exposure to the weather will not interfere with su ccessful operation. (CMP-1) Informational Note: Rainproof, raintight, or watertight equipment can fulfill the requiremenlS for weatherproof where varying ,-v eather conditions other than wetness, such as snow, ice, dust, or ten1perature extremes, are not a factor.

Part II. Over 1000 Volts, Nominal Electronically Actuated Fuse. An overcurrent protective device that generally consists of a control module that provides current sensing, electronically derived time-current characteristics, e ne rgy to initiate tripping, and a n interrupting module that interrupts current when an overcurrent occurs. Electronically actuated fuses may or may not operate in a currentlimiting fashion, depending o n the type of control selected. (CMP-10) Fuse. An overcurrent protective device with a circuit-opening fusible part that is heated a nd severed by the passage of overcurrent throug h it. (CMP-10) Informational Note: A fuse comprises a ll the parts that form a unit capable of performing the p1·escribed functions. It may or may not be the complete device necessary to connect it into an electrical circuit.

Controlled Vented Power Fuse. A fuse with provision for controlling discharge circuit interruption such that no solid materia l may be exhausted into the su rrounding atm osphere. Informational Note: The fi.1se is designed so that discharged gases will not ignite or damage insulation in the path of the

2020 Edition

NATIONAL ELECTRJCAL CODE

70-41

CHAPTER!

AITTICLE l 00- DEFINITIONS

discharge or propagate a flashover lO or between grounded members or conduction members in the path of the discharge where the distance between the vent and such insulation or conduction members conforms to manufacwrer's recommendations.

Part III. Hazardous (Classified ) Locations (CMP-14). Aircraft Painting Hangar. An aircraft hangar constructed for the express purpose of spray/ coating/ dipping applications and provided with dedicated ventilation supply and exhaust.

Expulsion Fuse Unit (l!.xpulsion Fuse). A vented fuse unit in which the expulsion effect of gases produced by the arc and lining of the fuseholder, e ither alone or aided by a spring, extinguishes the arc.

Associated Apparatus. Apparatus in which the circuits are not necessarily intrinsically safe themselves but that affects the energy i n the i ntri nsically safe c ircui ts and is relied on to maintain intrinsic safety. Such apparatus is one of the following:

Nonvented Power Fuse. A fuse without intentional provision for the escape of arc gases, liquids, or solid particles to the atmosphere during c ircuit interruption .

(l)

Power Fuse Unit. A vented, nonvented, or con trolled vented fuse unit in which the arc is extinguished by being drawn through solid material, granular material, or liquid, either alone or aided by a spring.

(2)

Informational Note No. I: Associated apparatus has idemified imrinsically safe connections for imrinsically safe apparatus and also may have connections for nonintrinsically safe apparatus.

Vented Power Fuse. A fuse with provision for the escape of arc gases, liquids, or solid particles to the surrounding atmosphere during c ircuit interruption .

Informational Note No. 2: An example ofassocimed apparatus is an intrinsic safety barrier, which is a network designed lO limit the energy (voltage and currem) available lo the protected circuit in the hazardous (classified) location, under specified fault conditions.

Multiple Fuse. An assembly of t\vo or more single-pole fuses . (CMP-10) Substation. An assemblage of equipment (e.g., switches, interrupting devices, c ircuit breakers, buses, and transformers) through which electric energy is passed for the purpose of distribution, switching, or modifying its characteristics. (CMP-9) Switching Device. A device designed to close, open, or both, one or more electrical circuits. (CMP-1) Circuit Breake1: A switching device capable of making, carrying, and interrupting currents under normal c ircuit conditions, and a lso of making, carrying for a specified time , and interrupting currents under specified abnormal c ircuit conditions, such as those of short c ircuit. Cutout. An assembly of a fuse support with either a fuseholder, fuse carrier, or d isconnecting blade. The foseholder or fi.tse carrier may include a conducting e lement (fuse link) or may act as the d isconnecting blade by the inclusion of a nonfosible member. Disconnecting Means. A device, group of devices, or other means whereby the condu ctors of a circuit can be disconnected from their source of supply. Disconnecting (or Isolating) Suritch (Disconnectm; lsolatm). A mechanical switching device u sed for isolating a circuit or equipment from a source of power. Interrupter Switch. A switch capable of making, carrying, and interrupting specified currents. Oil Cutout (Oil-Filled Cutout). A cutout in wh ich all or part of the fuse support and its fuse link or disconnecting blade is mounted in oil with complete immersion of the contacts and the fusible portion of the condu cting element (fuse link) so that a rc interruption by severing of the fuse link or by opening of the contacts will occur under oil. Oil Switch. A switch having contacts that operate under o il (or askarel or other suitable liquid) . Regulator Bypass Switch. A specific device or combination of devices desig ned to bypass a regulator.

70-42

Electrical apparatus that has an a lternative type of protection for use in the appropriate h azardous ( classified) location Electrical apparatus n ot so pro tected that shall not be u sed within a hazardou s (classified) location

Associated Nonincendive Field Wrring Apparatus. App arams in which the circuits are not necessarily n onincendive themselves but that affect the energy in nonincendive field wiring circuits and are relied upon to maintain nonincendive energy levels. Such apparatus are one of the following: (1)

(2)

Electrical apparatus that has an a lternative type of protection for use in the appropriate hazardous (classified) location Electrical apparatus n ot so pro tected that shall not be u sed in a hazardous ( classified) location Informational Note: Associated nonincendive field wiring apparatus has designated associated nonincendive field wiring apparaLUs connections for nonincendive fi eld wiring apparams and may also have connections for other electrical apparams.

Combustible Dust. Dust particles that are 500 m icrons or smaller (i.e ., material passing a U .S. No. 35 Standard Sieve as defined in ASTM El 1-2015, Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves), and present a fire or explosion h azard when dispersed and ignited in a ir. Informational Note: See ASTM El226-2012a, Standard Test Method for t:xplosibility of Dust Clouds, or ISO 6184-1, t:xjJlosion j)rotection syswms - Part 1: Determination of exj)losion indices of combustible dusts in ai,; for procedures for determining the explo-

sib ility of dusts.

Combustible Gas Detection System. A protection technique utilizing stationary gas detectors in ind ustrial establishments. Control Drawing. A drawing or other document provided by the manufacturer of the intrinsically safe or associated apparatus, or of the non incendive fi eld wirin g apparatus or associated nonincendive field \viring a pparan1s, that details the allowed interconnections b et\veen the inu·insi cally safe and associated apparatus or bet\veen the nonincendive fie ld wiring apparams or associated nonincendive field wiring apparatus. Cord Connector. A fitting intended to term inate a cord to a box or similar device and reduce the strain at points of termination and may include an explosionproof, a dustignitionproof, or a flameproof seal.

NATIONAL ELECTRJCAL CODE

2020 Edition

ARf! CLE 100 -

Different Intrinsically Safe Circuits. Inu·insically safe circuits in which the possible interconnections have not been evaluated and identified as intrinsically safe. Dust-Ignitionproof. Equipment enclosed in a manner that excludes dusts and does not permit arcs, sparks, or heat otherwise ge nerated or liberated inside of the enclosu re to cause ig nition of exterior accumulations or atmospheric suspensions of a specified dust on or in the vicinity of the enclosure. Informational Note No. l: For further information on dustignitionproof enclosures, see ANSI/ UL 1203-2015, ExplosionProof and Dust-Ignition-Proof t:leclrical Equifimenl for Hazardous

(Classified) Locations. Informational Note No. 2: Dust-ignitionproof enclosures are sometimes additionally marked Type 9 per NEl\llA 250-2014, Enclosures/or Electrical Equijmienl.

Dusttight. Enclosures constructed so th at dust wi ll not enter under specified test conditions. Informational Note No. 1: For further information, see ANSI/ UL 121201 -2017, Nonincendive t :leclrical Equijmienl for Use in Class I and II, Division 2 and Class III, Divisions 1 and 2 H azardous (Classified) L ocations.

Informational Note No. 2: Enclosure Types 3, 3X, 3S, 3SX, 4, 4X, 5, 6, 6 P, 12, 12K, a nd 13, per NEMA 250-2014, Enclosures for Electrical Equijmienl and ANSI/ UL 50£-2015, EncloS1.tres for Electrical Equijmienl, Environnienlal Considerations, are considered dusttight.

Electrical Resistance Trace Heating "60079-30-1 ". Type of protection for the purpose of producing hea t on the principle of elecu·ical resistance and typically composed of one or more metallic conductors and/ or an elecu·ically conductive material , suitably electrically insulated and protected. Informational Note: See ANSI/ UL 60079-30-1-2017, fat1losive Atmospheres - Part 30-l: l~leclrical Resistance Trace Healing General and Testing Requirements.

Encapsulation "m". Type of protection where e lecu·ical parts that could ignite an explosive atmosphere by either sparking or heating are enclosed in a compound in such a way that this explosive atmosphere cannot be ign ited. Informational Note: See ANSI/ UL 60079-IS-2015, Explosive atmosj1heres - Part 18: Equijmtenl protection IJy encaj1sulation "m ".

Explosionproof Equipment. Equipment enclosed in a case that is capable of withstanding an explosio n of a spec ified gas or vapor that may occur within it and of preventing the ignition of a specified gas or vapor surrounding the e nclosure by sparks, flashes, o r explosion of the gas or vapor within, and that operates at such an external temperature that a surrounding fla mmable atmosphere will not be ignited thereby. (CMP-14) Informational Note No. I: For further information, see ANSI/ UL 1203-2015, Exf1losion-Proof and Dust-Ignition-Proof Electrical Equijirnent for Use in Hazardous (Classified) Locations.

Informational Note No. 2: Explosion proof enclosures are sometimes additio nally marked Type 7 per N EMA 250-2014, Enclosures for Electrical Equipment.

Flameproof "d". Type of protection where the enclosure will withstand an internal explosion of a flammable mixture that has penetrated into the interior, without suffering damag e and ,vithout causing ig nition, through any joints o r strucniral ope nings in the enclosure of an external explosive gas atm osphere

2020 Edition

NATIONAL ELECTRJCAL CODE

DEFINITIONS

CHAPTER I

consisting of one or m ore of the gases or vapors for which it is designed. Informational Note: See ANSI/UL 60079-1-2015, Explosive Atmosfiheres -

Part I: Equipment Protection IJy FlameproofEnclosw~s "d ".

Hermetically Sealed. Equipment sealed against the enu·ance of an external atmosphere where the seal is made by fusion , for example, soldering, brazing, welding, or the fusion of glass to metal. Informational Note: For further information, see ANSI/ ISA-12.12.01-2013, Nonincendive Electrical Equifmient for Use in Class I and II, Division 2, and Class II I, Divisions I and 2 Hazardous (Classi,fied) L ocations.

Increased Safety "e". Type of prntection applied to elecu·ical equipment that does not produce arcs or sparks in normal service and under specified abnormal conditions, in which additional m easures are applied so as to give increased security against the possibility of excessive temperanires a nd of the occurrence of arcs and sparks. Informational Note: See ANSI/UL 60079-7- 20 17, Explosive Part 7: Equipment P rotection iJy Increased Safety "e ".

Atmosphei~s -

Inherently Safe Optical Radiation "op is" . Type of pro tection to minimize the risk of ig nition i n explosive atmospheres from optical radiation where visible or infrared radiation is incapable of producing sufficient energy under normal o r specified fault conditions to ignite a specific explosive atmosphere. Informational Note: See ANSI/UL 60079-2&-20 17, Explosive Atmospheirs - Pa.rt 28: Protection of Equijmient and 1im1smission Systems Using O/ilical Radiation.

Intrinsic Safety "i". Type of protection where a n y spark or thermal effect is incapable of causing igniti o n of a m ixture of flammable or combustible mater ial in ai r under prescribed test conditions. Informational Note: See UL 913-2015, Intrinsically Safe Afijiamlus and Associated AjJ/ia.ratus for Use in Class I, II, and Ill, D ivision 1 Hazardous (Classified) Locations; and ANSI/ UL 60079-11-2013, Explosive Atnwsfilie,rs - Pa.rt II: Equipnienl protection iJy int·1i11sic safely "i".

Intrinsically Safe Apparatus. Apparan1s in which all the circu its are inu·insically safe. Intrinsically Safe Circuit. A circuit in which any spark or therm al effect is incapable of causing ignition of a mixture of fla m mable or combus tible m aterial in air unde r prescribed test conditions. Informational Note: Test cond it ions are described in ANSI/ UL 913-2013, Standard for Safety, I ntrinsically Safe Af1paralus and Associated Ajijiaralus for Use in Class I, II, and I II, Division I, Ha.za,·dous (Classified) L ocalio11s.

Intrinsically Safe System. An assembly o f interconnected intrinsically safe apparatus, associated apparatus, a nd interconnecting cables, in that those parts of the system that may be u sed in hazardous (classified) locations are intrinsically safe circuits. Informational Note: An intrinsically safe system may include more t han one intrinsically safe circuit.

Limited Finishing Workstation. An apparatus that is capable of confining the vapors, mists, residues, dusts, o r deposits that are generated by a spray application process but does no t meet the

70--43

CHAPTER!

AITTICLE l 00- DEFINITIONS

requirements of a spray booth or spray room, as herein defined. [33:3.3.18.l l Informational Nore: See Section 14.3 of NFPA 33, Standard for Sj1my Aj,j,lication Usi11g Flammable or Combustible Materials, for limited finishing workstations.

Liquid Immersion "o". Type of protection where electrical equipment is immersed in a protective liquid in such a way that an explosive atmosphere that may be above the liquid or outside the enclosure cannot be ignited. Informational Nore: See ANSI/ UL 60079-6-2016, Ex-plosiveAtnwspheres - Part 6: Eqztijmumt Jn·otection by liquid immersion "o ".

Major Repair Garage. A building or portions of a building where major repairs, such as engine overhauls, painting, body and fender work, and repairs that require draining of the motor ve hicle fuel tank are performed on motor vehicles, including associated floor space used for offices, parking, or showrooms. [30A:3.3.1 2.l ] Membrane Enclosure. A temporary enclosure used for the spraying of workpieces that cannot be moved into a spray booth where open spraying is not practical due to the proximity to other operations, finish quality, or concerns such as the collection of overspray. Informational Note: See Chaprer 18 of NFPA 33-2016, Standard for Spray Application Using Flammable or Combustible Materials, for information on rhe construction and use of membrane enclosures.

Minor Repair Garage. A building or portions of a building used for lubrication, inspection, and minor automotive maintenance work, such as engine tune-ups, replacement of parts, fluid changes (e.g., oil, antifreeze, transmission fluid, brake fluid, air-condition ing refrigerants), brake system repairs, tire rotation, and similar routine maintenance work, including associated floor space used for offices, parking, or showrooms. [30A:3.3. l 2.2l Mobile Equipment. Equipment with elecu-ical compone n ts suitable to be moved only with mechanical a ids or is provided with wheels for movement by person (s) or powered devices. Motor Fuel Dispensing Facility. That portion of a property where motor fuels are stored a nd d ispensed from fixed equipment into the fuel tanks of motor vehicles or marine craft or into approved containe rs, including all equipment used in connection therewith . [30A:3.3.l l l Informational Nore: Refer ro Articles 510 and 511 with respect to elecrrical wiring and equipmem for orher areas used as lubritoriun1s, service rooms, repair rooms, offices, salesrooms, compressor rooms, and similar locations.

Nonincendive Circuit. A ci1-cuit, other than field wiring, in wh ich any arc or thermal effect produced under intended operating conditions of the equi pment, is not capable, under specified test conditions, of igniting the flammable gas-air, vapor-air, or dust-air mixture. In formational Note: Conditions are described in ANSI/ ISA-12.12.01-2013, Nonincendive Electrical Equipment for Use in Class I and 11, Division 2, and Class Ill, D ivisions I and 2 Hazanlous ( Classifu:d) Locations.

Nonincendive Component. A compone nt having contacts for making or breaking an incendive circuit and the contacting mechanism is constrncted so that the component is incapable of igniting the specified flammable gas-air or vapor-air 70-44

mixture. The housing of a nonincendive component is not intended to exclude the flammable atmosphere or contain an explosion . Informational Nore: For further information, see ANSI/ ISA- 12. 12.01-2013, Nonincendive Electrical Eqztipnu:nt for Use in Class I and II, D ivision 2, and Class Ill, Divisio11s I and 2 Hazardous (Classified) Locations.

Nonincendive Equipment. Equipment having e lectrical/electronic circuiu·y th at is incapable, under normal operating con ditions, of causing ignition of a specified flammable gas-air, vapor-air, or dust-air mixture due to a rcing or thermal means. In formational Nore: For further information, see ANSI / I SA- 12 .1 2.01 -2013, Nonincendive t.1ectrical t,·qztifmu:nt for Use in Class I and 11, D ivision 2, and Class 111, Divisions 1 and 2 Hazardous (Classified) Locations.

Nonincendive Field Wiring. Wir ing that enters or leaves an equipment enclosure and, under normal operating conditions of the equipment, is not capable, due to arcing or thermal effects, of igniting the flammable gas-air, vapor-air, or dust-air m ixmre. Normal operation in cludes opening, shorting, or grounding the field wiring. Nonincendive Field Wiring Apparatus. Apparams intended to be connected to nonincendive field wi ring. Informational Nore: For further information, see ANSI / ISA-12.12.01-2013, Nonincendive Electrical Equifmu:nt for Use in Class I and II, D ivision 2, and Class I11, Divisio11s I and 2 Hazardous (Classified) Locations.

Oil Immersion. Electrical equipment immersed in a protective liquid in such a way th at an explosive atmosphere that may be above the liquid or outside the enclosure cannot be ignited. Optical Radiation. Electromagnetic radiation at wavelengths in vacuum between the region of u·ans itio n to X-rays and the region of u·ansiti on to radio waves, that is approximately between 1 nm and 1000 µm . Informational Note: For additional information on types of protection rhat can be applied [O minimize rhe risk of ignition in explosive atmospheres from optical radiation in the wavelength range from 380 nm Lo I O µm, see ANSI/ UL 60079-28--2017, Explosive Atmospheres - Part 28: Protection ofEquipment and Trcmsmission Systems Using Optical Radiation.

Optical System With Interlock "op sh". Type of protection to m inimize the risk of ign ition in exp los ive atmospheres from optical radiation wh ere visible or in frared radiation is confin ed inside optical fiber or other transmission medium with i nterlock cut-off provided to reliably reduce the unconfined beam strength to safe levels within a specified time in case the confinement fai ls and the radiation becomes unconfined. Informational Note: See ANSI/UL 60079-28--2017, fatJlosive AtnwsfJheres - Part 28: Pmteclion of Equifmu:nt and Transmission Systems Using Optical Radiation.

Outdoor Spray Area. A spray area that is outside the confin es of a building or that has a canopy or roof that does not limit the d issipation of the heat of a fire 01- d ispersion of fl ammable vapors an d does not restrict fire-fig hting access and conu·ol. For the purpose of this standard, an outdoor spray area can be u·eated as an unenclosed sp ray area. [33:3.3.2.3.l J Portable Equipment. Equipme nt with electrical components suitable to be moved by a sing le pe1·son witho u t mechanical aids.

NATIONAL ELECTRJCAL CODE

2020 Edition

ARf! CLE 100-DEFINITIONS

Powder Filling "q". Type of protection where electrical parts capable of igniting an explosive atmosphere are fixed in position and completely surrounded by fi lli ng material (glass or quartz powder) to prevent the ignition ofan external explosive atmosphere.

and 25 mW, or a passive component that does not dissipate more than 1.3 watts and is compatible with the intrinsic safety of the ci rcuit in wh ich it is used. Informational Note No. I: The following apparatus are examples of simple apparatus:

Informational Note: See ANSI/ UL 60079-5-2016, Exfilosive Atmospheres - Parl 5: Eq,.,ifmum.l proleclion fry fiowder filling "q ".

( l)

Pressurized. The process of supplying an enclosure with a protective gas with or without continuous flow, at sufficient pressure to prevent the entrance of combustible dust or ignitible fibers/ flyings.

(2)

Pressurized Enclosure "p". Type of protection for electrical equipment that uses the technique of guarding against the ingress of the external aunosphere, which may be explosive, into an enclosure by maintaining a protective gas therein at a pressure above that of the external atmosphere. Informational Note: See ANSI/ UL-60079-2-2017, Explosive Atmospheres - Part 2: Eqttipmenl protection fry pressurized enclosures "Ji''.

Process Seal. A seal betvveen electrical systems and flammable or combustible process fluids where a failure could allow the migration of process fluids into the premises' wiring system. Protected Optical Fiber Cable. Optical fiber cable protected from releasing optical radiation into the atmosphere during normal operating conditions and foreseeable malfunctions by additional armoring, conduit, cable tray, or raceway. Informational Note: See ANSI/ UL 60079-28--2017, Expl-Osive Atmospheres - Parl 28: Protection of Equijmtenl and 1iw1smission Systems Using Optical Radiation.

Protected Optical Radiation "op pr". Type of protection to minimize the risk of ignition in explosive atmospheres from optical radiation where visible or infrared radiation is confined inside optical fiber or other u·ansmission medium under normal constructions or constructions with additional mechanical protection based on the assumption that th ere is no escape of radiation from the confinement. Informational Note: See ANSI/ UL 60079-28--2017, Explosive Almosj1heres - Part 28: Protection of tquijm,enl and Transmission Systems Using Optical Radiation.

Protection by Enclosure "t". Type of protection for explosive dust atmospheres where electrical equipment is provided with an enclosure providi ng dust ingress protection and a means to limit surface temperatures. Informational Note: For additional information, see ANSI/ U L 60079-31-2015, Exfilosive Atmospheres - Part 31: Equipment Dust Ignition Protection fry Enclosure "l ".

Purged and Pressurized. The process of ( 1) purging, supplying an enclosure with a protective gas at a sufficient flow and positive pressure to reduce the con ce ntration of any flammable gas or vapor initially present to an acceptable level; and (2) pressurization, supplying an enclosure with a protective gas with or without continuous flow at sufficient pressure to prevent the entrance of a flammable gas or vapor, a combustible dust, or an ignitible fiber. Informational Note: For further information, see ANSI/ NFPA 496-2013, Purged and Pmssurized Enclosm~s for Electrical Equipment.

Simple Apparatus. An electrical component or combination of components of simple constrnction with well-defined elecu·ical parameters that does not generate more than 1.5 volts, 100 mA,

2020 Edition

NATIONAL ELECTRJCAL CODE

CHAPTER I

(3)

Passive components; for example, switches, instrument connectors, plugs and sockets, junction boxes, resistance temperature devices, and simple semiconduetor devices such as LEDs Sources of stored energy consisting of sing le components in simple circuits with well-defined parameters; for example, capacitors or inductors, whose values are considered when determining the overall safety of the system Sources of generated energy; for example, thermocouples and photocells, that do not generate more than 1.5 volts, 100 mA, and 25 mW

Informational Note No. 2: For further information, refer to ANSI/ UL 913-2013, Intrinsically Safe Afijiaralus and Associali!d Afifiamlusfor Use in Class I, II, Ill, Division 1, Hazardous (Classified) Locations; and ANSI/UL 60079-11-2013, Explosive Atnwsphems Part 11: Eq,.,ipmenl Protection fry Intrinsic Safely "i. "

Spray Area. Any fully enclosed, partly enclosed, or unenclosed area in which dangerous quantities of flammable or combustible vapors, mists, residues, dusts, or deposits are present due to the operation of spray processes, including (1) any area in the direct path of a spray application process; (2) the interior of a spray booth, spray room, or limited finishing workstation, as herein defined; (3) the interior of any exh aust plenum, eliminator section, or scrubber section; ( 4) the interior of any exhaust duct or exhaust stack leading from a spray application process; (5) the interior of any a ir recirculation path up to and including recirculation particul ate filters; (6) any solvent concentrator (pollution abatement) unit or solvent recovery (distillation) unit; and (7) the inside of a membrane enclosure. The following are n ot part of the spray area: (1) fresh air makeup units; (2) air supply ducts and air supply plenums; (3) recirculation air su pply ducts downstream of recirculation particulate filters; and (4) exhaust ducts from solvent concentrator (pollution abatement) units. [33:3.3.2.31 Informational Note: Unenclosed spray areas are locations outside of buildings or are localized operations within a larger room or space. Such are normally provided with some local vapor extraction/ ventilation system . In automated operations, the area limi ts are the maximum area in the direct path of spray operations. In manual operations, the area limi ts are the maximum area of spray when aimed at 90 degrees to the application surface.

Spray Booth. A power-ventilated enclosure for a spray application operation or process that confines and limits the escape of the material being sprayed, including vapors, mists, dusts, and residues that are produced by the spraying operation and conducts or d irects these materials to an exhaust system. [33:3.3.1 5 l Informational Note: A spray booth is an enclosure or insert within a larger room used for spray/ coating/ dipping applications. A spray booth can be fully enclosed or have open front or face and can include separate conveyor entrance and exit. The spray booth is provided with a dedicated ventilation exhaust with supply air from the larger room or from a dedicated air supply.

Spray Room. A power-ventilated fully enclosed room used exclusively for open spraying of flammable or combustible materials. [33:3.3 .1 61

70-45

110.1

ARTICLE HO-REQUIREMENTS FOR ELECTRICAL INSTALLATIONS or other limitations and other pertinent information may be marked on the equipment, included in the product instructions, or included in the appropriate listing and labeling information. Suitability of equipment may be evidenced by listing or labeling.

Type of Protection "n". Type of protection where electrical equipment, in normal operation, is not capable of igniting a surrounding explosive gas atmosphere and a fault capable of causing ignition is not likely to occur. Informational Note: See ANSI/ U L 60079-15-2013, Explodve Atmospheres - Parl 15: Equipnum.l Proleclion !Jy Type of Proleclion

(2)

Mechanical strength and durability, including, for parts designed to enclose and protect oth er equipment, the adequacy of the protection th us provided Wire-bending and connection space Electrical insulation Heating effects under normal conditions of use and also under abnormal conditions likely to arise in service Arcing effects Classification by type, size, voltage, current capacity, and speci fie use Other factors that contribute to the practical safeguarding of persons using or likely to come in contact with the equipment

"n".

Unclassified Locations. Locations determined to be neither Class I, Divisio n 1; Class I, Division 2; Zone 0; Zone 1; Zone 2; Class II, Division I ; Class II, Division 2; Class III, Division I; Class III, Division 2; Zone 20; Zone 21; Zone 22; nor any combination thereof. Unenclosed Spray Area. Any spray area that is not confined by a limited finishing workstation, spray booth, or spray room, as herein defined. [33: 3.3.2.3 .21 Ventilated. Provided with a means to permit circulation of air sufficient to remove an excess of heat, fumes, or vapors . Volatile Flammable Liquid. A flammable liquid having a flash point below 38°C (100°F), or a flammable liquid whose temperature is above its flash point, or a Class II combustible liquid that has a vapor pressure n ot exceeding 276 kPa (40 psia) at 38°C (100°F) and whose temperanire is above its flash point.

(3) (4) (5) (6) (7) (8)

(B) Installation and Use. Equipment that is listed, labeled, or both shall be installed and u sed in accordance with any instructions included in the listing or labeling. (C) Listing. Product testing, evaluation, and listing (product certification ) shall be performed by recognized qualified electrical testing laboratories and shall be in accordance with applicable product standards recognized as achieving equivalent and effective safety for equipment installed to comply with this

Code.

ARTICLE 110 Requirements for Electrical Installations Part I. General

110.1 Scope. This article covers general requirements for the examination and approval, installation and use, access to and spaces about electrical conductors and eq uipment; enclosures intended for personnel entry; and nmnel installations. Informational Note: See Informative Annex J for information regarding ADA accessibility design.

110.2 Approval. The conductors and equipment required or permitted by this Code shall be acceptable only if approved. Informational Note: See 90.7, Examination of EquipmenL for Safety, and 110.3, Examination, Identification, Installation, and Use of Equipment. See definitions of Aj)j)roved, ldenlified, Labeled, and Liswd.

110.3 Examination, Identification, Installation, Use, and Listing (Product Certification) of Equipment. (A) Examination. In judging equipment, considerations such as the following shall be evaluated: (1)

Suitability for installation and use in conformity with this

Code Informational Note No. I: EquipmenL may be new, reconditioned, refurbished, or remanufacrnred. Informational Note No. 2: Suitability of equipmenL use may be idenLified by a description ma rked on or provided with a product ro identify the suitability of the product for a specific purpose, environment, or application. Special conditions of use

70-46

Informational Note: The Occupational Safety and Health Administration (OSHA) recognizes qualified electrical testing laboratories d,at perform evaluations, resting, and certification of certain products to ensure that they meet the requirements of bod, the construction and general industry OSHA e lectrical standards. If the listing (product certification) is done under a qualified electrical testing laboratory program, this listing mark signifies that the tested and certified product complies with the requirements of one or more app ropriate product safety test standards.

110.4 Voltages. Throughout this Code, the voltage con sidered shall be that at which the ci rcuit operates. The voltage rating of electrical equipment shall not be less than the nominal voltage of a circuit to which it is connected. 110.5 Conductors. Conductors used to carry current shall be of copper, alum inum, or copper-clad alumi num unless otherwise provided in this Code. Where the conductor material is not specified, the sizes given in this Code sh all apply to copper conductors. V.'here other materials are used, the size shall be c hanged accordingly. 110.6 Conductor Sizes. Conductor sizes are expressed in American Wire Gage (AWG) or in circular m ils. 110.7 Wiring Integrity. Completed wiring installations shall be free from short c ircuits, ground faults, or any connections to ground other than as required or pe,,mitted elsewhere in this

Code. 110.8 Wiring Methods. Only wiring meth ods recognized as suitable are included in this Code. The recognized methods of wiring sh all be permitted to be installed in any type of building or occupancy, except as otherwise provided in this Code. 110.9 Interrupting Rating. Equipment intended to interrupt current at fault levels shall have an interrupting rating at n o minal circuit voltage at least equal to the current that is available at the line terminals of the equipment.

NAT IO NAL ELECTRJCAL CODE

2020 Edition

ARTICLE 110-REQUIREMENTS FOR ELECTRICAL INSTALLATIONS Equipment intended to interrupt current at other than fault levels shall have an interrupting rating at nominal circuit voltage at least equal to the current that must be interrupted. 110.10 Circuit Impe dance, Short-Circuit Current Ratings, and Other Characteristics. The overcurrent protective devices, the total impedance, the equipment short-circuit current ratings, and other characteristics of the circuit to be protected shall be selected and coordinated to permit the circuit protective devices used to clear a fault to do so without extensive damage to the elecu·ical equipment of the circuit. This fault shall be assumed to be either between two or more of the circuit conductors or between any circuit conductor and the equipment grounding conductor(s) permitted in 250.118. Listed equipment applied in accordance with their listing shall be considered to meet the requirements of this section. 110.11 Deteriorating Agents. Unless identified for use in the operating environment, no conductors or equipment shall be located in damp or wet locations; where exposed to gases, fomes, vapors, liquids, or other agents that have a deteriorating effect on the conductors or equipment; or where exposed to excessive temperatures. Informational Note No. I: See 300.6 for protection against corrosion. Informational Note No. 2: Some cleaning and lubricating compound s can cause severe deterioration of many plastic materials used for insulating and structural applications in equipment.

Equipment not identified for outdoor use and equipment identified only for indoor use, such as "dry locations," "indoor use only," "damp locations," or enclosure Types 1, 2, 5, 12, 12K, and/ or 13, shall be protected against damage from the weather during construction. Informational Note No. 3: See Table 110.28 for appropriate enclosure-type designations. Informational Note No. 4: Minimum Aood provisions are provided in NFPA 5000-2015 Buildi11g Conslruclion and Safety Code, the International Building Code ( !BC), and the International Residentu,/ Code for One- and Tw(}-Fa11tily Dwellings ( !RC).

110.12 Mechanical Execution of Work. Electrical equipment shall be installed in a neat and workmanlike manner. Informational Note: Accepted industry practices are described in ANSI/ NECA 1-20 15, Standard/or Good Workmanship in 1'1ectrical Construction, and other ANSI-approved installation standards.

(A) Unused Openings. Unused openings, other than those intended for the operation of equipment, those intended for mounting purposes, or those permitted as part of the design for listed equipment, shall be closed to afford protection substantially equivalen t to the wall of the equipment. vVhere metallic plugs or plates are used with nonmetallic enclosures, they shall be recessed a t least 6 mm ( V., in.) from the outer surface of the enclosure. (B) Integrity of Electrical Equipment and Connections. Internal parts of electrical equipment, including busbars, wiring terminals, insulators, and other surfaces, shall not be damaged or contaminated by foreign materials such as paint, plaster, cleaners, abrasives, or corrosive residues. There shall be no damaged parts that may adversely affect safe operation or mechanical strength of the equipment such as parts that are broke n ; bent; cut; or deteriorated by corrosion, chemical action, or overheating. 2020 Edition

NATIONAL ELECTRJCAL CODE

110.14

(C) Cables and Conductors. Cables and conductors insta lled exposed on the surfaces of ceilings and sidewalls shall be supported by the building structure in such a manner that the cables and conductors will not be damaged by normal building u se. Such cables and conductors shall be secured by hardware including straps, staples, cable ties, hangers, or similar fittings designed and installed so as not to damage the cable. The installation shall also conform with 300.4 and 300.11. Nonmetallic cable ties and other nonmetallic cable accessories used to secure and support cables in other spaces used for environmental a ir (plenums) shall be listed as having low smoke and heat release properties. Informational Note No. I: Accepted industry practices are described in ANSI/ NECA/ FOA 301-2009, Standard for lnslalling and Testing Rber 0/1tic Cables, and other ANSI-approved installation standards. Informational Note No. 2: See 4.3 .11.2.6.5 and 4.3.11.5.5.6 of NFPA 90A-2018, Standard for the inslallalion of Air-Conditioning and Venlilaling Systems, for discrete combustible com pone ms installed in accordance with 300.22(C). Informational Note No. 3: Paint, plaster, cleaners, abrasives, corrosive residues, or other contar11inan ts 111ay result in an undetermined a lteration of optical fiber cable properties.

110.13 Mounting and Cooling of Equipment. (A) Mounting. Electrical equipment shall be firmly secured to the surface on which it is mounted. Wooden plugs driven into holes in masonry, concrete, plaster, or similar materials shall not be used. (B) Cooling. Electrical equipment that depends on the natural circulation of air and convection principles for cooling of exposed surfaces shall be installed so that room a irflow over such surfaces is not prevented by walls or by adjacent insta lled equipment. For equipment designed for floor mounting, clearance between top surfaces and a~ Doors and Other Opening Pro/Relives.

Table 110.31 Minimum Distance from Fence to Live Parts Minimtun Distance to Live Parts

Nominal Voltage

1001-13,799 13,800-230,000 Over 230,000

m

ft

3.05 4.57 5.49

15 18

IO

Note: For clearances of conductors fo r specifi c system voltages and typical BIL ratings, see ANSI/ IEEE C2-2017, Nalional Electrical Safety Code.

Informational Note No. 2: A typical 3-h our construction is 150 mm (6 in.) thick reinforced concrete.

2020 Edition

NATIONAL ELECTRJCAL CODE

70-53

110.31

ARTICLE HO -

REQUIREMENTS FOR ELECTRICAL INSTALLATIONS

(B) Indoor Installations.

110.33 Entrance to Enclosures and Access to Working Space.

(1) In Places Accessible to Unqualified Persons. Indoor electrical installa tions that are accessible to unqualified persons shall be made with metal-enclosed equipment. Switchgear, transformers, pull boxes, connection boxes, and other similar associated equipment shall be marked with appropriate caution signs. Openings in ven tilated dry-type transformers or similar openings in other equipment shall be designed so that foreign o bjects inserted through these openings are deflected from energized parts.

(A) Entrance. At least o ne entrance to enclosu res for electrical installations as described in 110.31 not less than 610 mm (24 in. ) wide and 2.0 m (6½ ft) high shall be provided to g ive access to th e working space about electrical equipment.

(2) In Places Accessible to Qualified Persons Only. Indoor electrical installations considered accessible only to qualified persons in accordance with this section shall comply with 110.34, 110.36, and 490.24. (C) Outdoor Installations.

(1) In Places Accessible to Unqualified Persons. Outdoor electrical installations that are open to unqualified persons shall comply with Parts I, II, and III of Article 225. (2) In Places Accessible to Qualified Persons Only. Outdoor electrical installations that have exposed live parts shall be accessible to qualified persons only in accordance with the first paragraph of this section and sh all comply with 110.34, 110.36, and 490.24. (D) Enclosed Equipment Accessible to Unqualified Persons. Ventilating or similar openings in equipment shal l be designed such that foreign objects inserted through these openings are deflected from energized parts. vVhere exposed to physical damage from veh icular traffic, suitable guards shall be provided. Equipment located outdoors and accessible to unqualified persons sha ll be designed such t hat exposed nuts or bolts cannot be readily removed, permitting access to live parts. v\lhere equipment is accessible to unqualified persons a nd the bottom of the enclosure is less than 2.5 m (8 ft) above the floor or grade level, the enclosure door or hinged cover shall be kept locked. Doors and covers of enclosures used sole ly as pull boxes, splice boxes, or junction boxes shall be locked, bolted, or screwed on . Underground box covers that weigh over 45.4 kg (100 lb) shall be considered as meeting this requirement. 110.32 Work Space About Equipment. Sufficient space s hall be provided and maintained about electrical equipment to permit ready a nd safe operation and maintenance of such equipment. ,~'here energized parts are exposed, the minimum clear work space shall be not less than 2.0 m (6½ ft) high (measured vertically from the floor or platform) and the width of the equipment or 914 mm (3 ft) wide (measured parallel to the equipment), whichever is g reater. The depth shall be as required in 110.34(A) . In all cases, the work space shall permit at least a 90-degree opening of doors or hinged pan els. W ithin the heig ht requirements of this section, oth er equipment that is associated with the e lectrical installation and is located above or below the electrical equipment shall be permitted to extend not more than 150 mm (6 in. ) beyond the front of the e lecu·ical e qui pment. Working space required by this section sh all not be used for storage. When normally enclosed live parts are exposed for inspection or servicing, the working space, if in a passageway or general open space, shall be suitably guarded.

70-54

(1) Large Equipment. On switchgear and control pa ne ls exceeding 1.8 m (6 ft) in width , there shall be one enu·ance at each end of the equipment. A single e ntrance to the required working space shall be permitted wh ere e ither of the conditions in ll 0.33(A)( l )(a) or (A)( l )(b ) is met. (a) Unobstructed Exit. Where the location permits a continuous and unobstructed way of exit travel, a single enu·ance to the working space shall be per mitted . (b ) l!.xtra Working Space. ,~ere the depth of the working space is twice that required by l 10.34(A), a single entrance shall be permitted. It shall be located so that the d istance from the equipment to the nearest edge of the entrance is not less than the minimum clear distance specified in Table l 10.34(A) for equipment operating at that voltage a nd in that condition. (2) Guarding. ,~'here bare energized parts at any voltage or insulated energ ized parts above 1000 volts, nominal, are located adjacent to such entrance, they sha ll be suitably guarded. (3) Personnel Doors. Where there are personnel doors intended for entrance to and egress from the working space less than 7.6 m (25 ft) from the nearest edge of the working space, the doors shall open in th e direction of egress a nd be equipped with listed panic hardware or listed fire exit hardware. (B) Access. Permanent ladders or stairways shall be provided to g ive safe access to the working space around elecu·ical equipment installed o n platforms, balcon ies, o r mezzanine floors or in attic or roof rooms or spaces. 110.34 Work Space and Guarding. (A) Working Space. Except as elsewhere required or permitted in this Code, equipment like ly to requi re examination, adjustment, servicing, or maintenance while energized shall have clear working space in the d irection of access to live parts of the e lectrical equipment a nd shall be not less than specified in Table 110.34(A) . Distances sha ll be measured from the live parts, if su ch are exposed, or from the enclosure front or opening if such are enclosed.

Exception: Working space shall not be required in back of equipment such as switchgear or control assemblies where there are no renewable or adjustable parts (such as fuses or switches) on the back and where all connections are accessible fivm locations other than the back. Where rear access is required to work on nonelectrical parts on the back of enclosed equipment, a minimum working space of 762 mm (30 in.) hori.zontally shall be p1vvided. (B) Separation from Low-Voltage Equipment. Where switches, cutouts, or other equipment operating at 1000 volts, nominal, or less are installed in a vault, room , or enclosure wh ere there are exposed live parts or exposed wiring operating at over 1000 volts, nominal, the high-voltage e quipment shall be effectively separated from the space occupied by the low-voltage equipme nt by a suitable partition, fence, or screen .

Exception: Switches or other equipment operating at 1000 volts, nominal, or less and serving only equipment within the high-voltage vault, room, or enclosure shall be permitted to be installed in the high-voltage vault, 1vom, or enclosure without a partition, fence, or screen if accessible to qualified persons only. NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTIC LE 110 -

REQUIREMENT S FO R ELECTRICAL INSTALLATIONS

Table 110.34(A) Minimum Depth of Clear Working Space at Electrical Equipment Minimum Clear Distance

Nominal Voltage to Ground l00l - 2500V 250l - 9000V 9001-25,000 V 25,001 V-75 kV Above 75 kV

Condition l 900 m m (3 ft) l.2 m (4 ft) 1.5 m (5ft) l.8 m (6 ft) 2.5 m (8 ft)

Condition 2

Condition 3

l.2 1.5 1.8 2.5 3.0

1.5 m (5 ft) 1.8 m (6 ft) 2.8 m (9 ft) 3.0 m (JO ft) 3.7 m (12 ft)

m m m m m

(4 ft) (5 ft) (6 ft) (8 ft) (10 ft)

Nore: Where the conditions are as follows: (1) Condition I - Exposed live pans on one side of 1.he working space and no live or grounded parts on the other side of the working space, or exposed live parts on both sides of the working space that are effectively guarded by insulating materials. (2) Condition 2 - Exposed live parts on one side of the working space and grounded pans on 1.he mher side of 1.he working space. Concre1.e, brick, or tile walls shall be considered as grounded. (3) Condition 3 - Exposed live parts on both sides of the working space. (C) Locked Rooms or Enclosures. T he entrance to all build-

ings, vaults, rooms, or enclosu res con tain ing exposed live parts or exposed cond uctors operating at over 1000 volts, n om inal, shall be kept locked unless su ch entrances are under the o bservation of a q ual ified person at all times. Permanent a nd conspicuo us danger sig ns shall be provided . The dan ge r sign shall m eet th e requirem ents in 110.21 (B) and shall read as follows: DANGER -

HIGH VOLTAGE - KEEP O UT

(D) Illumination. Illumination shall be provided for all working spaces about e lectrical eq u ip m e n t. Con trol by au tom atic means only shall not be permitted. The ligh ting outlets shall be arranged so that persons changing lamps or making repairs o n the lig h ting system are not e n dangered by live parts or o ther equip m ent. T he points of conu·ol shall be located so that perso ns a re n o t likely to come in contact with a n y live part or m oving part of th e eq uipment while turning on th e ligh ts. (E) Elevation of Unguarded Live Parts. Unguarded live parts a bove working space shall be maintained at elevatio ns not less than required by Ta ble 11 0.34 (E) .

110.51

(F) Protection of Service Equipment, Switchgear, and Industrial Control Assemblies. Pipes or d u cts fo reign to the elecu·ical installation and requiring pe1·iodic m a in tenance or wh ose malfunction would endanger th e operation of the elecu·ical system shall not be located in the vic ini ty o f th e service equipment, switchgear, or ind ustrial control assemblies. Protection shall be provided where necessary to avoid damage fro m condensation leaks a nd b reaks in su ch foreign systems. Pip ing and oth er facili ties shall n o t be considered foreign if provided for fi re protection of th e electrical installation .

110.36 Circuit Conductors. Circuit con ductors sh all be permitted to be installed in raceways; in cable trays; as metal-cla d cable Type MC; as bare wire, cable, a n d busbars; or as Type MV cables o r con d uctors as provided in 300.37, 300.39, 300.40, and 300.50. Bare live conductors sha ll comply with 490.24. I nsulators, togeth er with th e ir mo u nting and con d uctor attachmen ts, where used as su pports for wires, sing le-con d uctor cables, or b usbars, shall be capable o f safely withsta nd ing th e maxi mum m agnetic forces that would prevail if two or more conductors of a c ircui t were subjected to short-circuit cu rre n t. Exposed runs of insulated wi res and cables that have a bare lead sheath or a b raided o uter covering sh all be su pported in a man ner designed to prevent physical dam age to the b raid or sheath. Supports for lead-covered cables sh all be designe d to prevent electrolysis o f the sheath. 110.40 Temperature Limitations at Terminations. Cond ucto rs shall be permitted to be termi nated based on the 90°C (] 94°F) temperature rating and ampacity as g iven in Table 311.60(C) (67 ) through Table 311.60(C) (86), unl ess o therwise identified . 110.41 Inspections and Tests. (A) Pre-energization and Operating Tests. v\Th ere requi red elsewhere in th is Code, th e complete e lectrical system desig n, includ ing settings fo r protective, switching, and con u·ol circuits, sh all be prepared in advan ce and made availa ble o n request to th e authority h aving j urisdiction a nd shall be tested when fi rst installed o n-site. (B) Test Report. A test report covering th e results of the tests requi red in 110.4 1 (A) sh all be available to th e authority having jurisdiction prio r to energization a n d m ade available to those au thorized to install, operate, test, and ma intain th e system.

Part IV. Tunnel Installations over 1000 Volts, Nominal 110.51 General.

Table 110.34(E) Elevation of Unguarded Live Parts Above Working Space Elevation Nominal Voltage _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _~ Between Phases m ft 1001-7500 V 7501-35,000 V Over 35 kV

2020 Edition

2.7 2.9 Add 9.5 mm per kV above 35 kV

NATIONAL ELECTRJCAL CODE

9 9ft 6 in. Add 0.37 in . per kV above 35 kV

(A) Covered. This part sh all apply to th e installatio n and use of high-voltage power d istribution an d u tilization equip ment that is portable, mobile, or both, such as su bstatio ns, trailers, cars, mo bile sh ovels, d ragli nes, hoists, drills, dredges, com pressors, pumps, con veyors, undergroun d excavators, and the like. (B) Other Articles. The req ui rem ents of this part shall be additional to, or am endatory of, those prescribed in Articles 100 th rough 490 of this Code. (C) Protection Against Physical Damage. Conductors and

cables in tunnels sh all be located above the tunnel fl oor an d so placed or guarded to protect t hem from p hysical damage.

70-55

110.52

ARTIC LE HO -

REQUIREMENTS FOR ELECTRICAL INSTALLATIONS

110.52 Overcurrent Protection. Motor-operated equipment shall be protected from overcurre n t in accordance with Parts III, IV, and V of Article 430. Tran sformers shall be protected from overcurrent in accordance wi th 450.3 . 110.53 Conductors. High-vol tage conductors in tunnels shall be installed in metal conduit or other metal raceway, Type MC cable, or other approved multiconductor cable. Multiconductor portable cable shall be permitted to supply mobile equipment. 110.54 Bonding and Equipment Grounding Conductors. (A) Grounded and Bonded. All non-current-carrying metal parts of e lectrical equipment and all metal raceways and cable sheaths shall be solidly grounded a nd bonded to al l metal pipes and ra ils at the portal and at intervals n ot exceeding 300 m (1000 ft) th roug hout the nmnel. (B) Equipment Grounding Conductors. An equipment grounding conductor shall be run with circuit conductors inside the metal raceway or inside the multiconductor cable jacket. The equipment grounding conductor shall be permitted to be insulated or bare. 110.55 Transformers, Switches, and Electrical Equipment. All transformers, switches, motor controllers, motors, rectifiers, and other equipment installed belowground shall be protected from physical damage by location or gua rding. 110.56 Energized Parts. Bare terminals of transformers, switches, motor controllers, and other equipment shall be enclosed to prevent accidental contact with energized parts. 110.57 Ventilation System Controls. Electrical controls for the ventilation system shall be arran ged so that the airflow can be reversed. 110.58 Disconnecting Means. A switch or circuit b reaker that simultaneously opens all ungrounded conductors of the circuit shall be instal led with in sigh t of each transformer or motor location for d isconnecting the transformer or motor. The switch or circuit breaker for a transformer shall h ave an ampere rating not less than the ampacit:y of the transformer supply conductors. The switc h or c ircuit breaker for a motor shall comply with the applicable requirements of Article 430. 110.59 Enclosures. Enclosures for use in tunnels shall be dripproof, weatherproof, or submersible as required by the environmental conditions. Switch or contactor enclosures shall not be used as junction boxes or as raceways for conductors feeding through or tapping off to other switches, unless the enclosures comply with 312.8 .

Part V. Manholes and Other Electrical Enclosures Intended for Personne l Entry 110.70 General. Electrical enclosures intended for personnel entry and specifically fabricated fo r this purpose sh all be of sufficient size to provide safe work space abo u t electrical equipment with live parts that is likely to require examination, adjustment, se rvicing, or maintenance while energized. Such e nclosures sh all have sufficient size to permit ready installation or withdrawal of the conductors employed without damage to the conductors or to their insulation . They shall comply with this part.

70-56

1'.xception: l-Wiere electrical enclosures covered by Part V of this article are part of an industrial wiring system vperating under conditions of maintenance and supervision that ensure that only qualified persons monitor and supervise the system, they shall be permitted to be designed and installed in accordance with apprvpriate enginee1ing practice. ff required by the authO'lity having jU1isdiction, design documentation shall be provided.

110.71 Strength. Manholes, vaults, and their means of access shall be designed under qualified engineering supervision and shall withstan d all loads likely to be imposed on the strucnires. Informational Note: See ANSI C2-2007, National Electrical Safety

Code, for additional information on the loading that can be expected to bear on underground enclosures.

110.72 Cabling Work Space. A clear work space not less than 900 mm (3 ft) wide shall be provided where cables are located o n both sides, and not less th an 750 mm (2½ ft) where cables are only on o ne side . The vertical headroom shall be not less than 1.8 m (6 ft) u nless the open ing is within 300 mm (1 ft), m easured horizontally, of the adjacent interior side wall of the enclosu re. 1'.xception: A manhole containing only one or more of the following shall be permitted to have one of the horizontal work space dimensions reduced to 600 mm (2 ft) where the other horizontal clear work space is increased so the sum of the two dimensions is not less than 1.8 m (6 ft): (1)

(2) (3)

Optical fiber cables as covered in Article 770 Powet limited fire alarm circuits supplied in accordance with 760.121 Class 2 or Class 3 remote-control and signaling circuits, or both, supplied in accordance with 725.121 0

110.73 Equipment Work Space. \'\/here electrical equipment with live parts that is likely to require examination, adjustm ent, servicing, o r maintenance while en ergized is installed in a manhole, vault, or other enclosure designed for personne l access, the work space and associated requirements in ll0.26 shall be met for installation s o perati ng at 1000 volts or less. Where the installation is over 1000 volts, the work space a nd associated requirements in ll0.34 sh all be met. A manhole access cover that weig hs over 45.4 kg (100 lb) shall be considered as meeting the requirements of l 10.34(C) . 110.74 Conductor Installation. Conductors instal led in manholes and other enclosures intended for personnel enU)' shall be cabled, racked up, or arran ged in an approved manner that provides ready and safe access for persons to enter for installation and maintenance. The installation shall comply with ll 0.74(A) or l 10.74(B), as applicable. (A) 1000 Volts, Nominal, or Less. W ire bending space for conductors operating at 1000 volts or less sh all be provided in accordance with the requirements o f 314.28.

(B) Over 1000 Volts, Nominal. Conductors operati ng at over 1000 volts sh all be provided with bending space in acco rdance with 314.71 (A) and (B), as applicable. Exception: l-Wiere 314. 71(B) applies, each row or column of ducts on one wall of the enclosure shall be calculated individually, and the single row or column that provides the maximum distance shall be used.

110.75 Access to Manholes. (A) Dimensions. Rectan gular access openings sh all not be less than 650 mm x 550 mm (26 in. x 22 in .) . Ro u nd access open-

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTIC LE 110 -

REQUIREMENTS FOR ELECTRICAL INSTALLATIONS

ings in a manhole shall be not less than 650 mm (26 in. ) in diameter. Exception: A manhole that has a fixed ladder that does not obstruct the opening or that contains only one or more of the following shall be permitted to reduce the minimum cover diameter to 600 mm (2 ft): ( 1) (2) (3)

Optical fiber cables as covered in Article 770 Power-limited fire alarm circuits supplied in accordance with 760.121 Class 2 or Class 3 remote-control and signaling circuits, or both, supplied in accordance with 725.121

(B) Obstructions. Man ho le o penings shall be free of protrusions t hat could injure personnel or prevent ready egress. (C) Location. Manhole openings for personnel shall be loca-

ted whe re they are not directly above e lectrica l equipment or conductors in the e nclosure . v\'here this is not practicable, e ither a protective ba rrier or a fi xed ladder shall be provided. (D) Covers. Covers shall be over 45 kg (100 lb) or othenvise designed to require the use of tools to open. They shall be designed or restra ined so they cannot fall into the manhole or protrude sufficiently to contact electrical conductors or equipment within the manhole. (E) Marking. Manhole covers shall have an identifying mark or logo that prominen tly indicates their func tion, such as "electric."

2020 Edition

NATIONAL ELECTRJCAL CODE

110.79

110.76 Access to Vaults and Tunnels.

(A) Location. Access openings for personnel shall be located where they are not directly above electrical equipment or conductors in the enclosure . Other openings shall be permitted over equipment to facilitate installatio n , maintenance, or replacement of equipment. (B) Locks. In addition to compliance with the requirements of 110.34, if applicable , access openings for personn el sha ll be arranged such that a person on the inside can ex it when the access door is locked fro m the outside, or in the case of normally locking by padlock, the locking arrangement shall be such that the padlock can be closed o n the locking system to prevent locking from the o u tside .

110.77 Ventilation. \~The re ma nholes, tunnels, a nd vaults have communicating openings into enclosed areas used by th e public, ventilation to open a ir shall be provided wherever practicable. 110.78 Guarding. Where conductors or equipment, or both, could be contacted by o bjects fal ling or being pushed through a ventilating grating, both condu ctors and live parts sh all be protected in accordance with th e requirements of l 10.27(A) (2) o r 110.31 (B)(l), depe nding on the voltage . 110.79 Fixed Ladders. Fixed ladders sh all be corrosion resistant.

70-57

CHAPTER2

ARTICLE 200- USE AND IDENTIFICATION OF GROUNDED CONDUCTORS

Chapter 2 Wiring and Protection Exception No. 1: The requirement for gmuping or identifying shall not apply if the branch-circuit or feeder conductors enter from a cable or a raceway uniqite to the circuit that makes the g,·O'llping obvious.

ARTICLE 200 Use and Identification of Grounded Conductors 200.1 Scope. This article provides requirements for the following: (1) (2) (3)

Identification of terminals Grounded conductors in premises wiring systems Identification of g rounded conductors

conductors

shall

comply

200.6 Means of Identifying Grounded Conductors. (A) Sizes 6 AWG or Smaller. An insulated grounded conductor of 6 AWG or smaller shall be identified by one of the following means:

Informational Note: See Article 100 for definitions of Grounded Conductor, t,quipment Grounding Conductor, and Grounding Ekctrode Conductor.

200.2 General. Grounded 200.2 (A) and (B) .

Exception No. 2: The requirement for grO'llping or identifiing shall nol apply where &ranch-circuit conditctors pass through a box or conduit body without a loop as described in 314.16(B)(l) or without a splice or termination.

(1) (2)

with (3)

(A) Insulation. The grounded conductor, if insulated, shall have insulation that is ( I) suitable, other than color, for any ungrounded conductor of the same c ircuit for systems of 1000 volts or less, or impedance grounded neutral systems of over 1000 vol ts, or (2) rated not less than 600 volts for solidly grounded neutral systems of over 1000 volts as described in 250. l 84(A) . (B) Continuity. The continuity of a grounded conductor shall not depend on a connection to a metallic enclosure, raceway, or cable armor.

(4)

(5)

(6)

Informational Note: See 300.13 (B) for the continuity of grounded conductors used in rnultiwire branch circuits.

200.3 Connection to Grounded System. Grounded conductors of premises wiring systems shall be e lectrically connected to the supply system grounded conductor to e nsure a common , continuous g rounded system. For the purpose of this section, electrically connected shall mean making a direct e lectrical connection capable of carrying current, as d istinguished from induced c urrents. Exception: Listed interactive inverters identified for use in distributed res&urce generation systems such as photovoltaic and fuel cell power systems shall be permitted lo be connected to premises wiring without a grounded conductor if the connected premises wiring or utility system includes a grounded wnduclm:

200.4 Neutral Conductors. Neutral conductors installed in accordance with 200.4(A) and ( B) .

shall

be

(A) Installation. Neutral conductors shall not be used for more than one branch circuit, for more than one multiwire branch circuit, or for more than one set of ungrounded feeder conductors unless specifically permitted elsewhere in this Code. (B) Multiple Circuits. Where more than one neutral conductor associated with different c ircuits is in an enclosure, grounded circuit conductors of each circuit shall be identified or grouped to correspond with the ungrounded circ uit conductor(s) by wire markers, cable ties, or similar m ean s in at least one location within the enclosure.

70-58

(7)

(8)

The insulated conductor shall h ave a continuous white outer fini sh. The insulated conductor shall have a continuous gray outer fini sh. The insulated conductor sh all have three continuous white o r gray stripes along the conductor's entire length on o ther than green insulation. Insulated conductors that have their o uter covering finished to show a white or gray color but have colored tracer threads in the braid identifying the source of manufacture are acceptable means of identification . A single-conductor, sunlight-resistant, outdoor-rated cable u sed as a solidly grounded conductor in photovoltaic power systems, as permitted by 690.41, shall be identified at the time of installation by markings at terminations in accordance with 200.6(A) (1) through (A) (4) . The grounded conductor of a mine ral-insulated, metalsheathed cable (Type MI) shall be identified at the time of installation by disti nctive marking at its terminations. Fixnire wire shall comply with the requirements for grounded conductor identification as specified in 402.8 . For aerial cable, the identification shall comply with o ne of the methods in 200.6(A)( l ) through (A)(5), or by means of a ridge located on the exterior of the cable so as to identify it.

(B) Sizes 4 AWG or Larger. An insulated grounded conductor 4 AWG or larger shall be identified by one of the following means: (1)

(2) (3) (4)

A continuous white outer finish . A continuous gray o uter finish . Three continuous wh ite or gray stripes alo ng the conductor's entire length on other than green insulatio n. At the time of installation, by a distinctive white or gray marking at its terminations. Th is marking shall encircle the conductor or insulation .

(C) Flexible Cords. An insulated conductor that is intended for use as a grounded conductor, where contained within a flexibl e cord, shall be identified by a white or gray outer finish or by meth ods permitted by 400.22.

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 200- USE AND IDENTIFICATION OF GROUNDED CON DUCTORS

(D) Grounded Conductors of Different Systems. vVhere grounded conductors of different systems are installed in the same raceway, cable, box, aux iliary gutter, or other type of enclosure, each grounded condu ctor shall be identified by system. Identification that distinguishes each system grounded condu ctor shall be permitted by one of the following means: (I )

(2)

(3)

One system grounded condu ctor shall h ave an outer covering conform ing to 200.6(A) or (B) . The grounded condu ctor(s) of other systems sha ll have a different o uter covering conform ing to 200.6(A) or 200.6(B) or by an. o u ter covering of white or gray with a readily d istinguishable colored stripe other than green running along the insulation. Other a nd different mea ns of identification allowed b y 200.6(A) or (B) shall d istinguish each system grounded cond uctor.

If part of a cable assembly that has th e insulation permanently reidentified to indicate its u se as a n ungrounded conductor by marking tape, pa inting, or other effective means at its termination and at each location wh ere the conductor is visible a nd accessible. Identification sh all encircle th e insulation and sh all be a color other than. white, gray, or green. If used for single-pole, 3-way or 4-way switch loops, the reidentified conductor with white or gray insulation or three continuous white or gray stripes shall be u sed only fo1· the supply to the switch , but not as a return conductor from the switch to the o utlet. A flexible cord having one conductor identified by a white or gray outer finish o r three continuou s white or gray stripes, or by any othe1· means permitted by 400.22, that is u sed for connecting an appliance or equipment permitted by 400.1 0. This shall apply to flex ible cords connected to outlets whether or not the outlet is suppli ed by a circuit that has a grounded conductor.

(I )

(2)

The means of ide ntification shall be documented in a manner that is readily available o r shall b e permanently posted wh ere the condu ctors of different systems originate.

(E) Grounded Conductors of Multiconductor Cables. The insulated grounded condu ctor(s) in a multiconductor cable shall b e identified by a continuous white or gray outer finish or b y three continuous wh ite or gray stripes on other than green insulation along its enti1·e length . For conductors that are 4 AWG or larger in cables, identification of the grounded condu ctor shall be permitted to comply with 200.6(B) . For mul ticondu ctor flat cable with conductors that are 4 AWG or larger, an external ridge shall be permitted to identify the grounded condu ctor. Exception No. I: Conductors within mulliconductor cables shall be permitted to be re-identified at their terminations at the time of installation by a distinctive white or gray mmking m· other equally effective means. Exception No. 2: The grounded conductor of a mulliconductor varnished-cloth-insulated cable shall be permitted to be identified at its terminations at the time of installation by a distinctive white marking or other equally effective means. Informational Note: The color gray may have been used in the past as an ungrounded conductor. Care should be taken when working on existing systems.

200.7 Use of Insulation of a White or Gray Color or with Three Continuous White or Gray Stripes. (A) General. The following shall b e used o nly for the grounded circuit condu ctor, unless othenvise permitted in 200.7(B) a nd (C) : (I) (2)

(3)

A condu ctor with continuous white or gray covering A condu ctor with three continuous white or g ray su-ipes on other than green insulation A marking of white or gray color at the termination

(B) Circuits of Less Than 50 Volts. A condu ctor with white or gray color insulation 0 1· three continuous white sU'ipes or having a marking of whi te or gray at the termination for circuits of less than 50 volts sh all b e required to b e grounded only as required by 250.20(A) . (C) Circuits of 50 Volts or More. The u se of insulation that is wh ite or gray or that h as three continuou s wh ite or gray stripes for other than a grounded condu ctor for circuits of 50 volts or more shall be permitted only as in ( I ) a nd (2) .

2020 Edition

NATIONAL ELECTRJCAL CODE

200.10

Informational Note: The color gray may have been used in the past as an ungrounded co nducwr. Care should be taken when working on existing systems.

200.9 Means of Identification of Terminals. In devices or u tilization equipment with pola1·ized connections, identification of terminals to which a grounded conductor is to be connected sh all b e sub stantially white or silver in color. The identification of other terminals shall b e of a readily distinguish able different color. l!.xception: Where the conditions of maintenance and supervision ensure that only qualified persons service the installations, terminals f m· grounded conductors shall be permitted to be pennanently identified at the time of installation by a distinctive white marking or other equally effective means. 200.10 Identification of Terminals. (A) Device Terminals. All devices, excluding p a nelboards, provided with terminals for the a ttachmen t of conductors and intended for connection to more th an o ne side of the circuit sh all have terminals properly m a 1·ked for ide ntification , unless the electrical connection of the terminal intended to be con nected to the grounded conductor is clearly evident. Exception: 1e1minal identification shall not be required for devices that have a normal current rating of over 30 amperes, other than polarized attachment plugs and polarized receptacles for attachment plugs as required in 200.J0(B). (B) Receptacles, Plugs, and Connectors. Receptacles, polarized attachment plugs, and cord connectors for plugs and polarized plugs shall have the terminal intended for connection to the grounded con d u ctor identified as follows:

(I )

(2)

Identification shall b e by a m etal or m etal coati ng that is substantially white o r silver in color or by the word "whi te" or the letter "W" located adjacent to the identified terminal. lf th e terminal is not visible, the condu ctor enu·ance hole for th e connection shall be colored wh ite or marked with the word "white" or the letter "V\1."

Informational Note: See 250.126 for identification of wiring device equipment grounding conductor terminals.

(C) Screw Shells. For devices with screw shells, the termina l for the grounded condu ctor shall be the one connected to the screw s hell.

70-59

200.10

ARTICLE 210- BRANCH CIRCUITS

(D) Screw Shell Devices with Leads. For screw shell devices with attached leads, the conductor attached to the screw shell shall have a wh ite or gray fin ish. The outer finish of the other conductor shall be of a solid color that will not be confused with the white or gray finish used to identify the grounded condu ctor. Informational Note: The color gray may have been used in the past as an ungrounded conductor. Care should be taken when working on existing systems.

(E) Appliances. Appliances that h ave a single-pole switch or a single-pole overcurrent device in the line or any line-con nected screw shell lampholders, and that are to be connected by (1) a permanent wi ring method or (2) field-installed attachment plugs and cords with three or more wires (including the equipment grounding conductor), shall have means to identify the terminal for the grounded circuit conductor (if a ny) . 200.11 Polarity of Connections. No grounded conductor shall be attached to any terminal or lead so as to reverse the designated polarity.

210.4 Multiwire Branch Circuits. (A) General. Branch circuits recognized by th is article shall be permitted as multiwire c ircuits. A multiwire c ircuit shall be permitted to be considered as multiple circuits. Al l conductors of a multiwire bran ch circuit shall orig inate from the same panelboard or similar d istribution equipment. I nformational Note No. 1: A 3-phase, 4-wire, wye-connected power system used LO supply power to nonlinear loads may necessitate that the power system design allow for the possibility of high harmonic currents on the nemral conductor. Informational Note No. 2: See 300.1 3(8) for continuity of grounded conductors on multiwire circuits.

(B) Disconnecting Means. Each multiwire b ranch circuit shall be provided with a means that will simultan eously disconnect a ll ungrounded conductors at the point where the bra nch c ircu it originates. I nformational Note: See 240 .1 5(8 ) for information on the use of single-pole circuit breakers as the disconnecLing means.

(C) Line-to-Neutral Loads. Multiwire branch circuits sh all supply only line-to-neutral loads. J,,xception No. I: A mulliwire branch circuit that supplies only one utilization equipment.

ARTICLE 210 Branch Circuits

Exception No. 2: Where all ungrounded conductors of the multiwire /Jranch circuit are opened simultaneously by the branch-circuit overcu, rent device. 0

Part I. General Provisions

210.1 Scope. This article provides the general requirements for branch c ircuits. 210.3 Other Articles for Specific-Purpose Branch Circuits. Table 210.3 lists references for specific equipment and applications not located in Chapters 5, 6, and 7 that amend or supplement the requirements of this article.

Equipment

70-60

Article

210.5 Identification for Branch Circuits. (A) Grounded Conductor. The grounded conductor of a branch circuit shall be ide ntified in accordance with 200.6 . (B) Equipment Grounding Conductor. The equipment grounding conductor shall be identified in accordance with 250.119. (C) Identification of Ungrounded Conductors. Ungrounded con ductors shall be ide ntified in accordance with 210.5(C)(l) or (2), as applicable.

Table 210.3 Specific-Purpose Branch Circuits

Air-conditioning and refrigerating equipment Busways Central heating equipment o ther than fixed e lectric space-heating equipment Fixed e lectric heating equipment for pipe lines and vessels Fixed e lectric space-heating equipment Fixed outdoor electrical deicing and snow-melting equipment Infrared lamp indust,ial heating equipment Motors, motor circuits, and controllers Switchboards and panelboards

(D) Grouping. The ungrounded and grounded circuit conductors of each multiwire branch ci rcuit sh all be grouped in accordance with 200.4 (B) .

Section 440.6, 440.31, 440.32 368.17 422.12

427.4

424.3 426.4

422.48, 424.3 430 408.52

(1) Branch Circuits Supplied from More Than One Nominal Voltage Syste m. \!\There the premises wiring system h as branch circuits supplied from more than one nominal voltage system, each ungrounded conductor of a branch circuit shall be identified by phase or line and by system voltage class at a ll termination, connection , and splice points in compliance with 210.5(C)( l )(a) and (b ) . Different systems within the same premises that h ave the same system voltage class shall be permitted to use the same identification . (a) Means of Identification. The means of identification shall be permitted to be by separate color coding, marking tape, tagging, or other approved means. (b ) Posting of Identification Means. The method utilized for conductors originating within each branch-circuit panelboard or similar branch-circuit disu·ibution equipment shall be documented in a manner that is readily available or shall be permanently posted at each branch-circuit panelboard or similar bra nc h-circuit distribution equipment. The label shall be of suffic ient durabili ty to withstand the e nvironment involved and shall not be handwritten.

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 210- BRANCH CIRCUITS Exception: In e>."isting installations where a voltage system(s) already exists and a different voltage system is being added, it shall be permissible lo mark only the new system voltage..Existing unidentifi.ed systems shall not be required to be identified at each tennination, connection, and splice point in compliance with 210.5(C)(l)(a) and (b). Labeling shall be required at each voltage system distribution equipment to identifi' that only one voltage system has been marked for a new system(s). 17ie new system label(s) shall include the words "other unidentified systems exist on the premises. "

(2) Branch Circuits Supplied from Direct-Current Systems. \l\'here a branch circuit is supplied from a de system o pe rating at more than 60 volts, each ungrounded conductor of 4 AWG or la rger shall be iden tified b y polarity at all termination, connection, and splice points by marking tape, tagging, or other approved means; each ungrounded conductor of 6 AWG or smalle r shall be ide ntified by polarity at all termination, connection, and splice points in compliance with 210.5(C) (2) (a ) and (b ) . The identification methods utilized for conductors originating within each branch-circuit panelboard or similar branch-circuit distribution equipment shall be documented in a manner that is readily available or shall be permanently posted at each branch-circuit panelboard or similar bran ch-circuit distribution equipment. (a) Positive Polari.ty, Sizes 6 A WC or Smaller. \!\'here the positive polarity of a de system does not serve as the connection point for the grounded conductor, each positive ungrounded conductor shall be identified by one of the following means: A continuous red oute r finish A continuous red stripe durably marked along the conductor's entire length on insula tio n of a color other than green, white, gray, or black (3) Imprinted plus sign s (+) or the word POSITIVE or POS durably marked on insulation of a colo r other than green , white, gray, or black a nd repeated at intervals not exceeding610111111 (24 in.) in accordance with 310.S(B) ( 4) An approved permanent marking means such as sleeving or shrink-tubing that is suitable for the conductor size, at all termination, connection, and splice points, with imprinted plus signs (+) or the word POSITIVE or POS durably marked on insulation of a colo r other than green, white, gray, o r black (b ) Negative Pol.arity, Sizes 6 A WC or Smaller. \!\'here the negative polarity of a de syste m does not serve as the connection point for the grounded conductor, each negative ungrounded conductor shall be identified by one of the following means: (1 )

(2)

( 1) (2)

(3)

( 4)

A continuous black outer finish A continuous blac k stripe durably marked along the conductor's entire length o n insulation of a color other than green, white, gray, or red Imprinted minus signs (-) or the word NEGATIVE or NEG durably marked on insulation of a color other than green, white, gray, or red and repeated at intervals not exceeding610111111 (24 in.) in accordance with 310.S(B) An approved permanent m arking means such as sleeving or shrink-tubing that is suitable for the conductor size, at all termination, connection, and splice points, with imprinted minus signs (-) or the word NEGATIVE or NEG durably marked on insulation of a color other than green, white, gray, o r red

2020 Edition

NATIONAL ELECTRJCAL CODE

210.6

210.6 Branch-Circuit Voltage Limitations. The nominal voltage of branch c ircuits sh all n ot exceed the values permitted by 210.6(A) through (E) . (A) Occupancy Limitation. In dwelling units and g uest rooms or guest suites of h otels, motels, and similar occupa nc ies, the voltage shall not exceed 120 volts, nominal, between conductors that supply the terminals o f the following: (1) (2)

Luminaires Cord-and-plug-connected loads 1440 volt-amperes, nominal, or less or less than ¼ hp

(B) 120 Volts Between Conductors. Ci rcuits not exceeding 120 volts, nominal, between conductors shall be permitted to supply the following: (1)

The term inals of lampholders applied within their voltage ratings Auxiliary equipment of electric-discharge la mps

(2)

Informational Note: See 410.137 for aw,iliary equipment limitations.

(3)

Cord-and-plug-connected utilization equipment

or

perma nently

connected

(C) 277 Volts to Ground. Circuits exceeding 120 volts, nomi-

nal, between conductors but not exceeding 277 vol ts, nominal, to ground shall be permitted to supply cord-and-plugcon nected or permanently connected utilization equipment, or the following types oflisted luminaires: (1) (2) (3)

Electric-disch arge luminaires with integral ballasts LED luminaires with LED drivers between the branch circuit and the lamph olders Incandescent or LED lumin a ires, equipped with mediumbase or smaller screw shell lampholders, where the la mph o lders are supplied at 120 volts or less from the output of a stepdown autotran sformer, LED driver, o r o ther type of power supply that is an integral component of the luminaire

Informational Note: See 410.90 for requirements regarding the connection of screw shell lampholders to grounded conductors.

(4) (5)

(6)

Luminaires equipped with mogul-base screw shell la mph o lders Luminaires equipped with lampholders, o ther tha n the screw shell type, wh en used within their voltage ratings of their lampholders Luminaires without lampholders Informational Note: Luminaires with nonserviceable LEDs are examples of lum inaires without lampholders.

(7)

Auxiliary equipment of electric-discharge or LED-type lamps Informational Note: See 410. 137 for auxiliary equipment limitations.

(8)

Luminaires converted with listed retrofit kits incorporating integral LED light sornrces or accepting LED lamps that also conforms with 210 .6(C)( l ), (C)(2), (C)(3), (C) (4), or (C)(5)

70-61

210.6

ARTICLE 210 - BRANCH CIRCUITS

(D) 600 Volts Between Conductors. Circuits exceeding 277 volts, n om inal, to gro u nd and not exceeding 600 volts, nominal, bet\veen conductors shall be permitted to supply the fo llowing: (1)

T he aux iliary eq u ipment of electric-discharge lam ps mounted in permanently installed luminaires where the lum inaires are mou nted in accordance with one of the following: a . Not less than a he igh t of 6 .7 m (22 ft) on poles or sim ilar structures for th e illum ination of o u tdoor areas such as highways, roads, b ridges, ath letic fields, or parking lots b. Not less than a h e ight o f 5.5 m (18 ft) on other structures such as tunnels

For the purposes of this section, wh en determi ning the d istance from receptacles the d istance shall be measured as the shortest path the su pply cord of an a pplia nce connected to the receptacle would follow without piercing a floor, wall, ceiling, or fixed barrier, o r the shortest path withou t passing th rough a window. (A) Dwelling Units. All 125-volt through 250-volt receptacles

installed in the locations specified in 210.8(A)( l ) th rough (A) (II ) a nd su pplied by single-ph ase b ranch ci rcuits rated 150 volts or less to ground shall h ave ground-faul t ci rcuitinterrupter protection for person nel. (l ) (2)

Informational Note: See 4 10. 137 for auxiliary equipment limitations. (3)

(2) (3)

Cord-and-plug-connected o r permanently connected utilization equipment other than lum inaires Lu minaires powered from d irect-current system s where e ithe r of th e fo llowing ap ply: a . The lu minaire contains a listed, de-rated ballast that provides isolatio n bewee n the de power sou rce a nd the la m p circuit and protectio n from electric shock wh en cha nging la m ps. b . The lum inaire contains a listed, de-rated ballast a nd h as n o provision for changi ng lamps.

Exception No. I to (B), (C), and (D): For lampholders of infrared industrial heating appliances as provided in 4 25.14.

Exception to (3 ): Receptacles that are not readily accessible and are supplied by a branch circuit dedicated to electric sno11rmelting, deicing, m· pipeline and vessel heating equipment shall be permitted to be installed in accordance with 426.28 or 427. 22, as applicable. ( 4)

(5)

210.8 Ground-Fault Circuit-Interrupter Protection for Personnel. Grou nd-fault c ircuit-interrupter protection for personnel shall be provided as required in 210.8(A) th rough (F) . T he ground-fault circuit interrupter shall be installed in a readily accessible location . Informational Note No. I : See 2 15.9 for ground-fault circuitinterrupter protection tor personnel on feeders. Informational Nole No. 2: See 422.5(A) for GFCI requirements for appliances. Informational Nole No. 3: See 555.9 for GFCI requiremems for boat hoists. Informational Note No. 4: Additional GFCI requirements for specific circuits and equipment are contained in Chaplers 4, 5, and 6.

(6) (7)

(9)

(10)

Receptacles installed u nder the exception to 21 0.8(A) (5) shall not be considered as meeting the requi rements of210.52(G) . Kitchens - where the receptacles a re installed to serve the cou n tertop su rfaces Sinks - where receptacles are installed within 1.8 m (6 ft) from the top inside edge of the bowl of the sink Boathouses Bathtubs or shower stalls where receptacles are installed wi thin 1.8 m (6 ft) of th e o u tside edge of the bathtu b or sh ower stall Laundry areas

faception lo (1) through (3), (5) tlnvugh (8), and (10): Listed locking support and mounting receptacles utilized in combination with compatible attachment fittings installed for the purpose of serving a ceiling luminaire or ceiling fan shall not be required to be gmund-fault circuitinterrupter pmtected. If a general-purpose convenience receptacle is integral lo the ceiling luminaire or ceiling fan, GFCI protection shall be provided.

( 11 ) Indoor damp a n d wet location s (B) Othe r Than Dwelling Units. All 125-volt th rough 250-volt receptacles s u pplied by single-phase b ranch ci rcu its rated 150 volts or less to grou nd, 50 amperes or less, a nd a ll receptacles su pplied by three-ph ase bra n ch circuits rated 150 volts or less to grou nd, 100 amperes or less, installed in the locatio ns specified in 210.S(B)( l ) th rough (B) (1 2) shall have grou ndfault ci rcuit-interru pter pro tection for personnel.

(1) (2)

70-62

at or below grade level

Informational Note: See 760.41(8) and 760.121(8 ) for power supply requirements for fire alarm systems.

(8)

210.7 Multiple Branch Circuits. Wh ere wo or more branch circuits su pply devices or equi pment o n the same yo ke or mou nting su·ap, a m eans to simultaneou sly d isconnect th e ungrounded su pply conductors shall be provided at t he point at wh ich the branch circuits originate.

Crawl spaces Basements

Exception to (5 ): A receptacle supplying only a permanently installed fire alarm or burglar alarm system shall not be required to have groundfaull, circuit-intm1·upter protection.

Exception No. 2 to (B), (C), and (D): For railway properties as described in 110.19.

(E) Over 600 Volts Between Conductors. C ircuits exceeding 600 volts, nominal, bet\veen conductors sh all be permitted to su pply utilizatio n equipment in installations where conditions of ma intenance and su pervision ensu re that only quali fied persons service the installation.

Bathrooms Garages and also accessory b uild ings that have a fl oor located at or below grade level n ot intended as h abi table rooms and limited to storage areas, work areas, and areas of similar use Outdoors

Bathrooms Kitchens o r areas with a sink a n d perm anen t provisions for e ither food preparation or cooking

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 210- BRANCH CIRCUITS (3)

Rooftops

Exception: Receptacles on rooftops shall not be required lo be readily accessible other than fimn the rooftop.

(4)

Outdoors

Exception No. 1 to (3) and (4 ): R eceptacles that are not readily accessible and are supplied by a branch circuit dedicated lo electric snowmelting, deicing, or pipeline and vessel heating equipment shall be permitted to be installed in accordance with 426.28 or 427.22, as applicable. Exception No. 2 to (4 ): In indust1ial establishments only, where the conditions of maintenance and supervision ensure that only qualified personnel are involved, an assured equipment gmunding conductor program as specified in 590.6(B)(2) shall be permitted for only those receptacle 01.lllets used lo supply equipment that would create a greater hazard if power is interrupted or having a design that is not compatible with CFC/ protection.

(5)

Sinks - where receptacles are installed within 1.8 m (6 ft) from the top inside edge of the bowl of the sink

Exception No. 1 lo (5 ): In indusl1ial laboratories, receptacles used lo supply equipment where removal of power wm.dd introduce a greater hazard shall be permitted to be installed without CFC! pmtection. Exception No. 2 to (5 ): R eceptacles located in patient bed locations of Category 2 (general care) or Catego1y 1 (critical care) spaces of health care facilities shall be permitted to comply urith 517. 21.

(6) (7) (8) (9) (10)

Indoor damp a nd wet locations Locker rooms with associated showering facilities Garages, accessory buildings, service bays, and similar areas other than vehicle exhibition halls and showrooms Crawl spaces - at or be low grade level Unfinished areas of basements

Exception to (1) through (5), (8), and ( 10): Listed locking support and mounting receptacles utilized in combination with compatible attachment fittings installed for the purpose of serving a ceiling luminaire or ceiling Jan shall not be reqitired to be groundjault circuit-interrupter protected. If a general-purpose convenience receptacle is integral to the ceiling luminaire or ceilingJan, CFC/ protection shall be provided. (11)

(12)

Laundry areas Bathtubs and shower stalls - where receptacles are installed with in 1.8 m (6 ft) of the outside edge of the bathtub or shower stall

(C) Crawl Space Lighting Outlets. GFCI protection shall be provided for lighting outlets not exceeding 120 vol ts installed in crawl spaces.

(D) Specific Appliances. Unless GFCI protection is provided in accordance with 422.5( B) (3) through (B)(5), the outlets supplying the appliances specified in 422.5(A) shall have GFCI protection in accordan ce with 422.5( B)( l ) or (B)(2) .

Where the appliance is a vending machine as specified in 422.5(A) (5) and GFCI protection is not provided in accordance with 422.5( B)(3) or (B)(4), branch circuits supplying vending machines shall have GFCI protection in accordance with 422.5( B)(l ) or (B)(2) . (E) Equipment Requiring Servicing. GFCI protection shall be provided for the receptacles required by 210.63.

210.11

supplied by single-phase branch circuits rated 150 volts to ground or less, 50 amperes or less, shall have ground-fault circuit-interrupter protection for personnel. l!.xception: Croundjault circuit-interrupter protection shall not be required on lighting outlets other than those covered in 210.8(C).

210.9 Circuits Derived from Autotransformers. Branch circuits shall not be derived from autotransformers u n less the circuit supplied has a grounded conductor th at is electrically con nected to a grounded conductor of the system supplying the autotransformer. Exception No. 1: An autotransformer shall be permitted without the connection to a grounded conductor where transforming from a nominal 208 volts lo a nominal 240-volt supply or similarly fiwn 240 volts to 208 volts. Exception No. 2: In industrial occupancies, where conditions of maintenance and supervision ensure that only qualified persons service the installation, autotransformers shall be permitted lo supply nominal 600-volt loads from nominal 480-volt systems, and 480-volt loads from nominal 600-volt systeins, without the connection to a similar grounded conduclm:

210.10 Ungrounded Conductors Tapped from Grounded Systems. Two-wire de circuits and ac circuits of two or more ungrounded conductors shall be permitted to be tapped from the ungrounded conductors of c ircuits that have a grounded neuu·al conductor. Switching devices in each tapped circuit shall have a pole in each ungrounded conductor. All poles of multipole switching devices shall manually switch together where such switching devices also serve as a d isconnecting means as required by the following:

(1) (2) (3) (4) (5) (6) (7)

410.93 for double-pole switched lampholders 410.1 04(B) for electric-discharge lamp auxilia ry e quipment switching devices 422.31 (B) for an appliance 424.20 for a fixed e lectric space-h eating unit 426.51 for e lectric deicing and snow-melting equipment 430.85 for a motor controlle r 430.1 03 for a motor

210.11 Branch Circuits Required. Branch circuits for lighting and for appliances, including mo tor-operated appliances, sha ll be provided to supply the loads calculated in accordance with 220.1 0. In addition, branch circuits shall be provided for specific loads n ot covered by 220 .10 where required elsewhere in this Code and for dwelling unit loads as specified 111 210.11 (C) . (A) Number of Branch Circuits. The minimum number o f branch circuits shall be determined from the total calculated load and the size or rating of the c ircuits used. In all installations, the number of circuits shall be sufficient to supply the load served. In no case shall the load on any c ircuit exceed the maximum specified by 220.18. (B) Load Evenly Proportioned Among Branch Circuits. Where the load is calculated on the basis of volt-amperes per square meter or per square foot, the wiring system up to and including the branch-circuit panelboard(s) shall be provided to serve no t less than the calculated load. Thi s load sha ll be evenly proportioned a mong multioutlet bra nch circuits within the panelboard(s) . Branch-circuit overcurrent devices and circuits shall be required to be installed o nly to serve the connected load.

(F) Outdoor Outlets. All o utdoor o utlets for dwellings, other

than those covered in 210.8(A) (3) , Exception to (3), that are 2020 Edition

NATIONAL ELECTRJCAL CODE

70-63

210.11

ARTICLE 210- BRANCH CIRCUITS

(C) Dwelling Units.

(I) Small-Appliance number of branch section, two or more shall be provided 210.52(B) .

Branch Circuits. In addition to the circuits required by other parts of this 20-ampere small-appliance b ranch circuits for all receptacle outlets specified by

(2) Laundry Branch Circuits. In addition to the number of b ranch circuits required by other parts of this section, at least one additional 20-ampere branch circuit shall be provided to supply the laund1y receptacle outlet(s) required by 210.52(F) . This circ uit shall have no other outlets.

(4)

(3) Bathroom Branch Circuits. In addition to the number of

b ranch circuits required by other parts of this section , one or more 120-volt, 20-ampere branch circuit shall be provided to supply bath room(s) receptacle outlet(s) required by 2 10.52(0) and any countertop and similar work surface receptacle outlets. Such c ircuits shal l have no other outlets. Exception: Where the 20-ampere circuit supplies a sing!,e bathroom, outlets for other equipment within the same bathroom shall be permitted to be supplied in accordance with 210.23(A)(l) and (A)(2). (4) Garage Branch Circuits. In addition to the number of b ranch circuits required by other parts of this section , at least one 120-volt, 20-ampere branch circuit shall be installed to supply receptacle outlets required by 210.52(C) (1) for attached garages and in detached garages with elecu·ic power. This circuit shall have no other o utlets.

(5)

Exception: This circuit shall be permilled to supply readily accessible outdoor receptacle outlets.

210.12 Arc-Fault Circuit-Interrupter Protection. Arc-fault circuit-interrupte r protection shall be p rovided as required in 210.1 2(A), (B), (C), and (D ) . The arc-fault ci rcuit interrupter shall be instal led in a readily accessible location. (A) Dwelling Units. All 120-volt, single-phase, 15- and 20-

ampere branch circuits supplying outlets or devices installed in dwelling unit kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, ha llways, laund1y a reas, or similar rooms or areas shall be protected by any of the means described in 210.1 2(A) (1) through (6) : (1)

(2)

(3)

A listed combination-type arc-fault circuit interrupter installed to p rovide protection of tl1e en tire branch ci rcuit A listed branch/feeder-type AFCI installed at the orig in of the b ranch-circuit in combination with a listed outlet branch-circuit-type arc-fault c ircuit interrupter installed at the first outlet box on th e branch circuit. The first outlet box in the branch c ircuit sh all be marked to ind icate that it is the first o u tlet of the circuit. A listed supplemental arc protection c ircuit breaker installed at the origin of the bra nch circuit in combination with a listed outlet branch-circuit-type arc-fault circuit interrupter installed at the first outlet box on the branch circuit where all of the following conditions are met: a . The branch-circuit wiring shall be continuous from the branch-circuit overcu rrent device to the outlet branch-circuit arc-fault c ircuit interrupter.

70-64

(6)

b. The maximum length of the b ranch-circuit w1nng from the branch-circuit overcurrent device to the first outlet shall not exceed 15 .2 m (50 ft) for a 14 A.WC conductor or 21 .3 m (70 ft) for a 12 A.WC conducto r. c. The first outlet box in the branch circuit sha ll be marked to ind icate that it is the first outlet of the c ircu it. A listed outlet bran ch-ci rcuit-typ e arc-fault ci rcuit interrupter installed at the first outlet on th e branch circuit in combinatio n with a listed bra n ch-circuit overcurrent p rotective device where all of the following conditions are m et: a . The bra nch-circuit wiring sh all be continuous from the branch-circuit overcurrent device to the o utlet branch-circuit arc-fault ci rcuit interrupter. b. The m aximum length of the branch-circu it wiring from the b ranch-circuit overcurrent device to the fi rst outlet shall not exceed 15 .2 m (50 ft) for a 14 A.WC conductor or 21.3 m (70 ft) for a 12 A.WC conductor. c. The first outlet box in the b ranch circuit shall be marked to ind icate that it is the first outlet of the circuit. cl. The combination of the b 1·anch-circuit overcu rrent device a nd o utlet branch-circuit AFCI sh all be identifi ed as meeting the requirem ents for a system combination-type AFCI and shall be listed as such. If m etal raceway, metal wireways, m etal auxiliary gutters, or Type MC, or Type AC cable meeting the applicable requirements of 250.11 8, with m etal boxes, metal conduit bodies, and metal enclosures are installed for the portion of the branch circuit between the branch-circuit overcurrent device and the first outlet, it shall be permitted to install a listed outlet branch-circuit-type AFCI at the first outlet to provide protection for the remain ing portion of the branch circuit. Where a listed m etal or nonmetallic conduit or tubing or Type MC cable is en cased in not less than 50 mm (2 in. ) of concrete for the portion of the branch circuit between the branch-circuit overcurren t device and the fi rst ou tlet, it sh all be permitted to install a listed outlet b ranchcircuit-type AFCI at the first outlet to provide protection for the remaining portion of the b ranch circuit.

Exception: AFC! protection shall not be required for an individual /Jmnch circuit supplying a fire alarm system instal!.ed in accordance with 760Al(B) or 760.121 (B). The &ranch circuit shall be installed in a rnetal raceway, metal auxilimy gutte1; steel-mmored cable, Type MC or 1)pe AC, meeting the applicable requirements of 250.118, with metal boxes, conduit bodies, and enclosures. Informational Note No. 1: For information on combination-type and branch/ feeder-type arc-fat~l circuit imerrupters, see UL 1699-2011, Standard for Arc-Faull Circuit Interrupters. for information on outlet branch-circuit type arc-fau lt circuit imerrupters, see UL SubjecL 1699A, Outline of Investigation for Out/cl Branch Circuit Arc-Faull Circuit-Interrupters. for information on system combination AFCis, see UL Su~ject 1699C, Oullin£ of Investigation for System Combination Arc-Faull Circuit Interrupters. Informational Note No. 2: See 29.6.3(5) of NI-PA 72-20 13, National Fire Alarm and Signaling Code, for information related 10 secondary power-supply requiremem s for smoke alarms installed in dwelling units. Informational Note No. 3: See 760.41( 8 ) and 760.1 21(8) for power-supply requirements for fire alarm systems.

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 210 - BRANCH CIRCUITS

(B) Dormitory Units. AIi 120-volt, single-phase, 15· and 20· ampere branch circ uits supplying o utlets and devices installed in dormitory unit bedrooms, living rooms, hallways, closets, bathrooms, and similar rooms shall be pro tec ted by any of t he means described in 21 0. l 2 (A) (]) through (6) . (C) Guest Rooms, Guest Suites, and Patient Sleeping Rooms in Nursing Homes and Limited-Care Facilities. All 120-volt, sing le-phase, 15- and 20-ampere branch circuits supplying outlets and devices installed in guest rooms and g uest suites of hote ls and motels and patient sleeping rooms in nursing homes and limited-care facilities shall be protected by any of th e means described in 210.12(A)( l ) through (6) .

(D) Branch Circuit Extensions or Modifications - Dwelling Units, Dormitory Units, and Guest Rooms and Guest Suites. VI/here b ranch circ uit wiring fo r any of the a reas specified in 210.1 2(A) , (B), or (C) is modified, replaced, or extended, the branch circuit shall be protected by one of the following: (])

By an y of the means described in 210.12(A)(l) through (A) (6) A listed outlet b ranch-circuit-type AFCI located at the fi rst receptacle outlet of the existing b ranch ci rcuit

(2)

Exception: AFC/ protection shall not be required where the extension of the existing branch circuit conductors is not more than 1.8 m (6 ft) and does not include any additional outlets or devices, other than splicing devices. This measurement shall not include the conductors inside an enclosure, cabinet, orjunction box.

210.13 Ground-Fault Protection of Equipment. Each b ranchci rcuit d isconnect rated 1000 A o r more and installed on solidly grounded wye electrical systems of more than 150 volts to ground, but not exceeding 600 volts phase-to-phase, shall be provided with ground-fault protection of equipment in accordance with 230.95. Informatio nal Note: Fo r buildings that contain h ealth care occu• pancies, see the requirements of 517.1 7.

Exception No. 1: This section shall not apply to a disconnecting rneans for a continuom indusl1ial process where a nonorderly shutdo11m will introduce additional or increased hazards. Exception No. 2: This section shall not apply if ground{ault protection of equipment is provided on the supply side of the branch circuit and on the load side of any transformer supplying the branch circuit.

210.15 Reconditioned Equipment. The following shall not be reconditioned: ( 1) (2) (3)

Equipment that provides g round-fault circuit-interrupter protection for personnel Equipment that provides arc-fault circuit-interrupter protection Equipment that provides gro und-fault protectio n of equipment

210.17 Guest Rooms and Guest Suites. Guest rooms and guest su ites that are provided with permane nt provisions for cooking shall have branch circuits installed to meet the rules for dwelling units.

Part II. Branch-Circuit Ratings 210.18 Rating. Bra nch circuits recognized by this article shall be rated in accordance wi th the maximum permitted ampere rating or setting of the overcu rrent device . The rating for other

2020 Edition

NATIONAL ELECTRJCAL CODE

210.19

than ind ividual b ranch circuits shall be 15, 20, 30, 40, and 50 a mperes. Where conductors of hig h er ampaci ty are used for any reason, the a mpere rating 0 1· setting of the speci fied overcu rrent device shall determine the circuit rating. l!.xception: Multioutlet branch circuits greater than 50 amperes shall be permitted to supply nonlighting outlet loads on industrial premises where conditions of maintenance and supervision ensure that only qualified persons service the equipment.

210.19 Conductors - Minimum Ampacity and Size. (A) Branch Circuits Not More Than 600 Volts. Informational Note No. l: See 310.14 fo r am pa city and temperature limitations of conductors. Informational Note No. 2: See Part II of Article 4 30 for minimum rating of motor branch-circuit conductors. Informational Note No. 3: Conductors for branch circuits as defined in Article 100, sized to prevent a voltage drop exceed ing 3 percent at the farthest outlet o f power, h eati ng, and lighting loads, or combination s of such loads, and wh ere the maximum total voltage drop on both feeders and bra nch circuits to the farthest omlet does not exceed 5 percent, provide reason able efficie ncy of operation. See Informational Note No. 2 of 215.2(A) ( I) fo r voltage drop o n feeder conductors.

(1) General. Branch-circuit conductors sh all h ave a n ampacity not less than the larger of 2 I0.19(A) (1 )(a) or (A)(] )(b ) and comply with 110.14(C) for equipment term inations. (a) Where a branch circuit supplies continuo us loads o r any combinatio n of continuous a nd noncontinuo us loads, the min imum bran ch-circuit conductor size sh all h ave an ampacity no t less th an the noncontinuous load plus 125 percent o f the continuous load in accordance with 310.14. (b) The m inimum branch-circuit conductor size shall have an ampacity not less th an th e maximum load to be served after the application of any adjustment or correctio n factors in accordance with 310.15 . Exception No. 1 to ( 1 )(a): If the assembly, including the overcummt devices protecting the branch circuit(s), is listed for operation at 100 percent of its rating, the ampacity of the &ranch-circuit conductors shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load in accordance with 110.14(C). Exception No. 2 to (1)(a) and (l)(b): Where a portion of a branch circuit is connected at both its supply and load ends to separately installed pressure connections as covered in 110.14(C)(2), it shall be permitted to have an allowable ampacity, in accordance with 3 10. I 5, not less than the sum of the continuous load plus the noncontinuous load. No portion of a branch circuit installed under this exception shall extend into an enclosure containing either the branch-circuit supply or the &ranch-circuit load teiminations.

(2) Branch Circuits with More than One Receptacle. Conductors of branch circui ts supplying more tha n o ne receptacle for cord-an d-plug-connected portable loads shall have a n ampacity of not less than the rating of the b ranch ci rcuit. (3) Household Ranges and Cooking Appliances. Bra nchcircuit conductors supplying household ranges, wall-mounted ovens, counter-m ounted cooking units, and o ther ho useh o ld cooking applia nces shall h ave an arn pacity not less than the rating of the branch circuit a nd not less than the m ax imum load to be served. For ranges of 8¾ kW or more rating, the m inimum branch-circuit rating sh all be 40 a mperes.

70-65

210.19

ARTICLE 210- BRANCH CIRCUITS

Exception No. 1: Conductors tapped frrmi a /Jranch circuit not exceeding 50 amperes supplying electric ranges, wall-mounted electric ovens, and counteM1unmted electric cooking units shall have an ampacity of not less than 20 amperes and shall be sufficient for the load to be served. These tap conductors include any conductors that are a part of the leads supplied with the appliance that are smaller than the branchcircuit conductors. The taps shall not be longer than necessary for servicing the appliance. Exception No. 2: The neutral conduct/Jr of a 3-wire !Jranch circuit supplying a househol.d electric range, a wall-m1JUnted oven, or a counteMnounted cooking unit shall be permitted to be smaller than the ungrounded conductors where the maximum demand of a range of 831, kW or more rating has been calculated according to Column C of Table 220.55, but such conductor shall have an ampacity of not less than 70 percent of the branch-circuit rating and shall not be smaller than JOAWG. (4) Other Loads. Branch-circ uit conductors that supply loads other than those specified in 210.3 and other than cooking appliances as covered in 210.19(A) (3) shall have an a mpacity sufficient for the loads served and shall not be smaller than 14AV-7G.

Exception No. 1: Tap conductors shall have an ampacity sufficient for the load served. In addition, they shall have an ampacity of not less than 15 for circuits rated less than 40 amperes and not less than 20 for circuits rated at 40 or 50 amperes and only where these tap conductors supply any of the follmving loads: ( 1)

(2) (3) ( 4) (5)

Individual lampholders or luminaires 1vith taps extending not l1Jnger than 450 mm (18 in.) beyond any portion of the lam-pholder or lmninaire A luminaire having tap conductors as provided in 410.117 Individual outlets, other than receptacle 1Jutlets, with taps not over 450 mm (18 in.) long Infrared lamp indiistrial heating appliances Nonheating leads of deicing and snow-melting cables and mats

Exception No. 2: Fixture wi:res and jlexib!.e cords shall be permitted to be smaller than 14 A WC as permitted by 240.5. (B) Branch Circuits Over 600 Volls. The ampacity of conductors shall be in accordance with 3 10.14 and 3ll.60, as applicable. Branch-circuit conductors over 600 volts shall be sized in accordance with 210.1 9(B)(l) or (B)(2) . (1) General. The a mpac ity of bra nch-circuit conductors shall not be less than 125 percent of the designed potential load of utilization equipment that will be operated simultaneously. (2) Supervised Installations. For supervised installations, branch-circuit conductor sizing shall be permitted to be determined by qualified persons under engineering supervision. Supervised installations are defined as those portions of a facility where both of the following conditions are met:

(1) (2)

Conditions of design and installation are provided under engineering supervision. Qualified persons with documented training and experience in over 60().volt systems provide maintenance, monitoring, and servicing of the system.

210.20 Overcurrent Protection. Branch-circuit conductors and equipment shall be protected by overcurrent protective devices that have a rating or setting that complies with 210.20(A) through ( D ) .

70-66

(A) Continuous and Noncontinuous Loads. Where a branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the 1·ating of the overcurrent device shall not be less than the n oncontinuous load plus 125 percent of the continuous load.

1'.xception: Where the assembly, including the overettrrent devices protecting the branch cirmit(s), is listed for operation at 100 percent of its rating, the ampere rating of the overcurrent device shall be permitted to be not less than the sum of the continu1JUs load phis the nonwntiml/JUS load. (B ) Conductor Protection. Conductors shall be protected in accordance with 240.4. Flexible cords and fixture wires shall be protected in accordance with 240.5. (C) Equipment. The rating or setting of the overcurrent protective device shall not exceed that specified in the applicable articles referenced in Table 240.3 for equipment. (D) Outlet Devices. The rating or setti ng sh all not exceed that specified in 210.21 for outlet devices.

210.21 Outlet Devices. Outlet devices sh all have an ampere rating that is not less than the load to be served and shall complywith 210.2l(A) and (B) . (A) Lampholders. Where con nected to a branch circuit having a rating in excess of 20 amperes, lampholders shall be of the heavy-duty type. A heavy-duty lampholder shall have a rating of not less than 660 watts if of the admed ium type, o r not less than 750 watts if of any other type.

(B ) Receptacles. (1) Single Receptacle on an Individual Branch Circuit. A single receptacle installed on an individual branch c ircuit shall have an ampere rating not less than that of the branch circuit.

1'.xception No. 1: A receptacle installed in accordance with 430.81(B). Exception No. 2: A receptacle instal!.ed exclusively for the iise of a wrdand-plug-connected arc welder shall be permitted to have an ampere rating not less than the minimum branch-circuit conductor ampacity determined by 630.11 (A) for arc welders. I nformational Nole: See Lhe definition of ,·ecefilacle in Anic le 100.

(2) Total Cord-and-Plug-Connected Load. Where connected to a branch circuit supplying two or more receptacles or outlets, a receptacle shall not supply a total cord-and-plugconnected load in excess of the maximum specified in Table 210.21 (B) (2) .

(3) Receptacle Ratings. Where connected to a branch circuit supplyi ng two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table 2I0.2 l (B)(3), or, where rated higher than 50 amperes, the receptacle rating shall not be less than the branch-circuit rating. Table 210.2l(B)(2) Maximum Cord-and-Plug-Connected Load to Receptacle Circuit Rating (Amperes)

15 or 20 20 30

Receptacle Rating (Amperes)

Maximum Load (Amperes)

15 20 30

12 16 24

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 210- BRANCH CIRCUITS

210.25

Exception No. 1: Receptacles installed exclusively for the use of one or more cord-and.plug-connected arc welders shall be permitted to have ampere ratings not less than the minimum !;ranch-circuit conductor ampacity determined by 630.1 l(A) or (B) for arc welders.

(1) Cord-and-Plug-Connected Equipment Not Fastened in Place. The rating of any one c01·d-and-plug-connected utilization equipment not fastened in place shall not exceed 80 percent of the branch-circuit a mpere rating .

Exception No. 2: The ampere rating of a receptacle installed for electric discharge lighting shall be permitted to be based on 410.62(C).

(2) Utilization Equipment Fastened in Place. The total rating of utilization equipment fastened in place, other than luminaires, shall n ot exceed 50 percent of the bra n ch-circuit ampere rating where lighting units, cord-and-plug-connected utilization equipment not fastened in place, or both , are a lso suppli ed.

(4) Range Receptacle Rating. The ampere rating of a range receptacle shall be permitted to be based o n a single range demand load as specified in Table 220.55. 210.22 P ermissible Loads, Individual Branch Circuits. An individual branch circuit shall be permitted to supply any load for which it is rated, but in no case shall the load exceed the branch-circuit ampere rating. 210.23 Permissible Loads, Multiple-Outlet Branch Circuits. In no case shall the load exceed the branch-circuit ampere rating. A branch circuit supplying two or more o utlets or receptacles shall supply only the loads specified according to its size as specified in 210.23(A) through (D ) and as summarized in 210.24 and Table 210.24. (A) 15- and 20-Ampere Branch Circuits. A 15- or 20-ampere branch c ircuit shall be permitted to supply lighting units or other utilization equipment, or a combination of both, and shall comply with 210.23(A) (1) and (A) (2) .

Exception: The small-appliance branch circuits, laundry branch circuits, and bathroom branch circuits required in a dwelling unit(s) by 210. 11 (C)( I), (C)(2), and (C)(3) shall supply only the receptacle outlets specified in that section.

Table 210.2l(B)(3) Receptacle Ratings for Various Size Circuits Circuit Rating (Amperes)

(C) 40- and SO.Ampere Branch Circuits. A 40- or 50-ampere branch circuit shall be permitted to supply cooking applia nces that are fastened in place in any occupancy. In other than dwelling units, such circuits sh all be permitted to supply fixed lig hting units with heavy-duty lampholders, infrared heating units, or other utilization equipment. (D) Branch Circuits Larger Than 50 Amperes. Bra nch circu its larger than 50 amperes shall supply only nonlig hting outle t loads. 210.24 Branch-Circuit Requirements Summary. The requirements for circuits that have two or more outlets or receptacles, other than the receptacle circuits of 210.11 (C) (1), (C) (2), and (C) (3), are summarized in Table 210.24. This table provides only a summary of m inimum requireme nts. See 210.1 9, 210.20, and 210.21 for the specific requirements applying to b ranch circuits. 210.25 Branch Circuits in Buildings with More Than One Occupancy. (A) Dwelling Unit Branch Circuits. Bra n ch circuits in each dwelling unit shall supply only loads within that dwelling unit or loads associated only with that dwelling unit.

Receptacle Rating (Amperes)

15 20 30 40 50

(B) 30-Ampere Branch Circuits. A 30-ampere b ranch circuit shall be permitted to supply fixed lighting units with heavy-duty lampholders in other than a dwelling unit(s) or utilization equipment in any occupa ncy. A rating of a ny one cord-andplug-connected utilization equipment shall not exceed 80 percent of the branch-circuit a mpere rating.

Not over 15 15 or 20 30 40 or 50 50

(B) Common Area Branch Circuits. Branc h circui ts install ed for lighting, central alarm, signal, communications, or other purposes for public or commo n areas of a two-family dwelling, a multifamily dwelling, or a multi-occupancy building shall no t

Table 210.24 Summary of Branch-Circuit Requirements Circuit Rating

15A

20A

30A

40A

50A

14 14

12 14

10 14

8 12

12

Overcurrent Protection

15A

20A

30A

40A

50A

Outle t d evices: Lampho ldcrs permitted Receptacle rating2

Any type 15 max. A

Any type 15 or 20 A

Heavy d uty 30A

H eavy duty 40 or 50 A

Heavy duty 50A

Maximum Load

15A

20A

30A

40A

50A

Sec 2l0.23(A)

Sec 210.23(A)

Sec 210.23(8 )

Sec 2l0.23(C)

Sec 210.23(C)

Conductors (min. size) : Circuit wircs 1 Taps Fixture wires and cords -sec 240.5

Pe1missiblc load

6

1

These gauges are for copper conductors. 2 For receptacle rating of cord-connected electric-discharge luminaires, see 410.62(C).

2020 Edition

NATIONAL ELECTRJCAL CODE

70-67

210.50

ARTICLE 210- BRANCH CIRCUITS

be supplied from equipment that supplies an individual dwelling unit or tenant space.

(3)

Informational Noce: Examples of public or common areas include, buc are not limiced to, lobbies, corridors, scairn•ays, laundry rooms, roofs, e levators, washrooms, store rooms, driveways (parking), and mechanical rooms.

shall

be

In formational Note: See Informative Annex J for information regarding ADA accessibility design.

(A) Cord Pendants. A cord connector that is supplied by a permanently connected cord pendant shall be considered a receptacle outlet. (B) Cord Connections. A receptacle outlet shall be installed wherever flexible cords with attachment plugs are used. v\lhere flexible cords are permitted to be permanently connected, receptacles shall be permitted to be omitted for such cords. (C) Appliance

Receptacle Outlets. Appliance receptacle outlets installed in a dwelling unit for specific appliances, such as laundry equipment, shall be installed within 1.8 m (6 ft) of the intended location of the appliance. 210.52 Dwelling Unit Receptacle Outlets. This section provides requirements for 125-volt, 15- and 20-am pere receptacle outlets. The receptacles required by this section shall be in addition to any receptacle that is as follows: (1) (2) (3) (4)

The space occupied by fixed panels in walls, excluding sliding panels The space afforded by fixed room dividers, such as freestanding bar-type counters or railings

(3) Floor Receptacles. Receptacle outlets in or on floors shall not be counted as part of the required number of receptacle outlets unless located within 450 mm ( 18 in. ) of the wall.

Part III. Required Outlets 210.50 Receptacle Outlets. Receptacle outlets installed as specified in 210.52 through 210.65.

(2)

Part of a luminaire or appliance, or Controlled by a listed wall-mounted control device in accordance with 210.70(A) (1), Exception No. 1, or Located within cabinets o r cupboards, or Located more than 1.7 m (5½ ft) above the fl oor

(4) Countertop and Similar Work Surface Receptacle Outlets. Receptacles installed for countertop and similar work surfaces as specified in 210.52(C) shall not be considered as the receptacle outlets required by 210.52(A) . (B) Small Appliances. (1) Receptacle Outlets Served. In the kitchen, pantry, breakfast room, dining room , or similar area of a dwelling unit, the two or more 20-ampere small-appliance bra nch circuits required b y 210. ll (C) (I ) shall serve a ll wall and floor receptacle outlets covered by 210.52(A), all countertop outlets covered by 210.52(C), and receptacle outlets for refrigeration equipment.

Exception No. 1: In addition to the required receptacles specified by 210.5 2, switched receptacles supplied Jro111 a general-pmpose 15- or 20ampere branch circuit as required in 210.70(A)(l), Exception No. 1, shall be permitted. Exception No. 2: In addition to the required receptacles specified by 210.5 2, a receptacle outlet to serve a specific appliance shall be permitted to be supplied from an individual branch circuit rated 15 amperes or greater. (2) No Other Outlets. The two or more small-applia nce branch circuits specified in 210.52(B) (I ) shall h ave no other outlets.

1'.xception No. 1: A receptacle installed solely for the electrical supply to and support of an elect1ic clock in any of the rooms specified in 210.52(B)(1).

Permanently installed e lectric baseboard h eaters equipped with factory-installed receptacle ou tlets or outlets provided as a separate assembly by the manufacturer shall be permitted as the required outlet or outlets for the wall space utilized by such permanently installed heaters . Such receptacle outlets shall not be connected to the heater circuits . In formational Note: Listed baseboard heaters include instructions that may not permit their installation below receptacle outlets.

(A) General Provisions. In every kitchen, family room, dining room, living room, parlor, library, den, sunroom, bedroom, recreation room, or similar room or area of dwelling units, receptacle outlets shall be installed in accordance with the general provisions specified in 210.52(A) (1) through (A) ( 4). (1) Spacing. Receptacles shall be installed such that no point measured horizontally a long the floor line of any wall space is more than 1.8 m (6 ft) from a receptacle outlet. (2) Wall Space. As used in this section, a wall space shall include the following: (1)

Any space 600 111111 (2 ft) or more in width (including space measured around corners) and unbroken along the floor line by doorways and similar openings, fireplaces, and fixed cabinets that do not have countertops or similar work surfaces

70-68

Exception No. 2: Receptacles installed to provide power for supplemental equipment and lighting on gas-fired ranges, ovens, or countermounted cooking units. (3) Kitchen Receptacle Requirements. Receptacles installed in a kitch en to serve countertop surfaces shall be supplied by not fewer than tw·o small-appliance branch circuits, e ither or both of which shall also be permitted to supply receptacle outlets in the same kitchen and in other rooms specified in 210.52(B) (1) . Additional small-appliance branch circuits sha ll be permitted to supply rece ptacle outlets in the kitch en and other rooms specified in 2 10.52(B) (I ) . No small-appliance bra nch circuit shall serve more than one kitchen . (C) Countertops and Work Surfaces. In kitchens, pantries, breakfast rooms, dining rooms, and similar areas of dwelling units, receptacle outlets for countertop and work surfaces that are 300 mm (12 in. ) or wider shall be insta lled in accordance with 210.52(C)(l) through (C)(3) and shall not be considered as the receptacle outlets required by 210.52(A) .

For the purposes of this section, where using multioutlet assemblies, each 300 mm (12 in. ) of multioutlet assembly containing two or more receptacles installed in individua l or continuous lengths shall be conside1·ed to be one receptacle outlet.

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 210- BRANCH CIRCUITS (1) Wall Spaces. Receptacle outlets shall be installed so that no point along the wall line is more than 600 mm (24 in.) measured horizontally from a receptacle outlet in that space. Exception: Receptacle outlets shall not be reqiti:red directly behind a range, counter-mounted cooking unit, or sink in the installation described in Fzgitre 210.52(C)(1). (2) Island and Peninsular Countertops and Work Surfaces. Receptacle outlets shal l be installed in accordance with 210.52(C) (2)(a) and (C) (2)(b) . (a) At least one receptacle outlet shall be provided for the first 0.84 m 2 (9 ft2 ), or fraction thereof, of the countertop or work surface. A receptacle outlet shall be provided for every additional 1. 7 m 2 (18 ft2 ), or fraction thereof, of the countertop or work surface. (b) At least one receptacle outlet shall be located within 600 mm (2 ft) of the outer end of a peninsular countertop or work surface. Additional required receptacle outlets shall be permitted to be located as determined by the installer, designer, or building owner. The location of the receptacle outlets shall be in accordance with 210.52(C) (3) .

space exempt fram wa Outlet within ..__ Outlet within .+ line if X < 300 mm (12 in.) i-600 mm ( 24 in.~ 600 mm (24 in.)

210.52

A peninsular countertop shall be measured from the connected perpend icular wall. (3) Receptacle Outlet Location. Rece ptacle outlets shall be located in one or more of the following: (1)

(2)

(3)

On or above countertop or work surfaces: On or above, but not more than 500 mm (20 in .) above, the countertop or work surface. In countertop or work surfaces: Receptacle outlet assemblies listed for use in countertops or work surfaces shall be permitted to be installed in countertops or work sudaces. Below countertop or works su1faces: Not mo re than 300 mm (12 in. ) below the countertop or work su1-face. Receptacles installed below a countertop or work surface shall not be located where the countertop or work surface extends more than 150 mm (6 in. ) beyond its support base.

Receptacle outlets rendered not readily accessible by appliances fastened in place, appliance garages, sinks, or rangetops as covered in 210.52(C) (1 ), Exception , or appliances occupying assigned spaces shall not be cons idered as these required outlets.

t

Informational Nore No. 1: See 406.5(E) and 406.S(G) for installation of receptacles in counrerrops and 406.5(F) and 406.5(G) for installation of receptacles in work surfaces. See 380.10 for installation of multiomlet a ssemblies.

!

Informational Note No. 2: See Annex J and ANSI/ ICC Al 17.1-2009, Standa1'd on Accessible and Usable Buildings and Facili-

X

ties.

Range, counter-mounted cooking unit, or sink extending from face of counter

Space exempt from wall line if X < 450 mm (18 in.)

Outlet within 600 mm (24 in.)

(D) Bathrooms. At least one receptacle outlet shall be installed in bathrooms within 900 mm (3 ft) of the o utside edge of each basin . The receptacle outlet shall be located on a wall or partition that is adjacent to the basin or basin countertop, located on the countertop, or installed on th e side or face of the basin cabinet. In no case shall the receptacle be located more than 300 mm (12 in. ) below the top of the basin or basin countertop. Receptacle outlet assemblies listed for use in countertops shall be permitted to be installed in the countertop. Informational Note: See 406.5(E) and 406.5(G) for requiremenrs for installation of receptacles in counrertops.

(E) Outdoor Outlets. Outdoor receptacle outlets shall be installed in accordance with 210.52(E) (1) through (E)(3) . X

Informational Note: See 210.S(A) (3).

(1) One-Family and Two-Family Dwellings. For a one-family dwell ing and each unit of a two-family dwelling that is at grade level, at least one receptacle outlet readily accessible from grade and not more than 2.0 m (6½ ft) above grade level shall be installed at the front and back of the dwelling. Outlet within 600mm (24 in.)

(2) Multifamily Dwellings. For each dwelling unit of a multifamily dwelli ng where the dwellin g unit is located at grade level and provided with individual exterior entrance/ egress, at least one receptacle outlet readily accessible from grade and not more than 2.0 m (6½ ft) above grade level shall be insta lled.

Range, counter-mounted cooking unit, or sink mounted in corner

FIGURE 210.52(C)(l) Determination of Area Behind a Range, Counter-Mounted Cooking Unit, or Sink. 2020 Edition

NATIONAL ELECTRJCAL CODE

(3) Balconies, Decks, and Porches. Balconies, decks, and porches that are within 102 mm ( 4 in. ) horizontally of the dwell ing unit shall have at least one receptacle outlet accessible from the balcony, deck, or porch . The receptacle o utlet shall not be located more than 2.0 m (6½ ft) above the balcony, deck, or porch walking surface . 70-69

210.52

ARTICLE 210- BRANCH CIRCUITS

(F) Laundry Areas. In dwelling units, at least one receptacle outlet shall be installed in areas designated for the instal lation of laundry equipment.

Exception No. I: A receptac/,e for laundry equipment shall not be required in a dwelling unit of a multifamily building where laund1y facilities are provided on the premises for use by all building occupants. Exception No. 2: A receptacle for laund1y equipment shall not be required in other than onefamily dwellings where laund1y facilities are not to be installed or permitted.

(G) Basements, Garages, and Accessory Buildings. For oneand two-family dwellings, and multifamily dwellings, at least one receptacle outlet shall be installed in the areas specified in 210.52(G)( l ) through (G)(3) . These receptacles shall be in addition to receptacles required for specifi c equipment. (1) Garages. In each attached garage and in each detached garage with electric power, at least one receptacle outlet shall b e installed in each veh icle bay and not more than 1.7 m (5½ ft) above the floor. Exception: Garage spaces not attached to an individual dwelling unit of a multifamily dwelling shall not require a receptacle outlet in each vehicle bay.

(2) Accessory Buildings. In each accessory building with electric power. (3) Basements. In each separate unfinished portion of a basement. (H) Hallways. In dwelling units, hallways of 3 .0 m (IO ft) or more in length shall have at least one receptacle outlet. As used in this subsection, the hallway length shall b e considered the length along the centerline of the hallway without passing through a doorway. (I) Foyers. Foyers that are not part of a hallway in accordan ce with 210.52(H ) and that have an area that is greater than 5 .6 1112 (60 ft2 ) shall have a receptacle(s) located in each wall space 900 mm (3 ft) or more in width. Doorways, door-side windows that extend to the floor, and similar openings shall not be considered wall space.

210.60 Guest Rooms, Guest Suites, Dormitory Units, and Similar Occupancies. (A) General. Guest rooms or guest suites in hotels or mote ls, sleeping rooms in dormitory units, and similar occupancies shall have receptacle outlets installed in accordance with 210.52(A) and (D) . Guest rooms or guest suites provided with permanent provisions for cooking shall have receptacle outlets installed in accordance with all of the applicable rules in 210.52. (B) Receptacle Placement. The total number of receptacle outlets shall not be less than required in 210.52(A) . These receptacle outlets shall be permitted to be located conveniently for permanent furniture layout. At least two receptacle outlets shall be readily accessible. ,1/here receptacles are installed behind the bed, the receptacle sha ll be located to prevent the b ed from contacting any attachment p lug that may b e installed or the receptacle shall be provided with a suitable guard. 210.62 Show Windows. At least one 125-volt, single-phase, 15or 20-ampere-rated receptacle outlet shall be installed within 450 mm (18 in.) of the top of a show window for each

70-70

3.7 linear m (12 linear ft) or major fraction thereof of show window area measured horizontally at its maximum width.

210.63 Equipment Requiring Servicing. A 125-volt, sing lephase, 15- or 20-ampere-rated receptacle outlet shall be installed at an accessible location within 7 .5 m (25 ft) of the equi pment as specified in 210.63(A) a nd (B) . (A) H eating, Air-Conditioning, and Refrigeration Equipment. The required receptacle outlet sh all be located on the same level as the heating, air-conditioning, and refrigeration equipm ent. The receptacle outlet shall not be connected to the load side of the equipment's branch-ci rcuit d isconn ecting means. .Exception: A receptacle outlet shall not be required at one- and twfamily dwellings for the service of evaporative coolers. (B) Other Electrical Equipment. I n other than o ne- a nd twofamily dwellings, a receptacle outlet shall be located as specified in 210.63(B)(l) and ( B)(2) .

(1) Indoor Service Equipment. The required receptacle o utlet shall b e located within the same room or area as the service equipme nt. (2) Indoor Equipment Requiring Dedicated Equipment Spaces. Where equipment, other than service equipment, requires dedicated equipment space as specified in 110 .26(E), the required receptacle outlet shall be located within the same room or area as the electrical equipment a nd shall not be con nected to the load side of the e quipment's branch-circuit disconnecting means. 210.65 Meeting Rooms. (A) General. Each meeting room of n ot more than 93 1112 (1000 ft: 2) in other than dwelling units shall have outlets for nonlocking-type, 125-volt, 15- or 20-ampere receptacles. The outlets shall be installed in accordance with 2 10 .65(B) . Where a room or space is provided with movable partit ion(s), each room size sh all be determined with the partition in the position that results in the smallest size meeting room. Informational Note No. 1: For the purposes of this section, meeting rooms are typically designed or inte nded for the gathering of seated occupants for such purposes as conferences, deliberations, or similar purposes, where portable electronic equipment such as computers, projectors, or similar equipment is likely to be used. Informational Note No. 2: Exam p ies of rooms that are not meeting rooms include auditoriums, schoolrooms, and coffee shops.

(B) Receptacle Outlets Required. The total number of receptacle outlets, including floor outlets and recep tacle outlets in fixed furniture, sh all not be less than as determined in ( I ) a nd (2) .

(1) Receptacle Outlets in Fixed Walls. The required number of receptacle outlets shall be determined in accordan ce with 210.52 (A) (1 ) through (A) ( 4) . These receptacle outlets sha ll b e permitted to be located as determined by the installer, designer, o r building owner. (2) Floor Outlets. A meeting room with any floor d im ension that is 3 .7 m (12 ft) or g reater in an y direction and that has a floor area of at least 20 1112 (215 ft2 ) shall have at least one fl oor receptacle outlet, or at least one floor o utlet to serve receptacle(s), located at a distance n ot less than 1.8 m (6 ft) from any

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 215 fixed wall for each 20 m 2 (215 ft2 ) or major portio n o f fl oor space . Informational Note No. 1: See 314.27(B) fo r floo r boxes used for receptacles located in t he floor. Informational Note No. 2: See Article 518 for assembly occupancies designed for 100 o r more persons.

210.70 Lighting Outlets Required. Ligh ting o utlets sh all be installed where specified in 210.70 (A), (B), and (C) . (A) Dwelling Units. In dwelling units, lighting o utlets sh all be installed in accordance w ith 210.70 (A) (1), (A) (2 ), and (A) (3) . (1) Habitable Rooms. At least one lighting o utlet con tro lled b y a listed wall-m ounted control d evice sh all be installed in every habitable room, k itch e n , an d bath room. T he wallmo unted con trol device shall be located near a n e n u·an ce to th e room o n a wall.

215.2

FEEDERS

Exception No. 2: Lighting outlets shall be permitted to be controlled by occupancy sensors that are (1) in addition to listed wall-mounted control devices or (2) located at a customary wall switch location and equipped with a manual override that allows the sensor to fitnction as a wall switch.

(C) All Occupancies. For attics and underfloor spaces, utility rooms, an d basements, at least one lig hting o utlet containing a switch or con u·olled by a wall switch or listed wall-m o unted con trol device sha ll be installed where these spaces are used for storage or conta in equi pm e n t requi ring servicing. A po int o f control sh all be at each en u-y that permits access to th e attic and underfloo r space , u tili ty room , o r baseme nt. Whe re a ligh ting outlet is installed for equipme nt req uiring service, the lighting ou tlet sh all be installed at o r n ear the equipment.

Exception No. 1: In other than kitchens and bathrooms, one or more receptacles controlled by a listed wall-moitnted control device shall be permitted in lieit of lighting 01ttlets.

ARTICLE 215 Feeders

Exception No. 2: Lighting oittlets shall be permitted to be controlled by occupancy sensors that are ( 1) in addition to listed wall-mounted control devices or (2) located at a customary wall switch location and eqitipped with a manual override that will all.ow the sensor to function as a wall switch.

215.1 Scope. This article covers the insta llatio n requirem en ts, overcu rrent protectio n requi rem e n ts, minimum size, and a m pacity of co nductors for feede1·s.

(2) Additional Locations. Additio n al lig hti ng o utlets sh all be installed in accordan ce with the foll owing:

Exception: Feeders for electrolytic cells as covered in 668.J(C)(l) and (C)(4 ).

( 1)

215.2 Minimum Rating and Size.

(2)

(3)

At least o ne lig hting o utlet co n trolled by a listed wallmo unted con u·ol device shall be installed in h allways, stairways, a ttached garages, and detached garages with electric power. For dwelling uni ts, attached garages, a nd detached garages with elecu·ic power, at least one lig hting ou tlet con trolled by a listed wall-mo u nted control device sh all be installed to provide illuminatio n o n th e exterior side of ou tdoor en trances o r exi ts with g rade-level access. A ve hicle d oor in a garage sha ll not be co nsidere d as a n o u tdoor e ntrance or exit. \!\There o ne o r mo1·e lig h ting o utlet(s) a re installed for inte rior stainvays, there sh all be a listed wall-m oun ted con trol device at each floor level a n d la nd ing level that includes a n e ntryway to co ntrol the ligh ting o utlet(s) where the stai n vay between floor levels h as six risers or more.

Exception lo (A)(2)(1), (A)(2)(2), and (A)(2)(3): In hallways, in stairways, and at outdoor entrances, remote, central, or automatic control oflighting shall be permitted.

(4)

Lig hting o utlets conu·olled in accordance with 210.70(A) (2) (3) sha ll not be controlled by use of listed wallmounted control devices unless they provide th e full range o f d imming con trol at each locatio n.

(B) Guest Rooms or Guest Suites. In hotels, motels, or similar occu pancies, guest rooms or guest suites sh all have a t least one lighting o u tle t controlled by a listed wall-mounted control device installed in every habitable room and bathroom. Exception No. 1: In other than bathrooms and kitchens where provided, one or more receptacles controlled by a listed wall-mounted control device shall be permitted in lieu of lighting oittlets.

2020 Ed ition

NATIONAL ELECTRJCAL CODE

(A) Feeders Not More Than 1000 Volts. (1) General. Feeder conductors shall h ave an a mpacity not less t han the larger of 215 .2(A) (l)(a) o r (A)( l )(b ) and sh all com plywith 110.14(C) . (a) W here a feeder supplies con tinuous loads o r any combination of contin uo us an d no n con tinuo us loads, the min imum feede r conductor size s ha ll h ave a n a mpacity not less than th e no ncon tinuous load plus 125 percent of the con tinuous load. l!,xception No. 1: If the assembl)\ including the overwrrent devices protecting the feeder(s ), is listed for operation at 100 percent of its rating, the ampacity of the feeder conditclors shall be permitted lo be not less than the wm of the continuous load plus the noncontinitoits load. Exception No. 2: \!Vhere a portion of a feeder is connected at both its wpply and load ends to separately installed pressure connections as covered in 110.14(C)(2), it shall be permitted to have an ampacity not less than the sum of the continitous load plus the noncontinuous load. No portion of a feeder installed itnder this exception shall extend into an enclowre containing either the feeder supply or the feeder load tenninations, as covered in 110.14(C)(1). l!,xception No. 3: Grounded conductors that are not connected to an overCitrrent device shall be permitted to be sized at 100 percent of the continitous and nonconlinitous load.

(b ) The minimum feed e r conductor size shall h ave an a m pacity not less than the maximum load to be served afte r the a pplicatio n of a ny adjustme nt o r correc tio n factors in accordance with 310.14. Informatio nal Note No. 1: See Examples D I through D11 in Informative Annex D.

70-71

ARTICLE 215 - FEEDERS

215.2

Informational Note No. 2: Conductors for feeders, as defined in Article 100, sized to prevent a voltage drop exceeding 3 percent at the farthest outlet of power; heating, and lighting loads, or combinations of such loads, and where the maximum LOtal volLage drop on both feeders and branch circuits to the farthest outlet does not exceed 5 percent, will provide reasonable efficiency of operation . In formational Note No. 3: See 2 10. 19(A), Informational Note No. 4, for voltage drop for branch circuits.

(2) Grounded Conductor. The size of the feeder circuit grounded conductor sha ll not be smaller than that requ ired by 250.1 22, except that 250.1 22(F) shall not apply where grounded conductors are run in parallel.

Additional minimum sizes shall be as specified in 2 15.2(A) (3) under the conditions stipulated. (3) Ampacity Relative to Service Conductors. The feeder conductor ampacity shall not be le ss than that of the service cond uctors where the feede1- conductors carry the total load supplied by service conductors with an ampacity of 55 amperes o r less.

(B) Feeders over 1000 Volts. The ampacity of conductors shall be in accordance with 310.14 a nd 311.60 as applicable . v\There installed, the size of the feeder-circuit grounded conductor shall not be smaller than that required by 250.122, except that 250.1 22 (F) shall not apply where grounded conductors are run in parallel. Feeder conductors over 1000 volts shall be sized in accordance with 215.2(B)( l ), (B)(2), o r (B)(3) . (1) Feeders Supplying Transformers. The a mpacity of feeder conductors shall not be less than the sum of the nameplate ratings of the transformers supplied whe n only transformers a re supplied.

(2) Feeders Supplying Transformers and Utilization Equipment. The ampacity of feeders supplyin g a combination of transformers and utilization equipment sha ll not be less than the sum of the nameplate ratings of the transformers and 125 percent of the designed potential load of the utilization equipment that wi ll be operated simultaneously. (3) Supervised Installations. For supervised installations, feeder cond uctor sizing sh a ll b e permitted to be determined by qualified persons under engineering supervision in accordan ce with 310.14( B) o r 311.60(B) . Supervised instal lations are defined as those portions of a facility where all of the following conditions are met: (I)

(2)

Conditions of design and installation are provided under engineering supervision . Qualified persons with documented training and experience in over 1000-volt systems provide maintenance, monitoring, and servicing of the system.

215.3 Overcurrent Protection. Feeders shall be protected against overcurrent in accordance with Part I of Article 240. \>\There a feeder supplies continuous loads or any combination of continuous and noncontinuous loads, the rating of the overcu rrent device shall not be less than the noncontinuous load plus 125 percent of the continuous load.

Exception: Where the assembl)\ including the overcwmmt devices protecting the feedmYs), is listed for operation at 100 percent of its rating, the ampere rating of the overcurrent device shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load.

70-72

215.4 Feeders with Common Neutral Conductor. (A) Feeders with Common Neutral. Up to three sets of 3-wire feeders or two sets of 4-wire or 5-wire feeders sha ll be permitted to utilize a common neutral. (B) In Metal Raceway or Enclosure. V,There installed in a metal raceway or other metal enclosure, all conductors of a ll feeders u sing a common neutral conductor shall be enclosed within the same raceway or other enclosure as required in 300.20.

215.5 Diagrams of Feeders. If req uired by the authority having jurisdiction, a d iagram showing feeder details shall be provided prior to the installation of the feeders. Such a diagram shall show the area in square feet of the building o r other strucnire supplied by each feeder, th e total calculated load before applying demand factors, the demand factors used , the calculated load after applying demand factors, and the size and type of conductors to be used . 215.6 Feeder Equipment Grounding Conductor. v\There a feeder supplies b ranch circuits in which equipment grounding conductors are required, the feeder sh all include or provide an equipment grounding conductor, to which the equipment grounding conductors of th e branc h circuits shall be connected. \>\There the feeder supplies a separate building or structure, the requirements of 250.32 shall apply. 215.7 Ungrounded Conductors Tapped from Grounded Systems. Two-wire de c ircuits and ac circuits of two or more ungrounded conductors shall be perm itted to be tapped from the ungrounded conductors of circuits h aving a grounded neutral conducto r. Switching devices in each tapped circuit shall have a pole in each ungrounded conductor. 215.9 Ground-Fault Circuit-Interrupter Protection for Personnel. Feeders shall be permitted to be protected by a groundfau lt c ircuit interrupter installed in a 1-eadily accessible location in lieu of the provisions for such interrupters as specified in 210.8 a nd 590.6(A) . 215.10 Ground-Fault Protection of Equipment. Each feeder disconnect rated 1000 amperes or more and installed on solidly grounded wye electrical systems of mo re than 150 volts to ground, but not exceeding 600 volts phase-to-phase, shall be provided with ground-fault protection of equipment in accordance with 230.95. I nformational Note: For buildings tl,at contain healtl1 care occupancies, see .517.17.

Exception No. 1: 17iis section shall not apply to a disconnecting means for a continuous industrial process where a nonorderly shutdown will intwduce additional or increased hazards. Exception No. 2: This section shall not apply if ground-fault protection of equifnnent is provided on the supply side of the feeder and on the load side of any transformer supplying the f eede1: 1'.xception No. 3: If temporaiy feeder cond1ictors are used to connect a generator to a facility fm· repail; maintenance, m· emergencies, groundfauU protection of equipment shall not be required. Temporary feedeis withmtt grmmd-fault protection shall be permitted for the time period necessmy but shall not exceed 90 days. 215.11 Circuits Derived from Autotransformers. Feeders shall not be derived from autotransformers unless the system supplied has a grounded conductor th at is e lectrically connected to a grounded conductor of the system supplying the a utotransformer.

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 220- BRANCH-CIRCUIT, FEEDER, AND SERVICE LOAD CALCULATIONS Exception No. I: An autotransformer shall be pennitted without the connection lo a grounded conditctor where transforming firmz a nominal 208 volts lo a nominal 240-volt supply or similarly jimn 240 vo11s lo 208 volts. Exception No. 2: In industrial occupancies, where conditions of maintenance and supervision ensure that only qualified persons service the installation, autotransfonners shall be permitted lo supply nominal 600-volt loads jimn nominal 480-volt systems, and 480-volt loads fr!Ym norninal 600-voU systems, withmtt the wnnection to a similar grounded conducto1: 215.12 Identification for Feeders. (A) Grounded Conductor. The g ro unded conductor of a feeder, if insulated, sh a ll be identified in accordance with 200.6 . (B) Equipment Grounding Conductor. The equipment grounding conductor shall be identified in accordance with 250.11 9 . (C) Identification of Ungrounded Conductors. Ungrounded conductors shall be identified in accordance with 215.1 2(C) (I ) or (C) (2), as applicable.

(1) Feeders Supplied from More Than One Nominal Voltage System. vVh ere the premises wiring system h as feeders supplied from more than one nominal voltage system , each ungrounded conductor of a feeder shall be identified by phase or line and system at a ll termination, connection, and splice points in compliance with 2 I 5. I 2(C) (1 )(a) and (b ) . (a) Means of Identification. The means of identification shall be permitted to be by separate color coding, marking tape, tagging, o r other approved means. (b) Posting of Identification Means. The method utilized for conductors orig inating within each feeder panelboard or similar feeder distribution equipment shall be documented in a manner that is readily available or shall be permanently posted at each feeder panelboard or similar feeder distribution equipment. (2) Feeders Supplied from Direct-Current Systems. Where a feeder is supplied from a de system operating at more than 60 volts, each ungrounded conductor of 4 AWG or larger shall be identified b y polarity at all termination, con nection, and splice points by marking tape, tagging, or other approved means; each ungrounded conductor of 6 AWG or smaller shall be identified by polarity at all termination, con nection, and splice points in complia n ce with 215.1 2(C)(2)(a) and (b) . The identification methods utilized for conductors originating within each feeder panelboard o r similar feeder d istribution equipment shall be documented in a manner that is readily available or shall be permanently posted at each feeder panelboard or similar feeder distribution equipment. (a) Positive Polarity, Sizes 6 A WC or Smaller. \-\'he re the positive polarity of a de system does not serve as the connection for the grounded conductor, each positive ungrounded conductor shall be identified by one of the following means: ( 1) (2)

(3)

A continuous red outer finish A continuo us red stripe durably marked a long the condu ctor's entire length on insulation of a color other than green, white, gray, or black Imprinted plus sign s (+) or the word POSITIVE or POS durably marked on insulation of a colo r other than green, white, gray, or black, a nd repeated at intervals not exceeding 610 111111 (24 in.) in accordance with 310.S(B)

2020 Edition

NATIONAL ELECTRJCAL CODE

220.5

( 4)

An approved permanent marking m eans such as sleeving or shrink-nibing that is suitable for the conductor size, at all termination, connection, and splice points, with imprinted plus signs (+) or the word POSITIVE or POS durably marked on insula tion of a color other than green, white, gray, or black (b) Negative Polarity, Sizes 6 A WC or Smallei: Where the negative polarity of a de system does n ot serve as the connection for the grounded condu ctor, each negative ungrounded conductor shall be identified by one of the following means: (1) (2)

(3)

( 4)

A continuous black outer finish A continuous black stripe durably marked along the conductor's entire length on insulation of a color other than gree n, white, g ray, or red Imprinted minus signs (-) or the word NEGATIVE or NEG durably marked o n insulatio n of a color other than green, white, gray, or red, and repeated at intervals not exceeding 610 111111 (24 in. ) in accordance with 310.S(B) An approved permanent marking m eans such as sleeving or shrink-tubing that is suitable for the conductor size, at all termination, connection, and splice points, with imprinted minus signs (-) or the word NEGATIVE or NEG durably marked on insulatio n of a color other than green, white, gray, or red

ARTICLE 220 Branch-Circuit, Feeder, and Service Load Calculations Part I. General 220.1 Scope. This article provides requirements for calculating branch-circuit, feeder, and service loads. Part I provides general requirements for calculation methods. Part II provides calculation methods for branch-circuit loads . Parts III a nd IV provide calculation m ethods for feeder and service loads. Part V provides calculati on methods for farm loads. Informationa l Note No. Annex D.

I: See examples in Informative

Informational Note No. 2: See Figure 220.l for information o n the o rganization of Article 220.

220.3 Other Articles for Specific-Purpose Calculations. Ta ble 220.3 shall provide references for specific-purpose calculatio n requirements no t located in Chapters 5, 6, or 7 that amend or supplement the requirements of this article . 220.5 Calculations. (A) Voltages. U nless other voltages are specified, for purposes of calculating bra n ch-ci rcuit a nd feeder loads, nominal syste m voltages of 120, 120/ 240, 208Y/ 120, 240, 347, 480Y/ 277, 480, 600Y/ 347, and 600 volts shall be used. (B) Fractions of an Ampere. Calculations shall be permitted to be rounded to the nearest whole ampere, with decimal fractions smaller than 0.5 dropped.

70-73

220.10

ARTICLE 220- BRANCH-CIRCUIT, FEEDER, AND SERVICE LOAD CALCULATIONS

Part I General

Part 11 Branch-circuit load calculations

(B) Energy Code. Where the building is designed and con structed to comply with an energy code adopted by the local authority, the lighting load shall be permitted to be calculated using the unit values specified in the energy code where the following cond itions are m et:

(1)

Part Ill Feeder and service load calculations

220.61 Neutral Loads

Part IV Optional feeder and service load calculations

(2)

(3) Farm dwellings only

Farm dwellings only

(4)

A power mon itoring system is insta lled that will provide continuous information regard ing the total general lighting load of the building. The power mon itoring system will be set with alarm values to alert the building owner or m anager if the lighting load exceeds the values set by the en ergy code . Autom atic means to take actio n to reduce the connected load shall be permitted. The demand factors specified in 220.42 are not applied to the general lighting load. The continuo us load multiplier of 125 percent shall be applied.

FIGURE 220.1 Branch-Circuit, Feeder, and Service Load Calculation Methods.

220.14 Other Loads - All Occupancies. In a ll occupancies, the minimum load for each outlet for general-use receptacles a nd outlets not used for general illumination sh all not be less than that calculated in 220.1 4(A) th rough (M), the loads shown being based on nominal branch-circuit voltages.

Part II. Branch-Circuit Load Calculations

Exception: The loads of outlets serving switchboards and switching frames in telephone exchanges shall be waived ftmn the calculations.

Part V Farm load calculations

220.10 General. Branch-circuit loads shall be calculated as shown in 220.12, 220.14, and 220.1 6. 220.11 Floor Area. The floor area for each floor shall be calculated from the outside dimensions of the build ing, dwelling unit, or other area involved. For dwelling units, the calculated floor area shall not include open porches, garages, or unused or unfinished spaces not adaptable for future use. 220.12 Lighting Load for Non-Dwelling Occupancies. (A) General. A unit load of not less than that specified in Table 220.1 2 for non-dwel ling occupancies and the floor area determined in 220.11 sha ll be used to calculate the minimum lighting load. Motors rated less than Ys HP and connected to a lighting c ircui t shall be considered general lighting load. Informational Note: The unit values of Table 220.12 are based on mini mum load conditions and 100 percent power factor and may not provide sufficienL capacity for the installation conLemp lated.

(A) Specific Appliances or Loads. An ou tlet for a specific appl ian ce or other load not covered in 220.14(B) through (M) shall be calculated based on the ampe1·e rating of the appliance or load served. (B) Electric Dryers and Electric Cooking Appliances in Dwellings and Household Cooking Appliances Used in Instructional Prograins. Load calculations sha ll be permitted as spec ified in 220.54 for electric dryers a nd in 220.55 for electric ranges a nd other cooking appliances. (C) Motor Outlets. Loads for motor o utlets shall be calculated in accordance with the requirements in 430.22, 430.24, and 440.6. (D) Luminaires. An o utlet supplying luminaire(s) shall be calculated based on the maximum volt-ampere rating of the equipment and la mps for whic h the luminaire(s) is rated. (E) Heavy-Duty Lampholders. Outlets for heavy-du ty lampholders sh all be calculated at a minimum of 600 volt-am peres.

Table 220.3 Specific-Purpose Calculation References Calculation Air-cond itioning and refrigerating equipment, branchcircuit conductor sizing Fixed e lectric heating equipmen t for pipelines and vessels, branch-circuit sizing Fixed e lectric space-heati ng equipment, branch-circuit sizing Fixed outdoor electric deicing and snow-melting equipment, branch-circuit sizing \io tors, feeder demand factor Motors, multimotor and combination-load equipment \iotors, several motors or a motor(s) and other load(s) Over 600-volt branch-circuit calculations Over 600-volt feeder calculations Phase converters, conductors Storage-type water heaters

70-74

Article

Section ( or Part)

440

Part IV

427

427.4

424 426

424.3 426.4

430 430 430

430.26 430.25 430.24 210.19 (8 ) 215.2(8 ) 455.6 422.ll (E)

210 215 455 422

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 220 -

BRANCH-CIRCUIT, FEEDER, AND SERVICE LOAD CALCULATIONS

Table 220.12 General Lighting Loads by Non-Dwelling Occupancy Unit Load Volt-amperes/ Type of Occupancy

m2

Volt-amperes/ ft2

Automotive facility Convention center Courthouse D01mitory Exercise center Fire station Gymnasium" Health care clinic Hospital Ho te ls and motels, inclu d ing apartmen t houses without p rovisions for cooking by tenantsh Library Manufactu1ing facility" Mo tion picture theater Museu m Officed Parking garagec Penitentiary Pe i-forming arts theater Po lice station Post office Religious facility Restau ran tr Retailg.h School/ un iversity Sports arena Town hall Transportation Warehouse Workshop

16 15 15 16 15 14 18 17 17 18

1.5 1.4 1.4 1.5 1.4 1.3 1.7 1.6 1.6 1.7

16 24 17 17 14 3 13 16 14 17 24 16 20 33 33 15 13 13 18

1.5 2.2 1.6 1.6 1.3 0.3 1.2 l.5 1.3

1.6 2.2 1.5 1.9 3 3 1.4 1.2 1.2 1.7

Note: The 12.5 percent multi.plier for a continuous load as specified in 210.20(A) is included when using the unit loads in this table for calculating the minimum lig hting load for a specified occupancy. "Armories and auditoriums are considered gymnasium-type occupancies. bLodge rooms are simila r to hotels and motels. ' Industrial commercial loft buildings are considered manufacturingtype occupancies. "Banks are office-type occupancies. "Garages - commercial (storage) are considered parking garage occupancies. rclubs are considered restaurant occupancies. gBarber shops and beauty parlors are considered retail occupancies. hStores are considered retail occupancies.

(F) Sign and Outline Lighting. Sign an d outline lighting outlets shall be calculated at a min im u m of 1200 volt-am peres for each required b ranch circuit specified in 600.5(A) .

(H) Fixed Multioutlet Assemblies. Fixed m ultiou tlet assem blies used in other th a n dwelling units or the g uest room s or guest suites of h otels or motels sh all be calculated in accordance wi th (H ) (1) o r (H ) (2) . For the purposes of this section, the calculation sh all be permitted to be based on the portio n that contains receptacle outlets . (1)

(2 )

180 volt-amperes for each single or for each multiple receptacle on one yoke. A single p iece of equipmen t con sisting of a m ultiple receptacle com prised of four or mo re recep tacl es shall be calculated at not less th an 90 volt-am peres per receptacle . T h is provision sh all n ot be ap plicable to the receptacle o u tlets specified in 2 10.ll (C)( l ) and (C)(2) .

(J) Dwelling Units. In o n e-family, two-family, a nd multifa mily d welli ngs, the minimum u n it load shall be not less than 33 voltarnperes/ m2 (3 vol t-am peres/ ft2) . T he ligh ting and receptacle outlets specified in 220.14(J)(l ) , (J)(2 ), a nd (J)(3) are included in the mi n imu m u n it load. No additional load calculatio ns shall be required for such ou tlets. The m inimum lig hting load shall be determ ined using the mi n imum u n it load a nd the floor area as determined in 220.11 for dwelling occupa ncies. Motors rated less th an 1/s hp a n d connected to a lighting circuit shall be considered part of the m inimum lighting load. (I)

(2) (3)

(1) (2)

(M) Hotel and Motel O ccupancies. In guest room s or guest suites of h o tels a n d m otels, the ligh ting and receptacle o utlets specified in 220.14(M)(1), (M)(2), and (M)(3) are included in the m inimum u n it load in Table 220.1 2. No additio nal load calculatio ns shall be required for suc h o u tlets. The minim u m ligh tin g load sh all be determined using the min im um u n it load and th e floo r area as determined in 220.11 for h otel and m otel occupancies.

(1)

(2)

NATIONAL ELECTRJCAL CODE

The calculated load from 220.14(1) after a ll demand factors h ave been applied 11 volt-amperes/ m2 or 1 volt-ampere/ ft2

(L) Other Outlets. Other outlets not covered in 220.14(A) through (K) shall be calculated b ased on 180 volt-amperes per outlet.

(3)

2020 Edition

All general-use receptacle o utlets of 20-am pere rati ng or less, includ ing rece p tacles connected to th e circuits in 210.11 (C)(3) a n d 210.11 (C)( 4) The receptacle ou tlets specified in 210.52(E) and (G) The ligh ting outlets specified in 21 0.70

(K) Office Buildings. In office build ings, the receptacle loads shall be calculated to be the large1· of (1) or (2) :

(1) (2)

Where appliances are unlike ly to be used simultaneously, each 1.5 m (5 ft) or fractio n th ereof of each separate and con tinuo us le ngth shall be con sidered as one o utlet of not less than 180 volt-amperes. ' "' here applian ces are likely to be used simultan eously, each 300 mm (1 ft) o r fraction thereof shall be considered as an ou tlet of not less than 180 vol t-amperes.

(I) Receptacle Outlets. Except as covered in 220.14(J) and (K), receptacle ou tlets s hall be calculated at not less than

(G) Show Windows. Show windows shall be calculated in accordance with e ither of the following: T he u n it load per o u tlet as required in other provisions of this sectio n At 200 volt-am peres per linear 300 mm (1 ft) of sh ow window

220.14

All general-use receptacle outlets of 20-am pere rati ng or less, including receptacles connected to the circuits m 210.11 (C) (3) a n d 210.11 (C) (4) T he receptacle ou tlets specified in 210.52(E) (3) The ligh ting o u tlets specified in 210.70

70-75

220.16

ARTICLE 220- BRANCH-CIRCUIT, FEEDER, AND SERVICE LOAD CALCULATIONS

220.16 Loads for Additions to Existing Installations.

Table 220.42 Lighting Load Demand Factors

(A) Dwelling Units. Loads added to an existi ng dwelling unit(s) shall comply with the following as applicable: (1)

(2)

Loads for structu ral additions to an existing dwelling unit or for a previously unwired portion of an existing dwelling unit shall be calculated in accordance with 220.14. Loads for new circuits or extended circuits in previously wired dwelling units shall be calculated in accordan ce with 220.14.

(B) Other Than Dwelling Units. Loads for new circuits or extended circuits in other than dwelling units shall be calculated in accordance with e ither 220.1 2 or 220.1 4, as applicable . 220.18 Maximum Loads. The total load shall not exceed the rating of the branch circuit, and it shall not exceed the maximum loads specified in 220.IS(A) through (C) under the conditions specified th erein. (A) Motor-Operated and Combination Loads. Where a circuit supplies only motor-operated loads, Article 430 shall apply. Where a circuit supplies only air-conditioning equipme nt, refrigerating equipment, or both , Article 440 shall apply. For circuits supplying loads consisting of motor-operated utilization equipment that is fastened in place and has a motor larger than 1/s hp in combination with other loads, the total calculated load shall be based on 125 percent of the largest motor load plus the sum of the other loads. (B) Inductive and LED Lighting Loads. For c ircuits su pplying lighting uni ts that have ba llasts, transformers, autou·ansformers, or LED drivers, the calculated load shall be based on the total ampere ratings of such units and not on the total watts of the lamps. (C) Range Loads. It sha ll be permissible to apply demand factors for range loads in accorda nce with Table 220.55, including Note 4.

Part III. Feeder and Service Load Calculations 220.40 General. The calculated load of a feeder or service shall not be less than the sum of the loads o n the branch circuits supplied, as determined by Part II of this article, after any applicable demand factors permitted by Part III o r IV or required by Part V have been applied. Informational Note: See Examples Dl (a) through D10 in Informative Annex D. See 220.18(8 ) for the maximum load in ampe res permilted for lighting unilS operaling at less than 100 percent power facto r.

220.42 General Lighting. The demand factors specified in Table 220.42 shall apply to that portion of the total branch.circuit load calculated for general illumination . They shall not be applied in determining the number of bra nch circuits for general illumination. 220.43 Show-Window and Track Lighting. (A) Show Windows. For show-window ligh ting, a load of not less than 660 volt-amperes/ linear meter o r 200 volt-amperes/ Ii near foot shall be included for a show window, measured horizontally a long its base.

Type of Occupancy

Dwelling units

Portion of Lighting Load to Which Demand Factor Applies (Volt-Amperes)

First 3000 al From 3001 to 120,000 at Remainder over 120,000 at

Hotels and motels, includi ng apartmen t houses without provision for cooking by tenants*

First 20,000 or less at From 20,001 to 100,000 at Remainder over 100,000 at

Warehouses (storage)

First 12,500 or less at Remainder over 12,500 at

All others

Demand Factor (%)

100 35 25 60 50

35 100 50

Total volt-ampe1·es

100

*The demand facwrs of this table shall not apply to Lhe calculaLed load offeeders or services supplying areas in hote ls and motels where the entire lighting is likely to be used at one time, as in ballrooms or d ining rooms.

(B) Track Lighting. For track lighting in other th an dwelling units or guest rooms or guest suites of hotels or motels, an additional load of 150 volt-amperes shall be included for evet)' 600 mm (2 ft) of lighting track or fraction thereof. Where multicircuit u·ack is installed, the load shall be considered to be divided equally benveen the track circuits. Axception: If the track lighting is supplied through a device that limits the current to the track, the load shall be permitted to be calculated based on the rating of the device med to limit the current. 220.44 Receptacle Loads Other Than Dwelling Units. Receptacle loads calculated in accordance with 220.1 4(H ) and (I) shall be permitted to be made subject to the demand factors given in Table 220.42 or Table 220.44. 220.50 Motors. Motor loads shall be calculated in accordance with 430.24, 430.25, and 430.26 an d with 440.6 for hermetic refrigerant motor-compressors.

Table 220.44 Demand Factors for Non-Dwelling Receptacle Loads Portion of Receptacle Load to Which Demand Factor Applies (Volt-Amperes)

First 10 kVA or less at Remainder over JO kVA a t

Demand Factor (%)

100 50

Informational Note: See 220.14(G) for branch circu ils supplying show windows.

70-76

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 220 -

BRANCH-CIRCUIT, FEEDER, AND SERVICE LOAD CALCULATIONS

220.51 Fixed Electric Space Heating. Fixed electric spaceheating loads shal l be calcu lated at 100 percen t of the total connected load . H owever, in no case shall a feeder or service load current rating be less than the rating of th e largest bran ch circuit su pplied . Exception: Where reduced loading of the conductors results from units operating on duty-cycle, intermittently, or from all units not operating at the same time, the authority having jurisdiction may grant pennission for feeder and service conductors to have an ampacity less than 100 percent, provided the conductors have an ampacity for the load so determined.

220.52 Small-Appliance and Laundry Loads -

Dwelling Unit.

(A) Small-Appliance Circuit Load. In each dwelling u nit, the load shall be calculated at 1500 volt-amperes for each 2-wire small-appliance branch c ircui t as covered by 210.11 (C) (1 ) . , l\1here the load is subd ivided th rough two or m ore feeders, the calc ulated load for each shall include not less than 1500 voltamperes for each 2-wire sma ll-appliance branch circuit. These loads shall be permitted to be included with th e gen eral lighting load and subjected to t he demand facto rs provided in Table 220.42. Exception: The individual branch circuit permitted by 210.52(8)(1), Exception No. 2, shall be permitted to be excluded from the calculation required by 220.52.

(B) Laundry Circuit Load. A load of not less th an 1500 voltamperes shall be incl uded for each 2-wire laundry branch circuit installed as covered by 210.ll (C)(2) . T h is load sh all be permitted to be included with the general lig hting load and shall be subjected to the demand factors provided in Table 220.42. 220.53 Appliance Load - Dwelling Unit(s) . It shall be pennissible to apply a de mand factor of 75 percent to the nameplate rating load of fou r or more appliances rated 1/., h p o r greater, or 500 watts or greater, that are fastened in place, and that are served by the same feeder or service in a one-family, nvo-family, or multifa mily dwelling. Th is demand factor shall not apply to: (1 )

(2) (3) ( 4)

Ho usehold e lectric cooking equipme nt that is faste ned in place Clothes d ryers Space heating equipment Air-conditioning equipmen t

220.54 Electric Clothes Dryers - Dwelling Unit(s). The load for ho usehold e lectric clothes drye rs in a dwelling u nit(s) sh all be e ither 5000 watts (volt-amperes) or the nameplate rating, whic hever is la rger, for each dryer served. T he use of the demand factors in Table 220.54 shall be permitted. Whe re two or more single-phase dryers are supplied by a 3-phase, 4-wire feeder o r service, the total load shall be calculated on the basis of nvice the maximum numbe r connected between any nvo phases. Kilovolt-amperes (kVA) shall be considered eq uivale n t to kilowatts (kW) for load s calculated in th is sectio n.

2020 Edition

NATIONAL ELECTRJCAL CODE

220.60

Table 220.54 Demand Factors for Household Electric Clothes Drye rs Nmnberof Dryers

Demand Factor (%)

7 8

100 85 75 65 60

9

55

10

50 47

1-4

5 6

11

12-23

47% min us l % for each dryer exceeding l l

24-42

35% m inus 0.5% for each dryer exceeding 23

43 and over

25%

220.55 Electric Cooking Appliances in Dwelling Units and Household Cooking Appliances Used in Instructional Programs. The load for household electric ranges, wallmounted ovens, counter-mounted coo king u nits, a n d other household cooking appliances individ ually rated in excess of l % kW shall be permitted to be calculated in accordance with Table 220.55. Kilovolt-amperes (kVA) shall be considered equivale nt to kilowatts (kW) for loads calculated under this section .

Where two or more single-phase ranges are sup plied by a 3-phase, 4-wire feeder or service, t he total load shall be calcul ated on the basis of twice the maximum number connected between any two ph ases. Informational Note No. 1: See the examples in Informative Annex D. Informational Note No. 2: See Table 220.56 for commercial cooking equipment.

220.56 Kitchen Equipment - Other Than Dwelling Unit(s). It shall be permissible to calculate t he load for commercial electric cooking equipment, d ishwashe r booster heaters, water heaters, and o ther kitchen equip ment in accordance with Table 220.56. These demand factors shall be appli ed to a ll equi pment that h as e ither thermostatic control or intermi ttent use as kitchen equipment. T hese demand factors shall no t a pply to space-heating, ventilating, or a ir-cond itioning equipment.

However, in n o case shall the feeder or service calculated load be less than the sum of the largest two kitch e n equip ment loads. 220.60 Noncoincident Loads. , l\'here it is unli kely that t\vo or more noncoincident loads will be in use simultan eously, it sha ll be perm issible to use o nly the largest load(s) that will be used at one t ime for calcula ting the total load of a feeder or service. Where a motor is part of the no ncoincident load and is not the largest of th e non coincident loads, 125 percent of the m otor load shall be used in the calculation if it is the largest motor.

70-77

220.60

ARTICLE 220- BRANCH-CIRCUIT, FEEDER, AND SERVICE LOAD CALCULATIONS

Table 220.55 Demand Factors and Loads for Household Electric Ranges, Wall-Mounted Ovens, Counter-Mounted Cooking Units, and Other Household Cooking Appliances over I ¾ kW Rating (Column C to be used in all cases except as otherwise permitted in Note 3.) Demand Factor(%) (See Notes) Column A (Less than 3½ kW Rating)

(3'/2 kW through 8¾ kW Rating)

3 4 5

80 75 70 66 62

80 65 55 50 45

14 17 20

6 7 8 9 10

59 56 53 51 49

43 40 36 35 34

21 22 23 24 25

11

12 13 14 15

47 45 43 41 40

32 32 32 32 32

26 27 28 29 30

16 17 18 19 20

39 38 37 36 35

28 28 28 28 28

31 32 33 34 35

21 22 23 24 25

34 33 32 31 30

26 26 26 26 26

36 37 38 39 40

26-30 31-40

30 30

24 22

15 kW+ 1 kW for each range

41 - 50 51-60

30 30 30

20 18 16

25 kvV + ¾kW for each

Number of Appliances

1 2

61 and over

ColumnB

Column C Maximum Demand (kW) (See Notes) (Not over I 2 kW Rating)

8 ]]

range

Notes: l. Over 12 kW through 27 kW ranges all of same rating. For ranges individually rated more than 12 kW but not more than 27 kW, the maximum demand in Column C shall be increased 5 percent for each additional kilowatt of rating or m~jor fraction thereof by wh ich the rating of individual ranges exceeds 12 kW. 2. Over 8¾ kW through 27 kW ranges of unequal ratings. For ranges individually rated more than 81/. kW and of different ratings, but none exceeding 27 kW, an average value of rating shall be calcu lated by adding together the ratings of a ll ranges to obtain the total connected load (using 12 kW for any range rated less than 12 kW) and d ividing by the total number of ranges. Then the maximum demand in Column C sh all be increased 5 percent for each kilowatt or m~jor fraction thereof by which this average value exceeds 12 kW. 3. Over 1¾ kW through 8¾ kW. In lieu of the method provided in Column C, it shall be permissible to add the nameplate ratings of all household cooking appliances rated more than l ¾ kW but not more than 8¾ kW and multip ly d1e sum by the demand factors specified in Column A or Colu mn B for the given number of appliances. Where d1e rating of cooking appliances falls under both Column A and Column B, the demand facto rs fo r each column shall be applied to the appliances for that column, and the results added togetheic 4. Branch-Circuit Load. It shall be permissible to calculate the branch-circuit load for one range in accordance with Table 220.55. The branch-circuit load for one wall-mounted oven or one counter-mounted cooking unit shall be d1e nameplate rating of d1e appliance. The branch-circuit load for a counter-mounted cooking unit and not more than two wall-mounted ovens, all supplied from a single branch circuit and located in the same room, shall be calculated by adding the nameplate rating of the individual appliances and treating this total as equivalent to one range. 5. This table shall a lso apply to household cooking appliances rated over I¾ kW and used in instructional programs.

70-78

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 220 -

BRANCH-CIRCUIT, FEEDER, AND SERVICE LOAD CALCULATIONS

Table 220.56 Demand Factors for Kitchen Equipment Other Than Dwelling Unit(s) Demand Factor Number of Units of Equipment 1

2 3 4

5

6and over

(%)

100 100 90 80 70 65

220.61 Feeder or Service Neutral Load. (A) Basic Calculation. T he feeder or service neutral load shall be the maximum unba la n ce of the load determined by this article. The maximum unbalanced load shall be the maximum net calc ulated load between the neutral conductor and any one ungrounded conductor. Exception: For 3-wire, 2-phase or 5-wire, 2-phase systems, the maximum unbalanced load shall be the maximum net calculated l.oad between the neutral conductor and any one ungrounded conductor muUiplied by 140 percent.

(B) Permitted Reductions. A service or feeder supplying the following loads shall be permitted to have an additional demand factor of 70 percent applied to the amount in 220.6 l (B)(l ) or portion of the amount in 220.6 l(B)(2) determined by the following basic calculations: ( 1)

(2)

A feeder or service supplying household elecu·ic ranges, wall-mounted ovens, counter-mounted cooking units, and electric dryers, wher e the maximum unbalanced load has been determined in accordance with Table 220.55 for ranges and Table 220.54 for dryers That portion of the unbalanced load in excess of 200 amperes where the feeder or service is su pplied from a 3-wire de or single-phase ac system; or a 4-wire, 3-phase system; or a 3-wire, 2-phase system; or a 5-wire, 2-phase system

220.82 Dwelling Unit. (A) Feeder and Service Load. This section applies to a dwelling unit having the total connected load served by a single 120/240-volt or 208Y/ 120-volt set of 3-wire service or feeder conductors with an ampacity of 100 or greater. It shall be permissible to calculate the feeder and service loads in accordance with this sectio n instead of the method specified in Part III of this article . The calculated load shall be the result of adding the loads from 220.82(B) and (C) . Feeder a nd serviceentrance conductors wh ose calculated load is determined by this optional calculation s hall be permitted to have the ne u u·al load determined by 220.61. (B) General Loads. The gene ral calculated load shall be not less than 100 percent of the fi rst 10 kVA plus 40 percent of the remainde r of the following loads: (1)

(2)

(3)

( 4)

(1) (2)

(C) Prohibited Reductions. There shall be no reduction of the neutral or grounded conductor capacity applied to the amount in 220.61 (C) (1), or portion of the amount in (C) (2), from that determined by the basic calculation:

(3)

(2)

Any portion of a 3-wire circuit consisting of 2 ungrounded conductors and the neutral conductor of a 4-wire, 3phase, wye-connected system That portion consisting of nonlinear loads supplied from a 4-wire , "'Ye-connected, 3-phase system

Informational Note: A 3-phase, 4-wire, wye-connected power system used lO supply power to non linear loads may necessitate that the power system d esign allow for the possib ility of high harmonic neutral conducwr currents.

Part IV. Optional Feeder and Service Load Calculations

33 volt-amperes/m2 or 3 volt-amperes/ft2 for general lighting a nd general-use receptacles. The floor area for each floor shall be calculated from the outside dimensions of the dwelling unit. The calcula ted floor area sh all not include open porches, garages, or unused or unfinished spaces not adaptable for future use. 1500 volt-amperes for each 2-wire, 20-ampere sma llappliance branch circuit and each laundry branch circuit covered in 210.11 (C) (1) and (C) (2) . The nameplate rating of the following: a . All appliances that are fastened in place, per manently connected, or located to be on a specific circuit b. Ranges, wall-mounted oven s, counter-mounted cooking units c . C lothes dryers that are not connected to the laundry branch circuit s pecified in ite m (2) d . Water heaters The nameplate a mpere or kVA rating of all permanently connected motors not included in item (3) .

(C) Heating and Air-Conditioning Load. The largest of the following six selections (load in kVA) shall be included:

Informational Note: See Examples Dl (a), Dl (b), D2(b), D4(a), and D5(a) in Informative Annex D.

( 1)

220.82

(4) (5) (6)

100 percent of the namepla te rating(s) of the air conditioning a nd cooli ng. 100 percent of the nameplate rating(s) of the heat pump when the heat pump is used without any su pplementa l electric heating. 100 percent of the nameplate rating(s) of the heat pump compressor and 65 percent of the supplemental elecu·ic heating for central e lectric space-heating systems. If the heat pum p compressor is prevented from operating at the same time as the supplementary heat, it d oes not need to be added to the supplementary heat for th e tota l central space h eating load. 65 percent of the na meplate rating(s) of electric space heating if less than four separately controlled units. 40 percent of the namepla te rating(s) of electric space heating if four o r more separately controlled units. 100 percent of the nameplate ratings of e lectric therm al storage and other heating systems where the usual load is expected to be continuous at the full name plate value. Systems qualifying under this selectio n shall no t be calculated under any other selection in 220.82(C) .

220.80 General. Optional feeder and service load calculations shall be permitted in accordance with Part IV.

2020 Edition

NATIONAL ELECTRJCAL CODE

70-79

220.83

ARTICLE 220- BRANCH-CIRCUIT, FEEDER, AND SERVICE LOAD CALCULATIONS

220.83 Existing Dwelling Unit. This section shall be permitted to be used to determine if the existing service or feeder is of sufficient capacity to serve additiona l loads. Where the dwelling unit is served by a 120/ 240-volt or 208Y/ 120-volt, 3-wire service, it shall be permissible to calculate the total load in accordance with 220.83(A) or (B) . (A) Where Additional Air-Conditioning Equipment or Electric Space-Heating Equipment Is Not to Be Installed. The following percentages shall be used for existing a nd additional new loads. Load (kVA)

Percent of Load

First 8 kVA of load a t Remainder of load at

100 40

220.84 Multifamily Dwelling. (A) Feeder or Service Load. It shall be permissible to calculate the load of a feeder or service that supplies three or more dwelling uni ts of a multifamily dwelling in accordance with Table 220.84 instead of Part III of this article if all the following conditions are met: (1)

(2)

Exception: When the calculated load for muUifamily dwellings without electric cooking in Part !II of this article exceeds that calculated under Part N for the identical load plus electric cooking (based on 8 kW per unit), the lesser of the two loads shall be permitted to be used.

(3)

Load calculations shall include the following: (1)

(2)

(3)

General lighting and general-use receptacles at 33 voltamperes/ m2 or 3 volt-amperes/ ft2 as determined by 220.1 2 1500 volt-amperes for each 2-wire, 20-ampere smallappliance branch circuit and each laundry branch circuit covered in 210.11 (C) (1 ) and (C)(2) The nameplate rating of the following: a. All appliances that are fastened in place, permanently connected, or located to be o n a specific c ircuit b. Ranges, wall-mounted ovens, counter-mounted cooking units c. Cloth es dryers that are not conn ected to the laundry branch circuit specified in item (2) d . ,l kV), a nd IEEE C62.22-2009, Guide for the Application of Metal-Oxide Surge Arresters for Allernating-Cun ·e nt Syswms. In formational Note No. 2: The selection of a properly rated metal oxide arrester is based o n consideration s of maximum continuous operating voltage a nd die magnin,de and duration of overvoltages at the arrester location as affected by phase-toground faults, system grounding techniques, switching surges, and o dier causes. See die manufacturer's application rules for selection of me specific arrester to be used at a particular location.

242.44 Number Required. Where used at a point on a circuit, a surge arrester shall be c onnected to each ungrounded conductor. A single installation of such surge arresters shall be perm itted to protect a number of interconnected circuits if no circuit is exposed to surges while disconnected from the surge a rresters. 242.46 Location. Surge arresters shall be permitted to be located indoors or outdoors . Surge arresters shall be made inaccessible to unqualified persons unless liste d for installation in accessible locations. 242.48 Routing of Surge Arrester Equipment Grounding Conductors. The conductor u sed to connect the surge arrester to line, bus, or equipment and to an equipment grounding conductor or grounding e lectrode connection point as provided in 242.50 shall not be any longer than necessary and shall avoid unnecessary be nds. 242.50 Connection. The arrester shall be connected to o ne of the following: (1)

Grounded service conductor

70-110

(2) (3) (4)

Ground ing electrode conductor Ground ing e lecu-ode for the se rvice Equipment grou nding term inal in the service equipment

242.52 Surge-Arrester Conductors. The conductor between the surge arrester and the line, and the su rge arrester and the grounding connectio n, shall not be smaller than 6 AWG copper or aluminum. 242.54 Interconnections. The surge arrester protecting a transformer that supplies a secondary distributio n system shall be interconnected as specified in 242.54(A), (B), or (C) . (A) Metal Interconnections. A metal interconnection shall be made to the seconda1y grounded c ircuit condu ctor or the secondary c ircuit grounding electrode conductor, if, in addition to the direct grounding connection at the surge arrester, the connection complies with 242.54(A) (1 ) or (A) (2) . (I ) Additional Grounding Connection. The grounded conductor of the seconda1y has a grounding connection elsewhere to a continuous metal underground wate r piping system. In urba n water-pipe areas where there are at least four ,vater-pipe connections on the neutral conducto1· and not fewer than fou r such connection s in each mile of neuu·al conductor, the me tal interconnection shall be permitted to be made to the seco ndary neutral conductor with omission of the direct grounding connection at the surge arrester. (2) Multigrounded Neutral System Connection. The grounded conductor of the secondary system is part of a multigrounded neutral system or static wire of which the prima1y neutral con ductor or static wire h as at least fou r grounding conn ections in each 1.6 km (1 mile) of line in addition to a grounding connection at each service. (B) Through Spark Gap or Device. \i\There the surge arrester grounding electrode conductor is n ot connected as in 242.54(A), or where the secondary is not grounded as in 242.54(A) but is otherwise grounded as in 250.52, an interconnectio n shall be made thro ugh a spark gap or listed device as required by 242.54(B) (1) or (B) (2) . (1) Ungrounded or U nigrounded Primary System. For ungrounded or un igrounded primary systems, the spark gap for a listed device shall have a 60-H z breakdown voltage of at least twice the prima1y circuit voltage but not necessar ily more than 10 kV, and there shall be at least one other ground on the grounded conductor of the secondary that is no t less than 6.0 m (20 ft) d istant fro m the surge-arrester grounding electrode. (2) Multigrounded Neutral Primary System. Fo r multigrounded neutral primary systems, the spark gap or listed device shall have a 60-H z breakdown of not more than 3 kV, and there shall be at least one other ground on the grounded conducto r of the secondary that is not less than 6.0 m (20 ft) distant from the surge-arrester grounding electrod e. (C) By Special Permission. An interconnectio n of the surgearrester ground and the secondary neutral conductor, o ther than as provided in 242.54(A) or (B), shall be permitted to be made o nly by special pe rmission. 242.56 Grounding Electrode Conductor Connections and Enclosures. Except as indicated in this article, surge-arrester grounding electrode conductor connectio ns shall be made as specified in Article 250, Parts III and X. Grounding elecu·ode conductors installed in metal enclosures shall comply with 250.64(£ ) .

NAT IO NAL ELECTRJCAL CODE

2020 Edition

ARTICLE 250- GROUNDING AND BONDING

ARTICLE 250 Grounding and Bonding Part I. General

250.1 Scope. This article covers general requirements for grounding and bonding of electrical installations, and the specific requirements in (1) through (6) . ( 1) (2) (3) ( 4) (5) (6)

Systems, circuits, and equipment required, permitted, or not permitted to be grounded Circuit conductor to be grounded on grounded system s Location of grounding connections Types and sizes of grounding a nd bonding conductors and electrodes Methods of grounding and bonding Conditions under which gua rds, isolation, o r insulation may be substitu ted for grounding

Informational Note: See Figure 250.1 for information on the organization of Article 250 covering grounding and bonding requirements.

250.3 Application of Other Articles. For other articles applying to particular cases of installation of conductors and equipment, grounding and bo nding requirem e n ts are identified in Table 250.3 that are in addition to, or modifications of, th ose of this article.

250.4

250.4 General Requirements for Grounding and Bonding. The foll owing general requirements identify what gro unding and bonding of elecu·ical systems are required to accomplish. The prescriptive meth ods conta ined in Article 250 shall be followed to comply with the performance require m e n ts of this section. (A) Grounded Systems. (1) Electrical System Grounding. Electrical system s that are grounded shall be connected to earth in a m anner that will limit the voltage imposed by lig htning, line surges, or unintentional contact with higher-voltage lines a nd that will stabilize the voltage to earth during n ormal o peration. Informational Note No. l: An importalll consi deration for limiting the imposed voltage is the routing of bonding and grounding electrode conducwrs so that they are not any longer than necessa,y Lo compl ete the connection withom di srnrbing the permanent parts of the installation and so that unnecessary bends and l oops are avoided . Informational Note No. 2: See NFPA 780.2017, Slandard for lhe lnslallalion of Lighlni11g Proleclion !,)'swms, for information on installation of grounding and bonding for lighming protection systems.

(2) Grounding of Electrical Equipment. Normally noncurrent-carrying conductive materials enclosing elecu·ical conductors or e quipment, or forming part of such equipment, shall be connected to earth so as to limit the voltage to ground on these materials. (3) Bonding of Electrical Equipment. Normally non-current-carrying conductive materials e nclosing elecu·ical conductors or equipment, or forming part of such equipment, shall be con nected together a nd to the elecu·ical supply source in a manner that establishes an effective ground-fault current path.

Part I General

Part 11 System grounding

(4) Bonding of Electrically Conductive Materials and Other Equipment. Normally non-current-carrying electrically conductive materials that are likely to becom e en ergized shall be connected together and to the electrical su pply source in a manner that establishes an effective ground-fault current path.

Part VIII Direct-current systems Part X Grounding of systems and circuits of over 1000 volts

Part 111 Grounding electrode system and grounding electrode conductor

Part V Bonding

Part IV Enclosure, raceway, and service cable connections

(5) Effective Ground-Fault Current Path. Electrical e quipment and wiring an d other electrically conductive materia l likely to become energized shall be installed in a manner that creates a low-impedance circuit facilitating the operation o f the overcurrent device or ground detector for hig h-impedan ce grounded systems. It sh all be capable of safely carryin g the maximum groun d-fault current likely to be i mposed on it from any point on the wiring system wh ere a ground fault may occur to the e lectrical supply source. The earth sh all n ot be considered as an effective ground-fault cu rrent path. (B) Ungrounded Systems.

Part VI Equipment grounding and equipment grounding conductors

(1) Grounding Electrical Equipment. Non-current-carrying conductive materials enclosing electrical conducto rs or equipment, or forming part of such equipment, sh all be connected to earth in a m anner that will limit the voltage imposed by lightning or unintentio nal contact with higher-vol tage lines and limit the voltage to ground o n these materials.

Part VII Methods of equipment grounding conductor connections

Part IX Instruments, meters, and relays

FIGURE 250.1 2020 Edition

Informational Note: See NFPA 780-20 17, Slandardfor lhe fnslallalion of Lighlning Proleclion Sys/iims, for information on installation of grounding and bonding for lighming protection systems.

Grounding and Bonding.

NATIONAL ELECTRJCAL CODE

70- 111

250.4

ARTICLE 250-GROUNDING AND BONDING

Table 250.3 Additional Grounding and Bonding Requirements Conductor/ Equipment Agricultural build ings Audio signal processing, amplification, and reproduction equipmen t Branch circuits Cablebus Cable trays Capacitors Circuits and equipment operating a t less than 50 volts Communications circuits Community antenna television and radio distribution systems Conductors for general wiring Yled ium voltage conductors and cables Cranes and hoistS Electrically driven or con trolled irrigation machines Electric signs and outline lighting Electrolytic cells Elevators, d umb\1°aiters, escalators, moving walks, wheelchair lifts, and stairway chairlifts Fixed e lectric heating equipmen t for pipelines and vessels Fixed outdoor electric deicing a nd snow-melting equipment Flexible cords and cables Floating buildings Ground ing-type receptacles, adapters, cord connectors, and attachment plugs Hazardous (classified) locations Health care facilities Ind uction and dielecuic heating equipment Industrial machinery Information technology equipment Intri nsically safe systems Lum inaires and lighting equipment Lum inaires, lampholders, and lamps Ylarinas and boatyards Ylobile homes and mobile home park Motion picture and television stud ios and similar locations Motors, motor circu its, and contro lle rs Natural and artificia lly made bodies of water Network powered broadband communications circuits Optical fiber cables Outle t, device, pull, and junction boxes; conduit bodies; and fittings Over 600 volts, nominal, underground wiring methods Panelboards Pipe organs Radio and television equipment Receptacles and cord connector, Recreational veh icles and recreational vehicle parks Services Solar photovoltaic systems Swimming pools, fo untains, and similar installa tions Switchboards and pane lboards Switches Theaters, aud ience areas of motion p icture and television studios, and similar locations Transfonners and transformer vaults Use and identification of grounded conductors X-ray equipme nt

70-112

Article

Section 547.9 and 547.10 640.7

392

210.5, 210.6, 406.3 370.60 392.60 460.1 0, 460.27

720 800 820.93, 820.100, 820.103, 800.106, 800.100 310 311 610

675.l l ( C), 675.12, 67 5.1 3, 675.14, 675.15 600 668 620 427.29, 427.48 426.27 400.22, 400.23 555.54, 555.55, 555.56 406.10 500- 517 517 665 670 645.1 4, 645.l 5 504.50 410.40, 410.42, 410.46, 410.1 55(8 ) 410 555.37, 555.38 550 530.20, 530.64( 8 ) 430 682

682.30, 682.31, 682.32, 682.33 800.100, 800.106, 830.93 770.100 314.4, 314.25 300.50(C) 408.40

650 810 406.3 551 230 690.41 , 690.42, 690.43, 690.45, 690.47 680 408.] 8(C) 404.12 520.81 450.10 200 660

517.78

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 250- GROUNDING AND BONDING (2) Bonding of Electrical Equipment. Non-current-carrying conductive materials enclosing elecu·ical conductors or equipment, or forming part of such equipment, shall be connected together and to the supply syste m grounded equipment in a manner that creates a low-impedance path for ground-fault current that is capable of carrying the maximum fault current likely to be imposed on it. (3) Bonding of Electrically Conductive Materials and Other Equipment. Elecu-ically conductive materials that are likely to become energized shall be connected together and to the supply system grounded equipment in a manner that creates a low-impedance path for ground-fault current that is capable of carrying the maximum fault current likely to be im posed on it. (4) Path for Fault Current. Electrical equipment, wiring, and othe r electrically conductive material likely to become energized shall be installed in a manner that creates a lowimpedance circuit from any point on th e wiring system to the electrical supply source to facilitate the operation of overcurrent devices should a second ground fault from a d ifferent phase occur on the wiring system. The earth shall not be cons idered as an effective fault-current path. 250.6 Objectionable Current. (A) Arrangement to Prevent Objectionable Current. The grounding of elecu·ical systems, circuit conductors, surge arresters, surge-protective devices, and conductive normally non-current-carrying metal parts of equipment shall be installed and arranged in a manner that will prevent objectionable current. (B) Alterations to Stop Objectionable Current. If the use of multiple grounding connections results in o bjectionable current and the requirements of 250.4(A)(5) or (B)(4) are met, one or more of the following alterations shall be permitted: (I)

(2) (3) ( 4)

Discontinue one or more but not all of such grounding connections. Change the locations of the grounding connections. Interrupt the continuity of the conductor or conductive path causing the objectionable current. Take other suitable remedial and approved action.

(C) Temporary Currents Not Classified as Objectionable Currents. Temporary currents resulting from abnormal conditions, such as ground faults, shall not be classified as objectionable current for the purposes specified in 250.6(A) and (B) .

(D) Limitations to Permissible Alterations. This section shall not be considered as permitting elecu·onic equipment to be operated on ac systems or branch c ircuits that are not connected to an equipment grounding conductor as required by this article. Currents that introduce electromagnetic interference or data errors in e lectronic equipment shall not be considered the objectionable currents addressed in this sectio n. (E) Isolation of Objectionable Direct-Current Ground Currents. Where isolation of o bjectionable de ground currents from cathodic protection systems is required, a listed ac coupling/de isolating device shall be permitted in the equipment grounding condu ctor path to provide an effective return path for ac ground-fault current while blocking de current.

2020 Edition

NATIONAL ELECTRJCAL CODE

250.20

250.8 Connection of Grounding and Bonding Equipment. (A) Permitted Methods. Equipment grounding conductors, grounding electrode conductors, and bonding jumpers shall be connected by one or more of the following means:

Listed pressure connectors Terminal bars Pressure connectors listed as grounding and bonding equipment Exothermic welding process Machine screw-type fasteners that engage not less than two threads or are secured 1vith a nut Thread-forming machine screws that engage not less than two threads in the enclosure Connections that are part of a listed assembly Other listed means

(1)

(2) (3) (4) (5) (6) (7) (8)

(B) Methods Not Permitted. Connection devices or fittings that depend solely on solder shall not be used. 250.10 Protection of Ground Clamps and Fittings. Ground clamps or other fitt ings exposed to physical damage shall be enclosed in metal, wood, or equivalent protective covering. 250.12 Clean Surfaces. Nonconductive coatings (such as paint, lacquer, and enamel) on equipment to be grounded or bonded sha ll be removed from threads a nd other contact surfaces to ensure good electrical continuity o r shall be connected by means of fittings designed so as to make such removal unnecessary.

Part II. System Grounding 250.20 Alternating-Current Systems to Be Grounded. Alternating-current systems shall be grounded as provided for in 250.20(A), (B), (C), or (D) . Other systems shall be permitted to be grounded. If such systems are grounded, they shall comply with the applicable provisions of this article . Informational Note: An example of a system permitted to be grounded is a corner-grounded delta transformer connection. See 250.26( 4) for conductor to be grounded.

(A) Alternating-Current Systems of Less Than 50 Volts. Alternating-current syste ms of less than 50 volts shall be grounded under a n y of the following conditions: ( 1)

(2)

(3)

Where supplied by u·ansformers, if the transformer supply system exceeds 150 volts to g round Where supplied by transformers, if the transformer supply system is ungro unded Vihere installed outside as overhead conductors

(B) Alternating-Current Systems of 50 Volts to 1000 Volts. Alternating-current systems of 50 volts to 1000 volts that supply premises wiring and premises wiring systems shall be grounded under any of the following conditions:

(1)

(2)

Where the system can be grounded so that the maximum voltage to ground on the ungrou nded conductors does not exceed 150 volts Where the system is 3-phase, 4-wire, wye connected in which the neutral conductor is used as a circuit conductor

70-113

250.20

(3)

ARTICLE 250-GROUNDING AND BONDING

vVhere the system is 3-phase, 4-wire, delta connected in which the midpoint of one phase winding is used as a circuit conductor In formational Note: According to Annex O of NF'PA 70E-20l8, Standard for Eleclrical Safety in the Worilplace, high impedance grounding is an effective tool to reduce arc flash hazards.

(5) (6)

Seconda1y circuits of lighting systems as provided in 680.23(A) (2) Class 2 load side circuits for suspended ceiling low-voltage power grid d istribution systems as provided in 393.60(B)

250.24 Grounding of Service-Supplied Alternating-Current Systems.

(C) Alternating-Current Systems of over 1000 Volts. Alternating-current systems supplying mobile or portable equipment shall be grounded as specified in 250.188. vVhere supplying other than mobile or portable equipment, such systems shall be permitted to b e grounded.

(A) System Grounding Connections. A premises wiring system supplied by a grounded ac service shall have a grounding electrode conductor connected to the grnunded service conductor , at each service, in accordance with 250.24(A) ( 1) through

(D) Impedance Grounded Neutral Systems. Impedance grounded neutral systems shall be grounded in accordance with 250.36 or 250.187.

(1) General. The grounding e lectrode conductor connection shall be made at any accessible point from the load end of the overhead service conductors, service drop, underground service conductors, or service lateral to, including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means.

250.21 Alternating-Current Systems of 50 Volts to 1000 Volts Not Required to Be Grounded. (A) General. The following ac systems of 50 volts to l 000 volts shall be permitted to be grounded but shall not be required to be grounded: (l)

(2) (3)

(4)

Elecu·ical systems used exclusively to supply industrial elecu-ic fornaces for melting, refining, tempering, and the like Separately derived systems used exclusively for rectifiers that supply only adjustable-speed industrial drives Separately derived systems supplied by transformers that have a primary voltage rating of 1000 volts or less if all the following conditions are met: a. The system is used exclusively for conu·ol circuits. b. The conditions of maintenance and supervision ensure that only qualified persons se rvice the installation. c. Continuity of control power is required. Other systems that are not required to be grounded in accordance with the requirements of250.20(B)

(B) Ground Detectors. Ground detectors shall be installed in accordance with 250.21 (B) (1 ) and (B)(2) .

(1)

(2)

Ungrounded ac systems as permitted in 250.2l(A)(l) through (A)( 4) operating at not less than 120 vol ts and at 1000 volts or less shall have ground detectors installed on the system. The ground detection sensing equipment shall be connected as close as practicable to where the system receives its supply.

(C) Marking. Ungrounded systems shall be legibly marked "Caution: Ungrounded System Operating _ _Volts Between Conductors" at the source or first d isconnecting means of the system. The marking shall be of sufficient durability to withstand the environment involved.

250.22 Circuits Not to Be Grounded. The following circuits shall not be grounded: (1)

(2) (3) ( 4)

Circuits for electric cranes operating over combustible fibers in Class III locations, as provided in 503.1 55 Circuits in health care facilities as provided in 517.61 and 5 17.160 Circuits for equipment within electrolytic cell line working zones as provided in Article 668 Secondary c ircuits of lighting systems as provided in 411 .6(A)

70-114

(A) (5) .

Informational Note: See definitions of Service Conductors, Overhead; Service Conductors, Underground; Service Drop; and Service Lateral in Article 100.

(2) Outdoor Transformer. Where the transformer supplying the service is located o utside the building, at least one additional grounding connection shall be made from the grounded service conductor to a grounding electrode, e ither at the transformer or elsewhere outside the building. E xception: 'The additional grounding electrode condi1ctm· cminection shall not be made on high-impedance grounded neutral systems. The system shall meet the requirements of250.36. (3) Dual-Fed Services. For services that are dual fed (double ended) in a commo n enclosure o r g1:ouped together in separate enclosures and employing a secondary tie, a single grounding electrode conductor connection to the tie point of the grounded conductor(s) from each power source shall be permitted.

(4) Main Bonding Jumper as Wire or Busbar. Where the main bonding jumper specified in 250.28 is a wire or busbar and is installed from the grounded conductor terminal bar or bus to the equipment grounding terminal bar or bus in the service equipment, the grounding electrode conductor shall be permitted to be connected to the equ ipment grounding terminal, bar, or bus to which the main bonding jumper is connected. (5) Load-Side Grounding Connections. A grounded conductor shall not be connected to normally non-current-carrying metal parts of equipment, to equipment groundi ng conductor(s), or be reconnected to ground on the load side of the service disconnecting means except as otherwise permitted 111 this article . Informational Note: See 250.30 for separately derived systems, 250.32 for connections at separate buildings or structures, and 250.142 for use of the grounded circui t conducwr for grounding equipmenL

(B) Main Bonding Jumper. For a grounded system , an unspliced main bonding jumper shall be used to connect the equipment grounding conductor(s) a nd the service-disconnect enclosure to the grounded conductor within the enclosure for each service disconnect in accordance with 250.28.

NAT IO NAL ELECTRJCAL CODE

2020 Edition

ARTICLE 250- GROUNDING AND BONDING Exception No. 1: VWzere more than one service disconnecting means is located in an assembly listed for use as service equipment, an unspliced main bonding jumper shall bond the gmunded conductor(s) to the assembly enclosure. Exception No. 2: Impedance gmunded neutral systems shall be permitted to be connected as provided in 250.36 and 250.187. (C) Grounded Conductor Brought to Service Equipment.

\!\/here an ac system operating at 1000 volts or less is grounded at any point, the grounded conductor(s) shall be routed with the ungrounded conductors to each service disconnecting means and shall be con nected to each d isconnecting means grounded conductor(s) terminal or bus. A ma in bonding jumper shall connect the grounded conductor(s) to each service disconnecting means enclosure. The grounded conductor(s) shall be installed in accordance with 250.24(C) (1) through (C)(4) . Exception: W'here two or more service disconnecting means are located in a single assembly listed for use as service equipment, it shall be permitted to connect the gmunded conductor(s) to the assembly common grounded conductor(s) terminal or bus. The assembly shall include a main bonding jumper for connecting the grounded conductor(s) to the assembly enclosure.

250.25 Grounding Systems Permitted to Be Connected on the Supply Side of the Disconnect. The grounding of systems con nected on the supply side of th e service disconnect, as permitted in 230.82, that are in enclosures separate from the service equipment enclosure shall comply with 250.25(A) or (B) .

(A) Grounded System. If the utility supply system is grounded, the grounding of systems permitted to be connected on the supply side of the service disconnect and a re installed in one or more separate enclosures from the service equipment enclosure shall comply with the require me nts of 250.24(A) through (D) . (B) Ungrounded Systems. If the utility supply system is ungrounded, the gro unding of systems permitted to be connected on the supply side of the service disconnect and are installed in one or more separate e nclosures from the service equipment enclosure shall comply with the requirements of 250.24(E) . 250.26 Conductor to Be Grounded - Alternating-Current Systems. For grounded ac premises wiring systems, the conductor to be grounded shall be as specified in the following:

(I) Sizing for a Single Raceway or Cable. The grounded conductor shall not be smaller than specified in Table 250.1 02(C)(l) .

(I ) (2) (3)

(2) Parallel Conductors in Two or More Raceways or Cables. If the ungrounded service-entrance conductors are installed in

(4)

parallel in two or more raceways or cables, the grounded conductor shall also be installed in parallel. The s ize of the grounded conductor in each raceway or cable shall be based on the total circular mil area of the parallel ungrounded conductors in the raceway or cable, as indicated 111 250.24(C) (1) , but not smaller than 1/ 0 AWG.

(5)

Informational Note: See 310.l0(G) for grounded conduCLors connected in parallel.

(3) Delta-Connected Service. The grounded conductor of a 3phase, 3-wire delta service shall have an ampacity not less than that of the ungrounded conductors. (4) High Impedance. The grounded conductor o n a high-impeda nce grounded neutral system shall be grounded in accordance with 250.36. (D) Grounding Electrode Conductor. A grounding electrode conductor shall be used to connect the equipment grounding conductors, the service-equipment enclosures, and, where the system is grounded, the grounded service conductor to the g ro unding electrode(s) required by Part III of this article. This conductor shall be sized in accordance with 250.66.

H igh-impedance grounded neutral system connections shall be made as covered in 250.36. (E) Ungrounded System Grounding Connections. A premises wiring system that is supplied by an ac service that is ungrounded shall have, at each service, a g rounding e lectrode conductor connected to the grounding electrode(s) required by Part III of this article. The grounding electrode conductor shall be connected to a metal enclosure of the service conductors at a ny accessible point from the load end of the overhead service conductors, service drop, underground service conductors, or service lateral to the servi ce disconnecting means.

2020 Edition

NATIONAL ELECTRJCAL CODE

250.28

Single-phase, 2-wire - one conductor Single-phase, 3-wire - the n eutral conductor Multiphase systems having one wire common to all phases - the neutral conductor Multiphase system s where one ph ase is grounded - that phase conductor Multiphase system s in which one phase is used as in (2) - the neutral conductor

250.28 Main Bonding Jumper and System Bonding Jumper. For a grounded system, main bonding jumpers and syste m bonding jumpers shall be installed as follows: (A) Material. Main bonding jumpers and system bonding jumpers s hall be of copper, aluminum, copper-clad aluminum, or other corrosion-resistant material. A main bonding jumper and a system bonding jumper shall be a wire, bus, screw, or similar suitable conductor. (B) Construction. Where a main bonding jumper or a syste m bonding jumper is a screw only, the screw shall be identified with a green finish that shall be visible with the screw insta lled. (C) Attachment. Main bonding jumpers an d system bonding jumpers shall be connected in the manner specified in 250.8. (D) Size. Main bonding jumpers and system bo nding jumpe rs shall be sized in accordance with 250.28(0 ) ( I ) through (D ) (3) .

(1) General. Main bonding jumpers a nd system bonding jum pers shall not be smaller than specified in Ta ble 250.102(C) (1) . (2) Main Bonding Jumper for Service with More Than One Enclosure. If a service consists of more than a single enclosure as permitted in 230.71 (B), the main bo nding jumper for each enclosure shall be sized in accordance with 250.28(0) (I ) based on the largest ungro unded service conductor serving that enclosure. (3) Separately Derived System with More Than One Enclosure. \!\/here a separately derived system supplies more than a single enclosure, the system bonding jumper for each enclosure shall

70- 115

250.30

ARTICLE 250-GROUNDING AND BONDING

be sized in accordance with 250.28(0)(1) based on the largest ungrounded feeder condu ctor serving that e nclosure, or a single system bonding jumper shall be installed at the source and sized in accordance with 250.28 ( D ) (1) based on the equivalent size of the largest supply conductor determined by the largest sum of the areas of the corresponding conductors of each set. 250.30 Grounding Separately Derived Alternating-Current Systems. In addition to com p lying with 250.30(A) for grounded systems, or as provided in 250.30(B) for ungrounded systems, separately derived systems shall comply with 250.20, 250.21, 250.22, or 250.26, as applicable. Multiple power sources of the same type that are con nected in parallel to form one system that supplies premises wiring shall be considered as a single separately derived system and shall be installed in accordance with 250.30. In formational Note No. l: An alternate ac power source, such as an on-site generator, is not a separately derived system if die grounded conductor is solid ly interconnected to a servicesupplied system grounded conductor. An example of such a situation is where a lternate source transfer equipment does not include a switching action in the grounded conductor and a llows it to remain solid ly connected to the service-supplied grounded conductor when the a lternate source is operational and supplying die load served . In formational Note No. 2: See 445.13 for the minimum size of conductors diat carry fau lt currenL

(A) Grounded Systems. A separately derived ac system that is grounded shall com ply with 250.30(A) (1) through (A) (8) . Except as otherwise permitted in this article, a grounded cond uctor shall not be connected to normally non-currentcarrying metal parts of equipment, be connected to equipment grounding conductors, o r be reconnected to ground on the load side of the system bonding jumper. Informational Note: See 2.50.32 for connections at separate buildings or su-uctures and 250.142 for use of die grounded circuit conductor for grounding equipment.

Exception: Impedance grounded neutral system grounding connections shall be made as specified in 250.36 or 250.187, as applicable. (I) System Bonding Jumper. An unspliced system bonding jumper shall comply with 250.28(A) through ( D ) . This connection shall be made at any single point on the separately derived system from the source to the first system disconnecting means or overcurrent device, or it sha ll be made at the source of a separately derived system that has no d isconnecting means or overcurrent devices, in accordance with 250.30(A) (1) (a) or (A) (] ) (b) . The system bonding jumper shall remain within the enclosure where it originates . If the source is located outside the building or structure supplied, a system bonding jumper shall be installed at the grounding electrode connection in compliance with 250.30(C) .

Exception No. 1: For systems installed in accordance with 450.6, a single system bonding jumper connection to the tie point of the grounded circuit conductors from each power source shall be permitted. Exception No. 2: If a building or structure is supplied by a feeder from an outdoor separately de1ived system, a system bonding jumper at both the source and the first disconnecting means shall be permitted if doing so does not establish a parallel path for the grounded conducto1: If a grounded conductor is used in this manne1; it shall not be smal/,er than the size specified for the system bonding jumper but shall not be required to be larger than the ungrounded conductor(s). For the purposes of this

70-11 6

exception, connection through the earth shall not be considered as providing a parallel path. l'.xception No. 3: The size of the system bonding jumper for a system that supplies a Class 1, Class 2, or Class 3 circuit, and is de1ived from a transformer rated not more than 1000 volt-amperes, shall not be smaller than the de1ived ungrounded conductors and shall not be smaller than 14 A WC copper or 12 A WC aluminum. (a) Installed at the Source. T he system bonding jumper sha ll connect the grounded conduct01- to the supply-side bonding jumper a nd the normally non-current-carrying metal enclosure. (b ) Installed at the First Disconnecting Means. The system bonding jumper shall connect the g ro unded conductor to the supply-side bonding jumper, the disconnecting means enclosure, and the equipment grounding conductor(s) . Exception: Separately derived systems consisting of mulliple sources of the same type that are connected in parallel shall be permitted to have the system bonding jumper installed at the paralleling switchgea1; switchboard, or other paralleling connection point instead of at the disconnecting means located at each separate source.

(2) Supply-Side Bonding Jumper. If the source of a separately derived system and the first disconnecting means are located in separate e nclosu res, a su pply-side bonding jumper shall be installed with the circuit conductors from the sou rce enclosure to the first disconnecting means enclosure. A supply-side bonding jumper shall not be required to be larger than the derived ung rounded conductors. The supply-side bonding jumper shall be permitted to be of nonflexible metal raceway type or of the wire or bus type as follows: (1)

(2)

A supply-side bonding jumper of the wire type sh all comply with 250.1 02(C), based on the size of the derived ung rounded conductors. A supply-side bonding jumper of the bus type shall have a cross-sectional area not smaller than a supply-side bondingjumper of the wire type as determined in 250.1 02(C) .

l'.xception: A supply-side bonding jumper shall not be required between enclosures for installations made in compliance with 250.30(A)(1 ), Exception No. 2.

(3) Grounded Conductor. If a grounded conductor is installed a nd the system bonding jumper connection is not located at the source, 250.30(A) (3) (a) through (A) (3)(d) shall apply. The grounded conductor shall n ot be required to be larger than the derived ungrounded conductors. (a) Sizing for a Single Raceway. The grounded conductor shall not be smaller than specified in Ta ble 250.1 02(C) (1 ) . (b ) Parallel Conductors in Two or More Raceways. If the ungrounded conductors are installed in parallel in two or more raceways, the grounded conducto r s ha ll also be installed in parallel. The size of the grounded conductor in each raceway shall be based on the total c ircular mil area of the parallel derived ungrounded conductors in the raceway as indicated in 250.30(A) (3) (a), but not smaller than 1/ 0 AWG. I nformational Note: See 310.l0(G) for grounded conduccors connected in parallel.

(c) Delta-Connected System. The grounded conductor of a 3-phase, 3-wire delta system shall have an ampacity not less than that of the ungrounded conductors. (d) Impedance Grounded System. The grounded con d uctor of an impedance grounded ne utral syste m sh all be installed in accordance with 250.36 or 250.187, as applicable.

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 250- GROUNDING AND BONDING (4) Grounding Electrode. The building or structure ground· ing elecu·ode system shall be used as the gro unding electrode for t he separately derived system. If located outdoors, the grounding electrode shall be in accordance with 250.30 (C) .

Exception: If a separately derived system originates in equipment that is listed and identified CL5 suitable for tL5e as service equipment, the grounding electrode used for the service or feeder equipment shall be permitted to be used as the grounding electrode for the separately de1ived system. Informational Note No. I : See 250.104( 0 ) for bonding requirements for interior metal water piping in the area served by separately derived systems. Informational Note No. 2: See 250..50 and 250..58 for require• ments for bonding all electrodes together if located at the same building or structure.

(5) Grounding Electrode Conductor, Single Separately Derived System. A grounding e lectrode conductor for a single separately derived system sha ll be sized in accordance with 250.66 for the derived ungrounded conductors. It shall be used to connect the grounded conductor of the derived system to the grounding electrode in accordance with 250.30(A) ( 4), or as permitted in 250.68(C) (1) a nd (C) (2) . This connection shall be made at the same point on the separately derived system where the system bonding jumper is connected.

Exception No. 1: If the system bonding jumper specified in 250.30(A )(1) is a wire or busbm; it shall be permitted to connect the grounding electrode conductor to the equipment grounding terminal, bar, or bus if the equipment grounding terminal, bar, or biL5 is of sufficient size for the separately derived system. Exception No. 2: If the source of a separately derived system is located within equipment listed and identified as suitable for tL5e as service equiprnent, the grounding electrode conductor fivm the service or feeder equipment to the grounding electrode shall be permitted as the grounding electrode conductor for the separately derived system, if the grounding elecl1vde conductor is of sufficient size for the separately de1ived system. If the equipment grounding bus internal to the equipment is not smaller than the required grounding electrode conductor for the separately derived system, the grounding electrode connection for the separately derived system shall be permitted to be made lo the bus. Exception No. 3: A grounding electrode conductor shall not be required for a system that mpplies a Class 1, Class 2, or Class 3 circuit and is derived ji-otn a transformer rated not more than 1000 volt-amperes, provided the grounded conductor is bonded to the transformerjrame or enclosure by a jumper sized in accordance with 250.30(A)(l ), Exception No. 3, and the transformer frame or enclosure is grounded by one of the means specified in 250.134. (6) Grounding Electrode Conductor, Multiple Separately Derived Systems. A common grounding electrode conductor for multiple separately derived systems shall be permitted. If installed, the commo n g1·ound ing electrode conductor shall be used to connect the grounded conductor of each separately derived system to the grounding e lectrode as specified in 250.30(A) ( 4) . A grounding electrode conductor tap shall then be installed from each separate ly derived system to the common grounding elecu·ode conductor. Each tap conductor shall connect the grounded conductor of the separately derived system to the common grounding e lectrode conductor. This connection shall be made at the same point o n the separately derived system wh ere the system bonding jumper is connected.

2020 Edition

NATIONAL ELECTRJCAL CODE

250.30

Exception No. 1: If the system bonding jumper specified in 250.30(A)(l) is a wire or busba1; it shall be permitted to connect the grounding electrode conductor tap to the equipment grounding terrninal, bar; or bus, provided the equipment grounding terminal, bar, or bus is of sufficient size for the separately derived system. Lxception No. 2: A grounding electrode conductor shall not be required for a system that supplies a Class 1, ClcL5s 2, 01· Class 3 circuit and is derived fivm a transforrner rated not more than 1000 voU-amperes, provided the system grounded conductor is bonded to the transf01mer frarne or enclosure by a jumper sized in accordance with 250.30(A)(l ), Lxception No. 3, and the transjmmer frame or enclosure is grounded by one of the means specified in 250.134. Exception No. 3: If the source of a separately derived system is located within equipment listed and identified as suitable for use as service equipment, the grounding electrode conductor from the service or feeder equipment to the grounding electrode shall be permitted CL5 the grounding electrode conductor for the separately derived system, if the grounding electrode conductor is of siifficient size for the separately derived system. If the equipment grounding bus internal lo the equipment is not smaller than the required grounding electrvde conductor for the separcllely derived system, the grounding electrode connection for the separately derived system shall be permitted to be made lo the bus. (a) Common Grounding Electrode Conduclm: The commo n grounding electrode conductor shall be permitted to be one of the following: A conductor of th e wire type not smaller than 3/ 0 AWG copper o r 250 kcmil aluminum (2) A metal water pipe that com plies with 250.68(C) (1) (3) The metal structural frame of the building o r structure that complies with 250.68(C) (2) or is connected to the grounding electrode system by a conductor not smaller than 3/ 0 AWG copper o r 250 kcmil aluminum (b) Tap Conductor Size. Each tap conductor shall be sized in accordance with 250.66 based on the derived ungrounded conducto rs of the sepa rately derived system it serves. (I)

Exception to (a)(l) and (b): If the only electrodes that are present are of the types in 250.66(A), (B), or (C), the size of the common grounding electrode conductor shall not be required to be larger than the largest conductm· required by 250.66(A), (B), or (C) fm· the type of electrode that is present. (c) Connections. All tap connections to the commo n grounding electrode conductor shall be made at an accessible locatio n by one of the following m ethods: (1 )

(2)

(3)

A connector listed as ground ing and bonding equipme nt. Listed con nectio ns to aluminum or copper busbars no t smaller than 6 mm thick x 50 mm wide ( 1/., in. thick x 2 in . wide) and of suffic ient length to accom modate the number of terminations necessary for the installation. If aluminum busbars are used, the installation shall also com ply with 250.64(A) . The exothermic welding process.

Tap conductors shall be connected to the common grounding elecu·ode conductor in such a manner that the comm o n grounding electrode conductor remains without a splice or jo int.

70- 117

250.30

ARTICLE 250-GROUNDING AND BONDING

(7) Installation. The installation of all grounding electrode conductors shall comply with 250.64(A), (B), (C), a nd (E) .

(8) Bonding. Structural steel a nd metal piping shall be connected to the grounded conductor of a separately derived system in accordance with 250.1 04(0) . (B) Ungrounded Systems. The equipment of an ungrounded separately derived system shall be grounded and bonded as specified in 250.30(B) (1) through (B) (3) . (I) Grounding Electrode Conductor. A grounding electrode conductor, sized in accordance with 250.66 for the largest derived ungrounded condu ctor(s) or set of derived ungrou nded conductors, shall be used to con nect the metal enclosures of the derived system to the grounding electrode as specified in 250.30(A) (5) or (A) (6), as applicable. This connection sh a ll be made at any point on the separately derived system from the source to the first system d isconnecting means . If the source is located o utside the building or structure supplied, a grounding electrode connection shall be made in compl iance with 250.30(C).

(B) Grounded Systems. (I) Supplied by a Feeder or Branch Circuit. An equipment grounding conductor, as described in 250.118, sh all be run with the supply conductors a nd be con nected to the building or structure disconnecting means a nd to the grounding electrode (s) . The equipment grounding conductor sh all be used for grounding or bonding of equipment, strucnires, or frames requi red to be grounded or bo nded. The equipment grounding conductor sh all be sized in acco1-dance with 250.1 22. Any installed grounded conductor shall not be connected to the equipment grounding conductor or to the grounding electrode (s) .

Exception No. 1: For installations made in compliance with previous editions of this Code that permitted such connection, the grounded conductor run with the s11pply to the building or structure shall be permitted to serve as the groundfault return path if all of the following requirements continue to be met: (1) (2)

An equipment grounding conductor is not run with the supply to the building or stnicture. There are no continuous metallic paths bonded to the grounding system in each building or structure involved. Groundfault protection of equipment has not been installed on the supply side of the feeder(s).

(2) Grounding Electrode. Except as permitted by 250.34 for portable and vehicle-mo unted generators, the grounding electrode shall comply with 250.30(A) ( 4) .

(3)

(3) Bonding Path and Conductor. A supply-side bonding jumper shall be installed from the source of a separately derived system to the first d isconnecting means in compliance with 250.30 (A) (2) .

If the grounded conductor is used for grounding in accordance wi.th the provision of this exception, the size of the grounded conductor shall not be smaller than the larger of either of the following:

(C) Outdoor Source. If the source of the separately derived system is located outside the building or structure supplied, a grounding electrode connection shall be made at the source location to one or more grounding electrodes in complian ce with 250.50. In addition, the installation sh a ll comply with 250.30(A) for grounded systems or with 250.30(B) for ungrounded systems.

(2)

Exception: The grounding dectrode conductor connection for impedance grounded neutral systems shall comply with 250.36 or 250.187, as applicable. 250.32 Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s). (A) Grounding Electrode. A build ing(s) or structure(s) supplied by a feeder(s) or branch c ircuit(s) shall have a grounding e lectrode system and grounding e lectrode conductor installed in accordance with Part III of Article 250. V.'here there is no existing grounding elecu·ode , the grounding electrode(s) required in 250.50 shall be instal led. Exception: A grounding electrode shall not be required where only a singf,e branch circuit, including a multiwire branch circuit, supplies the building or structure and the branch circuit includes an equipment grounding conductor for grounding the n01mally non-current-carrying metal parts of equipment.

70-11 8

(1)

That required by 220.61 That required by 250.122

.Exception No. 2: If system bonding jumpers are installed in accordance with 250.J0(A)(l), faception No. 2, the feeder grounded circuit conduct01· at the building or structure served shall be connected to the equipment grounding conductors, grounding electrode conduct01; and the enclosure for the first disconnecting means. (2) Supplied by Separately Derived System. (a) With Overcurrent Protection. If overcurrent protection is provided where the conductors origi nate, the installation shall complywith 250.32(B)( l ) . (b ) Without Overcurrent Protection. If ove rcurrent protectio n is not provided where the conductors originate, the installation shall comply with 250.30 (A) . If installed, the supply-side bonding jum per shall be connected to the building or structure disconnecting means and to the grounding electrode(s) . (C) Ungrounded Systems. (I) Supplied by a Feeder or Branch Circuit. An equipment grounding conductor, as described in 250.118, shall be installed with the supply conducto rs a nd be connected to th e building or structure disconnecting means and to the ground ing e lectrode(s) . The grounding e lectrode(s) shall also be connected to the building or structure d isconnecting means.

(2) Supplied by a Separately Derived System. (a) With Overcurrent Protection. If overcurrent protection is provided where the conductors o riginate, the installation shall com plywith 250.32(C) (l ) . (b) Without Overcurrent Protection. If overcurren t protection is not provided where the conduc tors originate , the installation shall comply with 250.30(B) . If installed, th e supply-side bonding jumper shall be connected to the building or structure d isconnecting means and to the g rounding elecu·ode(s) .

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 250- GROUNDING AND BONDING

(D) Disconnecting Means Located in Separate Building or Structure on the Same Premises. Where o ne o r more d isconnecting means supply one o r more additional buildings or structures under single m anagement, and where th ese disconnecting means are located re mote from those buildings or structures in accordance with 225.32, Exception No. 1 and No. 2, 700.12 (0 )(5), 701.12(0)(5), or 702.1 2, all of the following conditions shall be met: (1)

(2)

(3)

The connection of the grounded condu ctor to the grounding electrode, to normally n o n-current-carrying metal parts of equipment, or to th e equip ment grounding conductor at a separate building or structure shall not b e made. An equipment grounding condu ctor for grounding and bond ing any normally non-current-carrying metal parts of eq uipment, interior metal piping systems, and building or stru ctural metal frames is run with the ci rcuit conductors to a separate building or structure and connected to existing grounding electrode(s) required in Part III of this article, or, wh e1·e t here are no existin g electrodes, the grounding e lectrode(s) required in Part III of this article shall b e installed where a separate building or structure is supplied by more than one bran ch circuit. The connectio n b etween th e equipment grounding condu ctor and the ground ing electrode at a separate building or stru cture shall be made in a junction box, panelboard, or similar enclosu re located immediately inside or outside the separate building o r structure .

(E) Grounding Electrode Conductor. The size of the grounding e lectrode condu ctor to the grounding e lectrode (s) shall not b e smaller than given in 250.66, based on the la rgest ungrounded supply condu ctor. The installation shall comply with Pa rt III of th is article .

(3)

Vehicle-Mounted,

and

Informational Note: For grounding portable generators supply· ing fixed wiring systems, see 250.30.

250.35 Permanently Installed Generators. A conductor that provides an effective ground-faul t current path shall b e installed with the supply conductors from a permanently insta lled generator(s) to the fi rst disconnecting mean(s) in accordan ce with 250.35(A) or (B) . (A) Separately Derived System. If the generator is instal led as a separately derived system, the requi remen ts in 250.30 shall apply. (B) Nonseparately Derived System. If the generator is installed as a nonseparately derived system , and overcurrent protection is not integral with the generator assembly, a supp ly-side b onding jumper sh all be installed between the generator equi pment grounding termin al a nd the equipment grounding terminal, b ar, or bus of the disconnecting m ean (s) . It sh all be sized in accordan ce with 250.1 02(C) based on the size of the conductors supplied by the generator. 250.36 High-Impedance Grounded Neutral Systems. High-impedan ce grounded neutral systems in which a gro unding impedan ce, u su ally a resistor, limits the gro und-fault current to a low value shall be permitted for 3-ph ase ac systems of 480 vol ts to 1000 volts if all the following conditio n s are me t:

Trailer-Mounted

(A) Portable Generators. The fram e of a portable gen erator shall not b e required to b e connected to a grounding electrode as defined in 250.52 fo1· a system su pplied by the gen erator under both of the following condition s: ( 1)

(2)

The generator supplies only equipment mounted on the generator, cord-and-plug-connected equipment through receptacles mounted on the generator, or both. The normally non-current-carrying metal parts of equipment a nd the equipment grounding conductor terminals of the receptacles a 1·e connected to the gen erator frame.

(B) Vehicle-Mounted and Trailer-Mounted Generators. The frame of a vehicle or trailer shall not b e required to be connected to a g ro und ing electrode as defined in 250.52 for a system supplied by a generator located on this veh icle or trailer under a ll of the followin g conditions: ( 1) (2)

The frame of the g enerator is bonded to the vehicle or u·ailer frame . The generator supplies on ly equipme nt located on the ve hicle o r trailer; cord-and-plug-connected equipme nt through receptacles mounted on the veh icle; or both equipment located on the vehicle or trailer and cord-an d-plug-connected equipment through receptacles mounted on the veh icle, trailer, or on the generator.

2020 Edition

NATIONAL ELECTRJCAL CODE

The normally non-current-carrying metal parts of equipment and the equipment grounding conductor terminals of the receptacles are conn ected to the generator fra me.

(C) Grounded Conductor Bonding. A system conductor that is required to b e grounded by 250.26 shall b e connected to the generator frame where the generator is a component of a separately derived syste m.

(1)

250.34 Portable, Generators.

250.36

(2) (3)

The conditions of m a intenan ce and supervision en sure that o nly qualified persons service the installatio n. Ground detectors are install ed on the system. Li ne-to-neutral loads are not served.

High-impedance grounded neutral system s shall comply with 250.36(A) through (G) . Informationa l Note: According to Annex O of NFPJ\ 70£:2018, Standard for Electrical Safely in the Worhf1lace, high-impedance grounding is an effective tool to reduce arc flash hazards .

(A) Location. The grounding impedance shall be insta lled between the ground ing electrode conductor a nd the syste m neuu·al point. If a neutral point is n ot available, the grounding impedance shall be installed between the groun d ing electrode conductor and the neutral poin t derived from a gro unding transformer. (B) Conductor Insulation and Ampacity. The grounded system condu ctor from the neuu·al point of the transformer or gen e rator to its connection point to the grounding i mpedance shall be fully insulated.

The grounded system con d u ctor shall h ave an ampacity of not less than the maximum cutTent rating of the gro unding impeda n ce but in n o case shall the grounded system conductor b e smaller than 8 AWG copper or 6 AV•lG aluminum or copper-clad aluminum .

70- 119

250.36

ARTICLE 250-GROUNDING AND BONDING

(C) System Grounding Connection. The system shall not be connected to ground except through the grounding impedance.

250.52 Grounding Electrodes. (A) Electrodes Permitted for Grounding.

Informational Note: The impedance is normally selected to limit the ground-fault current to a value slightly greater than or equal to tl1e capacitive charging current of the system. This value of impedance will also limit transient overvoltages to safe values. For guidance, refer to criteria for limiting transient overvoltages in ANSI/ IEEE 142-2007, Recommended Practice for Grounding of Industrial and Commercial Power Systems.

(I ) Metal Underground Water Pipe- A metal underground water pipe in direct contact with the earth for 3.0 m (10 ft) or more (including any metal well casing bonded to the pipe) and elecu·ically continuous (or made elecu·ically continuous by bonding around insulating joints or insulating pipe) to the points of connection of the grounding elecu·ode conductor and the bonding conductor(s) orjumper(s), if installed.

(D) Conductor Routing. The conductor connecting the neutral point of the transformer or generator to the grounding impedance shall be permitted to be installed in a separate raceway from the ungrounded conductors. It shall not be required to run this conductor with the phase conductors to the first system disconnecting means or overcurrent device.

(2) Metal In-ground Support Structure(s). One or more metal in-ground support structure(s) in direct contact with the earth vertically for 3.0 m (10 ft) or more, with or without concrete encasement. If multiple metal in-ground support structures are present at a building or a structure, it sh all be permissible to bond only one into the grounding e lectrode system.

(E) Equipment Bonding Jumper. The equipment bonding jumper (the connection between the equipment grounding conductors and the grounding impedance) shall be an unspliced conductor run from the first system d isconnecting means or overcurrent device to the grounded side of the grounding impedance.

Informational Note: Metal in-ground support structures include, bur are not limited to, pilings, casings, and other structural metal.

(3) Concrete-Encased Electrode. A concrete-encased elecu·ode shall consist of at least 6.0 m (20 ft) of either (1) or (2) :

(F) Grounding Electrode Conductor Connection Location. For services or separately derived systems, the grounding electrode conductor shall be connected at any point from the grounded side of the grounding impedance to the equipment grounding connection at the service equipment or the first system disconnecting means of a separately derived system .

(1)

(G) Equipment Bonding Jumper Size. The equipment bonding jumper shall be sized in accordance with (1) or (2) as follows:

(2)

(l)

(2)

If the grounding electrode conductor connection is made

at the grounding impedance, the equipment bonding jumper shall be sized in accordance with 250.66, based on the size of the service entrance conductors for a service or the derived phase conductors for a separately derived system. If the grounding electrode conductor is connected at the first system disconnecting means or overcurrent device, the equipment bonding jumper shall be sized the same as the neutral conductor in 250.36(B).

Part III. Grounding Electrode System and Grounding Electrode Conductor 250.50 Grounding Electrode System. All grounding electrodes as described in 250.52(A)( l ) through (A) (7) that are present at each building or su·ucture served shall be bonded together to form the grounding elecu·ode system . Where none of these grounding elecu·odes exist, one or more of the grounding electrodes specified in 250.52(A) (4) t hrough (A) (8) sh all be installed and used.

Exception: Concrete-encased electrodes of existing buildings or structures shall not be required to be part of the grounding dectrode system where the ste,el reinforcing bars or rods are not accessible for use without disturbing the concrete.

70-120

One or more bare or zinc galvan ized or other electrically conductive coated steel reinforcing bars or rods of not less than 13 mm (1/,, in. ) in diameter, installed in one continuo us 6.0 m (20 ft) length, or if in multiple pieces connected together by the usual steel tie wires, exothermic welding, welding, or other effective means to create a 6.0 m (20 ft) or greater length; or Bare copper conductor not smaller than 4 AWG

Metallic componen ts shall be encased by at least 50 mm (2 in. ) of concrete and shall be located horizontally within that portion of a concrete foundation or foot ing that is in d irect contact with the earth or within vertical foundations or structural components or members that are in d irect contact with the earth . If multiple concrete-encased elecu·odes are present at a build ing or su·ucture, it shall be perm issible to bond only one into the grounding electrode system . Informational Note: Concrete installed with insulation, vapor barriers, fi lms or similar items separating the concrete from tl1e earth is not considered to be in "direct contact" with the earth.

(4) Ground Ring. A ground ring encircling the buil d ing or structure, in direct contact with the earth, cons isting of at least 6.0 m (20 ft) of bare copper conductor not smaller than 2AWG. (5) Rod and Pipe Electrodes. Rod and pipe electrodes shall not be less th an 2.44 m (8 ft) in length and shall consist of the following materials. (a) Grounding e lectrodes of pipe or conduit shall not be smaller than metric designator 21 (u·ade size¾) and, wh ere of steel, shall have the outer surface galvan ized or otherwise metal-coated for corrosion protection. (b) Rod-type grounding electrodes of stainless steel and copper or zinc coated steel shall be at least 15.87 mm (¾ in. ) in diameter, unless listed. (6) Other Listed Electrodes. Other listed grounding elecu·odes shall be permitted.

NATIONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 250- GROUNDING AND BONDING (7) Plate Electrodes. Each plate electrode shall expose n ot less than 0.1 86 m 2 (2 ft2 ) of surface to exterior soil. Electrodes of bare or electrically condu ctive coated iron or stee l plates shall be at least 6.4 mm (1/., in. ) in thickness. Solid, uncoated elecu·odes of nonferrous metal shall be at least 1.5 mm (0.06 in. ) in th ickness.

(8) Other Local Metal U nderground Systems or Structures. Other local metal unde1·ground systems or structures suc h as piping systems, underground tanks, and underground metal well casings that are not bonded to a metal water pipe. (B) Not Permitted for Use as Grounding Electrodes. The following systems a nd materials shall not be used as g rounding electrodes:

Metal underground gas pi ping systems Aluminum The structures and structural reinforcing steel described in 680.26(B) (1) and (B) (2)

(1 )

(2) (3)

Informational Note: See 250.1 04(B) for b onding requ ire me nts of gas piping.

250.53 Grounding Electrode System Installation. (A) Rod, Pipe, and Plate Electrodes. Rod, pipe, and plate electrodes shall meet the requirements of 250.53(A) (1) through

250.58

(5) Plate Electrode. Plate electrodes shall be insta lled not le ss than 750 mm (30 in. ) below the surface of the earth . (B) Electrode Spacing. vVhere more than one of the electrodes of the type specified in 250.52(A)(5) or (A)(7) are used, each electrode of one grounding system (including that u sed for strike termination devices) sh all no t be less than 1.83 m (6 ft) from a ny other electrode of anoth er grounding system. Two or more grounding elecu·odes that are bonded together shall be considered a single g rounding electrode system . (C) BondingJumper. The bonding jumper(s) used to connect the grounding elecu·odes together to form the grounding e lectrode system shall be installed in accordance with 250.64(A), (B), a nd (E), shall be sized in accorda nce with 250.66, and shall be connected in the man ne r specified in 250.70. Rebar shall not be used as a conductor to interconnect the elecu·odes of grou nding e lectrode systems.

(D) Metal Underground Water Pipe. If used as a grounding electrode, metal underground water pipe sha ll meet the requirements of250.53(D)( l ) and (0 )(2) .

(I) Continuity. Continuity of the grounding path or the bonding connection to interior piping shall not rely on water meters or filtering devices a nd similar equipment.

(1) Below Permanent Moisture Level If practicable, rod, pipe, a nd plate e lectrodes shall be embedded below permanent moisture level. Rod, pipe, and plate electrodes shall be free from nonconductive coatings such as paint or enamel.

(2) Supplemental Electrode Required. A metal underground water pipe shall be supplemented by a n additional electrode of a type specified in 250.52(A) (2) throug h (A) (8) . If the suppleme ntal elecu·ode is of the rod , pipe, or plate type, it shall comply with 250.53(A) . The supplemental electrode shall be bo nded to one of the following:

(2) Supplemental Electrode Required. A single rod, pipe, or plate electrode shall be supplemented by an additional electrode of a type specified in 250.52(A) (2) through (A) (8) . The supplemental electrode shall be permitted to be bonded to o ne of the following:

(I ) (2) (3) ( 4) (5)

( 1) (2) (3) ( 4) (5)

Exception: The supplemental electrode shall be permitted to be bonded to the interior metal water piping as specified in 250. 68(C)( 1).

(A) (3) .

Rod, pipe, o r plate electrode Grounding electrod e conductor Grounded service-entrance conductor Non flexible g rounded service raceway Any grounded service enclosure

Exception: If a single rod, pipe, or plate grounding electrode has a resistance to earth of 25 ohms or less, the supplemental electrode shall not be required. (3) Supplemental Electrode. If multiple rod, pipe, or plate e lectrodes are installed to m eet the requirements of this section, they shall not be less than 1.8 m (6 ft) apart. Informational Note: The paralleling efficie ncy of rods is increased by spacing them twice the length of the lo ngest rod.

(4) Rod and Pipe Electrodes. The electrode shall be installed such that at least 2.44 m (8 ft) of length is in contact with the soil. I t shall be drive n to a depth of not less than 2.44 m (8 ft) exce pt that, where rock bottom is e nco untered, the electrode shall be driven at an oblique angle not to exceed 45 degrees from the vertical or, where rock bottom is encountered at a n angle up to 45 degrees, the electrode shall be permitted to be buried in a trench that is at least 750 mm (30 in.) deep. The upper end of the electrode shall be flush with or below ground level unless the aboveground e nd and the grounding electrode cond uctor attachment are protected against physical damage as specified in 250. l 0.

2020 Edition

NATIONAL ELECTRJCAL CODE

Grounding electrode conductor Grounded service-entrance conductor Non flexible grounded service raceway Any grounded service enclosure As provided by 250.32(B)

(E) Supplemental Electrode Bonding Connection Size. Where the supplemental elecu·ode is a md, pipe, or plate elecu·ode, that portion of the bo nding jumper that is the sole connection to the supplemental grounding electrode sh all not be required to be larger than 6 AWG copper wire or 4 AWG aluminum wire.

(F) Ground Ring. The g round ring shall be installed not less than 750 mm (30 in. ) below the surface of the earth .

250.54 Auxiliary Grounding Electrodes. One or mo re grounding e lectrodes shall be permitted to be connected to the equipment grounding conductors specified in 250.118 and shall not be required to comply with the electrode bonding requirements of 250.50 or 250.53(C) or the resistance requirements of 250.53(A) (2) Exceptio n, but the earth shall not be u sed as a n effective ground-fault current path as specified in 250.4(A)(5) and 250.4( B)(4) . 250.58 Common Grounding Electrode. '"'here a n ac system is connected to a grounding electrode in or at a buildin g or su·ucnire, the same elecu·ode sh all be used to ground cond uctor enclosures an d equipment in or on that building or su·ucture. Where separate services, feeders, or branch circuits su pply a building and are required to be connected to a grounding electrode (s), the same grounding electrode(s) shall be used .

70- 121

250.60

ARTICLE 250-GROUNDING AND BONDING

Two or more grounding electrodes that are bonded together shall be considered as a single grou nding elecu·ode system in this sense. 250.60 Use of Strike Termination Devices. Conductors and driven pipes, rods, or plate electrodes used for grounding su·ike termination devices shall not be used in lie u of the grounding electrodes requi red by 250.50 for grounding wiring systems and equipment. This provision shall not prohibit the required bonding together of grounding elecu·odes of different systems. Informational Note No. I: See 250.1 06 for the bonding requirement of the lighming protection system components w the building or structure grounding e lectrode system. Informational Note No. 2: Bonding lOgether of a ll separate grounding electrodes will limit voltage d ifferences between them and between their associated wiring systems.

250.62 Grounding Electrode Conductor Material. The grounding electrode conductor shall be of copper, aluminum , copper-clad aluminum, or the items as permitted in 250.68(C) . The material selected shall be resistant to any corrosive condition existing at the installation or shall be protected against corrosion. Conductors of the wire ty pe sh a ll be solid o r stranded, insulated, covered, or bare. 250.64 Grounding Electrode Conductor Installation. G ro unding e lectrode conductors at the service, at each building or su·ucture where supplied by a feeder( s) or branch circuit(s), or at a separately derived system shall be installed as specified in 250.64(A) through (F) . (A) Aluminum or Copper-Clad Aluminum Conductors. Grounding electrode conductors of bare , covered, or insulated aluminum or copper-clad aluminum shall comply with the following: (1)

(2)

(3)

Bare or covered conductors without a n exu·uded polymeric covering shall not be installed where subject to corrosive conditions or b e installed in d irect contact with concrete. Terminations made within o utdoor enclosures that are listed and identified for the environment shall be permitted within 450 mm (1 8 in. ) of the bottom of the e nclosure. Aluminum or copper-clad aluminum conductors external to build ings or equipment enclosures shall not be terminated within 450 mm (18 in. ) of the earth.

(B) Securing and Protection Against Physical Damage. Where exposed, a grounding e lectrode conductor o r its e nclosure shall be securely fastened to t he surface on which it is carried . Grounding electrode conductors shall be permitted to be installed on or through framing members. (I) Not Exposed to Physical Damage. A 6 AWG or larger copper or aluminum ground ing electrode cond uctor not exposed to physical damage shall be pe rmitte d to be run along the su rface of the build ing construction witho ut metal covering or protection.

(2) Exposed to Physical Damage. A 6 AWG or larger copper or aluminum g rounding electrode cond uctor exposed to physical damage shall be protected in rigid metal conduit (RMC), intermed ia te metal cond uit (IMC), Schedule 80 rigid polyvinyl chloride conduit (PVC), 1·e inforced thermosetting resin

70-122

conduit Type XW (RTRC-XW), electrical metallic tubing (EMT), o r cable a rmor. (3) Smaller Than 6 AWG. Grounding electrode conductors smaller than 6 AWG sha ll be protected in RMC, IMC, Schedule 80 PVC, RTRC-XW, EMT, or cable armor. (4) In Contact with the Earth. Grounding electrode conductors and grounding elecu·ode bonding jumpers in contact with the earth shall not be required to comply with 300.5, but shall be buried or otherwise protected if subject to physical damage. (C) Continuous. Except as provided in 250.30(A)(5) and (A)(6), 250.30 (B)( l ), and 250.68(C), grounding electrode conductor(s) shall be installed in one continuous length without a splice or j oint. If necessary, splices or connections shall be made as pe rmitted in ( I ) through (4) : (1 )

(2) (3) ( 4)

Splicing of the wire-type grounding electrode conductor shall be permitted only by irreversible compressio n-type connectors listed as grounding a nd bonding equipment or by the exothermic welding process. Sections of busbars shall be pennitted to be connected together to form a grounding electrode conductor. Bolted, riveted , o r welded conn ections of su·uctural metal frames of buildings or structures. Threaded, welded, brazed, soldered or bolted-flange connections of m etal water piping.

(D) Building or Structure with Multiple Disconnecting Means in Separate Enclosures. If a building or structure is supplied by a service or feeder with two or more disconnecting means in separate e nclosures, the grounding electrode connections shall be made in accordance with 250.64(D) (l ), 250.64(0)(2) , or 250.64(0 ) (3) . (I) Common Grounding Electrode Conductor and Taps. A common ground ing electrode cond uc tor a nd ground ing electrode conductor taps shall be installed. The commo n grounding electrode conductor shall be s ized in accordance with 250.66, based o n the sum of the circular mil area of the largest ung rounded conductor(s) of each set of conductors that supplies the d isconnecting mean s. If the service-entrance conducto rs connect directly to the overhead service conductors, service drop, underground service conductors, or service lateral, the commo n grounding electrode conduc tor shall be sized in accordance with Table 250.66, note 1.

A g rounding electrode conducto r tap shall extend to the inside of each disconnecting m eans enclosure. The grounding elec trode cond ucto r taps shall be sized in accordan ce with 250.66 for the largest service-entrance or feeder conductor serving the individual e nclosure. The tap cond uctors shall be connected to the common g rounding electrode conduc tor by o ne of the following methods in su ch a man ner that the common gro unding elecu·ode conductor rem ains witho ut a splice or j o int: ( 1)

(2) (3)

Exothermic welding. Connectors listed as ground ing and bonding equipment. Connectio ns to a n aluminum or copper busbar not less tha n 6 mm thick x 50 mm wide (1/., in. thi ck x 2 in. wide) and of sufficie nt length to accommodate the number of te rminations necessary for the installatio n. The busba r shall be securely fastened and shall be installed in an accessible locatio n. Connection s shall be made by a listed connector or by the exothermic welding process. If alumi-

NAT IONAL ELECTRJCAL CODE

2020 Edition

250.66

ARTICLE 250- GROUNDING AND BONDING mun busbars are used, the installation shall comply with 250.64(A) . (2) Individual Grounding Electrode Conductors. A grounding e lectrode conductor shall be connected between the grounding e lectrode system and one o r more of the following, as applicable: (I)

(2) (3)

Grounded conductor in each service equipment disconnecting means enclosu re Equipment g rounding conductor installed with the feeder Supply-side bonding jumper

Each grounding e lectrode conductor shall be sized in accordance with 250.66 based on the service-entrance or feeder condu ctor (s) supplying the individual disconnecting means. (3) Common Location. A grounding electrode conductor shall be connected in a wireway or other accessible enclosure on the supply side of the disconnecting mea ns to one or more of the following, as applicable: (I )

(2) (3)

Grounded sen~ce conductor(s) Equipment grounding conductor installed with the feeder Supply-side bonding jumper

The connection shall be made with exothermic welding or a connector listed as grounding and bonding equipment. The grounding electrode conductor shall be sized in accordance with 250.66 based on the service-entrance or feeder conductor(s) at the common location where the connection is made. (E) Raceways Conductors.

and Enclosures

for

armor for ground ing electrode conductors shall be electrically continuo us from the point of attachment to cabinets or equipment to the ground ing electrode and shall be secure ly faste ned to the ground clamp or fittin g. Ferrous metal raceways, enclosures, and cable armor shall be bonded at each end of the raceway or enclosure to the ground ing elecu·ode or ground ing e lectrode conductor to create an elecu·ically parallel path . Nonferrous metal raceways, enclosu res, and cable armor shall not be required to be electrically continuous. (2) Methods. Bonding shall be in compliance with 250.92(B) and ensured by o ne of the methods in 250.92(B)(2) through (B)(4) . (3) Size. The bonding jumper for a grounding electrode condu ctor(s), raceway(s), enclosure(s), or cable armor shall be the same size as, or large1· than, the largest enclosed ground ing e lectrode conductor. (4) Wiring Methods. If a raceway is used as protection for a grounding electrode conductor, the installation shall comply with the requirements of the appropriate raceway article. (F) Installation to Electrode(s). Grounding electrode conduc-

tor(s) and bonding jumpers interconnecting grounding electrodes shall be installed in accordance with (I), (2), or (3) . The ground ing electrode cond uctor shall be sized for the largest grounding e lectrode conductor required among all the electrodes connec ted to it. The grounding e lectrode conductor shall be pe rmitted to be run to any convenient ground ing e lectrode available

2020 Edition

NATIONAL ELECTRJCAL CODE

(3)

250.66 Size of Alternating-Current Grounding Electrode Conductor. The size of the grounding e lectrode conductor at the service, at each building or strucnire where suppli ed by a feeder(s) or branch circuit(s), or at a separately derived syste m of a grounded or ungrounded ac syste m sha ll not be less than given in Table 250.66, except as permitted in 250.66(A) through (C) .

Table 250.66 Grounding Electrode Conductor for AlternatingCurrent Systems

Grounding Electrode

(1) General. Ferrous metal raceways, enclosures, and cable

(I)

(2)

in the grounding elecu·ode system where the other electrode (s), if any, is connected by bonding jumpers that are installed in accordance with 250.53(C) . Grounding electrode conductor(s) sha ll be permitted to be run to one or more grounding electrode(s) individually. Bonding jumper(s) from grounding elecu·ode(s) shall be permitted to be connected to an aluminum or copper busbar not less than 6 mm thick x 50 mm wide (¼ in. thick x 2 in wide.) and of sufficient le ngth to accommodate the number of terminations necessary for the installation. The busbar shall be securely fastened and shall be installed in a n accessible location. Connections shall be made by a listed connector or by th e exothermic welding process. The grounding e lectrode conductor shall be permitted to be run to the busbar. vVh ere aluminum busbars are used, the installation shall comply with 250.64(A) .

Size of Largest Ungrounded Conductor or Equivalent Area for Parallel Conductors (AWG/ kcmil)

Copper

Aluminum or Copper-Clad Aluminun1

Size of Gr0tmding Electrode Conductor (AWG/ kcmil)

Copper

Aluminum or Copper-Clad Altmtinmn

2 or smaller

l / 0 or smaller

8

6

1 or 1/ 0

2/0 or 3/ 0

6

4

2/ 0 or 3/ 0

4/ 0 or 250

4

2

Over 3/ 0 through 350

Over 250 through 500

2

1/ 0

Over 350 through 600

Over 500 through 900

l/ 0

3/0

Over 600 through llOO

Over900 through 1750

2/ 0

4/ 0

Over 1100

Over 1750

3/ 0

250

Notes: I. If multiple secs of se,v ice-encrance conductors connect directly co a service drop, sec of overh ead se1vice conductors, sec of underground service conductors, or service lateral, the equivalem size of the largest service-entrance conductor shall be determined by the largest sum of the areas ofrhe corresponding conductors of each sec. 2. Where there are no service-enu·ance conductors, the grounding electrode conductor size shall be determined by the equivalent size of the largest service-emrance conductor required for the load co be served. 3. See installation restrictions in 250.64.

70- 123

250.66

ARTICLE 250-GROUNDING AND BONDING

(A) Connections to a Rod, Pipe, or Plate Electrode(s). If the grounding elecu·ode conductor or bonding jumpe r connected to a single or multiple rod, pipe, or plate elecu·ode(s), or any combination thereof; as described in 250.52(A) (5) or (A) (7), does not extend on to other types of electrodes that require a larger size conductor, the grounding electrode conductor shall not be required to be larger than 6 AWG copper wire or 4 AWG aluminum wire. (B) Connections to Concrete-Encased Electrodes. If the grounding electrode conductor or bonding jumper connected to a single or multiple concrete-encased elecu·ode(s), as described in 250.52(A) (3), does not extend on to other types of electrodes that require a larger size of conductor, the grounding elecu·ode conductor shall not be required to be larger than 4 AWG copper wire.

to interconnect electrodes of the grounding elecu·ode system.

l!.xception: In industrial, commercial, and institutional buildings or structures, if conditions of maintenance and supervision ensure that only qualified persons service the installation, interior metal water piping located more than 1.52 m (5 ft) from the point of entrance to the IYuilding shall be permitted as a bonding conductor to interconnect electrodes that are part of the grounding electrode system, or as a grounding electrode conductm; if the enti:re lengt,h, other than short sections passing perpendicularly through walls, floors, or ceilings, of the interior metal water pipe that is being used for the conductor is exposed. (2)

(C) Connections to Ground Rings. If the grounding electrode conductor or bonding jumper connected to a ground ring, as described in 250.52(A) (4), does not extend on to other types of electrodes that require a larger size of conductor, the grounding elecu·ode conductor shall not be required to be larger than the conductor used for the ground ring.

250.68 Grounding Electrode Conductor and Bonding Jwnper Connection to Grounding Electrodes. The connection of a grounding e lectrode conductor at the service, at each building or structure where supplied by a feeder(s) or branch circuit(s), or at a separately derived system and associated bonding jumper(s) shall be made as specified 250.68(A) through (C) .

(3)

(A) Accessibility. All mechanical elements used to terminate a grounding elecu-ode conductor or bonding jumper to a grounding electrode shall be accessible.

a. The additional rebar section shall be continuous with the grounding electrode rebar or shall be connected to the grounding electrode rebar and connected together by the usual steel tie wires, exothermic welding, welding, or other effective means. b. The rebar extension shall not be exposed to contact with the earth without corrosion protection. c. Re bar shall n ot be used as a conductor to interconnect the electrodes of grounding electrode systems.

Exception No. 1: An encased or buried connection to a concrete-encased, driven, or buried grounding electrode shall not be required to be accessible. Exception No. 2: l!.xothermic or irreversible compression connections used at terminations, together with the mechanical means used to attach such terminations to fireproofed structural metal whether or not the mechanical means is reversible, shall not be required lo be accessible. (B) Effective Grounding Path. The connection of a grounding electrode conductor or bonding jumper to a grounding electrode shall be made in a manner that will e nsure an effective grounding path. vVhere necessary to ensure the grounding path for a metal piping system used as a grounding e lectrode, bonding shall be provided around insulated joints a nd around any equipment likely to be disconnected for repairs or replacement. Bonding jumpers shall be of sufficient length to permit removal of such equipment while retaining the integrity of the grounding path . (C) Grounding Electrode Conductor Connections. Grounding electrode conductors and bonding jumpers shall be permitted to be connected at the following locations and used to extend the connection to an electrode(s):

(1)

Interior metal water piping that is electrically continuous with a metal undergro und water pipe elecu·ode and is located not more than 1.52 m (5 ft) from the point of entrance to the building shall be permitted to extend the connection to an electrode(s) . Interior metal water piping located more than 1.52 m (5 ft) from the point of enu-ance to the building shall not be used as a conductor

250.70 Methods of Grounding and Bonding Conductor Connection to Electrodes. The grounding or bonding conductor shall be connected to the grounding e lectrode by exothermic welding, listed lugs, listed pressure connectors, listed clamps, or other listed means. Connections depending on solder shall not be used. Ground cla mps shall be listed for the mater ials of the grounding electrode and the grounding electrode conductor and, where used on pipe, rod, or other buried electrodes, shall also be listed for direct soil burial or concrete encasement. Not more than one conductor shall be connected to the grounding e lectrode by a single clamp or fitting unless the clamp or fitting is listed for multiple conductors. One of the following methods shall be used:

(1) (2) (3)

(4)

70-124

The metal structural frame of a building shall be permitted to be used as a conductor to interconnect electrodes that are part of the gro unding electrode system, or as a grounding electrode conductor. Hold-down bolts securing the structural steel column that are connected to a concrete-encased electrode complying with 250.52(A)(3) and located in the support footing or foundation shall be permitted to connect the metal structural frame of a building or su-ucture to the concrete encased grounding electrode . The hold-down bolts shall be connected to the concrete-encased electrode by welding, exothermic welding, the u sual steel tie wires, or other approved means. A rebar-type concrete-encased electrode installed in accordance with 250.52(A) (3) with an additional re bar sectio n extended from its location within the concrete foundation or footing to an accessible location that is not subject to corrosion shall be permitted for connection of grounding electrode conductors and bonding jumpers in accordance with the following:

A pipe fitting, pipe plug, or other approved device screwed into a pipe or pipe fitting A listed bolted clamp of cast bronze or brass, or plain or malleable iron For indoor communicatio ns purposes only, a listed sheet metal strap-type ground clamp having a rigid metal base that seats on the electrode and having a strap of such material and dimensions that it is not likely to stretch during or after installation An equally substantial approved means

NAT IO NAL ELECTRJCAL CODE

2020 Edition

ARTICLE 250- GROUNDING AND BONDING

250.94

Part IV. Enclosure, Raceway, and Service Cable Connections

Part V. Bonding

250.80 Service Raceways and Enclosures. Metal enclosures and raceways for service conductors and equipment shall be connected to the grounded system conductor if the electrical system is grounded or to the grounding electrode conductor for electrical systems that are not grounded.

250.90 General. Bonding shall be provided where necessary to ensure electrical continuity and the capacity to conduct safely any fault c urrent likely to be imposed.

Exception: Metal components that are installed in a run of underground nonmetallic raceway(s) and are isolated from possible contact by a minimum cover of 450 mm (18 in.) to all parts of the metal components shall not be required to be connected to the grounded system conducto1; supply side bonding jumpe1; or grounding electrode conduc-

(A) Bonding of Equipment for Services. The normally noncu rrent-carrying metal parts of equipment indicated in 250.92(A) (1) and (A)(2) shall be bonded together.

250.92 Services.

( 1)

101:

250.84 Underground Service Cable or Raceway. (A) Underground Service Cable. The sheath or armor of a continuous underground metal-sheathed or armored service cable system that is connected to the grounded system conductor on the supply side shall not be required to be connected to the grounded system conductor at the building or structure. The sheath or armor shall be permitted to be insulated from the interior metal raceway or piping. (B) Underground Service Raceway Containing Cable. An underground metal se1vice raceway that contains a metalsheathed or armored cable connected to the grounded system conductor shall not be required to be connected to the grounded system conductor at the building or structure . The sheath or armor shall be permitted to be insulated from the interior metal raceway or piping. 250.86 Other Conductor Enclosures and Raceways. Except as permitted by 250.11 2 (I), metal enclosures and raceways for other than service conductors shall be connected to the equipment grounding conductor. Exception No. 1: Metal enclosures and raceways f01· conductors added to existing installations of open wire, knob-and-tube wi1ing, and nonmetallic-sheathed cable shall not be required to be connected to the equipment grounding conductor where these enclosures or wi1ing methods comply with ( 1) through (4) as follows: (1) (2) (3) (4)

Do not provide an equipment ground Are in runs of less than 7.5 m (25 ft) Are free from probable contact with ground, grounded metal, metal lath, or other conductive material Are guarded against contact by persons

Exception No. 2: Short sections of metal enclosures or raceways -used to provide support or protection of cable assemblies from physical damage shall not be required to be connected to the equipment grounding conducto1:

(2)

(B) Method of Bonding at the Service. Bo nding jumpers meeting the requirements of this article shall be used around impaired connections, such as reducing washers or oversized, concentric, or eccentric knockouts. Standard locknuts or bushings shall not be the only means for the bonding required by this section but shall be perm itted to be installed to make a mechanical connection of the raceway(s) .

Electrical continuity at service equipment, service raceways, and service conductor enclosures shall be ensured by one of the following methods: ( 1)

(2) (3)

(4)

(A) The Intersystem Bonding Termination D evice. An intersystem bonding termination (IBT) for connecting intersystem bonding conductors shall be provided external to enclosures at the service equ ipment or meteri ng equ ipment enclosure and at the d isconnecting means for any additional buildings or su·uctures. lf a n IBT is used, it shall comply with the following: (1)

(2)

(3)

( 1)

(4)

(2)

2020 Edition

NATIONAL ELECTRJCAL CODE

Bonding equipment to the grounded service conductor in a manner provided in 250.8 Connections using threaded couplings or listed threaded hubs on enclosu res if made u p wrenchtight Th readless couplings and connecto rs if made up tight for metal raceways and metal-clad cables Other listed devices, such as bon ding-type locknuts, bushings, or bushings with bondingjumpers

250.94 Bonding for Communication Systems. Communications system bonding terminations shall be connected in accordance with 250.94(A) or (B).

Exception No. 3: Metal wmponents shall not be required to be connected to the equipment grounding conductor or suppl:rside bonding jumper where either of the following conditions exist: The metal components are installed in a run of nonmetallic raceway(s) and isolated from possible contact by a minimum cover of 4 50 mm ( 18 in.) to any part of the metal components. The metal c01nponents are part of an installation of nonmetallic raceway(s) and are isolated from possible contact to any part of the metal components by being encased in not less than 50 mm ( 2 in.) of concrete.

All raceways, cable trays, cablebus framework, auxiliary gutters, or service cable armor or sheath that enclose, contain, or support service conductors, except as permitted in 250.80 All enclosures containing service conductors, including meter fittings, boxes, or the like, interposed in the service raceway or armor

Be accessible for conn ection and inspection. Consist of a set of terminals with the capacity for connection of not less than three intersystem bonding conductors. Not interfere with open ing the enclosure for a service, building or su·ucture d isconnecting means, or metering equipment. At the service equipment, be secu rely mounted and electrically connected to an enclosu re for the service equipment, to the meter enclosu re, or to an exposed nonflexible metallic service raceway, or be mounted at one of these enclosu res and be connected to the enclosure or to the gro unding elecu·ode conductor with a minimum 6 AWG copper conductor.

70- 125

250.94 (5)

(6)

ARTICLE 250-GROUNDING AND BONDING

At the disconnecting means for a building or structure, be secure ly mounted and elecu·ically connected to the metallic enclosure for the building or structure disconnecting means, or be mounted at the d isconnectin g means and be connected to the metallic enclosure or to the grounding electrode conductor with a minimum 6 AWG copper conductor. The terminals shall be listed as grounding and bonding equipment.

Exception: In existing buildings or structures where any of the intersystem bonding and grounding electrode conductors required by 770.I00(B)(2), 800.JO0(B)(2), 810.21(F)(2), 820.100, and 830.100 exist, installation of the intersystem bonding termination is not required. An accessible means external lo enclosures for connecting intersystem bonding and grounding electrode conductors shall be permitted at the service equipment and at the disconnecting means for any additional buildings or structures by at least one of the following means: ( 1)

(2) (3)

Exposed nonflexible metallic raceways An exposed grounding electrode conductor Approved means for the external connection of a copper or other corrosion-resistant bonding or grounding electrode conductor lo the grounded raceway m· equipment Informational Note No. 1: A 6 AWG copper conductor with one end bonded to the grounded nonflexible metallic raceway or equipment and with 150 mm (6 in.) or more of the other end made accessible on the outside wall is an example of the approved means covered in 2.50.94, Exception item (3). Informational Note No. 2: See 770.100, 800.100, 810.21, 820. I 00, and 830. 100 for intersystem bonding and grounding requirements for conductive optical fiber cables, communications circuits, radio and television equipment, CA1V circuits and network-powered broadband communications systems, respectively.

(B) Other Means. Connections to an aluminum or copper busbar not less than 6 mm thick x 50 mm wide (1/1 in. thick x 2 in. wide) and of sufficient length to accommodate at least three terminations for communication systems in addition to other connections. The busbar shall be securely fastened and shall be installed in an accessible locatio n. Connections shall b e made by a listed connector. If aluminum busbars are u sed, the installation shall also comply with 250.64(A) . Exception lo (A) and (B): Means for connecting intersystem bonding conductors are not required where communications systems are not likely to be used. Informational Note: The use of an !BT can reduce electrical noise on communication systems.

250.96 Bonding Other Enclosures. (A) General. Metal raceways, cable trays, cable armor, cable sheath, enclosures, frames, fittings, and other metal 11011current-carrying parts that are to se rve as equipment grounding conductors, with or without the use of supplementary equipment grounding conductors, shall be bonded where necessary to e n sure e lectrical continuity and the capacity to condu ct safely any fault current likely to be i mposed on them. Any n o n conductive paint, e namel, or similar coating shall be removed at threads, contact points, a nd contact surfaces or shall be connected by means of fittings designed so as to make such removal unnecessary.

70-126

(B) Isolated Grounding Circuits. Where installed for the reduction of elecu·omagnetic interfe1·ence on the grounding circuit, an equipment enclosure supplied by a branch circuit shall be permitted to be isolated from a raceway containi ng circuits supplying only that equipment by one o r more listed nonmetallic raceway fittin gs located at the point of attachment of the raceway to t h e equipment enclosure. The metal raceway shall comply with this article and shall be supplemented by an internal insulated equipment grounding conductor installed in accordance with 250.1 46(0) to ground the equipment enclosure. Informational Note: Use of an isolated equipment grounding conductor does not relieve the requirement for grounding the raceway system.

250.97 Bonding for Over 250 Volts. For circuits of over 250 volts to ground, the e lectrical continuity of metal raceways and cables with metal sheaths that contain any conductor other than service conductors shall be ensured by o ne or more of the methods specified for services in 250.92 (B), except for (B) (1). 1'.xception: Where oversized, concent1ic, or eccentric knockouts are not encountered, m· where a box m· enclosure with concentric or eccenhic knockouts is listed to provide a reliable bonding connection, the following methods shall be permitted: (1)

(2) (3)

(4)

Threadless couplings and connectors for cables with metal sheaths Two locknuts, on rigid metal conduit or intermediate metal conduit, one inside and one outside of boxes and cabinets Fittings with shoulders that seat firmly against the box or cabinet, such as electrical metallic tubing connectors, flexible metal conduit connectors, and cable connectm·s, with one locknut on the inside of boxes and cabinets Listed fittings

250.98 Bonding Loosely Jointed Metal Raceways. Expansion, expansion-deflection, or deflection fittings and telescoping sections of metal raceways shall be made electrically continuous by equipment bonding jumpers or other means. 250.100 Bonding in Hazardous (Classified) Locations. Regardless of the voltage of the electrical system , the electrical continuity of non-current-carrying metal parts of equipment, raceways, and other enclosures in any hazardous (classified) locatio n , as defined in 500.5, 505 .5, and 506.5, shall be ensured by any of the bonding methods specified in 250.92(B)(2) through (B)(4) . One or more of these bonding methods shall be u sed whether or not equipme nt grounding conductors of the wire type are installed. Informational Note: See 501.30, 502.30, 503.30, 50.5.25, or 506.25 fo r specific bonding requirements.

250.102 Grounded Conductor, Bonding Conductors, and Jumpers. (A) Material. Bonding jumpers shall be of copper, aluminum, copper-clad aluminum , or other corrosion-resistant material. A bonding jumper shall be a wire, bus, screw, or similar suitable conductor. (B) Attachment. Bonding jumpers shall be attached in the manner specified in 250.8 for circuits and equipment and in 250.70 for grounding elecu·odes.

NAT IO NAL ELECTRJCAL CODE

2020 Edition

250.104

ARTICLE 250- GROUNDI NG AND BONDI NG

(C) Size -

Supply-Side Bonding Jumper.

(I) Size for Supply Conductors in a Single Raceway or Cable. T h e supp ly-side b onding jumper sh all not be smaller t h an specified in Table 250.1 02(C)( l ) .

(2) Size for Parallel Conductor Installations in Two or More Raceways or Cables. W h e re the u ngrounded su pply condu ctors are paralle led in two or m ore raceways or cables, a nd an individ u al su pply-side b o n d ing j u mper is u sed for b onding th ese raceways or cables, the size of the su pply-side b onding jumpe r for each raceway or cable shall be selected from Table 250.1 02(C) (l ) b ased on the size of the u ngro u nded su pply condu ctors in each racev.1ay or cable . A single supply-side b on ding jumper installed for bo n d ing two o r more raceways or cables sh all b e sized in accordance with 250.1 02(C) (1) . Informational Note No. 1: The term SttfJply conductors includes ungrounded conductors that do not have overcurrent protection on their supply side and terminate at service equipment or the first disconnecting means of a separately derived system. Informational Note No. 2: See Chapter 9, Table 8, for the circular mil area of conductors 18 AWG through 4/0 AWG.

(D) Size - Equipment Bonding Jumper on Load Side of an Overcurrent Device. T he equipment bonding jumper on t he load side of an overcu rrent device(s) shall b e sized in accorda nce wit h 250.1 22. A single common contin u ou s equipm ent bonding jumper shall b e permi tted to connect two or more raceways or cables if th e b onding jumper is sized in accordance with 250.1 22 for the largest overcurren t device su pplyin g circu its therein.

(E) Installation. Bonding jumpers or cond u ctors and equipment bond ing jumpers sh all b e permi tted to be installed inside or o u tside of a raceway or an enclosu re. (I) Inside a Raceway or an Enclosure. If installed inside a raceway, eq uipme nt b onding jumpers and bonding jumpers or cond u ctors sh all com ply wit h t he requi reme nts of 250.11 9 a nd 250.1 48.

(2) Outside a Raceway or an Enclosure. If installed on the o u tside, t he length of the b onding jumper or conductor or equipment bonding jumper shall not exceed 1.8 m (6 ft) and shall be rou ted with the raceway o r enclosu re.

Exception: An equipment bonding jumper or supply-si,de bonding jumper longer than 1.8 m (6 ft) shall be permitted at outside pole locations for the pmpose of bonding or gmunding isolated sections of metal raceways or elbows installed in exposed risers of metal conduit or other metal raceway, and for bonding grounding electrodes, and shall not be required to be 1vuted zmth a raceway or enclosure. (3) Protection. Bo n d ing jumpers or condu ctors and equipment bonding jumpers shall be installed in acco rdance with 250.64(A) and (B) . 250.104 Bonding of Piping Systems and Exposed Structural Metal. (A) Metal Water Piping. The m etal water pip ing system shall be bonded as required in 250.1 04(A)( l ), (A)(2), or (A)(3) . (I) General. Metal water p ip ing system(s) installed in or attach ed to a build ing or structu re sh a ll be bo nded to any of th e following: (I)

Service equipme n t enclosure

2020 Edition

NATIONAL ELECTRJCAL CODE

Table 250.102(C)(l ) Grounded Conductor, Main Bonding Jumper, System Bonding Jumper, and Supply-Side Bonding Jumper for Alternating-Current Systems Size of Largest Ungrounded Conductor or Equivalent Area for Parallel Conductors (AWG/ kcmil)

Copper

Aluminum or Copper-Clad Ahunimun

2 or smaller l or l /0

Size of Grounded Conductor or BondingJumper* (AWG/kcmil)

Copper

Aluminum or Copper-Oad Alumimun

1/ 0 or smaller

8

6

2/0 or 3/0

6

4

2/ 0 or 3/0

4/0 or 250

4

2

Over 3/ 0 through 350

Over 250 throu gh 500

2

1/ 0

Over 350 through 600

Over 500 through 900

1/ 0

3/0

Over 600 through 1100

Ovcr900 throu gh 1750

2/ 0

4/0

Over 1100 Over 1750 Sec Notes 1 and 2. Notes: l. If the ungrounded supply conductors are larger than 1100 kcmil copper or 1750 kcmil aluminum, the grounded conductor or bond ing jumper shall have an area not less than 12½ percent of the area of the largest ungrounded supply conductor or equivalent area for parallel supply conductors. The grounded conductor or bonding jumper shall not be required to be larger than the largest ungrounded conductor or set of ungrounded conductors. 2. If the ungrounded supply conductors are larger t han 1100 kcmil copper or 1750 kcmil aluminum and if the ungrounded supply conductors and the bondingjumper are of different materials (copper, aluminum, or copper-clad alum inum), the minimum size of the grounded conductor or bondingjumper shall be based on the assumed use of ungrounded supply conductors of the same material as the grounded conduCLor or bondingjumper and will have an ampaciry equivalent to that of the installed ungrounded supply conductors. 3. If multiple sets of se,v ice-entrance conductors are used as permiued in 230.40, Exception No. 2, or if multiple sets of ungrounded supply conductors are installed for a separately derived system, the equivalent size of the largest ungrounded supply conductor(s) shall be determined by the largest sum of the a reas of the corresponding conductors of each set. 4. If there are no service-enu-ance conductors, the supply conductor size shall be determined by the equiva lent size of the largest serviceentrance conductor required for the load to be served. *For the purposes of applying this table and its notes, the term bonding jumper refers to main bondingjumper.s, system bondingjumpers, and supply-side bond ing jumpers. (2) (3)

(4)

Grounded con d u ctor at the service Grou nding elecu-ode cond u ctor, if of suffic ient size O n e or more grounding electrodes u sed, if the grounding e lectrode con d u cto r or bo n d ing jumper to th e ground ing electrode is o f sufficient size

T he b onding jumper(s) sh all b e installed in accorda n ce with 250.64(A), 250.64(B), and 250.64(E) . T he points of attachment of the bonding jumper(s) sh all be accessible. The bond-

70- 127

250.104

ARTICLE 250-GROUNDING AND BONDING

ing jumper(s) shall be sized in accordance with Table 250.1 02(C)(l) except that it shall not be required to be larger than 3/0 copper or 250 kcmiI aluminum or coppe1~clad alumimun and except as permitted in 250. l 04(A) (2) and 250. l 04(A)(3) . (2) Buildings of Multiple Occupancy. In buildings of multiple occupancy where the metal \vater piping system(s) installed in or attached to a building or structure for the individual occupancies is metallically isolated fro m all other occupancies by use of nonmetallic water piping, the metal \vater piping system(s) for each occupancy shall be permitted to be bonded to the equipment grounding terminal of the switc hgear, switchboard, or panelboard enclosure (other than service equipment) supplying that occupancy. The bonding jumper shall be sized in accordance with 250.102(D) . (3) Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s). The metal \vater piping system(s) installed in or attached to a building or strucnire shall be bonded to any of the following:

(3) (4) (5)

Disconnecting means for build ings or structures supplied by a feeder or branch circuit Grounding electrode conductor, if of sufficient size One or more grounding electrodes used, if the grounding electrode conductor or bonding jumper to the grounding electrode is of sufficient size

The bonding conductor(s) or jumper(s) shall be sized in accordance with Table 250.1 02(C)(l), except that it shall not be required to be larger than 3/0 copper or 250 kcmil aluminum o r copper-clad aluminum, and installed in accordance with 250.64(A) , 250.64(B), an d 250.64(E) . The points of attachment of the bondingjumper(s) shall be accessible unless installed in compliance with 250.68(A) Exception No. 2. (D) Separately D erived Systems. Metal \vater piping systems and sU'uctural metal that is interco nnected to form a building frame shall be bo nded to separately derived systems in accorda nce with 250.104(D) (1) through 250.104(D) (3) .

The bonding jumper(s) shall be sized in accordance with 250.102(D). The bonding j umper shall not be required to be larger than the largest ungrounded feeder or branch-circuit conductor supplying the building or structure.

(1) Metal Water Piping Syste m (s). Th e grounded conductor of each separately derived system shall be bonded to the nearest available point of the metal water p iping system(s) in the area served by each separately derived system. This connection shall be made at the same point on the separately derived system where the grounding e lectrode conductor is connected. Each bo nding jumper shall be sized in accordance with Table 250.l 02(C) (]) based on th e largest ungrounded conductor of the separately derived system except that it shall not be required to be larger than 3/ 0 coppe1· or 250 kcmil aluminum or copper-clad alum inum.

(B) Other Metal Piping. If installed in or attached to a building or su·ucnire, a metal piping system(s), including gas piping, that is likely to become e nergized shall be bonded to any of the follO\ving:

Exception No. 1: A separate bonding jumper to the metal water piping system shall not be required if the metal water piping system is used as the grounding electrode for the separately derived system and the water piping system is in the area served.

(1)

Exception No. 2: A separate water piping bonding jumper shall not be required if the metal frame of a building or structure is used as the grounding electrode for a separately derived system and is bonded to the metal water piping in the area served by the separately de,ived system.

Building or strucn1re disconnecting means enclosure where located at the building or structure Equipment grounding conductor run with the s upply conductors One or more grounding elecu·odes used

(l)

(2) (3)

(2) (3) ( 4) (5)

Equipment grounding conductor for the c ircuit that is likely to energize the piping system Service equipment enclosure Grounded conductor at the service Grounding electrode conductor, if of sufficient size One or more grounding elecu·odes used, if the grounding electrode conductor or bonding jumper to the grounding electrode is of sufficient size

The bonding conductor(s) or jumper(s) shall be sized in accordance with Table 250.122, a nd equipment grounding cond uctors shall be sized in accordance with Table 250.1 22 using the rating of the circuit that is likely to energize the piping system(s) . T he points of attachment of the bonding jumper(s) shall be accessible. Informational Note No. 1: Bonding all piping and metal air ducts within the premises will provide additional safety. Informational Note No. 2: Additional information for gas p ip ing systems can be found in NFPA 54-2018, National Fuel Gas Code, and NFPA 780-2017, Standard for the lnstallalion of Lightning Protection Systems.

(C) Structural Metal. Exposed structural metal that is interconnected to form a metal building frame, is not intentionally grounded or bonded, and is likely to become energized shall be bonded to any of the following:

(1) (2)

Service equipment enclosure Grounded conductor at the service

70-128

(2) Structural Metal. If exposed structural metal that is interconnected to form the building frame exists in the area served by the separately derived syste m, it shall be bonded to the grounded conductor of each separately derived system. This connection shall be made at the same point o n the separately derived system where the grounding electrode conductor is connected . Each bonding jumper shall be sized in accordance with Table 250.1 02(C)(l) based on the largest ungrounded conductor of the separately derived system except that it shall not be required to be larger than 3/0 copper or 250 kcmil aluminum or copper-clad aluminum. Exception No. I: A separate bonding jumper to the building structural metal shall not be requi:red if the metal frame of a building or structure is used as the grounding electrode for the separately derived system. E xception No. 2: A separate bonding jumpe,· to the building structural metal shall not be required if the water piping of a inlilding or structure is used as the grounding electrode for a separately derived system and is bonded to the IJ,uilding structural metal in the area served by the separately derived system.

(3) Common Grounding Electrode Conductor. If a common grounding electrode conductor is installed for multiple separately derived syste ms as permitted by 250.30(A)(6), and exposed structural metal that is interconnected to form the

NAT IO NAL ELECTRJCAL CODE

2020 Edition

ARTICLE 250- GROUNDING AND BONDING building frame or interior metal piping exists in th e area served by the separately derived system, the metal piping and the structural metal member shall be bonded to the common grounding elecu·ode conductor in the area served by the separately derived system. Exception: A separate bonding jumper from each derived system to metal water piping and Lo structural metal members shall not be required if the metal waler piping and the structural metal members in the area served by the separately derived system are bonded Lo the common grounding electrode conductor. 250.106 Lightning Protection Systems. The lightning protection system ground terminals shall be bonded to the building or strucnire grounding electrode system. Informational Note No. 1: See 250.60 for use of strike termination devices. For further information, see NFPA 780-2017, Standard for Lhe Installation of Lightning Protection Systems, which contains detailed information on grounding, bonding, and sideflash distance from lightning protection systems. Informational Note No. 2: Metal raceways, enclosures, frames, and other non-current-carrying metal parts of electrical equipment installed on a building equipped with a lightning protection system may require bonding or spacing from the lightn ing protection conductors in accordance with NFPA 780-2017, Standard for the Installation of Lightning Pro/JJction Systems.

Part VI. Equipment Grounding and Equipment Grounding Conductors 250.109 Metal Enclosures. Metal enclosures shall be permitted to be used to connect bonding jumpers or equipment grounding conductors, or both, together to become a part of an effective ground-fault current path. Metal covers and metal fittings attached to these metal enclosures shall be considered as being connected to bonding jumpers or equipment grounding conductors, or both. 250.110 Equipment Fastened in Place (Fixed) or Connected by Permanent Wiring Methods. Exposed, normally non-currentcarrying metal parts of fixed equipment supplied by or enclosing conductors or components that are likely to become energized shall be connected to an equipment grounding conductor under any of the following conditions: (I)

(2) (3) ( 4) (5)

(6)

\/\There with in 2.5 m (8 ft) vertically or 1.5 m (5 ft) horizontally of ground or grounded metal objects and subject to contact by persons \/\There located in a wet or damp location and not isolated Where in electrical contact with metal \/\There in a hazardous ( classified) location as covered by Articles 500 through 517 \!\There supplied by a wiring method that provides an equipment grounding conductor, except as permitted by 250.86, Exception No. 2, for short sections of metal enclosures \!\There equipment operates with any terminal at over 150 volts to ground

Exception No. 1: If exempted by special permission, the metal frame of electrically healed appliances that have the frame permanently and effectively insulated from ground shall not be required Lo be grounded. Exception No. 2: Dist1ibution apparatus, such as transformer and capacitor cases, mounted on wooden poles al a height exceeding 2.5 m ( 8 fl) above ground or grade level shall not be required Lo be grounded.

2020 Edition

NATIONAL ELECTRJCAL CODE

250.114

J,,xceplion No. 3: Listed equipment protected by a system of double insulation, or its equivalent, shall not be required Lo be connected Lo the equipment gmunding conductor: Where such a system is employed, the equipment shall be distinctively marked. 250.112 Specific Equipment Fastened in Place (Fixed) or Connected by Permanent Wiring Methods. Except as permitted in 250.11 2(F) and (I ), exposed, normally non-currentcarrying metal parts of equipment described in 250.11 2(A) through (K), and normally non-current-carrying metal parts of equipment and enclosures described in 250.11 2(L) and (M), shall be connected to an equipment grounding conductor, regardless of voltage. (A) Switchgear and Switchboard Frames and Structures. Switchgear or switchboard frames and structures supporting switching equipment, except frames of 2-wire de switchgear or switchboards where effectively insulated from ground. (B) Pipe Organs. Generator and motor frames in an elecu·ically operated pipe organ, unless effectively insulated from ground and the motor driving it. (C) Motor Frames. Motor frames, as provided by 430.242.

(D) Enclosures for Motor Controllers. Enclosures for motor controllers unless attached to ungrounded portable equipment. (E) Elevators and Cranes. Electrical equipment for elevators and cranes. (F) Garages, Theaters, and Motion Picture Studios. Elecu·ical equipment in commercial garages, theaters, and motio n picnire studios, except pendant lampholders suppl ied by circuits not over 150 volts to ground .

(G) Electric Signs. Electric signs, outline lighting, and associated equipment as provided in 600.7. (H) Motion Picture Projection Equipment. Motion picture projection equipment.

(I) Remote-Control, Signaling, and Fire Alarm Circuits. Equipment supplied by Class 1 circuits shall be grounded unless operating at less than 50 volts. Equipment supplied by Class 1 power-limited circuits, by Class 2 and Class 3 remote-control and s ignaling circuits, and by fi re alarm circuits shall be grounded where system grounding is required by Part II or Part VIII of th is article. U) Luminaires. Luminaires as provided in Part V of Article 410. (K) Skid-Mounted Equipment. Permanently mounted electrical equipment and skids shall be connected to the equipment grounding conductor. Wire-type equipment grounding conductors shall be sized as requi1·ed by 250.122.

Water Pumps. Motor-operated pumps, including the submersible type.

(L) Motor-Operated

water

(M) Metal Well Casings. Where a submersible pump is used in a metal well casing, the well casing shall be connected to the pump circuit equipment grounding conductor.

250.114 Equipment Connected by Cord and Plug. Exposed, normally non-current-carrying metal parts of cord-and-plugconnected equipment shall be connected to the equipment grounding conductor under a ny of the following conditions:

70-129

250.116

ARTICLE 250-GROUNDING AND BONDING

Exception: Listed tools, listed appliances, and listed equipment covered in 250.114(2) through (4) shall not be required to be connected to an equipment grounding conductor where protected by a system of double insulation or its equivalent. Double insulated equipment shall be distinctively marked.

(1) (2)

In hazardous ( classified) locations (see Articles 500 through 517) Where operated at over 150 volts to ground

Exception No. 1 to (2): Motors, where guarded, shall not be required to be connected to an equipment grounding conductor. Exception No. 2 to (2): Metal ji-arnes of electrically heated appliances, exempted by special permission, shall not be required to be connected to an equipment grounding conduct01; in which case the frames shall be permanently and effectively insulated from ground.

(3)

In residentia l occu pancies:

( 4)

a . Refrigerators, freeze1·s, and air conditioners b. Clothes-washing, clothes-drying, and dish-washing machines; ranges; kitchen waste disposers; informatio n technology equipment; sump pumps; a nd e lectrical aquarium equipment c. Ha nd-h eld motor-operated tools, stationary a nd fixed motor-operated tools, a nd lig ht industrial motoroperated tools d . Motor-operated appl ia nces of the following types: hedge clippers, lawn mowers, sn ow blowers, and wet scrubbers e . Portable handlamps and portable luminaires In other than residential occupancies: a . Refrigerators, freeze1·s, a nd a ir conditioners b. Clothes-washing, cloth es-drying, an d dish-washing machines; information tech nology equipment; sump pumps; and e lectrical aqua rium equipment c. Ha n d-held motor-operated tools, statio nary a nd fixed motor-operated tools, a nd lig h t industrial motoroperated tools d . Motor-operated appl ia nces of the following types: hedge clippers, lawn mowers, snow blowers, and wet scrubbers e . Portable handlamps and portable luminaires t: Cord-and-plug-connected appliances used in damp or wet locations o r by persons standing on the ground, stan d ing o n metal floo rs, or working inside of metal tanks or boilers g. Tools like ly to be used in wet or conductive locations Exception: Tools and portable handlarnps and portable lurninaires likely to be used in wet or conductive locations shall not be required to be connected to an equipment grounding conductor where si1pplied through an isolating transformer with an ungrounded secondary of not over 50 volts.

250.116 Nonelectrical Equipment. The metal parts of the following nonelectrical equipment described in this section shall be connected to th e equipment ground ing conductor: (1) (2)

Frames and tracks of electrically operated cran es a nd hoists Frames of nonelectrically driven elevator cars to which electi-ical conductors are attached

70-130

(3)

H a nd-operated metal shifting ropes or cables of electric elevators I nformational Nore: Where extensive metal in or on build ings or structures may become energized a n d is subject to personal contact, adequate bond ing and grounding will provide additional safety.

250.118 Types of Equipment Grounding Conductors. The equipment grounding conductor run with or enclosing the c ircuit conductors sh all be one o r more or a combination of the following: (1 )

(2) (3) ( 4) (5)

A copper, aluminum, o r coppe1·-clad aluminum conductor. This conductor shall be solid or stranded; insulated, covered, or bare; a nd in the form of a wire or a busbar o f a ny shape. Ri gid m etal conduit. I ntermediate metal conduit. Electrical metallic tubing. Listed flexible metal conduit meeting all the following conditions:

a . T he conduit is terminated in listed fittings. b. The circuit conductors conta ined in the conduit are protected by overcurrent devices rated at 20 amperes or less. c. The size of th e conduit does not exceed metric designator 35 ( trade size 1 Y,) . cl. The combined length of flexible metal conduit, flexible metallic tubing, and liquidtight flex ible metal conduit in the same effective ground-fault current path does not exceed 1.8 m (6 ft) . e . If used to connect equipment where flexibility is necessary to m in imize the transmissio n of vibration from equipment or to provide flexibil ity for equipment that requires movement after installation, a wire-type equipment grounding conductor shall be installed . (6) Listed liquidtight fl exible metal conduit meeting all the following condition s: a . The conduit is terminated in listed fittings. b. For metric designators 12 through 16 (u·ade sizes ¾ th rough ½), the c ircuit conductors conta ined in th e conduit are protected by overcurrent devices rated at 20 a mperes or less. c. For metric designators 21 through 35 (trade sizes ¾ through 1 ¼), the circuit conductors contained in the conduit are protected by overcurrent devices rated not more than 60 a m peres a nd there is n o flexible me tal conduit, fl exible m etallic tubing, or liquidtight flexible metal cond uit in metric designato rs 12 through 16 (u·ade sizes ¾ through ½) in th e effective ground-fault current path . cl. The combined length of flexible metal conduit, flexible metallic tubing, and liquidtight flex ible metal conduit in the same effective ground-fault cu rrent path does not exceed 1.8 m (6 ft) . e . If used to connect equipment where flexibility is necessary to m ini mize the u·ansm issio n of vibration from equipment or to provide flexibil ity for equipment that requires movem e nt after installation , a wire-type equipment grounding conductor shall be installed.

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 250- GROUNDING AND BONDING (7)

(8) (9) (10)

(11 ) (12) (13) (14)

250.120

Flexible metallic tubing where the tubing is terminated in listed fittings and meeting the following conditions:

have insulation or covering that is green with one or more yellow stripes.

a . The circuit conductors contained in the tubing are protected by overcu rrent devices rated at 20 amperes or less. b. The combined length of flex ible metal conduit, flexible metallic tubing, and liquidtight flexible metal conduit in the same effective ground-fault current path does not exceed 1.8 m (6 ft) . Armor of Type AC cable as provided in 320.108. The copper sheath of mineral-insulated, metal-sheathed cable Type MI. Type MC cable that provides an effective ground-fault current path in accordance with o ne or m ore of the following:

(A) Conductors 4 AWG and Larger. Equipme nt gro unding conductors 4 AWG and larger shall com ply with 250.l l 9(A) (1) and (A) (2) .

a . It contains an insulated or uninsulated equipment ground ing conductor in complia nce with 250.118 (1 ) . b. The combined metallic sheath and uninsulated equipment grounding/bonding conductor of interlocked metal tape-type MC cable that is listed and identified as a n equipment grounding conductor c. The m etallic sheath or the combined metallic sh eath and equipment ground ing conductors of the smooth or corrugated tube-type MC cable that is listed and identified as a n eq uipment grounding conductor Cable trays as permitted in 392.1 0 an d 392.60. Cablebus framewor k as permitted in 370.60(1) . Other listed e lectrically continuous metal raceways and listed auxiliary gutters. Surface metal raceways listed for grounding.

(1)

Exception: Conductors 4 A WC and larger shall not be required lo be marked in conduit bodies that contain no splices or unused hubs. (2)

Exception No. 1: Power-limited Class 2 or Class 3 cables, powe,~limited fire alarm cables, or communications cables containing only circuits ()/Jerating at less than 50 volts ac or 60 volts de where connected to equipment not required to be grounded shall be permitted to use a conductor zmth green insulation or green with one or more yellow stripes for other than equipment grmmding purposes.

(B) Multiconductor Cable. One or more insulated conductors in a multiconductor cable, at the ti me of installatio n , shall be permitted to be permanently identified as equipment grounding conductors at each e nd and at every point where the conductors a re accessible by one of the following means: (I)

(2) (3)

Exception No. 3: Conductors zmth green insulation shall be permitted to be used as ungrounded signal conductors where installed between the output terminations of traffic signal control and traffic signal indicating heads. Signaling circuits installed in accordance zmth this exception shall include an equipment grounding conductor in accordance with 250.118. Wire-type equipment grounding conductors shall be bare or

2020 Edition

NATIONAL ELECTRJCAL CODE

Stripping the insulation from the entire exposed length . Coloring the exposed insulation green. Marking the exposed insulatio n with green tape or green adh esive labels. Iden tification sh all encircle the conductor.

(C) Flexible Cord. Equipment ground ing conductors in flexible cords shall be insulated and shall h ave a continuous outer finish that is e ither green or green with one o r more yellow su·ipes.

250.120 Equipment Grounding Conductor Installation. An equipment grounding conductor sh all be installed in accordance with 250.120(A), (B), and (C) . (A) Raceway, Cable Trays, Cable Armor, Cablebus, or Cable Sheaths. Where it consists of a raceway, cable tray, cable arm or, cablebus framework, or cable sh eath or where it is a wire within a raceway or cable, it shall be installed in accord ance with the applicable provisions in this Code usi ng fittin gs for joints and terminations approved for u se with the type raceway or cable used. All connections, j o ints, and fittings shall be m ade tight using suitable tools. Informational Note: See the UL gu ide information on FHIT systems for equ ipment grounding conductors installed in a raceway that are part of an electrical circu it protective system or a fire-rated cable listed to maintain c ircuit integrity.

Exception No. 2: Flexible cords having an integral insulation and jacket zmthout an equipment grounding conductor shall be permitted to have a continuous outer finish that is green. Informational Note: An e xample ofa flex ible cord with imegraltype insulation is Type SPT-2, 2 conducto r.

Identification shall encircle the conductor and shall be accomplished by one of the following: a . Stripping the insulation or covering from th e entire exposed length b. Coloring the insulatio n or covering green at the terminatio n c . Marking th e i nsulation or covering with green tape or green adhesive labels at the termination

Informational Note: For a definition of effective ground-fault current jialh, see Article 100.

250.119 Identification of Equipment Grounding Conductors. Unless requi red elsewhe1·e in this Code, equipment grounding conductors shall be permitted to be bare, covered, or insulated. Individually covered o r insulated equipment g round ing conductors sha ll have a continuous o uter finish that is e ither g reen or green with o ne or more yellow stripes except as permitted in this section. Conductors with insulation o r individual covering that is green, green with one or more yellow stripes, or oth erwise identified as permitted by this section shall not be used for ungrounded or grounded circuit conductors.

An insulated o r covered conductor 4 AWG and larger sh all be permitted, at the time of install ation, to be permanently identified as an equipment grounding conductor at each encl and at every point where the conductor is accessible .

(B) Aluminum and Copper-Clad Aluminum Conductors. Equip m ent g ro und ing conductors of bare, covered, or insul ated aluminum or cop per-clad aluminum shall comply with the following: (1)

Unless part of a suitable Ch apter 3 cable wir ing method , bare or covered conductors sh all not be installed where subject to corrosive conditions or be installed in d irect con tact with concrete, masonry, or the earth.

70- 131

250.120 (2)

(3)

ARTICLE 250-GROUNDING AND BONDING

Terminations made within outdoor enclosures that are listed and identified for the environment shall be perm itted within 450 mm (18 in. ) of the bottom of the enclosure. Aluminum or copper-clad aluminum conductors external to buildings or enclosures shall not be terminated with in 450 mm (18 in. ) of the earth, unless terminated within a listed wire connector system.

(C) Equipment Grounding Conductors Smaller Than 6 AWG. v\There not routed with circuit conductors as permitted in 250.1 30(C) and 250.134(A) Exception No. 2, equipment grounding conductors smaller than 6 AWG sh all be protected from physical damage by an identified raceway or cable armor unless installed within hollow spaces of the frami ng members of buildings or structures and where not subject to physical damage.

250.121 Restricted Use of Equipment Grounding Conductors. (A) Grounding Electrode Conductor. An equipment grounding conductor shall not be used as a grounding elecu·ode conductor. Exception: A wi:re-type equipment grounding conductor installed in compliance with 250.6(A) and the applicable requirements for both the equipment grcrunding conductor and the grounding electrode conductor in Parts II, Ill, and VI of this articl.e shall be permitted to serve as both an equipment grounding conductor and a grounding electrode conductm:

(B) Metal Frame of Building or Structure. The structural metal frame of a building or structure shall not be used as an equipment grounding conductor. 250.122 Size of Equipment Grounding Conductors. (A) General. Copper, aluminum, or copper-clad aluminum equipment grounding conductors of the wire type shall not be smaller than shown in Table 250. 122. The equipment grounding conductor shall not be required to be larger than the circuit conductors supplying the equipment. If a cable tray, a raceway, or a cable armor or sheath is used as the equipment grounding conductor, as provided in 250.11 8 and 250.1 34(1), it shall comp ly with 250.4(A)(5) or (B) (4) . Equipment grounding conductors sh a ll be permitted to be sectioned within a multiconductor cable, provided the combined circular mil area complies with Table 250.1 22. (B) Increased in Size. If ungrounded conductors are in creased in size for any reason other than as required in 310.1 5( B) or 310.1 5(C), wire-type equipment grounding condu ctors, if installed, shall be increased in size proportionately to the increase in circular mil area of the ungrounded conductors. Exception: Equipment grounding conductors shall be permitted to be sized by a qualified person to provide an effective ground fault current path in accordance with 250.4(A)(5) or (B)(4 ). (C) Multiple Circuits. A single equipment grounding conduc-

tor shall be permitted to be installed for multiple circuits that are instal led in the same raceway, cable, trench, or cable tray. It shall be sized from Table 250.1 22 for the largest overcurrent device protecting circuit conductors in the raceway, cable, trench, or cable tray. Equipment grounding conductors installed in cable trays shall m eet the m inimum requirements of 392. l0(B)(l) (c) .

70-132

(D) Motor Circuits. Equipment grounding conductors for

motor c ircuits shall be sized in accordance with 250.1 22(0)(1) or (D)(2) . (1) General. The equipment grounding conductor size shall not be smaller than determined by 250.1 22(A)based on the rating of the branch-circuit sh ort-circuit and ground-fault protective device . (2) Instantaneous-Trip Circuit Breaker and Motor Short-Circuit Protector. If the overcurrent device is an insta ntaneo us-trip c ircuit breaker o r a motor short-circuit protector, the equipment grou nding conductor shall be sized not smaller than that given by 250.122 (A) using the maximum permitted rating of a dual element time-delay fuse selected for branch-circu it sh ortcircuit and ground-fault protection in accordance with 430.52(C)(l), Exceptio n No.1. (E) Flexible Cord and Fixture Wire. The equipment grounding conductor in a flexible cord with the largest circuit conductor 10 AWG or smaller, and the equipment grounding conductor used with fixture wires of any size in accordance with 240.5, shall not be smaller than 18 AWG copper and shall not be smaller than the circuit conductors. The equipment grounding conductor in a flexible cord with a circuit conductor larger than 10 AWG shall be sized in accordance with Table 250.122.

(F) Conductors in Parallel. For ci rcuits of parallel conductors as permitted in 310.l 0(G), the equipment grounding conductor shall be i nstalled in accordance with 250.1 22(F) (l) or (F)(2) .

(1) Conductor Installations in Raceways, Auxiliary Gutters, or Cable Trays. (a) Single Raceway or Cable 11·ay, Awd.limy Gutter, or Cable Tray. If circuit conductors are connected in parallel in the same raceway, auxil iary gutter, or cable u·ay, a single wire-type conductor shall be permitted as the equipme nt grounding conductor. The wire-type equipment grounding conductor shall be sized in accordance with 250.1 22, based on the overcurrent protective device for the feeder or branch ci rcuit. (b) Mul.tiple Raceways. If conductors are insta lled in multiple raceways and are connected in parallel, a wire-type equipment grounding conductor, if used, shall be installed in each raceway and shall be connected in parallel. T h e equipment grounding conductor installed in each raceway shall be sized in accordance with 250.122 based on the rating of the overcurrent protective device for the feeder or branch circuit. (c) Wire-Type Equipment Grounding Conductors in Cable 'frays. Wire-type equipment grounding conductors installed in cable trays shall meet the mmunum requirements of 392.l 0(B) (1) (c) . (cl) Metal Raceways, Auxilimy Gutters, or Cable 11·ays. Metal raceways or auxiliary gutters in accordance with 250.11 8 or cable trays complying with 392.60(B) shall be permitted as the equipment grounding conductor. (2) Multiconductor Cables. (a) Exce pt as provided in 250.1 22(F)(2)(c) for raceway or cable tray installations, the equipment grounding conductor in each multiconducto r cable shall be sized in accordance with 250.1 22 based on the overcurrent protective device for the feeder or branch c ircuit. (b) If circuit conductors of multiconductor cables are con nected in parallel, the equipme nt grounding conductor(s) in each cable shall be connected in paralle l.

NAT IO NAL ELECTRJCAL CODE

2020 Edition

ARTICLE 250- GROUNDING AND BONDING (c) If multiconductor cables are paralleled in the same raceway, auxiliary gutter, or cable u·ay, a single equipme n t grounding conductor that is sized in accordance with 250.1 22 shall be permitted in combination with the equipment groun ding conductors provided within the multiconductor cables and shall all be connected together. (d) Equipment grounding conductors installed in cable trays shall meet the minimum requirements of 392.l0(B)(l)(c) . Cable u·ays complying with 392.60(B), metal raceways in accordance with 250.118, or aux iliary gutters shall be permitted as the equipment grounding conductor.

system unless the opening of the cutout or switch d isconnects all sources of energy.

250.126 Identification of Wiring Device Terminals. The terminal for the connection of the equipment grounding conductor shall be identified by one of the following: (1)

(2) (3)

(G) Feeder Taps. Equipment grounding conductors installed with feeder taps shall not be smaller than shown in Table 250.1 22 based on the rating of the overcurrent device ahead of the feeder on the supply side ahead of the tap but shall not be required to be larger than the tap conductors.

250.124 Equipment Grounding Conductor Continuity. (A) Separable Connections. Separable connections such as those provided in drawout equipment or attachment plugs and mating connectors and receptacles shall provide for first-make, last-break of the equipment ground ing conductor. First-make , last-break shall not be required where inte rlocked equipment, plugs, receptacles, and connectors preclude energization without grounding continuity.

250.130

A green, not readily removable terminal screw with a hexagonal head. A green, hexagonal, not readily removable terminal nut. A green pressure wire connector. If the terminal for the equipment grounding conductor is not visible, the conductor entrance hole shall be marked with the word green or ground, the letters G or GR, a grounding symbol, or otherwise identified by a d istinctive green color. If the terminal for the equipment grounding conductor is readily removable , the area adjacent to the terminal shall be similarly marked. Informational Note: See Informational Note Figure 250. 126.

Informational Note Figure 250.126 One Example of a Symbol Used to Identify the Grounding Termination Point for an Equipment Grounding Conductor.

(B) Switches. No automatic cutout or switch shall be placed in the equipment grounding conductor of a premises wiring

Part VII. Methods of Equipment Grounding Conductor Connections

Table 250.122 Minimum Size Equipment Grounding Conductors for Grounding Raceway and Equipment

250.130 Equipment Grounding Conductor Connections. Equipment ground ing conductor connections at the source of separately derived systems shall b e made in accordance with 250.30(A) (1) . Equipment ground ing conductor connections at service equipment shall be made as indicated in 250.130(A) or (B) . For replacement of non-grounding-type receptacles with grounding-type receptacles and for branch-circuit extensions only in existing installations that do not have an equipment grounding conductor in the branch circuit, connections shall be permitted as indicated in 250.130(C) .

Rating or Setting of Automatic Overcurrent Device in Circuit Ahead of Equipment, Conduit, etc., Not Exceeding (Amperes)

Size (AWG or kcmil)

Copper

Aluminum or Copper-Clad Aluminum*

15 20 60 100

14 12 10 8

12 10 8 6

(A) For Grounded Systems. The connection shall be made by bonding the equipment grounding con ductor to the grounded service conductor a nd the grounding e lectrode conductor.

200 300 400

6 4 3

4 2

(B) For Ungrounded Systems. The connection shall be made by bonding the equipment grnunding conductor to the grounding electrode conductor.

500 600 800

2 1 1/ 0

1/ 0 2/ 0 3/ 0

1000 1200 1600

(C) Nongrounding Receptacle Replacement or Branch Circuit Extensions. The equipment ground ing conductor of a grounding-type receptacle or a b ranch-circuit extension shall be permitted to be connected to any of the following:

2/ 0 3/ 0 4/ 0

4/ 0 250 350

(I )

2000 2500 3000

250 350 400

400 600 600

(3)

4000 5000 6000

500 700 800

750 1250 1250

( 4)

1

Note: Where necessary to comply with 250.4(A)(5) or (B)(4), the equipmem grounding conductor shall be sized larger than given in this table. *See installation restrictions in 250.120.

2020 Edition

NATIONAL ELECTRJCAL CODE

(2)

(5)

Any accessible point on the grounding electrode syste m as described in 250.50 Any accessible point on the grounding e lectrode conductor The equipme nt grounding te rminal bar within the enclosure where the branch circuit for the receptacle or branch circuit orig inates An equipment gro unding condu ctor that is part of another branch c ircuit that originates from the enclosure where the branch circuit for the receptacle or branch c ircuit origi nates For grounded system s, the grounded service conductor with in the service e quipment enclosure

70- 133

250.132

ARTICLE 250-GROUNDING AND BONDING

For u ngrounded system s, th e grounding termin al bar wi thi n the service equipment enclosu re

(6)

Informational Note: See 406.4(0) for the use of a ground-fault circuit-interrupting type of receptacle.

250.132 Short Sections of Raceway. Isolated sectio n s of metal raceway or cable armor, if required to be connected to an equipment grou nding condu ctor, shall b e connected in accordance wi th 250.1 34. 250.134 Equipment Fastened in Place or Connecte d by Permanent Wiring Methods (Fixed). U nless connected to the grounded circuit condu ctor as perm itted by 250.32, 250.140, a nd 250.1 42, non-cu rrent-carrying metal parts of equi p ment, raceways, and other enclosu res, if grounded, shall b e con nected to an equipment grounding conductor by o n e of the following methods: (1)

By connecting to any of the equipment grounding condu ctors permitted by250.118(2) t h rou gh (14) By connecting to an equipment grou nding condu ctor of the wire type that is contained with in th e same raceway, contained wi thi n th e same cable, or otherwise run wi th the circuit conductors

(2)

Exception No. I: As provided in 250.130(C), the equipment grounding conductor shall be permitted lo be r-un separately from the circuit conductors. Exception No. 2: For de circuits, the equipment grounding conductor shall be permitted to be run separately from the circuit conductors Informational Note No. 1: See 250.102 and 250.168 for equipment bonding jumper requirements. Informational Note No. 2: See 400.10 for use of fl exible cords and flexible cables for fixed equipment.

250.136 Equipment Secured to Grounded Me tal Supports. Electrical equipment secu red to and in electrical contact with a metal rack or structure provided for its su pport shall be permitted to be considered as being connected to an equipme nt grounding conductor if the metal rack or structu re is connected to an equip m ent grounding conductor by one of the means indicated in 250.1 34. 250.138 Cord-and-Plug-Connected Equipment. Non-cu rren tcarrying metal parts of cord-a nd-plug-conn ected equip me n t, if required to b e connected to an equip m ent grou nding con d u ctor, sh al l b e con nected by o ne of the meth ods in 250.138 (A) or (B ) .

(A) By Means of an Equipment Grounding Conductor. By means of an equipment grou nding conductor run with the power su pply condu ctors in a cable assembly or flex ible cord p roperly terminated in a grou nding-type attach ment p lug with one fixed grounding contact. Exception: 77ze grounding contacting pole of grounding-type plug-in ground{ault circuit interrupters shall be per-milted to be of the movabl.e, self-restoring type on circuits operating at not over I 50 vo/J.s between any two conductors or over 150 volts between any conductor and ground.

(B) By Means of a Separate Flexible Wire or Strap. By means of a separate flexible wire or su·ap, insulated or bare, connected to an equipment grounding conductor, and protected as well as p racticable against physical damage, wh ere part of equipment.

70-134

250.140 Frames of Ranges and Clothes Dryers. Frames of e lectric ranges, wall-mou nted ovens, counter-m ou nted cooking u n its, clothes dryers, and o u tlet or j unction b oxes that are part of t he circuit for these appl iances sh all be connected to the equipment ground ing cond u ctor in the m a nner sp ecified by 250.1 34 or 250.138. Exception: For existing branch-circuit installations only where an equipment grounding conductor is not present in the outlet or junction box, the frames of electric ranges, wall-mounted ovens, counte1°mo-unted cooking units, clothes d1yers, and outlet or junction boxes that are part of the circuit for these appliances shall be permitted to be connected to the grounded cireitil conductor if all the following conditions are met. (1)

(2 ) (3)

(4)

The supply circuit is 120/240-volt, singl~hase, 3-wire; or 208Y/120-volt derived from a 3-phase, 4-wire, wye-connected system. The grounded conductor is not smaller than JO A WC co-pper or 8 A WC aluminum. The grounded conductor is insulated, or the grounded conductor is uninsulated and part of a Type SE service-entrance cable and the branch circuit originates at the service equipment. Grounding contacts of receptacl.es furnished as part of the equif>ment are bonded to the equipment.

250.142 Use of Grounded Circuit Conductor for Grounding Equipment. (A) Supply-Side Equipment. A grou nded circui t conductor shall be permitted to be connected to n o n-current-canying metal parts of equipment, raceways, and oth er enclosu res at any of the following location s: (1)

(2)

(3)

On the su pply side o r within th e enclosure of the ac service d isconnecti ng means O n the supply side or wit hin th e enclosure of th e m a in d isconn ecting mean s fo r separate buildings as provided in 250.32(B) ( 1) Exception No. 1 On the su pply side o r wit hin th e enclosure of the main d isconn ecting means or overcu rrent devices of a separately derived system wh ere permitted by 250.30(A) (1)

(B) Load-Side Equipment. Except as permitted in 250.30(A)( l ), 250.32(B)( l ), Exceptio n No. 1, a n d Part X of Article 250, a grou nded circuit conductor shall n ot be conn ected to non-cu rrent-canying metal parts of equip m ent on the load side of the service d isconn ectin g means or o n t h e load side of a separately derived system d isconnecting means o r the overcu r ren t devices for a separately derived system not having a main d iscon necting means.

Exception No. 1: The frames of ranges, wall-mounted ovens, counte1° mounted cooking units, and clothes dryers under the conditions permitted for existing installations by 250.14 0 shall be permitted to be connected to the grounded circuit conductor. Exception No. 2: It shall be permissible to connect meter enclosures to the grounded circuit conductor on the load side of the service disconnect if all of the following conditions apply: (1) (2) (3)

Gmundfault protection of equipment is not installed. All meter enclosures are located immediately adjacent to the sen>ice disco-nnecting means. The si.ze of the grounded circuit conductor is not smaller than the si.ze specified in Table 250.122 for equipnzenl grounding conductors.

~Exception No. 3: .Electrode-type boilers operating at over 1000 volts shall be grounded as required in 490. 72(E)(I) and 490. 74.

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 250- GROUNDING AND BONDING 250.144 Multiple Circuit Connections. '"'here equipment is grounded and is supplied by separate connection to more than one c ircuit or grounded prem ises wiring syste m, an equipment grounding conductor tennination shall be provided for each such connection as specified in 250.134 and 250.1 38. 250.146 Connecting Receptacle Grounding Terminal to an Equipment Grounding Conductor. An equipment bonding jumper sh all be used to connect the grounding terminal of a grounding-type receptacle to a metal box that is connected to a n equipment grounding conductor, except as permitted in 250.1 46(A) through (D ) . The equipment bond ing jumper shall be sized in accordance with Table 250.1 22. (A) Surface-Mounted Box. If a metal box is mounted on the surface, the direct metal-to-metal contact between the device yoke or su-ap to the box shall be permitted to provide the required effective ground fault current path . At least one of the insulating washers sha ll be removed from receptacles that do not have a contact yoke or device to ensure direct m etal-tometal contact. Direct metal-to-metal contact for providing continuity applies to cover-mounted receptacles if the box and cover combination are listed as providing satisfactory continuity between the box and the receptacle. A listed exposed work cover shall be permitted to be the grounding and bonding means under both of the following conditions: (])

(2)

The device is attached to the cover with at least two fasteners that are permanent (such as a rivet) or have a thread locking or screw or nut locking means The cover mounting holes a re located on a flat nonraised portion of the cover

(B) Contact Devices or Yokes. Contact devices or yokes designed and listed as self-ground ing shall be permitted in conjunction with the supporting screws to establish equipme nt bonding between the device yoke and flush-type boxes. (C) Floor Boxes. Floor boxes designed for and listed as providing satisfactory continuity between th e box an d the device sha ll be permitted .

(D) Isolated Ground Receptacles. Where installed for the reduction of electromagnetic interference on the equipme nt grounding conductor, a receptacle in which the grounding terminal is purposely insulated from the receptacle mounting means shall be permitted. The receptacle grounding terminal shall be connected to an insulated equipment grounding conductor run with the circuit conductors. This equipme nt grounding cond uctor shall be permitted to pass through one or more panelboards without a connection to the panelboard grounding terminal bar as permitted in 408.40, Exception, so as to terminate within the same building or structu re d irectly at an equipment grounding conductor terminal of the applicable derived system or service. "'/here installed in accordance with this section, this equipment grounding conductor shall also be permitted to pass through boxes, wireways, or other enclosures without being connected to such enclosures. Informational Nole: Use of an isolaled equipmem grounding conducwr does nol relieve lhe requiremem for connecting lhe raceway syslem and outlel box lO an equipment grounding conduclor.

250.148 Continuity of Equipment Grounding Conductors and Attachment in Boxes. If circuit cond uctors are spliced within a box or te rminated on equipment within or supported by a box, a ll wire-type equi pment ground ing conductor(s) associated

2020 Edition

NATIONAL ELECTRJCAL CODE

250.164

with any of those ci rcuit conductors sh all be conn ected within the box or to the box in accordan ce with 250.8 and 250.1 48(A) through (D) . l!.xception: The equipment grounding conductor permitted in 250.146(D) shall not be required to be connected to the other equipment grounding conductors or to the box.

(A) Connections and Splices. Connectio ns and splices shall be made in accordance with 110.14(B ) except th at insulation shall not be required. (B) Equipment Grounding Conductor Continuity. The arrangement of grounding con nections shall be such that the disconnection o r the removal of a lumina ire, receptacle, or other device fed from the box does not interrupt the electrical continuity of the equipment gro unding conductor(s) providing a n effective ground-fault current path . (C) Metal Boxes. A connection used for no other purpose shall be made between th e metal box a nd the equipment grounding conductor(s) in accordance with 250.8 . (D) Nonmetallic Boxes. One or more equipment grounding conductors b rou gh t into a n onmetallic outlet box sha ll be arran ged such that a connection can be made to any fitt ing or device in that box requiring connectio n to an equipment grounding conducto r.

Part VIII. Direct-Current Systems 250.160 General. Direct-current systems shall comply with Part VIII and other sections of Article 250 not specifically intended for ac systems. 250.162 Direct-Current Circuits and Systems to Be Grounded. Direct-current circuits and systems shall be grounded as provided for in 250.1 62(A) and (B) . (A) Two-Wire, Direct-Current Systems. A 2-wire, d e syste m supplying premises wiring and operating at greate r than 60 volts but not greater than 300 volts sh all be grounded. Exception No. 1: A system equipped with a ground detector and suppl~ ing only industrial equipment in limited areas shall not be required lo be grounded where installed adjacent to or integral with the source of supply. Exception No. 2: A rectifier-de1ived de system supplied from an ac system complying with 250. 20 shall not be required to be grounded. Exception No. 3: Direct-current fire alarm circuits having a maximum current of 0.030 ampere as specified in Article 760, Part Ill, shall not be required to be grounded.

(B) Three-Wire, Direct-Current Systems. The neutral conductor of all 3-wire, de systems supplying prem ises wiring sh al l be grounded. 250.164 Point of Connection for Direct-Current Systems. (A) Off-Premises Source. Direct-current systems to be grounded and supp lied from an off-premises source shall have the grounding connection made at one or more supply stations. A g ro unding connection shall n ot be made at individua l services o r at any point on the premises wir ing. (B) On-Premises Source. ½There the de system source is located on the prem ises, a grounding connection shall be made at one of the following :

70- 135

250.166

( 1) (2) (3)

ARTICLE 250-GROUNDING AND BONDING

The source The first system disconnection means or overcurrent device By other means that accomplish equivalent system protection and that utilize equipment listed and identified for the use

250.166 Size of the Direct-Current Grounding Electrode Conductor. The size of the grounding electrode conductor for a de system shall be as specified in 250.166(A) and (B), except as permitted by 250.166(C) through (E) . The grounding electrode conductor for a de system shall meet the sizing requirements in this section but shall not be required to be larger than 3/0 copper or 250 kcmil aluminum.

,l\

(A) Not Smaller Than the Neutral Conductor. 1here the de system consists of a 3-wire balancer set o r a balancer winding with overcurrent protection as provided in 445.1 2(D), the grounding electrode conductor shall not be smaller tha n the neutral conductor and not smaller than 8 AWG copper or 6 AWG aluminum. (B) Not Smaller Than the Largest Conductor. Where the de system is other than as in 250 .166(A), the grounding electrode conductor shall not be smal ler than the largest conductor supplied by the system, and not smaller than 8 AWG copper or 6 AWG aluminum. (C) Connected to Rod, Pipe, or Plate Electrodes. Where connected to rod, pipe, or plate electrodes as in 250.52(A) (5) or (A)(7), that portion of the grounding electrode conductor that is the sole connection to the grounding electrode shall not be required to be larger than 6 AWG copper wire or 4 AWG aluminum wire.

(D) Connected to a Concrete-Encased Electrode. Where connected to a concrete-encased electrode as in 250.52(A) (3), that portion of the grounding electrode conductor that is the sole connection to the grounding electrode shall not be required to be large r than 4 AWG copper wire. (E) Connected to a Ground Ring. Where connected to a ground ring as in 250.52(A) ( 4), that portion of the grounding electrode conductor that is the sole connection to the grounding electrode shall not be required to be larger than the conductor used for the ground ring. 250.167 Direct-Current Ground-Fault Detection. (A) Ungrounded Systems. Ground-fault shall be required for ungrounded systems. (B) Grounded Systems. Ground-fault permitted for grounded systems.

detection

detection

systems sha ll

be

(C) Marking. Direct-current systems shall be legibly marked to indicate the grounding type at the de source or the first disconnecting means of the system. The marking shall be of sufficient durability to withstand the environment involved. Informational Note: NFPA 70£2018, Standard for Elcct1'ical Safety in lhe Workplace, identifies four d e grounding types in detail.

250.168 Direct-Current System Bonding Jumper. For directcurrent systems that are to be grounded, an unspliced bonding jumper shall be used to connect the equipment grounding conductor(s) to the grounded conductor at the source or to the first system disconnecting means where the system is grounded. The size of the bonding jumper shall not be smaller than

70-136

the system grounding electrode conductor specified in 250.1 66 and shall comply with 250.28(A) , (B), and (C) . 250.169 Ungrounded Direct-Current Separately Derived Systems. Except as otherwise perm itted in 250.34 for portable and vehicle-mounted generators, an ungrounded de separately derived system supplied from a stand-alone power source (such as an engine-generator set) shall have a grounding electrode conductor connected to an electrode that complies with Part III of this article to provide for grounding of metal enclosures, raceways, cables, and exposed non-current-carrying metal parts of equipment. The grounding electrode conductor connection shall be to the metal enclosure at any point on the separately derived system from the source to the first system disconnecting means or overcurrent device, or it shall be made at the source of a separately derived system that has n o disconnecting means or overcurrent devices.

The size of the groundin g electrode conductor shall be in accordance with 250.166.

Part IX. Instruments, Meters, and Relays 250.170 Instrument Transformer Circuits. Secondary circuits of current and potential instrument transformers shall be grounded where the primary windings are connected to circuits of 300 volts or more to ground and, where installed on or in switchgear and on switchboards, shall be grounded irrespective of voltage.

1'.xception No. 1: Circuits where the primary windings are connected to circuits of 1000 vo!J,s or less with no live parts or wiring exposed or accessible to other than qualified persons. Exception No. 2: Ourrent transformer secondaries connected in a threi;phase delta configuration shall not be required to be grounded. 250.172 Instrument Transformer Cases. Cases or frames of instrument u·ansformers shall be connected to the equipment grounding conductor where accessible to other tha n qualified persons.

1'.xception: Cases or frames of current transformers, the primaries of which are not over 150 volts lo ground and that are used exclusively to supply current to meters. 250.174 Cases of Instruments, Meters, and Relays Operating at 1000 Volts or Less. Instrume nts, meters, a nd relays operating with windings or working parts at 1000 volts or less shall be connected to the equipment grounding conductor as specified in 250.174(A), (B), or (C) . (A) Not on Switchgear or Switchboards. Instruments, meters, and relays not located on switchgear or switchboards operating with wi ndings or working parts at 300 volts or more to ground, and accessible to other than qualified persons, shall have the cases and other exposed metal parts connected to the equipment grounding conductor. (B) On Switchgear or Dead-Front Switchboards. Instruments, meters, and re lays (whether operated from current and potential transformers or connected d irectly in the c ircuit) o n switchgear or switchboards having n o live parts on the front of the panels shall have the cases connected to the equipment grounding conductor. (C) On Live-Front Switchboards. Instrume nts, meters, and relays (whether operated from current and potential trans-

NAT IO NAL ELECTRJCAL CODE

2020 Edition

ARTICLE 250- GROUNDING AND BONDING formers o r connected directly in the circuit) on switc hboards having exposed live parts on the front of panels shall not have their cases connected to the equipment grounding conductor. Mats of insulating rubber or oth er suitable fl oor insulation shall be provided for the operator whe re the voltage to ground exceeds 150 volts.

250.176 Cases of Instruments, Meters, and Relays - Operating at Over 1000 Volts. v\There instruments, meters, and relays have current-carrying parts of over 1000 volts to ground, they shall be isolated by elevation or protected by suitable barriers, grounded metal, or insulating covers o r guards. Their cases shall not be connected to the equipment grounding conductor.

(2) Ampacity. The neutral conductor shall be of sufficient ampacity for the load imposed on the conductor but not less than 33½ percent of the ampacity of the phase conductors.

l!,xception: In indust·1ial and commercial premises under engineering supervision, it shall be permissib!.e to size the ampacity of the neutral conductor to not less than 20 percent of the ampacity of the phase conduct01: (B) Single-Point Grounded Neutral System. Where a singlepoint grounded neutral system is used, the following shall apply: (1)

Exception: Cases of electrostatic gro'llnd detectors shall be permitted to be connected to an eq'lliprnent gro'llnding cond'llctor if the internal gro'llnd segments of the instrument are connected to the instrument case and grounded and the gro'llnd detector is isolated by elevation. 250.178 Instrument Equipment Grounding Conductor. The equipment grounding conductor for secondary circuits of instrument transformers and for instrument cases shall not be smaller than 12 AWG copper or 10 AWG aluminum . Cases of insu·ument transformers, insu·uments, meters, and relays that are mounted d irectly on grounded metal surfaces of enclosures or grounded metal of switchgear or switchboard panels shall be considered to be grounded, a nd no additional equipme n t grounding conductor sha ll be required.

Part X. Grounding of Systems and Circuits of over 1000 Volts

250.180 General. If syste ms over 1000 volts are grounded, they shall comply with all applicable requirements of 250.l th rough 250.1 78 a nd with 250.182 through 250.194, which suppleme n t a nd modify the preceding sectio ns. 250.182 Derived Neutral Systems. A system neutral poin t derived from a grounding transformer shall be permitted to be used for g rounding systems over 1 kV. 250.184 Solidly Grounded Neutral Systems. Solidly grounded neuu·al system s shall be permitted to be either single point grounded or multigrounded neutral .

(2) (3) ( 4) (5) (6) (7) (8)

(2) (3)

Service-entrance conductors Service laterals or -undergro'llnd service conductors Direct-buried portions offeeders

Exception No. 2: Bare conductors shall be permitted for the neutral conductor of overhead portions installed outdoors. Exception No. 3: The grounded neutral conduct11r shall be permitted to be a bare conductor if isoktled from phase conductors and protected fivm physical damage. Informational Note: See 225.4 for conductor covering where within 3.0 m ( 10 tt) of any building o r other structure.

2020 Edition

NATIONAL ELECTRJCAL CODE

a . A separately derived system b. A multigrounded neu tral system with an equipment grounding conductor connected to the multigrounded neutral conductor at the source of the singlepoint grounded neutral system A grounding e lectrode shall be provided for the system. A grounding elecu·ode conductor shall connect the grounding electrode to the system neutral conductor. A bonding jumpe r sh all connect the equipment grounding conductor to the grounding electrode conductor. An equipment grounding conductor shall be provided to each building, structure, and equipment enclosure . A neutral conductor shall only be required wh ere phaseterneutral loads are supplied. The neutral conductor, where provided, shall be insul ated and isolated from earth except at on e location. An equipment grou nding conductor sh all be run with the phase conductors and shall comply with (a), (b), and (c) :

(C) Multigrounded Neutral Systems. Where a multigrounded neutral system is used, the following sha ll apply: (1)

(1) Insulation Level. T he m1111mum insulatio n level for neuu·al conductors of solidly grounded system s shall be 600 volts.

( 1)

A single-point grou nded neutral system shall be permitted to be su pplied from (a) or (b ):

a . Shall not carry continuous load b . May be bare or insulated c . Shall have sufficie nt ampacity for fault current duty

(A) Neutral Conductor.

Exception No. 1: For rnultigrounded neutral systems as permitted in 250. l 84(C), bare copper conductors shall be permitted to be ·used for the neutral conductor of the following:

250.184

(2)

(3)

The neutral con d ucto r o f a solid ly grou nded neuu·al syste m shall be permitted to be grounded at more than one point. Grounding shall be permitted at one or more of the following locations: a . Transformers su pplying conductors to a building or oth er su·ucture b. Underground circuits wh ere the neutral conductor is exposed c. Overhead circuits insta lled outdoors The multigrounded neutral conductor shall be grounded at each tran sformer a nd at other additional locatio ns by connectio n to a grounding e lectrode. At least o ne ground ing e lectrode sh all be installed and connected to the multigrounded n eutral conductor every

400 m (1300 ft) . (4) (5)

The maximum distance between any two adj acent electrodes shall not be more than 400 m (1300 ft) . In a multigrounded sh ielded cable syste m, the shielding shall be grounded at each cable j oint that is exposed to personnel contact.

Exception: In a multipoint grounded system, a grounding electrode shall not be required to bond the neutral conductor in an uninterrupted conduct01· exceeding 400 m (1300 ft) if the only purpose f01· removing the cable jacket is for bonding the neutral conductor to a grounding ekctrode.

70- 137

250.186

ARTICLE 250-GROUNDING AND BONDING Alternating-Current

250.l02(C) (1) but shall not be requi red to be larger than the la rgest ungrounded service-en u-ance conductor(s) .

(A) Systems with a Grounded Conductor at the Service Point. \lihere an ac system is grounded at any point and is provided with a grounded conductor at the service point, a grounded conductor(s) shall be installed and routed with the ungrounded conductors to each service disconnecting means and shall be connected to each disconnecting means grounded conductor(s) terminal or bus. A main bonding jumper shall connect the grounded conductor(s) to each service disconnecting means's enclosure. The grounded conductor(s) shall be installed in accordance with 250.186(A) (l ) through (A) ( 4) . The size of the solidly grounded circuit conductor(s) shall be the larger of that determined by 250.184 or 250.l86(A) (1) or (A)(2) .

(2) Parallel Conductors in 'Iwo or More Raceways or Overhead Conductors. If the ungrounded service-en u·ance conductors a re installed in pa rallel in two or more raceways or overhead conductors, the supply-side bonding jumper shall also be installed in paralle l. The size of the supply-side bo nding jumper in each raceway or overh ead shall be based on the total c ircular mil area of the parallel ungrounded conductors in the raceway or overhead, as indicated in 250.186(A)( l ), but not smaller than 1/ 0 A\I\TG.

250.186 Grounding Systems.

Service-Supplied

Exception: Where two or more service disconnecting means are located in a single assembly listed for use as service equipment, it shall be permitted to connect the grounded conductor(s) to the assembly common grounded conduct01{s) terminal or bus. 77ie assembly shall include a main bonding jumper for connecting the grounded conductor(s) lo the assembly enclosure.

(1) Sizing for a Single Raceway or Overhead Conductor. The grounded conductor shall not be smaller than the required grounding e lectrode conductor specified in Table 250.1 02(C) (1) but shall not be required to be larger than the largest ungrounded service-entrance conductor(s) .

(3) Impedance Grounded Neutral Systems. Impedance g rounded neutral systems sha ll be installed in accordance with 250.187. 250.187 Impedance Grounded Systems. Impedance grounded systems in which a grounding im pedance, usually a resistor, limi ts the ground-fault current shal l be permitted where all of the following cond itions are met:

(1) (2) (3)

The conditions of maintenance and supervision en sure that only qualified persons service the installation. Ground detectors are installed o n the system. Line-to-n eutral loads are not served .

Impedance grounded systems shall comply with 250.187(A) through (D) .

(2) Parallel Conductors in 'Iwo or More Raceways or Overhead Conductors. If the ungrounded service-entrance conductors are installed in parallel in t\vo or more raceways or as overhead parallel conductors, the grounded cond uctors shall a lso be installed in parallel. The size of the grounded conductor in each raceway or overhead shall be based on the total circular mil area of the parallel ungrounded conductors in the raceway or overhead, as ind icated in 250.186(A) (1 ), but not smaller than 1/ 0 AWG.

(A) Location. The grounding impeda n ce sha ll be inserted in the grounding electrode conductor beaveen the grounding electrode of the supply system and the neutral point of the supply transformer o r generator.

Informational Note: See 310.lO(G) for grounded conducwrs connected in paralle l.

(C) Grounded System Conductor Connection. The system grounded conductor shall not be connected to ground, exce pt through the grounding impedance.

(3) Delta-Connected Service. The grounded conductor of a 3pha.se, 3-wire delta service shall h ave a n ampacity not less than that of the ungrounded conductors. (4) Impedance Grounded Neutral Systems. Impedance grounded neutral systems shall be installed in accordance with 250.187. (B) Systems Without a Grounded Conductor at the Service Point. Where a n ac system is grounded at any point and is not provided with a grounded conductor at the service point, a supply-side bonding jumper shall be installed and routed with the ung rounded conductors to each service d isconnecting means and shall be connected to each d isconnecting means equipment grounding conductor terminal or bus. The supplyside bonding jumper shall be installed in accordance with 250.186( B)( l ) through (B)(3) . Exception: Where two or m1Jre service disconnecting means are located in a single assembly listed for use as service equipment, it shall be permitted lo connect the supply-side bonding jumper to the assembly common equipment grounding terminal or bus.

(1) Sizing for a Single Raceway or Overhead Conductor. The supply-side bonding jumper shall not be smaller than the required grounding electrode conductor specified in Table

70-138

(B) Insulated. The grounded conductor sh all be insulated for the maximum neuu·al voltage. I nformational Note: The maximum neuu-al vol rage in a 3-phase wye system is 57.7 percem of the phase-to-phase voltage.

(D) Equipment Grounding Conductors. Equipment grounding conductors shall be permitted to be bare and shall be electrically connected to the ground bus and grounding elecu·ode conductor. 250.188 Grounding of Systems Supplying Portable or Mobile Equipment. Systems supplying portable or mobile equi pment over 1000 volts, other than substations installed on a temporary basis, shall comply with 250.188(A) throug h (F) . (A) Portable or Mobile Equipment. Portable or mobile equipment over 1000 volts shall be supplied from a system having its neutral conductor grounded through an impedance. Where a delta-connected system over 1000 volts is used to supply portable or mobile equipment, a system neutral point and associated neuu·al conductor shall be derived. (B) Exposed Non-Current-Carrying Metal Parts. Ex posed non-current-carrying m etal parts of portable or mobile equipment shall be connected by a n equipment grounding cond uctor to the point at which the system neutral impeda n ce is grounded. (C) Ground-Fault Current. The voltage developed between the portable or mobile equipment frame a nd ground by the

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 250- GROUNDING AND BONDING

250.194

flow of maximum ground-fault cu rrent shall not exceed 100 volts.

shie ld and drain wire insulation shield shall not be used as an equipment g rounding conductor for solidly gro unded systems.

(D) Ground-Fault Detection and Relaying. Ground-fault detection and relaying shall be provided to automatically de-energize a ny component of a system over 1000 volts that has developed a ground fault. The contin uity of the equipment grounding conductor shall be continuously monitored so as to auto matically de-energize the circuit of t he system over 1000 volts to the portable or mobile equipment upo n loss of continuity of the equipment grounding conductor.

(3) Sizing. Equipment grounding conductors shall be sized in accordance with Table 250.1 22 based on the curre nt rating of the fuse or the overcurrent setting of the protective relay.

(E) Isolation. The grounding elecu·ode to which the portable or mobile equipment system neutral impedance is connected shall be isolated from and separated in the ground by at least 6.0 m (20 ft) from any other system or equipment grounding electrode, and there shall be no direct connection between the grounding electrodes, su c h as buried pipe and fence, and so forth . (F) Trailing Cable and Couplers. Trailing cable and couplers of systems over 1000 volts for interconnection of portable or mobile equipme nt shall meet the requirements of Part III of Article 400 for cables and 490.55 for couple rs.

250.190 Grounding of Equipment. (A) Equipment Grounding. All non-current-carrying metal parts of fixed, portable, a nd mobile equipme nt and associated fences, housings, enclosures, a nd supporting su·uctures shall be grounded.

Informationa l Note: The overcurrent rating for a circuit breaker is the combination of the current transformer ratio and the current pickup setting of the protective relay.

250.191 Grounding System at Alternating-Current Substations. For ac substation s, the grounding system shall be in accordance with Part III of Article 250. Informationa l Note: For further information on outdoor ac substation grounding, see IEEE 80-2013, IEEE Guide for Safety in AC Substation Grounding.

250.194 Grounding and Bonding of Fences and Other Metal Structures. Metallic fences e nclosing, a nd other metal su·uctures in or su rrounding, a substation with exposed electr ical conductors and equipme n t shall be grounded and bonded to limit step, touch , and transfer voltages. (A) Metal Fences. Where metal fences are located within 5 m (16 ft) of the exposed electrical conducto rs or equipment, the fence shall be bonded to the grounding electrode system with wire-type bonding jumpers as follows:

(1) (2)

Exception: \!Wzere isolated from ground and located such that any person in contact with ground cannot contact such metal parts when the equipment is energi.z.ed, the metal parts shall not be required to be grounded.

(3)

Informational Note: See 250.l 10, Exception No. 2, for polemounted distribmion apparanis.

(4)

(B) Grounding Electrode Conductor. If a grounding electrode conductor connects non-current-carrying metal parts to ground, the grounding electrode conductor shall be sized in accordance with Table 250.66, based on the size of the largest ungrounded service, feeder, or branch-circuit conductors supplying the equipment. The grounding electrode conductor shall not be smaller than 6 AWG copper or 4 AWG aluminum.

(5)

(C) Equipment Grounding Conductor. Equipment grounding conductors shall comply with 250.190(C) (1) through (C) (3) .

(1) General. Equipment grounding conductors that are not a n integral part of a cable assembly shall not be smaller than 6 AWG copper or 4AWG aluminum. (2) Shielded Cables. The metallic insulation shield e ncircling the current carrying conductors shall be permitted to be used as an equipment grounding conductor, if it is rated for clearing time of ground-fault current protective device operatio n without damaging the metallic sh ie ld. The metallic tape insulation

2020 Edition

NATIONAL ELECTRJCAL CODE

(6)

Bonding jumpers shall be installed at each fence corner and at maximum 50 m (160 ft) intervals a long the fence. Where bare overhead conductors cross the fence, bonding jumpers shall be installed on each side of the crossing . Gates s hall be bonded to th e gate support post, and each gate support post shall be bonded to the grounding electrode syste m. Any gate or other opening in the fence shall be bonded across the opening by a buried bonding jumper. The grounding grid or grounding electrode systems sh all be extended to cover the swing of all gates. The barbed wire strands above the fence shall be bonded to the grounding electrode system .

Alternate designs performed under engi neering supervisio n shall be permitted for grounding or bonding of metal fences. Informational Note No. I: A nonconducting fence or section may provide isolation for transfer of voltage to other areas. Informational Note No. 2: See IEEE 80-2013, JEEt: Guide for Safety In AC Substalion Gmundi11g, fo r design and installation of fence g rounding.

(B) Metal Structures. All exposed conductive metal structures, including guy wires within 2.5 m (8 ft) vertically or 5 m (1 6 ft) horizontally of exposed conductors or equipment and subject to contact by persons, shall be bonded to the grounding electrode systems in the area.

70- 139

CHAPTER3

ARTICLE 300 -GENERAL REQUIREMENTS FOR \r\TIRING METHODS AND MATERJALS

Chapter 3 Wiring Methods and Materials ARTICLE 300 General Requirements for Wiring Methods and Materials Part I. General RequiremenlS 300.1 Scope. (A) All Wiring Installations. This article covers general requirements for wiring methods a nd materials for a ll wiring installatio ns unless modified b y other articles in Chapter 3. (B) Integral Parts of Equipment. The provisions of this article are not intended to apply to the conductors that form a n integral part of equipment, such as moto rs, con trollers, motor control centers, or factory-assembled control equipment or listed utilization equipment. (C) Metric Designators and Trade Sizes. Metric designators and trade sizes for conduit, tubing, and associated fittin gs and accessories shall be as designated in Table 300. l (C) . 300.2 Limitations. (A) Voltage. Wiring methods specified in Chapter 3 shall be used for 1000 volts, nominal, or less where not specifically limited in some section of Chapter 3. They shall be permitted for over 1000 volts, nominal, where specifically permitted elsewhere in this Code. (B) Temperature. Temperature limitation of conductors shall be in accordance with 310.14(A)(3) . 300.3 Conductors. (A) Single Conductors. Single conductors specified in Table 3 10.4(A) sha ll only be installed where part of a recognized wiring method of Chapter 3.

Table 300.l(C) Metric Designators and Trade Sizes Metric Designator

Trade Size

12 16 21

½ ½ ¾

27

1

35 41 53 63

1¼ l½

78 91 103 129 155

2 2½ 3 3½ 4 5 6

Exception: Individual conductm·s shall be permitted where installed as separate overhead conductm·s in accordance with 225.6.

(B) Conductors of the Same Circuit. All conductors of the sam e circuit and, where used, the gTounded conductor and all equipment grounding conductors and bo nding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or cord, unless otherwise pe rmitted in accordance with 300.3(B) (I) through (B)(4) . (1) Paralleled Installations. Conductors shall be permitted to be run in parallel in accordance with the provisions of 3 10.l 0(G) . The requirement to run all circuit conductors within the same raceway, auxiliary g utter, cable tray, trench, cable, or cord shall apply separately to each portion of the paralleled installation , and the equipme nt grounding conductors sha ll comply with 250.122. Connectio ns, taps, or extensions made from paralleled conductors shall connect to all con ductors of the paralleled set, grounded and ungrounded, as appl icable . Parallel runs in cable trays shall comply with 392.20(C) . Exception: Conductors installed in nonmetallic raceways run unde1° ground shall be permitted lo be arranged as isolated phase, neutral, and grounded conductor installations. '17ze raceways shall be installed in close pivximity, and the isolated phase, neutral, and grounded conductors shall comply 1inlh 300.20(B).

(2) Grounding and Bonding Conductors. Equipment grounding conductors shall be permitted to be installed o utside a raceway or cable assembly where in accordance with the provisions of250.1 30(C) for certain existing installations or in accordance with 250.1 34, Exception No. 2, for de circuits. Equipment bonding conductors shall be permitted to be installed on the outside of raceways in accordance with 250.1 02(E) .

(3) Nonferrous Wiring Methods. Condu ctors in wiring m ethods with a nonmetallic or other nonmagnetic sheath , where run in different raceways, auxiliary g utters, cable trays, trenches, cables, or cords, shall comply with 300.20(B) . Conductors in single-conductor Type MI cable with a no nmagnetic sheath shall comply with 332.3 1. Conductors o f singleconductor Type MC cable with a nonmagnetic sheath shall comply with 330.31, 330.11 6, a nd 300.20(B) . (4) Column-Width Panelboard Enclosures. vVhere an auxiliary gutter runs betwee n a column-width panelboard and a pull box, and the pull box includes neutral term inations, the neutral conductors of circuits supplied from the panelboard shall be permitted to orig inate in the pull box. (C) Conductors of Different Systems. (1) 1000 VollS, Nominal, or Less. Conductors of ac and de c ircuits, rated 1000 volts, nominal, or less, shall be perm itted to occupy the same equipment wiring enclosure, cable, or raceway. All cond uctors shall have an insulatio n rating equal to at least the maximum c ircuit voltage applied to any conductor within the enclosure, cable , or raceway.

Note: The me tric designators and trade sizes are for idemification purposes on ly and are not actual dimensions.

70-140

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 300-GENERAL REQUIREMENTS FOR WIRING METHODS AND MATERIALS Secondary wiring to electric-discharge lamps of 1000 volts or less, if insulated for the secondary voltage involved, shall be permitted to occupy the same luminaire, sign, or outline lighting enclosure as the branch-circuit conductors. Informational Note No. I: See 725.136(A) for Class 2 and Class 3 circuit conductors. Informational Note No. 2: See 690.31 (B) for photovoltaic source and ompm circuits.

(2) Over 1000 Volls, Nominal. Conductors of circuits rated over 1000 volts, nominal, shall not occupy the same equipment wiring enclosure, cable, or raceway with conductors of circuits rated 1000 volts, nominal, or less unless otherwise permitted in 300.3(C) (2) (a) through 300.3(C) (2) (d) . (a) Primary leads of electric-discharge lamp ballasts insulated for the primary voltage of the ballast, where contained within the individual wiring enclosure, shall be permitted to occupy the same luminaire, sign, or outline lighting enclosure as the branch-circuit conductors. (b) Exc itation , control, relay, and ammeter conductors used in connection with any individual motor or starter shall be permitted to occupy the same enclosure as the motm~circuit conductors. (c) In motors, transformers, switchgear, switchboards, control assemblies, and similar equipment, conductors of different voltage ratings shall be permitted . (d) In manholes, if t he conductors of each system are permanently and effectively separated from the conductors of the other systems and securely fastened to racks, insulators, or other approved supports, conductors of different voltage ratings shall be permitted. Conductors having nonshielded insulation and operating at different voltage levels shall not occupy the same enclosure, cable, or raceway.

300.4 Protection Against Physical Damage. Where subject to physical damage, conductors, raceways, and cables shall be protected. (A) Cables and Raceways Through Wood Members. (I) Bored Holes. In both exposed and concealed locations, where a cable- or raceway-type wiring method is installed through bored holes in joists, rafters, or wood members, holes shall be bored so that the edge of the hole is not less than 32 mm (11/., in.) from the nearest edge of the wood member. Wl1ere this distance cannot be mainta ined, the cable or raceway shall be protected from penetration by screws or nails by a steel plate(s) or bushing(s), at least 1.6 mm (1/, 6 in.) th ick, and of appropriate length and width installed to cover the area of the wiring. Exce-ption No. 1: Steel plates shall not be required to protect rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, or electrical metallic tubing. Exception No. 2: A listed and marked steel plate less than 1.6 mm (1,16 in.) thick that provides equal or better protection against nail or screw penetration shall be permitted.

(2) Notches in Wood. Where there is no objection because of weakening the building structure, in both exposed and concealed locations, cables or raceways shall be permitted to be laid in notches in wood studs, joists, rafters, or other wood members where the cable or raceway at those points is protected against nails or screws by a steel plate at least 1.6 mm

2020 Edition

NATIONAL ELECTRJCAL CODE

300.4

(1/,6 in.) thick, and of appropriate length and width, install ed to cover th e area of the wiring. The steel plate shall be installed before the building finish is applied.

~Exception No. 1: Steel plates shall not be required lo protect rigid metal conduit, intermediate metal conduit, 1igid nonmetallic conduit, or electticcd metallic tubing. Exception No. 2: A listed and marked steel plate less than 1. 6 mm 1 ( /26 in.) thick that provides equal or better protection against nail or screw penetration shall be permitted.

(B) Nonmetallic-Sheathed Cables and Electrical Nonmetallic Tubing Through Metal Framing Members. (1) Nonmetallic-Sheathed Cable. In both exposed and concealed locations where nonmetallic-sheathed cables pass through either factory- or fie ld-punched, cut, or drilled slots or holes in metal members, the cable shall be protected by listed bushings or listed grommets covering all metal edges that are securely fastened in the open ing prior to installation of the cable. (2) Nonmetallic-Sheathed Cable and Electrical Nonmetallic Tubing. vVhere nails or screws are likely to penetrate nonmetallic-sheathed cable or electrical nonmetallic tubing, a steel sleeve, steel plate, or steel clip not less than 1.6 mm (1/,6 in. ) in thickness shall be u sed to protect the cable or tubing. Exception: A listed and marked steel plate less than 1. 6 mm ( 1/26 in.) thick that provides equal or better protection against nail or screw pen1Jtration shall be permitted. (C) Cables Through Spaces Behind Panels Designed to Allow Access. Cables or raceway-type wiring methods, insta lled behind panels designed to allow access, shall be supported according to their applicable articles. (D) Cables and Raceways Parallel to Framing Members and Furring Strips. In both exposed and concealed locations, where a cable- or raceway-type wiring method is installed parallel to framing members, such as joists, rafters, or snids, or is installed parallel to furring strips, the cable or raceway shall be installed and supported so that the nearest outside surface of the cable or raceway is not less than 32 mm (1 ¼ in. ) from the nearest edge of the framing member or furring strips where nails or screws are likely to penetrate. Where this distance cannot be maintained, the cable or raceway shall be protected from penetration by nails or screws by a steel plate, sleeve, or equivalent at least 1.6 mm (1/, 6 in.) thick. Exception No. 1: Steel plates, sleeves, or the equivalent shall not be required to protect rigid metal conduit, intermediate metal conduit, 1igid nonmetallic conduit, or electrical metallic tubing. l!.xception No. 2: For concealed work in finished buildings, or finished panels for prefabricated buildings where such supporting is impracticable, it sh.all be permissibl.e to fish the cables between access points. Exception No. 3: A listed and marked steel plate less than 1. 6 mm ('li6 in.) thick that provides equal or better protection against nail or screw penetration shall be permitted.

(E) Cables, Raceways, or Boxes Installed in or Under Roof D ecking. A cable, raceway, or box, install ed in exposed or concealed locations under metal-corrugated sheet roof decking, shall be installed and supported so there is not less than 38 mm (1 ½ in.) measured from the lowest su rface of the roof

70-141

300.4

ARTICLE 300 -GENERAL REQUIREMENTS FOR \r\TIRING METHODS AND MATERJALS

decking to th e top of the cable, raceway, or box. A cable, raceway, or box shall not be instal led in concealed locatio ns in metal-corrugated, sheet decking-type roof. In formational Note: Roof decking material is often repaired or replaced after the initial raceway or cabling and roofing installation and may be penetrated by d1e screws or od1er mechanical devices designed to provide "hold down" strength of the waterproof membrane or roof insulating material.

Exception: R igid metal conduit and intermediate metal conduit shall not be required to comply with 300.4(£). (F) Cables and Raceways Installed in Shallow Grooves. Cable-

or raceway-type wiring methods installed in a groove, to be covered by wal lboard, siding, paneling, carpeting, or similar finish, shall be protected by 1.6 mm (1/, 6 in. ) thick steel plate, sleeve, or equivalent or by not less than 32-mm (1 ¼-in.) free space for the fu ll length of the groove in wh ich the cable or raceway is installed . Exception No. 1: Steel plates, sleeves, or the equivalent shall not be required to protect rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, or electrical metallic tubing. Exception No. 2: A listed and marked steel plate less than 1. 6 mm 1 ( 1,6 in.) thick that provides equal or better protection against nail or screw penetration shall be permitted. (G) Fittings. Where raceways contain 4 AWG or larger insulated c ircuit conductors, and these cond uctors enter a cabinet, a box, an enclosure, or a raceway, the conductors shall be protected in accordance with any of the following: (1 ) (2) (3) (4)

An identified fitting providing a smoothly rounded insulating surface A listed metal fitting that has smoothly rounded edges Separation from the fitting or raceway using a n ide ntified insulating material that is securely faste ned in place Threaded hubs or bosses that are an integral part of a cabinet, box, enclosure, or raceway providing a sm oothly rounded or flared entt-y for conductors

Conduit bushings constructed who lly of insulating material shall not be used to secure a fitting or raceway. The insulating fitting or insulating material sha ll have a temperanire rating no t less than the insulation te mperanire rating of the installed conductors. (H) Structural Joints. A listed expansion/ deflection fitting or other approved means shall be used wh ere a raceway crosses a strucniral joint intended for expansion, contraction or deflection, used in buildings, bridges, parking garages, or other strucnires. 300.5 Underground Installations. (A) Minimwn Cover Requirements. Direct-buried cable , conduit, or other raceways sh all be installed to meet the minimum cover requirements of Table 300.5. (B) Wet Locations. The interior of enclosures or raceways installed underground shall be conside red to be a wet location. Insulated conductors and cables installed in these enclosures or raceways in underground installations sh all com ply with 3 10.l0(C) .

1'.xception No. 1: T'ype Ml cable shall be permitted under a building without installation in a raceway where embedded in concrete, fill, or other masomy in accordance with 332.10(6) or in underground runs where suitably protected against physical damage and corrosive conditions in accordance with 332.10(10). 1'.xception No. 2: Type MC cable listed for direct burial or concrete encasement shall be permitted under a building without installation in a raceway in accordance with 330.10(A)(5) and in wet locations in accordance with 330.l0(A)(11 ). (D) Protection from Damage. Direct-buried conductors and cables sha ll be protected from damage in accordance with 300.5(D )(l ) throug h (D )(4) . (1) Emerging from Grade. Direct-buried conductors and cables e merg ing fro m grade and specified in columns 1 a nd 4 of Table 300.5 shall be protected by enclosures or raceways extend ing from the minimum cover d istance below grade required by 300.5(A) to a point at least 2.5 m (8 ft) above finished grade. In no case shall the protection be required to exceed 450 111111 (18 in.) below fini shed grade. (2) Conductors Entering Buildings. Conductors e n tering a building sh all be protected to the point of e ntrance. (3) Service Conductors. Underground service conductors that are not encased in concrete and that a re buried 450 mm (18 in. ) or more below grade shall have their location identified by a warning ribbon that is placed in the trench at least 300 mm (12 in. ) above the underground installation. (4) Enclosure or Raceway Damage. , ,\/here the enclosu re or raceway is subject to physical damage, the conductors shall be installed in electr ical metallic tubing, 1·igid metal conduit, intermediate metal conduit, RTRC-XW, Schedule 80 PVC conduit, o r equivalent. (E) Splices and Taps. Direct-buried conductors or cables shall be perm itted to be spliced or tapped without the use o f splice boxes. The splices or taps sh all be made in accordan ce with 110.14(B) . (F) Backfill. Backfill that conta ins la1·ge rocks, paving materia ls, c inders, large or sharply angular substances, or corrosive mater ial shall not be placed in an excavation where materials may damage raceways, cables, conductors, or other substructures o r prevent adequate compaction of fill or contribute to corrosion of raceways, cables, or other substrucnires.

v\lhere necessary to prevent physical damage to the raceway, cable, or cond uctor, protection shall be provided in the form of gran ular or selected material, suitable running boards, sui table sleeves, or other approved mean s. (G) Raceway Seals. Cond uits or raceways th rough whi ch m o isnire may contact live parts shall be sealed or plugged at either or both ends. Spare or unused raceways shall also be sealed. Sealants shall be identified for use with the cable insulatio n , conductor insulation , bare conductor, shie ld, or other components. Informational Note: Presence of hazardous gases or vapors may also necessitate sealing of underground conduits or raceways entering buildings.

(C) Underground Cables and Conductors Under Buildings. Unde rground cable and conductors installed under a building shall be in a raceway.

70-142

NAT IONAL ELECTRJCAL CODE

2020 Edition

300.5

ARTICLE 300-GENERAL REQUIREMENTS FOR WIRING METHODS AND MATERIALS Table 300.5 Minimum Cover Requirements, 0 to 1000 Volts, Nominal, Burial in Millimeters (Inches) Type of Wiring Method or Circuit

Colunm l Direct Burial Cables or Conductors

Location of Wiring Method or Circuit

mm

in.

Columns Cohunn4 Circuits for Residential Branch Control of Cohunn3 Circuits Rated Irrigation and 120 Volts or Less Landscape Lighting Nonmetallic Raceways Listed withGFCI Limited to Not Column 2 for Direct Burial Protection and More Than 30 Volts Without Concrete Maximum and Installed with Rigid Metal Conduit or Encasement or Overcurrent Type UF orin Other Identified Intermediate Metal Other Approved Protection of Conduit Raceways 20Amperes Cable or Raceway mm

in.

mm

in.

mm

in.

mm

in.

5a.b

All locations not specified below

600

24

150

6

450

18

300

12

150"·b

In trench below 50 mm (2 in.) thick concrete or equivalent

450

18

150

6

300

12

150

6

150

6

0

0

0

0

0

0

0

0

0

0

Under a build ing

( in raceway or Type :VIC or Type :VII cable identified for d irect b urial)

18

(in raceway or Type :v!C or Type :v!l cable identified for direct buria l)

100

4

100

4

150

(in raceway or Type :v!C or Type :v.11 cable identified for direct burial)

Under m inimum of 102 mm (4 in.) thick concrete exterior slab with no vehicular traffic and the slab exte nding not less than 152 mm (6 in.) beyond the underground installa tion

450

Under streets, h ighways, roads, alleys, driveways, and parking lo ts

600

24

600

24

600

24

600

24

600

24

One- and two-family dwelling driveways and outdoor parking areas, and used on ly for dwe llingrelated purposes

450

18

450

18

450

18

300

12

450

18

In or under airport mnways, including adjacent areas where trespassing prohibited

450

18

450

18

450

18

450

18

450

18

6

(dir ect burial)

100

4

(in racew·ay)

150

6

(direct bu1ial)

4

100

(in raceway)

aA lesser depth shall be permitted where speci fi ed in the installation instructions ofa listed low-voltage lighting system. bA depth of 150 mm (6 in.) shall be permitted for pool, spa, and fountain lighting, installed in a nonmetallic raceway, limited to not more than

30 volts where part of a listed low-voltage lighting system. Notes: L Cover is defined as the shortest distance in mm (in.) measured between a point on the top surface of any direct-buried conductor, cable, conduit, or other raceway and the top surface of finished grade, concrete, or similar cover. 2. Raceways approved for burial only where concrete encased shall require concrete envelope not less than 50 mm (2 in.) thick. 3. Lesser depths shall be permitted where cables and conductors rise for terminations or splices or where access is otherwise required . 4. Where one of the wiring method types listed in Columns I through 3 is used for one of the circuit types in Columns 4 and 5, the shallowest depth of burial shall be permitted. 5. Where solid rock prevents compliance with the cover depths specified in this table, the wiring shall be installed in a metal raceway, or a nonmetallic raceway permiued for direct burial. The raceways shall be covered by a minimum of 50 mm (2 in.) of concrete extending down to rock.

2020 Edition

NATIONAL ELECTRJCAL CODE

70- 143

300.5

ARTICLE 300 -GENERAL REQUIREMENTS FOR \r\TIRING METHODS AND MATERJALS

(H) Bushing. A bushing, or terminal fitting, with an integral bushed opening shall be used at the end of a conduit or other raceway that terminates undergrou nd where the conductors or cables emerge as a direct burial wiring method. A seal incorporating the physical protection characteristics of a bushing shall be permitted to be used in lieu ofa bushing.

(I) Conductors of the Same Circuit. All conductors of the same circuit and, where u sed, the grounded conductor and all equipment grounding conductors shall be installed in the same raceway or cable or shall be installed in close proximity in the same trench. Exception No. 1: Conductors shall be permitted to be installed in parctllel in raceways, mulliconductor cables, or direct-bwied single conductor cables. Each raceway or multiconductor cable shall contain all conductors of the same circuit, including equipment grounding conductors. Each direct-buried single conductor cable shall be located in close proximity in the trench to the other single conductor cab/,es in the same parallel set ofconductors in the circuit, including equipment grounding conductors. Exception No. 2: Isolated phase, polarity, grounded conductm; and equipment grounding and bonding conductor installations shall be permitted in nonmetallic raceways m· cables with a nonmetallic covering or nonmagnetic sheath in close proximity where conductors are parctlleled as permitted in 310.I0(G), and where the conditions of 300.20(13) are met.

(J) Earth Movement. Wh ere direct-buried conductors, raceways, or cables are subject to movement by settle ment or frost, d irect-buried conductors, raceways, or cables sh all be arranged so as to prevent damage to the enclosed conductors or to equipment connected to the raceways. In formational Note: This section recognizes "S" loops in underground direct burial cables and conductors to raceway transitions, expansion fittings in raceway risers to fixed equipment, and, generally, the provision of flexible connections to equipment subject to settlement or frost heaves.

(K) Directional Boring. Cables or raceways installed using d irectional boring equipment shall be approved for the purpose. 300.6 Protection Against Corrosion and D eterioration. Raceways, cable trays, cablebus, auxiliary gutters, cable arm or, boxes, cable sheathing, cabinets, elbows, couplings, fittings, supports, and support hardware shall be of materials suitable for the environment in which they are to be installed. (A) Ferrous Metal Equipment. Ferrous metal raceways, cable trays, cablebus, a ux iliary gutters, cable armor, boxes, cable sheathing, cabinets, metal elbows, couplings, n ipples, fittings, supports, and support hardware shall be suitably protected against corrosion inside and outside (except threads at j oints) by a coating of approved corrosion-resistant material. \>\There corrosion protection is necessary and the conduit is threaded in the field, the threads shall be coated with an approved electrically conductive, corrosion-resistant compound. In formational Note: Field-cut threads are those threads that are cut in conduit, elbows, or nipples anywhere other than at the factory where the product is listed.

Exception: Stainless steel shall not be required lo have protective coatings.

(I) Protected from Corrosion Solely by Enamel. Where protected from corrosion sole ly by enamel, ferrous metal race-

70-144

ways, cable u·ays, cablebus, a ux iliary gutters, cable armor, boxes, cable sheathing, cabinets, metal elbows, couplings, nipples, fittings, supports, and suppo rt hardware sh all not be used outdoors or in wet locations as described in 300.6(0). (2) Organic Coatings on Boxes or Cabinets. Where boxes or cabinets have an approved system of organic coatings and are marked "Raintight," "Ra inproof," or "Outdoor Type," they shall be permitted outdoors.

(3) In Concrete or in Direct Contact with the Earth. Ferrous metal raceways, cable armor, boxes, cable sheathing, cabinets, elbows, couplings, nipples, fittings, supports, and support h ardware shall be permitted to be installed in concrete or in d irect contact with the earth, or in areas subject to severe corrosive influences where m ade of material approved for the conditio n , or wh ere provided with corrosion protection approved for the condition. (B) Aluminum Metal Equipment. Aluminum raceways, cable u·ays, cable bus, auxiliary gutters, cable armor, boxes, cable sheathing, cabinets, elbows, couplings, nipples, fittings, supports, and support ha rdware e mbedded or encased in con crete or in direct contact with the earth sh all be provided with supplementary corrosio n protection. (C) Nonmetallic Equipment. Nonmetallic raceways, cable trays, cablebus, a ux iliary gutters, boxes, cables with a nonmetallic o uter j acket and internal metal armor or jacket, cable sheathing, cabinets, elbows, couplings, nipples, fittings, supports, a nd support hardware shall be made of material approved for the condition and shall comply with 300.6(C) (1) and (C) (2) as applicable to the specific insta llatio n.

(I) Exposed to Sunlight. vVhere exposed to sunlight, the materials shall be listed as sunlight resistant or shall be identified as sunlight resistant. (2) Chemical Exposure. vVhere subject to exposure to chemical solvents, vapors, splashing, or immersio n , materials or coatings s hall e ither be inherently resistam to chemicals based on their listing or be identified for the specific chemical reagent. (D) Indoor Wet Locations. In portio ns of dairy processing facilities, laundries, canneries, and oth er indoor wet locations, and in location s where walls are freq uently wash ed or where there are su rfaces of absorbent mate rials, such as damp paper or wood, the entire wiring system, wh ere installed exposed, including all boxes, fittings, raceways, and cable used therewith , shall be mounted so that there is at least a 6-mm (1/.,-in. ) a irspace between it and the wall or supporting surface .

Exception: Nonmetallic raceways, boxes, and fittings shall be permitted to be installed without the airspace on a concrete, masomy, tile, or similar smface. I nformational Note: In general, areas where acids and alkali chemicals are handled and stored may present such corrosive conditions, particularly when wet or damp. Severe corrosive conditions may also be present in portions of meatpacking plants, tanneries, glue houses, and son1e stables; in installations

immediately adjacent to a seashore and swimming pool areas; in a reas where chemical deicers are used; and in storage cellars or rooms for hides, casings, fertilizer, salt, and bulk chemicals.

300.7 Raceways Exposed to Different Temperatures. (A) Sealing. Where portio ns of a raceway or sleeve are known to be subjected to d ifferent temperatures, a n d where conden sation is known to be a problem, as in cold storage areas of build-

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 300-GENERAL REQUIREMENTS FOR WIRING METHODS AN D MATERIALS ings or where passing from th e interior to the exterior of a building, the raceway or sleeve shall be sealed to prevent the circulation of warm air to a colder sectio n of the raceway or sleeve. Sealants shall be identified for use with cable insulation, condu ctor insulation, a bare conductor, a sh ield, or other components. An explosionproof seal shall not be required for this purpose. (B) Expansion, Expansion-Deflection, and Deflection Fittings. Raceways shall be provided with expansion, expansiondeflection, or deflection fittings where necessary to compensate for thermal expansion , deflection, and contraction. Informational Note: Table 352.44 and Table 355.44 provide the expansion information for polyvinyl ch loride (PVC) and for reinforced th e rmosetti ng resin conduit (RT RC), respectively. A nominal number for steel conduit can be determined by multip lying the expansion length in Table 352.44 by 0.20. The coefficient of expansion for steel electrical metallic tubing, intermediate metal cond u it, and rigid metal co nduit is 1.170 x 10·5 (0.0000117 mm per mm of conduit for each °C in temperature change) (0.650 x 10..; (0.0000065 in. per inch of conduit for each °Fin temperature change)] . A nominal number for alumin um condu it and aluminum e lectrical metallic tubing can be dete rmined by multiplying the expansion length in Table 352.44 by 0.40. The coeffici e nt of expansion for a luminum electrical metallic tubing and aluminum rigid metal conduit is 2.34 x 10-0 (0.0000234 mm per mm of conduit for each °C in temperature change) (1.30 x 10·5 (0.000013 in. per inch of conduit for each °F in temperature change)].

300.8 Installation of Conductors with Other Systems. Raceways or cable trays containing e lectrical conductors shall not contain any pipe, tube, 01· equal for stea m, water, ai r, gas, drainage, or any service other than electrical. 300.9 Raceways in Wet Locations Abovegrade. Where raceways a re installed in wet locations abovegrade, the interior of these raceways sha ll be considered to be a wet locatio n. Insulated conductors a nd cables installed in raceways in wet locations a bovegrade shall comply with 310.I 0(C) . 300.10 Electrical Continuity of Metal Raceways and Enclosures. Metal raceways, cable armor, and other metal enclosures for conductors shall be metallically j o ined togeth er into a continuo us elecu-ical conductor and sha ll be connected to all boxes, fittings, and cabin ets so as to provide effective electrical continuity. Unless specifically permitted e lsewhere in this Code, raceways and cable assemblies shall be mechanically secured to boxes, fittings, cabinets, and o ther enclosu res.

Exception No. I: Short sections of raceways med to provide support or protection ofcable assemblies from physical damage shall not be required lo be made electrically continuous. Exception No. 2: Equipment enclosures lo be isolated, as permitted by 250. 96(B), shall not be required to be nzetallically joined to the metal raceway. 300.11 Securing and Supporting. (A) Secured in Place. Raceways, cable assemblies, boxes, cabinets, and fittings shall be securely fastened in place. (B) Wiring Systems Installed Above Suspended Ceilings. Support wires that do not provide secure support shall not be permitted as the sole support. Support wires a nd associated fittings that provide secure support and th at are installed in additio n to the ceiling grid support wires shall be permitted as

2020 Edition

NATIONAL ELECTRJCAL CODE

300.13

the sole support. Where independent support wires are used, they shall be secured at both ends. Cables and raceways shall not be supported by ceiling grids. ( 1) Fire-Rated Assemblies. Wiring located within the cavity of a fire-rated floor-ceili ng or roof-ceiling assembly shall not be secured to, or supported by, the ceiling assembly, including the ceiling support wires. An independent means of secure suppo rt shall be provided and sh all be permitted to be attach ed to the assembly. V.There independent support wires are used, they shall be distinguishable by colo1·, tagging, or other effective means from those that are part of the fire-rated design .

Exception: The ceiling support system shall be permitted to support wiring and equipment that have been tested as part of the fire-rated assembly. Informational Note: One method of determining fire rating is testing in accordance with ANSI/ ASTM EJJ9-18b, Standa,-d Test Methods for Fire Tests of Building Construction and Materials.

(2) Non-Fire-Rated Assemblies. Wiring located within the cavity of a non-fire-rated floor-ceiling o r roof-ceiling assembly shall not be secured to, or supported by, the ceiling assembly, including the ceiling support wire s. An independent means of secure support sh all be provided a nd shall be permitted to be attached to the assembly. ,~There independent support wires are used, they shall be distinguishable by color, tagging, or other effective means.

.Exception: The ceiling support system shall be per-milled to support branch-circuit wiring and associated equipment where installed in accordance with the ceiling system manufacturer's instructions. (C) Raceways Used as Means of Support. Raceways shall be used only as a means of support for oth er raceways, cables, or nonelectrical equipment under any of the following conditions:

(I ) (2)

(3)

, ~ere the raceway or means of support is identified as a means of support Where the raceway contains power supply condu ctors for e lectrically controlled equi p ment and is used to support Class 2 circuit conductors 0 1· cables that are solely for the purpose of connection to th e equipment control circuits ,~There the raceway is used to support boxes or conduit bodies in accordance with 314.23 or to support lumina ires in accordan ce with 410.36(E)

(D) Cables Not Used as Means of Support. Cable wiring methods shal l not be used as a means of support for other cables, raceways, or nonelectrical equipment. 300.12 Mechanical Continuity - Raceways and Cables. Raceways, cable armors, and cable sheaths shall be continuous between cabinets, boxes, fitti ngs, o r other enclosures or outlets.

Exception No. 1: Short sections of raceways used to provide support or protection of cable assemblies from physical damage shall not be required to be mechanical!)• continuous. Exception No. 2: Raceways and cables installed into the bottom of open bottom equipment, such as switchboards, motor control centers, and floor or pad-mounted transformers, shall not be required to be meclzanically secured to tlze equipnient. 300.13 Mechanical and Electrical Continuity- Conductors. (A) General. Conductors in raceways shall be continuous between o utlets, boxes, devices, an d so forth. There sh all be no

70- 145

300.13

ARTICLE 300 -GENERAL REQUIREMENTS FOR \r\TIRING METHODS AND MATERIALS

splice or tap within a raceway unless permitted by 300.1 5, 368.56(A), 376.56, 378.56, 384.56, 386.56, 388.56, or 390.56.

accessible after installation , unless listed for con cealed installation.

(B) Device Removal. In multiwire branch circuits, the continuity of a grounded condu ctor shall not depend on device connections su ch as lampholders, receptacles, and so forth, where the removal of su ch devices would interrupt the continui ty.

(G) Direct-Buried Conductors. As p ermitted in 300.5(E), a box or conduit body shall not be required for splices a nd taps in direct-buried conductors and cables.

300.14 Length of Free Conductors at Outlets, Junctions, and Switch Points. At least 150 mm (6 in.) of free conductor, measured from the point in the b ox where it emerges from its raceway or cable sh eath , shall be left at each outlet, junction, a nd switch point for splices or the conn ection of luminaires or devices. Where the opening to a n outlet, junction, or switch point is less than 200 mm (8 in. ) in any dimension, each conductor shall be long e nough to extend at least 75 mm (3 in. ) outside the opening. Exception: Conductors that are not spliced or terminated at the outlet, junction, or switch point shall not be required to comply with 300.14.

300.15 Boxes, Conduit Bodies, or Fittings - Where Required. A box shall b e installed at each outlet and switch point for concealed kno b -and-tube wiring. Fittings and connectors sh a ll be used only with the specific wiring methods for which they are designed an d listed. \ .\1here the wi ring method is conduit, tubing, Type AC cable, Type MC cable, Type MI cable, nonmetallic-sheathed cable, or other cables, a box or conduit body sh all be installed at each condu ctor splice point, outlet point, switch point, junction point, termination point, o r pull point, unless otherwise permitted in 300.1 5(A) through (L) .

(A) Wiring Methods with Interior Access. A b ox or conduit b ody shall not b e required for each splice, junction, switch , pull, termination, or outlet points in wiring methods with removable covers, su ch as wireways, multioutlet asse mblies, auxiliary gutters, a nd surface raceways. The covers shall be accessible after installation. (B) Equipment. An integral junction box or wiring compartment as part of approved equipme nt shall b e permitted in lie u ofa b ox. (C) Protection. A box or conduit b ody shall not be required where cables enter or exit from conduit or tubing that is used to provide cable support or pmtection against physical damage. A fitting sh all be provided on the end(s) of the conduit or tubing to protect the cable from abras ion.

(D) Type MI Cable. A box or conduit b ody shall not be required where accessible fittings are u sed for straight-throu g h splices in mineral-insulated metal-sheathed cable. (E) Integral Enclosure. A wiring device with integral enclosu re id entified for the u se, having brackets th at securely fasten the device to walls or ceilings of conventiona l on-site frame construction, for u se with nonmetallic-sheathed cable, shall be permitted in lieu of a b ox or conduit body. Informational Note: See 334.30 (C); 545.l O; 550.15(1); 55 l.47(E), Exception No. l; and 552.48( E), Exception No. I.

(F) Fitting. A fitting identified for the u se shall b e permitted in lieu of a box o r condui t body where conductors are not spliced or terminated within the fitting. The fitting sha ll be

70-146

(H ) Insulated Devices. As permitted in 334.40(B), a box or conduit body shall n ot b e required for insulated devices supplied by nonmetallic-sheath ed cable. (I) Enclosures. A box or conduit b ody sh all not b e required wh e re a splice, switch , terminal, or pull point is in a cabinet or cutout box, in an enclosure for a switch o r overcurrent d evice as permitted in 312.8, in a motor cont roller as permitted in 430.l0 (A), o r in a motor control center.

(J) Luminaires. A box or conduit b ody shall n ot be required where a lumina ire is u sed as a raceway as perm itted in 410.64. (K) Embedded. A b ox or conduit body shall not be required for splices where conductors are embedded as permitted in 424.40, 424.41 ( D), 426.22(C), 426.24(A) , and 427.l 9(A) . (L) Manholes and Handhole Enclosures. A box or conduit b ody shall not be required for conductors in m a nholes o r h a ndhole enclosures, except wh ere connecting to electrical equipment. T he installation shall com ply with the provision s of Part V of Articl e ll0 for manholes, and 314.30 for handhole enclosures.

300.16 Raceway or Cable to Open or Concealed Wiring. (A) Box, Conduit Body, or Fitting. A box, con d uit b ody, o r terminal fitting having a separately bush ed hole for each con d u ctor sh all b e u sed wherever a change is m ade from conduit, elecu-ical meta llic tubing, elecu-ical n o nme tallic tubi ng, nonmetalli c-sheath ed cabl e, Type AC cable , Type MC cable, o r min eral-insulated, metal-sheathed cable and surface raceway wiring to open wiring o r to concealed knob-and-tube wiring . A fitting used for th is purpose shall con tain no taps or splices a nd shall not be u sed at luminaire outlets. A conduit body used for this purpose sh all conta in no taps or splices, unless it complies with 314.1 6(C) (2) . (B) Bushing. A bushing sh all be perm itted in lieu of a box or terminal wh ere the condu ctors emerge from a raceway and enter or terminate at equipment, su ch as open switchboards, unenclosed con trol equipment, or similar equipment. The bushing sh all b e of t h e insulating type for other th an leadsheathed conductors.

300.17 Number and Size of Conductors in Raceway. The number and size of conductors in any raceway shall not be m ore th an will permit d issipation of the heat a nd ready installation or withdrawal of the condu ctors without damage to the condu ctors or to their insulation . I nformational Note: See the following sections of this Code: intermediate metal conduit, 342.22; rigid metal conduit, 344.22; flexible metal conduit, 348.22; liquidtight flexible metal conduit, 350.22; PVC conduit, 352.22; HOPE conduit, 353.22; RTRC, 355 .22; liquidtight nonmetallic flexible conduit, 356.22; electrical metallic tubing, 358.22; flexible metallic cubing, 360.22; e lectrical nonmetallic tubing, 362 .22; cellular concrete floor raceways, 372.22; cellular metal floor raceways, 374.22; metal wireways, 376.22; nonmetallic wireways, 378.22; surface metal raceways, 386.22; surface nonmetallic raceways, 388.22; underfloor raceways, 390.22; fixture wire, 402. 7; theaters, .520.6; signs, 600.31 (C); elevators, 620.33; audio signal processing,

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 300-GENERAL REQUIREMENTS FOR WIRING METHODS AND MATERIALS amplification, and reproduction equipment, 640.23(A) and 640.24; Class 1, Class 2, and Class 3 circuits, Article 725; fire alarm circuits, Article 760; and oplical fiber cables and raceways, Article 770.

(C) Support Methods. One of the following m ethods of support sh all b e used: ( 1)

300.18 Raceway Installations. (A) Complete Runs. Raceways, other than busways or exposed raceways having hinged or removable covers, shall be installed complete between outlet, junction, or splicing points prior to the installation of conductors. Where required to facilitate the installation of utilization equipment, the raceway shall be permitted to be initially installed withou t a terminating connection at th e equipment. Prewired raceway assemblies shall be permitted only where specifically permitted in this Code for the applicable wiring method.

Exce-ption: Short sections of raceways used to contain conductors or cable assemblies for protection ji-om physical damage shall not be required to be installed complete between outlet, junction, or splicing points. (B) Welding. Metal raceways shall not b e supported, terminated, or connected by welding to the raceway unless specifically designed to be or otherwise specifically permitted to b e in this

Code. 300.19 Supporting Conductors in Vertical Raceways. (A) Spacing Intervals Maximum. Conductors in vertical raceways shall be supported if the vertical rise exceeds the values in Table 300.l 9(A) . At least o ne support method shall be provided for each conductor at the top of the vertical raceway or as close to the top as practical. Intermediate supports shall b e provided as necessary to limi t supported conductor lengths to not greater than th ose values specified in Table 300.1 9(A) .

Exce-ption: Steel wire armor cable shall be supported at the top of the riser with a cable support that clamps the steel wire arm01: A safety device shall be permitted at the lower end of the riser to hold the cabl.e in the event there is slippage of the cabl.e in the wir1rarmored cabl.e support. Additional wedge-type supports shall be permitted to relieve the strain on the equipment terminals caused by expansion of the cable under load. (B) Fire-Rated Cables and Conductors. Support methods and spacing intervals for fire-rated cables a nd con ductors shall comply with any restrictions provided in the listing of the electrical circuit protective system used and in no case shall exceed th e values in Table 300.19(A) .

300.20

(2)

(3)

( 4)

Cla mping devices constructed of or employing insulating wedges inserted in the ends of the raceways. Wh ere clamping of insulation does n ot adequ ately su pport the cable, the condu ctor also sh a ll b e clamped. Inserting boxes at the required intervals in which insulating supports are installed and secured in an approved manner to withstand the weight of the conductors attached thereto, the b oxes b e ing provided with covers. In junction b oxes, deflecting the cables not less than 90 degrees a nd carrying them horizontally to a distance not less than nvice the d ia mete r of the cable, the cables being carried on nvo or more insulating supports a nd additionally secured thereto by tie wires, if desired. Where th is method is used, cables shall be supported at intervals not greater than 20 percent of the support spaci ng in Table 300.1 9(A) . Other approved means.

300.20 Induced Currents in Ferrous Metal Enclosures or Ferrous Metal Raceways. (A) Conductors Grouped Toge ther. Where conductors carrying alternating current are installe d in ferrous metal enclosures or ferrous metal raceways, they shall be arranged so as to avoid heating the surrounding ferrous metal by induction. To accomplish this, all phase condu ctors and, where used, the grounded conductor and all equipme nt grounding conductors shall be grouped together.

J,,xce-ption No. 1: Equipment grounding conductors for certain existing installations shall be permitted to be installed se-parate fmm their associated circuit conductors where run in acwrdance with the pmvisions of 250.IJ0(C). J,,xce-ption No. 2: A single conductor shall be permitted to be installed in a ferromagnetic enclosure and used for skin-effect heating in accordance with the provisions of 426.42 and 427.47. (B) Individual Conductors. Where a sing le condu ctor carrying alternating curre nt passes through metal with magnetic properties, the inductive effect sh all be minimized by (1) cutting slots in the metal between the individual holes through which the individu al conductors pass or (2) passing a ll the condu ctors in the circuit through an insulating wall sufficiently large for all of the conductors of the circuit.

Exception: In the case of circuits supplying vacuum or electric-discha1ge lighting systems or signs or X-ray apparatus, the currents carried by the

Table 300.19(A) Spacings for Conductor Supports Conductors

Conductor Size 18 AWG th rough 8 AWG 6 AWG throu gh 1/ 0 AWG 2/ 0 AWG thro ugh 4/ 0 AWG Over 4/ 0 AWG through 350 kcmil Over 350 kcm il through 500 kcmil Over 500 kcm il through 750 kcmil Over 750 kcm il

2020 Edition

NATIONAL ELECTRJCAL CODE

Aluntinumor Copper-Clad Aluminum

Support of Conductors in Vertical Raceways

m

ft

m

ft

Not greater than Not greater than Not greater than Not greater than Not greater than Not greater than Not greater than

30 60 55 41 36 28 26

100 200 180 135 120 95 85

30 30 25 18 15 12

100 100 80 60 50 40 35

Copper

11

70- 147

300.21

ARTICLE 300 -GENERAL REQUIREMENTS FOR \r\TIRING METHODS AND MATERIALS

conductors are so small that the inductive heating effect can be ignored where these conductors are placed in metal encwsures or pass through metal. I nformational Note: Because alun1inun1 is not a magnetic metal,

there will be no heating due lO hysteresis; however, induced currents wi ll be present. They will not be of sufficient magnitude to require grouping of conductors or special tream1em in passing conducmrs through aluminum wall sections.

300.21 Spread of Fire or Products of Combustion. Electrical installatio n s in hollow spaces, ve rtical shafts, and ventilation or air-handling ducts shall be made so that the possible spread of fire or products of combustion will not be substantially increased. Openings around electrical penetrations into or through fire-resistant-rated walls, partitions, floors, or ceilings shall be firestopped using approved methods to maintain the fire resistance rating. Informational Note: Direcwries of electrical construction materials published by qualified testing laborawries contain many listing installation restrictions necessary to maintain the fireresistive rating of assemblies where penetrations or openings are made. Building codes also contain restrictions on membrane penetrations on opposite sides of a fire-resistance-rated wall assembly. An example is the 600-mm (24-in. ) minimum horizontal separation that usually applies between boxes installed on opposite sides of the wall. Assisrance in complying with 300.21 can be found in building codes, fire resistance direcwries, and product listings.

300.22 Wiring in Ducts Not Used for Air Handling, Fabricated Ducts for Environmental Air, and Other Spaces for Environmental Air (Plenums). The provisions of this section shall apply to the installation and u ses of e lectrical wiring and eq uipment in ducts u sed for dust, loose stock, or vapor removal; ducts specifically fabricated for environmental air; and other spaces u sed for environmental air (plenums) . In formational Note: See Article 424, Pan VI, for duct heaters.

(A) Ducts for Dust, Loose Stock, or Vapor Removal. No wiring systems of any type shall be installed in ducts u sed to transport dust, loose stock, o r flammable vapors. No wiring system of any type shall be installed in a n y d u ct, or shaft containing only su ch ducts, used for vapor removal or for ventilation of commercialtype cooking equipment. (B) Ducts Specifically Fabricated for Environmental Air. Equipment, devices, and the wiring methods specified in this section shall be permitted within su c h ducts only if necessary for the direct action upon, or sensing of, the contained air. v\There equipment or devices are installed and illumination is necessary to facili tare maintenance a nd repair, enclosed gasketed-type luminaires shall be permitted. Only wiring methods consisting of Type MI cable witho ut an overall nonmetallic covering, Type MC cable employing a smooth or corrugated impervious meta.I sheath without an overall nonmetallic covering, electr ical metallic tubi ng, flexible metallic tubing, interm ediate metal conduit, or rigid metal conduit witho ut a n overall nonmetallic covering sh all be installed in ducts specifically fabricated to transport environmental a ir. Flexible metal conduit sh a ll be permitted, in lengths not to exceed 1.2 m ( 4 ft), to connect physically adjustable equipment and devices permitted to be in these fabricated ducts. The connectors used w ith flexible metal conduit sh all effectively close any openings in the connection.

70-148

1'.xception: Wiring methods and cabling systems, listed j(rr use in other spaces used for environmental ai:r (plenurns ), shall be pe1mitted to be installed in ducts specifically fabricated for environmental air-handling purposes under the following conditions: (1)

(2)

The wiring methods or cabling systems shall be pe1mitted only if necessary to connect to equipment or devices associated with the direct action upon or sensing of the contained aii; and The total length of such wiring methods or cabling systems shall not exceed 1.2 m (4 ft).

(C) Other Spaces Used for Environmental Air (Plenums). This section sh all apply to spaces not specifically fabricated for environmental a ir-handling purposes but used for a ir-handling purposes as a plenum. This section sh all not apply to h abitable rooms or areas of buildings, the prime purpose of which is not a ir handl ing.

Informational Note No. 1: The space over a hung ceiling used for environmental air-handling purposes is an example of the type of other space lO which this section applies. Informational Note No. 2: The phrase other spaces used for environ.mental air (j)lenurn) as used in this section correlates with the use of the term j)lenurn in NFPA 90A-2018, Standard for the Installation of Ai1°Conclilioni11g and Ventilating Systems, and other mechanical codes where the plenum is used for return air purposes, as well as some other air-handling spaces. 1'.xception: This section shall not apply to the joist or stud spaces of dwelling units where the wi-1ing passes through such spaces perpendicular to the long dimension of such spaces.

(1) Wiring Methods. The wiring methods for such other space shall be limited to totally enclosed, n onventilated, insulated busway having no provisions for plug-in connections, Type MI cable without an overall nonmetallic covering, Type MC cable witho ut an overall nonmetallic covering, Type AC cable, o r other factory-assembled multiconductor control or power cable that is specifically listed for u se within an air-handling space, or listed prefabricated cable assemblies of m etallic manufactured wiring systems without nonmetallic sheath. Other types of cables, conductors, a nd raceways shall be permitted to b e installed in electrical metallic tubing, flexible metalli c tubing, intermediate metal conduit, r igid m etal conduit without an overall nonmetallic covering, fl ex ible metal condui t, or, where accessible, surface m etal raceway or m etal wireway with metal covers. Nonmetallic cable ties and other n o nmetallic cable accessories used to secure and support cables shall b e listed as h avi ng low smoke a nd heat release properties. Informational Note: One method LO determine low smoke and heat release properties is that the nonmetallic cable ties and other nonmetallic cable accessories exhibit a maximum peak optical density of 0.50 or less, an average optical density of 0.1 5 or less, and a peak heat release rate of 100 kW or less when tested in accordance with ANSI/ UL 204~2008, Fire Jest for H eal and Visible Smoke Release for D iscrete Proclucls an.cl Their Accessories Installed in Air-Handling Spaces.

(2) Cable Tray Systems. The provisions in 300.22(C) (2) (a) or (C) (2) (b ) shall apply to the u se of metallic cable tray system s in other spaces used for environme n tal air (plenums), where accessible, as follows: (a) M etal Cable Tray Systems. Metal cable tray systems sh all be permitted to support the wiring methods in 300.22(C) (1). (b) Solid Side and Bottom M etal Cable Tray Systems. Solid side and bottom metal cable tray systems with solid metal

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 300-GENERAL REQUIREMENTS FOR WIRING METHODS AND MATERIALS covers shall be permitted to enclose wiring methods and cables, not already covered in 300.22(C)(l), in accordance with 392.l 0(A) and (B) . (3) Equipment. Electrical equipment with a metal enclosure, or electrical equipment ,'Vith a nonmetallic enclosure listed for use ,'Vithin an air-handling space and having low smoke and heat release properties, and associated wiring material suitable for the ambient temperature shall be permitted to be installed in such other space unless prohibited elsewhere in this Code. Informational Note: One mechod to determine low smoke and heat release properties is that the equipment exh ibits a maximum peak optical density of 0.50 or less, an average optical density of 0.15 or less, and a peak heat release rate of 100 kW or less when tested in accordance with ANSI/ UL 204~2013, Fire Test for Heat and Visibi£ Smoke Rei£ase for Discrete Products and Their Accessories lnstali£d in Air-Handling S/Jaces.

Exception: Integral Jan systems shall be permitted where specifically identified Jor use within an ai1°handling space. (D) Information Technology Equipment. Where the installation complies with the special requirements in 645.4, electrical ,viring in ait~handling areas beneath raised floors for information technology equipment shall be permitted in accordance ,vi th 645.5 (E) . 300.23 Panels Designed to Allow Access. Cables, raceways, and equipment installed behind panels designed to allow access, including suspended ceiling panels, shall be arranged and secured so as to allow the re moval of panels and access to the equipment. 300.25 Exit Enclosures (Stair Towers). Where an exit enclosure is required to be separated from the building, only electrical wiring methods sen,ing equipment permitted by the authority having jurisdiction in the exit enclosure shall be installed ,vithin the exit enclosure. Informational Note: For more information, refer to NFPA 101-2018, Life Safety Code, 7.1.3.2.l(l0)(b).

Part II. Requirements for over 1000 Volts, Nominal 300.31 Covers Required. Suitable covers shall be installed on all boxes, fittings, and similar enclosures to prevent accidental contact with energized parts or physical damage to parts or insulation. 300.32 Conductors of Different Systems. See 300.3(C) (2) . 300.34 Conductor Bending Radius. The conductor shall not be bent to a radius less than 8 times the overall diameter for nonshielded conductors or 12 times the overall diameter for sh ielded or lead-covered conductors during or after installation . For multiconductor or multiplexed single-conductor cables having individually shielded conductors, the minimum bending radius is 12 times the d iameter of the individually sh ielded conductors or 7 times the overall diameter, whichever is greater. 300.35 Protection Against Induction Heating. Metallic raceways and associated conductors shall be arranged so as to avoid heating of the raceway in accordance with the applicable provisions of 300.20.

2020 Edition

NATIONAL ELECTRJCAL CODE

300.50

300.37 Aboveground Wiring Methods. Aboveground conductors shall be installed in rigid metal conduit, in intermediate metal conduit, in electrical metallic n1bing, in RTRC and PVC conduit, in cable trays, in auxiliary gutters, as busways, as cablebus, in other identified raceways, or as exposed runs of metalclad cable suitable for the use and purpose. In locations accessible to qual ified persons only, exposed runs of Type MV cables, bare conductors, and bare busbars shall also be permitted. Busbars shall be perm itted to be either copper or aluminum.

1'.xception: Airfield lighting cable used in series circuits that are powered by regulators and installed in restricted ai1port lighting vaults shall be permitted as exposed cable installations. Informational Note: FAA L-824 cables installed as exposed runs within a restricted vault area are common applications.

300.38 Raceways in Wet Locations Above Grade. vVhere raceways are installed in wet locations above grade, the interior of these raceways shall be considered to be a wet location . Insulated conductors and cables installed in raceways in wet locations above grade shall comply with 310.I0(C) . 300.39 Braid-Covered Insulated Conductors - Exposed Installation. Exposed runs of braid-covered insulated conductors shall have a flame-retardant braid. If the conductors used do not have this protection, a flame-retardant saturant shall be applied to the braid covering after installation. This treated braid covering shall be stripped back a safe distance at conductor terminals, according to the operating voltage . Where practicable, this distance shall not be less than 25 mm (1 in.) for each kilovolt of th e conductor-to-ground voltage of the circuit. 300.40 Insulation Shielding. Metallic and se miconducting insulation shielding components of shielded cables shall be removed for a distance dependent on the circuit voltage and insulation. Su·ess reduction means shall be pro\lided at all terminations of factory-applied shielding. Metallic shielding components such as tapes, ,vires, or bra ids, or combinations thereof, shall be connected to an equipment grounding conductor, an equipment grounding busbar, or a grounding electrode. 300.42 Moisture or Mechanical Protection for Metal-Sheathed Cables. \-\There cable conductors emerge from a metal sheath and where protection against moisture or physical damage is necessary, the insulatio n of the conductors shall be protected by a cable sh eath terminating device. 300.45 Danger Signs. Danger signs shall be conspicuously posted at points of access to conductors in all raceway systems and cable systems. The sign (s) shall meet the requirements in 110 .21 (B), shall be readily visible, and shall state the fol lowing: DANGER- HIGH VOLTAGE-KEEP OUT 300.50 Underground Installations. (A) General. Undergrou nd conductors shall be identified for the voltage and conditions under which they are installed . Direct-burial cables shall comply ,vith the provisions of 310.I0(E) . Underground cables shall be installed in accordance with 300.50(A)(l ), (A)(2), or (A)(3), and th e installation shall meet the depth requirements of Table 300.50.

70-149

300.50

ARTICLE 300 -GENERAL REQUIREMENTS FOR \r\TIRING METHODS AND MATERJALS

Table 300.50 Minimum Cover" Requirements General Conditions (not otherwise specified) Column 1

Direct-Buried Cable.sh Circuit Voltage

Column 2

RTRC, PVC, and HDPE Conduit


I S--12 JO

0.76 1. 14

30

Damp locations

Oil-resistant thermoplastic

45

300

Damp and w·et

locations ~)TOO

300

~JTOOW'

300

Oil-resistant

Damp

thermoplastic

locations Damp and

,..,·et locati ons Hard service cord SO7

600

IS--2

2 o r more

·1·hennoset

I S--15

0.76

30

None

Oil-resistant thennoset

Pendant or portable

Extrahard

Damp locations

usage SOW' ·'

600

SOO'

600

D,unp and wet locations Oil➔·esisr.am

chermoset

All th ermosel parallel cord

All elaslOrner

SOOW' ·'

600

Sl'-1

300

20--18

Sl'-2

300

Sl'-3

300

Sl'E- 1"

300

14-9 S--2

1.14 1.52

45

Damp locations

60

Oarnpand wet locations 20--18

0.76

30

I S--16

I S--16

1.14

45

IS--10

I S--16 15-14 12 10

1.52 2.03 2.41 2.80

60

20-18

(thermo-

2 or 3

2 or 3

Thennosel

·1·herrnoplaslic

20--18

0.76

None

None

None

None

Pendanl or

portable

elastomer

Damp locations

Nol hard

Damp loca-

Nol hard

usage

Refrigeralors, room air conditionet'S, and as permiued in 422.16(B)

80 95 110

30

Pendanl or portable

tions

usage

plastic) parallel cord Sl'E-2"

300

IS--16

IS--16

1.14

45

Sl'E-3"

300

IS--10

I S--16 15-14 12 10

1.52 2.03 2.41 2.80

60 80 95 I IO

Refrigeral0l'S, room air condilionet'S, and as permiued in 422.16(B)

(conlinues)

70--254

NAT IONAL ELECTRJCAL CODE

2020 Edition

400.6

ARTICLE 400 - FLEXIBLE CORDS AND FLEXIBLE CABLES Table 400.4

Continued Nominal

Insulation Thickt1css Bra id

Trade

Type Letter

N ame

All lhermoplastic SIY(CI parallel cord Sl'l''l \\19

AWG

N umber

or

of Conducto rs

Voltage

k c.mil

300

20--18

300

2 or 3

AWG

or ln~ula tion

kcmil

nun

nl.ils

·1·hermoplastic

20--18

0.76

30

on Each Conclucto r None

Outer Covering None

Use

Pe ndant or portable

2

Damp locations

Not hard

usage

Damp and wet

locations sr,1:2

300

Sl'l"2w"

300

1&-16

2 or 3

1&-1 6

1.14

45

Damp locations Damp and

2

wet

locations S1'1'3

300

1&-10

2 or 3

1&-1 6 I !>-14 12 10

1.52 2.03 2.41 2.$0

60

Damp locations

Not hard

Portable

Damp locations

Ranges, d ryers

Pe ndant or

Damp locations

Extrahard

Refrig-

era tors, room air condicioners, and as penn itted

$0 95 110

usage

in 422. 16(1!)

Range, dryer cable

SRD

300

10--4

3 or 4

Thennoset

SRDE

300

10--4

3 or 4

Thermoplastic

I 0--4

1.14

45

None

T h ennoset

None

Th ermoplastic e lasl0me1·

e la-5to m er

SRDT

Hard servi ce cord ST'

STW'·'

300

10--4

3 or 4

Thermoplastic

600

1&-2

2 or more

Thermoplastic

1&-15 14-9 &-2

0.76 1.14 1.52

None

T h ermoplastic

30 None 45

Thermoplastic

portable

60

usage Damp and

600

wet

locations STO7

STOW'· '

Damp

Oil-resistant thermoplastic

600

locations Damp and

600

wet

loca.tions ST00 7

600

STOOl\17

600

Damp locations

Oil-r esis1.ant thermoplastic

Damp and wet

locations Vacuum cleaner

sv

300

SVE

300

1&-16

2 or 3

The nnoset

1&-1 6

0.3$

15

None

Thennoset

cord Th ennoplastic

e lasw mer

SVEO

Pe ndant o r portable

Damp location.s

Not hard usage

Thenno-plastic e lastome1-

Oil-resistant

300

thermoplastic elastorn er SVEOO

3 00

Oil-r esistant thermoplastic

svo

300

Thennoset

Oil-resisr.ant

svoo

300

O il-r esis1.ant therrnoset

Oil-resistant therrnoset

SVT

3 00

The1111opla.stic

The1111opla.stic

e lastomer thermoset

(continues)

2020 Edition

NATIONAL ELECTRJCAL CODE

70-255

400.6 Table 400.4

ARTICLE 400- FLEXIBLE CORDS AND FLEXIBLE CABLES Continued Nominal Insulation Thickness Braid

Number of Conductors

AWG

Trade N ame

or

'fyJ>C Letter

svro

Voltage

kcmil

on Each

AWG

or ln,;ulation

kcmil

mm

mils

Conductor

Use

Oil➔·esisr.am

Thermoplastic

300

Outer

Covering

thermo-

plastic

SVTOO

300

TP1.' 11

300

Oil-resistam

thermoplastic Parallel tinsel

27

2

'l'h ennoplastic

27

0.76

30

None

cord

Attached to an

Damp locaLions

Not hard

Attached to Damp locaan tions appliance

Not hard

plastic Oil➔·esisr.am

Portable, extra-hard usage

'I 'hermo-

plastic

usage

appliance

Jacketed tinsel

TST 11

300

27

2

Thermoplastic

27

0.38

15

cord Portable power

cable

vi'

2000

1- 6 12- 500 501- 1000 I

Thennoset

12- 2 1-4/ 0 250---500 501- 1000

1.52 2.03 2.41 2.80

60 80 95 110

None

Thermo-

usage

thermoset

Notes: All types listed in Table 400.4 shall have individual conductors twisted together, except for Types HPN, SP-I, SP-2, SP-3, SPE-1, SPE-2, SPE-3, SPT- 1, SPT-2, SPT-3, SPT-lW, SPT-2W, TPT, NISP-1, NISP-2, NISPT-1, N ISPT-2, NISPE-1, N ISPE-2, and three---y - solid o r 7-strnnd ( nickel or nickel-coated copper)

PAF

Perfluoro-alkoxy flexible strnnding

PAFF

( nickel or n icke I-coated copper)

Fluorinated ethylene propylene fixture wire - solid or 7-strand

PF

Fluorinated ethylene propylene

18-14

0.51

20

None

200' C (392°F)

Fixture wiring

Fluorinated ethylene propylene fixture wire

PFF

Fluorinated ethylene propylene

18-14

0.51

20

None

150 ' C (302'F)

Fixture wiring

Fluo,;nated ethylene propylene fixture wire - solid or 7-strand

PGF

Fluorinated ethyle ne propylene

18-14

0.36

14

Glass braid

200' C (392'F)

Fixture wiring

Fluo,;nated ethylene propylene fixture wire - flexible stranding

PGFF

Fluorinated ethylene propylene

18- 14

0.36

14

Glass braid

150 ' C (302°F)

Fixture wiring

Extruded polytetrafluoroethylene

18-14

0.51

20

None

250°C (482°F)

Fixture wiring

18-14

0.51

20

None

150 ' C (302' F)

Fixture wiring (silver or nickel-coated copper)

18

0.38

15

Nonmetallic

75°C (I 67'F)

Fixlure wiring

75°C (167' F)

Fixture wiring

-

flexible stranding

Extruded polytetrafluoroethylene - solid o r 7-strand (nickel or nickelcoated copper)

PTF

Extruded polytetrafluoroethylene - fie xi ble stranding 26-36 (AWG silver or nickel-coated copper)

PTFF

Extruded polytetrafluoroethylene

Heat-resistant rubber•

RFH-1

Heat-resistant

rubber

covered fixture wire -

covering

solid or 7-strand RFH-2

Heat-resistan t rubber Cross-linked synthetic polymer

18-16

0.76

30

None or non-

metallic cove1ing

( nickel or nickel-coated copper)

- limited 300 volts

t0

(continues)

2020 Edition

NATIONAL ELECTRJCAL CODE

70-261

402.6

ARTICLE 402- FIXTURE \/{IRES

Table 402.3

Continued Thickness of Insulation

Name

Heat-resistant cross-linked synthetic polymer-

Type Letter

RFHH-2* RFHH-3*

insulated fixture \Vire

Outer

Insulation

Cross-linked synthetic polymer

AWG

mm

mils

18-16 18-16

0.76 1.14

30 45

Covering

None or nonmetallic

Maximun1 Operating Temperature

Application Provisions

90°c ( 194°F)

Fixture wiring

200°c (392°F)

Fixture wiring

200°c (392°F)

Fixture wiring

covering

- solid or 7-strand Silicone insulated fixture wire - solid or 7-strand

SF-I

SF-2 Silicone insulated fixture wire - flexible stranding

SFF-1

SFF-2

Silicone rubber

18

Silicone rubber

18-12 10

0.76 1.14

30 45

Nonmetallic

Silicone rubber

18

0.38

15

Nonmetallic covering

150°c (302°F)

Fixture wiring

Silicone rubber

18-12 10

0.76 1.14

30 45

Nonmetallic

1so0 c (302°F)

Fixture wiring

0.38

15

Nonmetallic covering

covering

covering

- limited to 300 volts

- limited to 300 volts

Thermoplastic covered fixture wire -solid or 7-strand

TF*

Thennoplast.ic

18-16

0.76

30

None

60°C (140°F)

Fixture wiring

Thermoplastic covered fixture wire - fl exible stranding

TFF*

Thennoplastic

18-16

0.76

30

None

60°C (140°F)

Fixture wiring

Heat-resistant

TFN*

Thennoplastic

18-16

0.38

15

Nylonjacketed or equivalent

90°c (194°F)

Fixture wiring

TFFN*

Thennoplastic

18-16

0.38

15

Nylonjacketed or equivale nt

90°c (I 94°F)

Fixture wiring

Cross-linked polyolefin

18-14 12-10

0.76 1.14

30 45

None

1so0 c (302°F)

Fixture wiring

Cross-linked polyolefin

18-14 12-10

0.76 1.14

30 45

None

1so0 c (302°F)

Fixture wiring

thennoplastic covered fixture wire -solid or 7-strand Heat-resistant

thennoplastic covered fixture wire - fl exible stranded Cross-linked polyolefin

XF*

insulated fixture \Vire

- solid or 7-strand Cross-linked polyolefin

XFF*

insulated fixture \Vire

-

fie xi ble stranded

- limited to 300 volts - limited to 300 volts

Modified ETFE - solid or 7-strand

ZF

Modified eth ylene tetrafluoroethylene

18-14

0.38

15

None

1so0 c (302°F)

Fixture wiring

Modified ETFE flexible stranding

ZFF

Modified ethylene tetrafluoroethylene

18-14

0.38

15

None

1so0 c (302°F)

Fixture wiring

High temp. modified ETFE-solid or 7strand

ZH F

Modified eth ylene tetrafluoroethylene

18-14

0.38

15

None

200°c

Fixture wiring

(392°F)

*Insulations and outer coverings that meet the requirements of flame retardant, limited smoke, and are so listed, shall be permitted LO be marked for limited smoke after the Code type designation.

70-262

NATIONAL ELECTRJCAL CODE 2020 Edition

ARTIC LE 404-SWIT CHES Table 402.5 Ampacity for Fixture Wires Size (AWG)

metal-armored cables, wiring between switch es and o u tlets shall be in accordance with 300.20(A) . Ampacity

18 16

6 8

14

17 23

12 10

28

402.7 Number of Conductors in Conduit or Tubing. The number of fixture wires permitted in a single conduit or tubing shall not exceed the percentage fill specified in Table I , Chapter 9 . 402.8 Grounded Conductor Identification. Fixture wires that are intended to be used as grounded conductors shall be identified b y one or more continuous white stripes on other than green insulation or by the means described in 400.22(A) through (E) . 402.9 Marking. (A) Method of Marking. Thermoplastic insulated fixture wire shall be durably marked on the su rface at intervals not exceeding 610 mm (24 in. ) . All other fixture wire shall be marked b y means of a printed tag attached to the coil, reel, or carton . (B) Optional Marking. Fixtu re wire types listed in Table 402.3 shall be permitted to be surface marked to indicate special ch aracteristics of the cable materials. These markin gs include, but are not limited to, markings for limited smoke, sunlight resistance, and so forth . 402.10 Uses Permitted. Fixture wires shall be permitted ( 1) for installation in luminaires and in similar equipmen t where enclosed or protected and not subject to bending or twisting in use, or (2) fo1- connecting lumina ires to the b ranchci rcuit conductors supplying the luminaires. 402.12 Uses Not Permitted. Fixnire wires shall not be used as branch-circuit conductors except as permitted elsewhere in this Code. 402.14 Overcurrent Protection. Overcurrent protection for fixture wires shall be as specified in 240.5 .

ARTICLE 404 Switches Part I. Installation 404.1 Scope. This article covers all switches, switchi ng devices, a nd circuit breakers used as switches operating at 1000 volts and below, unless specifically referenced elsewhere in this Code for higher voltages. 404.2 Switch Connections. (A) Three-Way and Four-Way Switches. Three-way an d fourway switches shall be wired so that all switching is done only in th e ungrounded circuit conductor. Where in metal raceways or

2020 Edition

NATIONAL ELECTRJCAL CODE

404.3

Exception: Switch lo(){ls shall not require a grounded conductm:

(B) Grounded Conductors. Switches or circuit b reakers shall not disconnect the grounded conductor ofa circuit. Exception: A switch or circuit breaker shall be permitted to disconnect a grounded circuit conductor where all circuit conductors are disconnected simultaneously, or where the device is arranged so that the grounded conductor cannot be disconnected until all the ungrounded conductors of the circuit have been disconnected.

(C) Switches Controlling Lighting Loads. The grounded circuit conductor for the controlled lighting circuit shall be installed at th e location where switches con trol lighting loads that are supplied by a grounded general-purpose branch circuit serving bathrooms, hallways, stairways, and habitable rooms or occupiable spaces as defined in the applicable building code. Whe re multiple switch locations control the sam e lighting load such that the entire floor area of th e room or space is visible from the single or combined switch locatio ns, the grounded circuit conductor shall only be required at one location. A grounded conductor sh all not be required to be installed at lighting switch locations under any of the followi ng con d itions: (I )

(2)

(3) (4) (5)

\i\7here conductors en ter th e box en closing the switch

through a raceway, provided that the raceway is large enough for all contained conductors, includ ing a grounded con d ucto r \i\There the box enclosing the switch is accessible for the installation of an additional or replacem ent cable without removing finish materials Where snap switches with integral enclosures comply with 300.1 5(E) \i\There lighting in the area is controlled by auto m atic means Where a switch controls a receptacle load

The grounded conductor sh all be extended to any switch location as necessary and sh all be connected to switching devices that require line-to-neutral voltage to operate the electronics of the switch in the standby mode and sha ll meet the requirements of 404.22. Exception: The connection requirement shall become effective on J anita1y 1, 2020. It shall not apply to replacement m· retmfit switches installed in locations prior to local adoption of 404.2(C) and where the grounded conductor cannot be extended without removing finish materials. The number of electronic control switches on a branch circuit shall not exceed five, and the number connected to any feeder on the load side of a system or main bonding jumper shall not exceed 25. For the purpose of this exception, a neutral busbm; in compliance with 200.2(B) and to which a main or system bonding jumper is connected shall not be limited as to the number of electronic lighting control switches connected. Informational Note: The provision for a (future) grou nded conductor is to complete a circuit path for electron ic lighting control devices.

404.3 Enclosure. (A) General. Switches and circuit breakers sh all be of the externally operable type mounted in an e nclosure listed for the intended use. The minimum ,vire-bending space at terminals and minimum gu tter space provided in s,vitch enclosures shall be as required in 312.6.

70-263

404.3

ARTICLE 404-SYI/JTCHES

Exception No. 1: Pendant- and surface-type snap switches and knife switches mounted on an open-face switchboard or panelboard shall be permitted without enclosures.

adjacent to open switches with the following words or equivalent: WARNING- LOAD SIDE TERMINALS MAY BE l!.1VERGIZED BY BACKFEED. The warning sign or label shall wmply with II0.21(B).

Exception No. 2: Switches and circuit breakers installed in accordance with I 10.27(A)( I), (A)(2), (A)(3), or (A)(4) shall be permitted without encl.osures.

404.7 Indicating. General-use and motor-circu it switch es, circuit breakers, and molded case switches, wh ere mounted in a n enclosure as described in 404.3, shall indicate, in a location that is visible when accessing the external operating m eans, whether they are in the open (off) or closed (on) position.

(B) Used as a Raceway. Enclosures shall not be used as junction b oxes, auxiliary gutters, or raceways for conductors feeding through or tapping off to oth er switches or overcurrent devices, unless the enclosure complies with 312.8 . 404.4 Damp or Wet Locations. (A) Surface-Mounted Switch or Circuit Breaker. A surfacemounted switch or circuit breaker shall b e enclosed in a weatherproof enclosure or cabinet that complies with 312.2. (B) Flush-Mounted Switch or Circuit Breaker. A flushmounted switch or c ircuit breaker shall be eq uipped with a weatherproof cover.

\.\There these switch or c ircuit b reaker handles are operated vertically rather than rotationally or horizontally, the up position of the handle shall be the closed ( on) position . Exception No. 1: Vertically operated double-throw switches shall be permitted to be in the closed (on) position with the handl.e in either the up or down position. Exception No. 2: On busway installations, tap switches empl.oying a center-pivoting handle shall be permitted to be open or closed with either end of the handle in the up or down position. The switch position shall be cl.early indicating and shall be visible from the floor or from the usual point of operation.

(C) Switches in Tub or Shower Spaces. Switches shall not be installed within tub or shower spaces unless installed as part of a listed tub or shower assembly.

404.8 Accessibility and Grouping.

404.5 Time Switches, Flashers, and Similar Devices. Time switches, flashers, and similar devices sh a ll be of the enclosed type or shall be mounted in cabinets or boxes or equipment e nclosures. Energized parts shall be barriered to prevent operator exposure when making manual adjustments or switching.

(A) Location. All switches a nd c ircuit breakers u sed as switches shall b e located so that they may be operated from a readily accessible place . They sh all be installed su ch that the cen ter of the grip of the operating handle of the switch or circuit breaker, when in its highest position, is not more than 2 .0 m (6 ft 7 in .) ab ove the floor or working p latform.

Exception: Devices mounted so they are accessible only to qualified persons shall be permitted withoitt barriers, provided they are l.ocated within an enclosure such that any energized parts within 152 mm ( 6. 0 in.) of the manual adjustment or switch are covered by suitable barriers.

Exception No. 1: On biisway installations, fused switches and circuit breakers shall be permitted to be located at the same level as the bmway. Suitable means shall be provided to operate the handle of the device from the f/001:

404.6 Position and Connection of Switches. (A) Single-Throw Knife Switches. Single-throw knife switc hes shall be placed so that g ravity will not tend to close them . Single-throw knife switches, approved for u se in the i nverted position, shall b e provided with an integral mechanical means that ensures that the blades remain in the open position when so set. (B) Double-Throw Knife Switches. Double-throw knife switches shall be permitted to be mounted so that the throw is e ither vertical or horizontal. Vihere the throw is vertical, integral mechanical means shall be provided to hold the blades in the open position when so set. (C) Connection of Switches. Single-throw knife switches a nd switches with butt contacts sh a ll be connected su ch that their b lades are de-energized when the switch is in the open position . Bolted pressure contact switches shall have b arriers that prevent inadvertent contact with energized blades. Singlethrow knife switches, b o lted pressure contact switches, molded case switch es, switches with butt contacts, and circuit breakers u sed as switch es sh all be connected so that the terminals supplying the load are de-energized when the switch is in the open position.

Exception: The blades and terminals supplying the l.oad of a switch shall be permitted to be energized when the switch is in the open position where the switch is connected to circuits or equipment inherently capable of providing a backfeed source of powe1: For such installations, a permanent sign shall be inslall.ed on the switch enclosure or immediately

70-264

Exception No. 2: Switches and circuit breakers installed adjacent to motors, appliances, or other equipment that they supply shall be permitted to be located higher than 2. 0 m ( 6 ft 7 in.) and lo be accessible by portable means. Exception No. 3: H ookstick operable isolating switches shall be permitted al greater heights.

(B) Voltage Between Adjacent Devices. A snap switch shall not be grouped or ganged in enclosures with other snap switches, receptacles, or similar devices, unless they are arranged so that the voltage between adj acent devices does not exceed 300 volts, or unless they are installed in enclosu res equipped with identified, securely installed barriers between adj acent devices. (C) Multipole Snap Switches. A multipo le, general-u se snap switch sh all not be permitted to be fed from more than a single circuit unless it is listed and marked as a two-circuit o r threecircuit switch . Informational Note: See 210.7 for d isconnect requiremems where more than one circuit supplies a switch.

404.9 General-Use Snap Switches, Dimmers, and Control Switches. (A) Faceplates. Faceplates provided for snap switch es, dimmers, and control switches mounted in boxes a nd other enclosures shall be installed so as to complete ly cover the opening and, where the switch is flush mounted, seat against the finish ed surface.

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 404-SWITCHES (B) Grounding. Snap switches, dimmers, and control switches shall be connected to an equipment grounding conductor and shall provide a means to connect metal face plates to the equipment grounding conductor, whether or not a metal faceplate is installed. Metal faceplates shall be bonded to the equipment grounding conductor. Snap switches, dimmers, control switches, and metal faceplates shall be connected to an equipment grounding conductor using either of the following methods: (I)

(2)

The switch is mounted with metal screws to a metal box or metal cover that is connected to an equipment grounding conductor or to a nonmetallic box with integral means for connecting to an equipment grounding conductor. An equipment g rounding conductor or equipment bonding jumper is connected to an equipment grounding termination of the snap switch.

Exce-ption No. 1 to (B): Where no means exists within the enclosure for bonding to the equipment grounding conduct01; or where the wiring method does not include or provide an equipment grounding conductm; a snap switch without a connection to an equipment grounding conductor shall be permitted for replacement pwposes only. A snap switch zirired under the provisions of this exception and located within 2.5 m (8 ft) vertically, or 1.5 m (5 ft) hmizontally, of ground or exposed grounded metal objects shall be provided wi.th a faceplate of nonconducting noncombustible mate1ial with nonmetallic attachment screws, unless the switch mounting strap or yoke is nonmetallic or the circuit is protected by a ground-fault circuit inten·uptei: Exception No. 2 to (B ): Listed kits or listed assemblies shall not be required to be bonlled to an equipment grounding conductm· if all of the following conditions are met: (1)

(2) (3) ( 4)

The device is provided with a nonmetallic faceplate, and the device is designed such that no metallic face-plate replaces the one provided. The device does not have mounting means to accept other configurations offaceplates. The device is equipped with a nonmetallic yoke. All parts of the device that are accessible after installation of the faceplate are manufactured of nonmetallic materials.

404.14

with the finished surface or project from it shall be installed so that the mo unting yoke or strap of the device is seated against the box. Screws used for the purpose of attaching a device to a box shall be of the type provided with a listed device, or shall be machine screws having 32 threads per inch or part of listed assemblies or syste ms, in accordance with the manufacturer's instructions. 404.11 Circuit Breakers as Switches. A hand-operable circuit breaker equipped with a lever 01· handle, o r a power-operated circuit breaker capable of being opened by hand in the event of a power failure, shall be permitted to serve as a switch if it has the required number of poles . Informational Note: See the provisions contained in 240.81 and 240.83.

404.12 Grounding of Enclosures. Metal enclosures for switches or circuit breakers shal l be connected to an equipment grounding conductor as specified in Part IV of Article 250. Metal enclosures for switches or circuit breakers used as service equipment shall comply with the provisions of Part V of Article 250. \-\There nonmetallic enclosures are used with metal raceways or metal-armored cables, they shall comply with 314.3, Exception No. 1 or No. 2.

Except as covered in 404.9(B), Exception No. 1, nonmetallic boxes for switches shall be installed with a wiring method that provides or includes an equipment grounding conductor. 404.13 Knife Switches. (A) Isolating Switches. Knife switches rated at over 1200 amperes at 250 volts or less, and at over 1000 amperes at 251 to 1000 volts, shall be used only as isolating switches and shall not be opened under load. (B) To Interrupt Currents. To interrupt currents over 1200 amperes at 250 volts, nominal, or less, or over 600 amperes at 251 to 1000 volts, nominal, a circuit breaker or a switch listed for such purpose shall be used. (C) General-Use Switches. Knife switch es of ratings less than specified in 404.13(A) and (B) shall be considered general-use switches.

Exception No. 3 to (B): A snap switch with integral nonmetallic enclosure complying with 300.15(E) shall be permitted without a bonding connection to an equipment grounding conduct01:

Informational Note: See the definition of General-Use Switch in Article 100.

(C) Construction. Metal faceplates shall be of ferrous metal

(D) Motor-Circuit Switches. Motor-circuit switches shall be permitted to be of the knife-switch type.

not less than 0.76 mm (0 .030 in. ) in thickness or of nonferrous metal not less than 1.02 mm (0.040 in.) in thickness. Face plates of insulating material shall be noncombustible and not less than 2.54 mm (0.1 00 in.) in thickness, but they shall be permitted to be less than 2.54 mm (0.100 in.) in thickness if formed or reinforced to provide adequate mechanical strength. 404.10 Mounting of General-Use Snap Switches, Dimmers, and Control Switches.

Informational Note: See the definition of a Motor-Circuit Switch in Article 100.

404 .14 Rating and Use of Switches. Switches shall be listed and used within their ratings. Switches of the types covered in 404.l 4(A) through (E) shall be limited to the control of loads as specified accordingly. Switches used to control cord-andplug-connected loads shall be limited as covered in 404.14(F) .

(A) Surface Type. Ge neral-use snap switches, dimmers, and control switches used with open wiring on insulators shall be mounted on insulating mate rial that separates the conductors at least 13 mm(½ in.) from the surface wired over.

Informational Note No. I: For switches for signs and outline lighting, see 600.6.

(B) Box Mounted. Flush-type general-use snap switches, dimmers, and control switches mounted in boxes that are set back of the finished srn·face as permitted in 314.20 shall be installed so that the extension plaster ears are seated against the surface. Flush-type devices mounted in boxes that are flush

(A) Alternating-Current General-Use Snap Switch. Thi s form of switch shall only be used on ac circuits and used for controlling the following:

2020 Edition

NATIONAL ELECTRJCAL CODE

Informational Note No. 2: For switches controlling motors, see 430.83, 430.109, and 430.110.

70-265

404.14 (1) (2) (3) (4) (5)

ARTICLE 406- RECEPTACLES, CORD CONNECTORS, AND ATTACH MENT PLUGS (CAPS)

Resistive and inductive loads not exceeding the ampere rating of the switch at the voltage applied Tungsten-filament lamp loads not exceeding the ampere rating of the switch at 120 volts Electric discharge lamp loads not exceedi ng the marked ampere and voltage rating of the switch Motor loads not exceeding 80 percent of the ampere rating of the switch at its rated voltage Elecu·onic ballasts, seif:ballasted lamps, compact fluorescent lamps, and LED lamp loads with their associated drivers, not exceeding 20 amperes and not exceeding the ampere rating of the switch at the voltage applied

(B) Alternating-Current or Direct-Current General-Use Snap Switch. This form of switch shall be permitted on either ac or de circuits and used only for controlling the following: (1)

(2)

(3) ( 4)

Resistive loads not exceeding the ampere rating of the switch at the voltage applied. Inductive loads not exceeding 50 percent of the ampere rating of the switch at the applied voltage. Switches rated in horsepower are suitable for conu-olling motor loads withi n their rating at the voltage applied. Tungsten-filament lamp loads not exceeding the ampere rating of the switch at the applied voltage ifT-rated. Electronic ballasts, seif:ballasted lamps, com pact fluorescent lamps, and LED lamp loads with their associated drivers, not exceeding the ampere rating of the switch at the voltage applied.

(C) CO/ ALR Snap Switches. Snap switches directly connected to aluminum conductors and rated 20 amperes or less shall be marked CO/ALR.

(D) Alternating-Current General-Use Snap Switches Rated for 347 Volts. This form of switch shall not be rated less than 15 amperes at a voltage of 347 volts ac, and they shall not be readily interchangeable in box mounting with switches covered in 404.1 4(A) and (B) . These switches shall be used only for controlling any of the following: (1)

(2)

(3)

Noninductive loads other than n111gsten-filament lamps not exceeding the ampere and voltage ratings of the switch . Inductive loads not exceeding the ampere and voltage ratings of the switch. Where particular load characteristics or limitations are specified as a condition of the listing, those resu·ictions shall be observed regardless of the ampere rating of the load. Electronic ballasts, self-ballasted lamps, compact fluorescent lamps, and LED lamp loads with their associated drivers, not exceeding 20 amperes and not exceeding the ampere rating of the switch at the voltage applied.

(E) Dimmer and Electronic Control Switches. General-use d immer switches shall be used only to con u·ol permanently installed incandescent luminaires unless listed for the control of other loads and installed accordingly. Other e lectronic control switches, such as timing switches and occupancy sensors, shall be used to conu-ol permanently connected loads. They shal l be marked by thei1· manufacturer with their current and voltage ratings and used for loads that do not exceed their ampere rating at the voltage applied. (F) Cord- and Plug-Connected Loads. Where a snap switch or control device is used to control cord-and-plug-connected equipment on a general-purpose branch circuit, each snap switch or control device controlling receptacle outlets or cord

70-266

connectors that are supplied by permanently connected cord pendants shall be rated at not less than the rating of the maximum permitted ampere rating or setting of the overcu rrent device protecting the receptacles or cord connectors, as provided in 210.21 (B) . Informational Note: See 2 10.50(A) and 400. I0(A) (I) for equivalency to a receptacle outlet of a cord connector tliat is supplied by a permanently connected cord pendanL

1'.xception: Where a snap switch or control device is used to control not more than one receptacle on a branch circuit, the switch or control device shall be permitted to be rated at not less than the rating of the

receptacle. Part II. Construction Specifications

404.20 Marking. (A) Ratings. Switches shall be marked with the current, voltage, and, if horsepower rated, the maximum rating for wh ich they are designed. (B) Off Indication. Where in the off position, a switching device with a marked OFF position shall completely disconnect all ungrounded conductors to the load it controls. 404.22 Electronic Control Switches. Electronic control switches shall be listed. Electronic control swi tches shall not introduce current on the equipment grounding conductor during normal operation . The requirement to not introduce current on the equipment grounding conductor shall take effect on January 1, 2020. 1'.xception: Electronic control switches that introduce current on the equipment grounding conductor shall be permitted for applications covered by 404.2(C), 1'.xception. Electronic control switches that introduce current on the equipment grounding conductor shall be listed and marked for use in replacement or retrofit applications only.

404.26 Knife Switches Rated 600 to 1000 Volts. Auxiliary contacts of a renewable or quick-break type or the equivalent shall be provided on all knife switches rated 600 to 1000 volts and designed for use in breaking current over 200 amperes. 404.27 Fused Switches. A fused switch shall not have fuses in parallel except as permitted in 240.8. 404.28 Wire-Bending Space. The wire-bending space required by 404.3 shall meet Table 312.6(B) spacings to the enclosure wall opposite the line and load term inals.

ARTICLE406 Receptacles, Cord Connectors, and Attachment Plugs (Caps) 406.1 Scope. This article covers the rnting, type, and installation of receptacles, cord connectors, and attachment plugs ( cord caps) . 406.2 Definitions. The definitions in th is section sh all apply o nly within this article.

NAT IO NAL ELECTRJCAL CODE

2020 Edition

ARTICLE 406- RECEPTACLES, CORD CONNECTORS, AND ATTACHMENT PLUGS (CAPS)

406.4

Child Care Facility. A build ing or structure, or portion thereof, for educational, supervisory, or personal care services for more than four children 7 years old or less . Outlet Box Hood. A housing shield intended to fit over a faceplate for flush-mounted w iring devices, or an integral component of an outlet box or of a faceplate for flush-mounted wiring devices. The hood does not serve to complete the electrical enclosure; it reduces the risk of water coming in contact with e lecu·ical components within the hood, such as attachment plugs, current taps, su rge protective devices, direct plugin transformer units, or wiring devices. 406.3 Receptacle Rating and Type. (A) Receptacles. Receptacles shall be listed and marked with th e manufacturer's name or identificatio n and voltage and ampere ratings. Receptacles shall not be permitted to be recond itioned. (B) Rating. Receptacles and cord connectors shall be rated not less than 15 a m peres, 125 volts, or 15 a mperes, 250 volts, and shall be of a ty pe not suitable for use as la mp holders. Informational Nore: See 210.21 (B) for receptacle ratings where installed o n branch c ircuits.

(C) Receptacles for Aluminum Conductors. Receptacles rated 20 amperes or less and designed for the direct connection of a luminum conductors shall be marked CO/ALR.

(D) Isolated Ground Receptacles. Receptacles incorporating an isolated equipment ground ing conductor connection intended for the reduction of electromagnetic interference as permitted in 250.146(0) shall be identified by an orange triangle located on the face of the receptacle. (I) Isolated

Equipment Grounding Conductor Required. Receptacles so identified shall be used only with equipment grounding conductors that are isolated in accordance with 250.1 46( 0 ). (2) Installation in Nonmetallic Boxes. Isolated ground receptacles instal led in nonmetallic boxes shall be covered with a nonmetallic faceplate.

Exception: Where an isolated ground receptacle is installed in a nonmetallic box, a metal faceplate shall be permitted if the box contains a feature or accessory that pernzils the connection of the faceplate lo the equipment grounding conduct01: (E) Controlled Receptacle Marking. All nonlocking-type, 125volt, 15- a nd 20-ampere receptacles that are controlled by an a utomatic control device, o r that incorporate conu·ol feanires that remove power from the receptacle for the purpose of energy management or building automation, shall be permanently marked with the symbol shown in Figure 406.3(E) and the word "controlled."

Fo r receptacles controlled by an automatic control device, the marking shall be located on the rece ptacle face and visible after installation. In both cases where a m ultiple receptacle device is used, the required marking of the word "con u·olled" and symbol sh all denote which contact device(s) are controlled.

Exception: The marking shall not be required for receptacles controlled by a wall swi.tch that provide the required room lighting outlets as permitted by 210. 70.

2020 Edition

NATIONAL ELECTRJCAL CODE

Controlled

FIGURE 406.3(E)

Controlled Receptacle Marking Symbol.

(F) Receptacle with USB Charger. A 125-volt 15- or 20-ampere receptacle that additionally provides Class 2 power shall be listed and constructed such that the Class 2 circuitry is integral with the receptacle. 406.4 General Installation Requirements. Receptacle outlets shall be located in branch circuits in accordance with Part III of Article 210. General installation require men ts sh all be in accordance with 406.4(A) through (F) . (A) Grounding Type. Except as provided in 406.4(0), receptacles installed on 15- and 20-ampere branch circuits shall be of the grounding type. Grounding-type receptacles sha ll be installed only on c ircui ts of the voltage class and current for which they are rated, except as provided in 210.21 (B) (1) for single receptacles or Table 210.21 (B) (2 ) and Table 210.21 (B) (3) for two or more receptacles. (B) To Be Grounded. Receptacles and cord connectors that have equipment ground ing conductor contacts shall have those contacts connected to a n equipment grounding conductor.

Exception No. 1: Receptacles mounted on portable and vehicle-mounted generator sets and generators in accordance with 250.34. Exception No. 2: Replacement receptacles as permitted by 406.4(D). (C) Methods of Grounding. The equipment grounding conductor con tacts of receptacles and cord connectors shall be connected to the equipment g ro und ing conductor of the circuit supplying the receptacle or cord connector. Informatio nal Nore: For installation requirements for the reduction of electromagnetic inre,+eren ce, see 250.l 46(0) .

The bra nch-circuit wiring method shall include o r provide an equipment grounding con d uctor to which the equipment grounding conductor contacts of the receptacle or cord connector are connecte d . Informational Note No. I : See 250.118 for acceptable grounding mean s. Informational Note No. 2: For extensions of existing branch circuits, see 250.1 30.

(D) Replacemenls. Replacement of receptacles shall comply with 406.4(0) (1) through (D ) (7), as applicable. Arc-fault circu it-interrupter type and ground-fault circuit-interrupter type receptacles shall be installed in a readily accessible location.

(1) Grounding-Type Receptacles. vVhere a grounding mean s exists in the receptacle enclosu re or an equipment ground ing conductor is installed in accordance with 250.130(C), grounding-type receptacles shall be used a nd shall be connected to the equipment grounding conductor in accordance with 406.4(C) or 250.130(C) . (2) Non-Grounding-Type Receptacles. Where attachment to an equipment grounding condu ctor does not exist in the

70-267

406.4

ARTICLE 406- RECEPTAC LES, CORD CONNECTORS, AND ATTACH MENT PLUGS (CAPS)

receptacle enclosure, the installation shall comply with 406.4(D) (2 ) (a), (D) (2) (b), or (D ) (2) (c) . (a) A non-grounding-type receptacle (s) sh all be permitted to be replaced with another non-grounding-type receptacle (s) . (b) A non-grounding-type receptacle(s) shall be permitted to be replaced with a ground-fault circuit interrupter-type of receptacle(s) . These receptacles or their cover plates shall be ma rked "No Equipmen t Ground." An equipment grounding conductor shall not be con nected from the ground-fault circuit-interrupter-type receptacle to any outlet supplied from the ground-fault c ircuit-inte rrupter receptacle . (c) A n on-grounding-type receptacle(s) sha ll b e perm itted to be replaced with a grounding-type receptacle(s) where supplied through a ground-fault c ircuit interrupter. Where grounding-type receptacles a.r e supplied through the g roundfault circuit interrupter, grounding-type receptacles or their cover plates shall be marked "GFCI Protected" a nd "No Equipment Ground," visible after installa tio n. An e quipment grounding condu ctor shall not b e connected between the groundingtype receptacles. Informational Note No. 1: Some equipmem or appliance manufacturers require that the branch circuit lo the equipmem or appliance includes an equipmem grounding conducw,: Informational Note No. 2: See 250.114 for a list of a cord-andp lug-connected equipmem or appliances that require an equipment grounding conductor.

(7) Controlled Receptacles. Automatically controlled receptacles shall be replaced with equivalently con troll ed receptacles. If automatic control is no longer required, the rece ptacle and any associated receptacles marked in accordance with 406.3 (E) shall be replaced with a receptacle and faceplate not marked in accordance with 406.3(E) . (E) Cord- and Plug-Connected Equipment. The installation of grounding-type receptacles shall n ot b e used as a requirement that a.II cord-and plug-conn ected equipment be of the grounded type . I nformational Note: See 250. 114 for types of cord-and p lug-

connected equipment to be grounded. (F) Noninterchangeable Types. Receptacles connected to c ircuits that h ave different voltages, frequencies, or types of current (ac or de) on the sam e premises s hall be of su c h design that th e attach ment plugs u sed on these circuits are n ot interc hangeable .

406.5 Receptacle Mounting. Rece ptacles sh all be m ounted in identified boxes o r assembl ies. The boxes o r assembl ies shall be securely fastened in place unless othenvise permitted elsewhere in th is Code. Screws u sed for th e purpose of a ttaching receptacles to a box shall b e of the type provided with a listed receptacle, or shall be machine screws h aving 32 threads per inch or p art of liste d assembl ies or systems, in accordance with the manufacturer's instru ctio n s.

(3) Ground-Fault Circuit-Interrupter Protection. Ground-fault circuit-interrupte r protected receptacles shall b e provided where re placemen ts a re made at receptacle o utlets that are required to b e so protected e lsewhere in this Code.

(A) Boxes That Are Set Back. Receptacles mounted in boxes that are set back from the fin ished surface as permitted in 314.20 shall be installed such that the mounting yoke or strap of the receptacle is held rigid ly at the fini sh ed surface.

Exception: \-Wiere the outlet box size will not permit the installation of the CFC/ receptacle, the receptacle shall be permitted lo be replaced with a new receptacle of the existing type, where GFCI protection is provided and the receptacle is marked "GFCI Protected" and "No Equipment Ground," in accordance with 406.4(D)(2)(a), (D)(2)(b), or (D )(2)(c), as applicable.

(B) Boxes That Are Flush. Receptacles mounted in b oxes that are flu sh with the finished surface or p roject therefrom sha ll be installed such that the mounting yoke or strap of the receptacle is he ld rig idly against the box or box co ver.

(4) Arc-Fault Circuit-Interrupter Protection. If a receptacle outlet located in any areas specified in 210 .12(A), ( B), or (C) is replaced, a replacemen t receptacle at this outlet sh all be one of the following: (1 )

(2 ) (3)

A listed outlet bra n c h-circuit type arc-fault circuitinterrupter receptacle A receptacle protected by a listed o utlet bra n ch-circuit type arc-fault circuit-interrupter type receptacle A receptacle protected by a listed combination ty pe arcfault c ircuit-interrupter type circuit breaker

Exception: Section 210. 12(D), Exception, shall not apply to replacement ofreceptacles. (5) Tamper-Resistant Receptacles. Listed tamper-resistant receptacles shall be provided where replacements a.re made at receptacle outlets that are required to be tamper-resistant elsewhere in this Code, except where a n on-ground ing receptacle is replaced with another non-grounding receptacle. (6) Weather-Resistant Receptacles. Weather-resistant receptacles shall be provided wh ere replacements a.re made at receptacle outlets that are required to be so protected elsewhere in this Code.

70-268

(C) Re ceptacles Mounted on Covers. Receptacles mounted to and supported by a cover shall b e held rigidly against the cover by m o re than one screw or s hall be a device assembly or b ox cover listed a nd identified for securing by a single screw. (D) Position of Receptacle Faces. After installation, receptacle faces sh all be flush with or project from facepla.tes of insu lating material a nd shall project a m inimum of 0 .4 mm (0.015 in. ) from metal faceplates. Exception: Listed kits or assemblies encompassing receptacles and nonmetallic facepl.ates lhal cover the receptacle face, where the plate cannot be installed on any other receptacle, shall be permitted. (E) Receptacles in Countertops. Receptacle assemb lies for installation in countertop surfaces sh all b e listed for countertop applications. ,!\There receptacle assemblies for countertop application s are required to provide ground-fau lt ci rcui tinte rrupter protection for personnel in accordance ,vith 21 0 .8, such assemblies shall be permitted to b e listed as GFCI receptacle assemblies for countertop applications. (F) Receptacles in \fork Surfaces. Receptacle assemblies and GFCI receptacle assemblies listed for work surface or countertop ap plications sh all be per mitted to be installed in work surfaces.

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 406- RECEPTACLES, CORD CONNECTORS, AND ATTACHMENT PLUGS (CAPS) (G) Receptacle Orientation. (I) Countertop and Work Surfaces. Receptacles shall not be

installed in a face-up position in or on countertop surfaces or work surfaces unless listed for countertop or work surface applications. (2) Under Sinks. Receptacles shall not be installed in a face-up position in the area below a sink. (H) Receptacles in Seating Areas and Other Similar Surfaces. In seating areas or similar surfaces, receptacles shall n ot be installed in a face-up position unless the receptacle is any of the following:

406.9

(A) Construction of Attachment Plugs and Cord Connectors. Attachment plugs and cord connectors shall be constructed so that there are no exposed current-carrying parts except the prongs, blades, or pins. The cover for wire term inations shall be a part that is essential for the operation of a n attachment plug or connector (dead-front construction) . (B) Connection of Attachment Plugs. Attachment plugs shall be installed so that their prongs, blades, or pins are not energized unless inserted into an energized receptacle or cord connectors. No receptacle shall be insta lled so as to require the insertion of an e nergized attachment plug as its source of supply.

Part of an assembly listed as a furniture power distribution unit Part of an assembly listed either as househ old furnishings or as commercial furnishings Listed either as a receptacle assembly for countertop applications or as a CFC! receptacle assembly for countertop applications Installed in a listed fl oor box

(C) Attachment Plug Ejector Mechanisms. Attachment plug ejector mechanisms shall not adversely affect engagement of the blades of the attachment plug with the contacts of the receptacle.

(I) Exposed Terminals. Receptacles shall be enclosed so that live wiring terminals are not exposed to contact.

406.8 Noninterchangeability. Receptacles, cord connectors, and attachment plugs shall be constructed such that receptacle or cord connectors do not accept an attachment plug with a different voltage or current rating from that for which the device is intended. However, a 20-ampere T-slot receptacle or cord connector shall be permitted to accept a 15-ampere attachment plug of the same voltage rating. Non-groundingtype receptacles and connectors shall not accept groundingtype attachment plugs.

(1)

(2) (3)

( 4)

(J) Voltage Between Adjacent Devices. A receptacle shall not be grouped or ganged in enclosures with other receptacles, snap switches, or similar devices, unless they are arranged so that the voltage between adjacent devices does not exceed 300 volts, or unless they are installed in enclosures equipped with identified, securely installed barriers between adjacent devices. 406.6 Receptacle Faceplates (Cover Plates). Receptacle faceplates shall be installed so as to completely cover the opening and seat against the mounting surface.

Receptacle face plates mounted inside a box having a recessmounted receptacle shall effectively close the opening and seat against the mounting surface . (A) Thickness of Metal Faceplates. Metal face plates shall be of ferrous metal not less than 0.76 mm (0.030 in.) in thickness or of nonferrous metal not less than 1.02 mm (0.040 in. ) in thickness. (B) Grounding. Metal faceplates shall be grounded. (C) Faceplates of Insulating Material. Faceplates of insulating material shall be noncombustible and not less than 2.54 mm (0.1 0 in.) in thickness but shall be permitted to be less than 2.54 mm (0.1 0 in. ) in thickness if formed o r reinforced to provide adequate mechanical strength.

(D) Receptacle Faceplate (Cover Plates) with Integral Night Light and/ or USB Charger. A flush device cover plate that additionally provides a night light and/ or Class 2 o utput connector(s) shall be listed and constructed such that the night light and/ or Class 2 circuitry is integral with the flush device cover plate . 406.7 Attachment Plugs, Cord Connectors, and Flanged Surface Devices. All attachment plugs, cord connectors, and flanged surface devices ( inlets and outlets) shall be listed and marked with the manufacturer's name or identification and voltage a nd ampere ratings. Attachment plugs, cord connectors, and flanged surface devices sha ll not be permitted to be reconditioned.

2020 Edition

NATIONAL ELECTRJCAL CODE

(D) Flanged Surface Inlet. A flanged surface inlet shall be installed such that the prongs, blades, or pins are not energized unless an en ergized cord connector is inserted into it.

406.9 Receptacles in Damp or Wet Locations. (A) Damp Locations. A receptacle installed outdoors in a location protected from the weathe1· or in other damp locatio ns shall have an enclosure for the receptacle that is weatherproof whe n the receptacle is covered (attachment plug cap not inserted and receptacle covers closed) .

An installation suitable for wet locations shall also be considered suitable for damp location s. A receptacle shall be considered to be in a location protected from the weather where located under roofed open porches, canopies, marquees, and the like , a nd will not be subjected to a beating rain or water runoff. All 15- and 20ampere, 125- and 250-volt no nlocking receptacles sh all be a listed weather-resistant type. Informational Note: The types of receptacles covered by this requirement are identified as 5-15, 5-20, 6-15, and 6-20 in ANSI/ NEMA WO 6--2016, Wiring Devices - Dimensional Specifications.

(B) Wet Locations. ( I ) Receptacles of 15 and 20 Amperes in a Wet Location. Receptacles of 15 a nd 20 amperes, 125 and 250 volts installed in a wet locatio n shall have a n enclosure that is weatherproof whether or not the attachment p lug cap is inserted. An outlet box hood installed for this pu rpose shall be listed and shall be identified as "extra-duty." Other Listed products, e nclosu res, or assemblies providing weatherproof protection that do not utilize an outlet box hood need not be marked "extra dmy." Informational Note No. l : Requi rements for extra-duty outlet box hoods are found in ANSI/UL 5140-2016, Cover Plates for Flush-Mounted Wiring Devices. "Extra duty" identification and requirements are not applicable to listed receptacles, faceplates,

70-269

406.9

ARTICLE 406- RECEPTAC LES, CORD CONNECTORS, AND ATTACHMENT PLUGS (CAPS)

outlet boxes, enclosures, or assemblies that are identified as eitl1er being suitable for wet locations or rated as one of tl1e outdoor enclosure- type numbers of Table 110.28 that does not utilize an outlet box hood.

Exception: 15- and 20-o.mpere, 125- through 25 0-volt receptacles installed in a wet wcation and subject to routine high-pressure spray washing shall be permitted to have an enclosure that is weatherproof when the attachment plug is removed.

A terminal for connection to the grounding pole shall be designated by one of the following: (1) (2) (3)

All 15- and 2~ampere, 125- and 25~volt nonlocking-type receptacles shall be listed and so identified as the weatherresistant type. In formational Note No. 2: The configuration of weatherresistant receptacles covered by this requirement are identified as 5-15, 5-20, 6-15, and &-20 in ANSI/NEMA WD 6---2016, Wiring

(4)

Devices - Dimensional Specifications. (2) Other Receptacles. All other receptacles installed in a wet location shall comply with 406 .9 (B) (2) (a) or ( B) (2) (b) . (a) A receptacle install ed in a wet location, where the product intended to be plugged into it is not attended while in use, shall have an enclosure t hat is weatherproof with the attachment plug cap inserted or removed. (b) A receptacle installed in a wet location wh ere the product intended to be plugged into it will be attended while in use (e.g., portable tools) shall have an e nclosure that is weatherproof when the attachment plug is removed.

(C) Bathtub and Shower Space. Receptacles sh all not be installed with in a zone measured 900 mm (3 ft) h o rizontally and 2.5 m (8 ft) vertically from the top of the bathtub r im or shower stall threshold. The identified zone is all-encompassing and shall include the space directly over the tub or shower stall.

Exception: In bathrooms with less than the requi:red zone the receptacle(s) shall be permitted to be installed opposite the bathtub rim or shower stall threshold on the farthest wall within the room. (D) Protection for Floor Receptacles. Standpipes of floor receptacles shall allow floor-cleaning equipment to be operated without damage to receptacles. (E) Flush Mounting with Faceplate. The enclosure for a receptacle installed in a n outlet box flush-mounted in a finished surface shall be made weatherproof by means of a weatherproof faceplate assembly that provides a watertight connection bet\veen the plate and the finished surface. 406.10 Grounding-Type Receptacles, Adapters, Cord Connectors, and Attachment Plugs. (A) Grounding Poles (Connections). Grounding-type receptacles, cord connectors, and attachment plugs shall be provided with o ne fixed grounding pole in addition to the circuit poles. The grounding contacting pole of grounding-type plug-in ground-fault c ircuit interrupters shall be permitted to be of the movable, self-restoring type on c ircui ts operating at not over 150 volts benvee n any nvo conductors or any conductor a nd ground. (B) Grounding-Pole (Connection) Identification. Groundingtype receptacles, adapters, cord connections, and attachment plugs shall have a means for connection of an equipment grounding conductor to the g rounding pole.

70-270

A green-colored hexagonal-headed or -shaped terminal screw or nut, not readily removable. A green-colored pressure wire connector body (a wire barrel) . A similar green-colored connection device, in the case of adapters. The grounding terminal of a grounding adapter shall be a green-colored rigid ear, lug, or similar device. The equipment grounding connection shall be so designed th at it cannot make con tact with currentcarrying parts of the receptacle, adapter, or attachment plug. The adapter shall be po larized. If the terminal for the equipment grounding conductor is not visible, the conductor entrance hole shall be marked with the word green or ground, the letters G or GR, a grounding symbol, or otherwise identified by a distinctive green color. If the terminal for the equipment grounding conductor is readily removable, the area adjacent to the terminal shall be similarly marked. Informational 406.10(8 )(4) .

Note:

See

Informational

Note

Figure

Informational Note Figure 4 06.IO(B) (4) One Example of a Symbol Used to Identify the Termination Point for an Equipment Grounding Conductor. (C) Grounding Terminal Use. A grounding terminal shall not be used for purposes other than connection to the equipment grounding conductor. (D) Grounding-Pole (Connection) Requirements. Groundingtype attachment plugs and mating co,-d connectors and receptacles shall be designed such that the equipment grounding con nection is made before the cu rrent-carryin g connections. Grounding-type devices shall be so designed that ground ing poles of attachment plugs cannot be brought into contact with current-carrying parts of receptacles 01· cord connectors. (E) Use. Grounding-type attachment plugs shall be used only with a cord having an equipment grounding conductor. Informational Note: See 250.126 for identification of equipment grounding conductor terminals.

406.11 Connecting Receptacle Grounding Terminal to Box. The connection of the receptacle grounding terminal sh all comply with 250.146. 406.12 Tamper-Resistant Receptacles. All 15- and 20-ampere, 125- and 250-volt nonlocking-type t·eceptacles in the areas specified in 406.12( l ) through (8) shall be listed tamperresistant receptacles. ( 1)

(2 ) (3)

Dwelli ng units, includ ing attached and detached garages and accessory buildings to dwelling units, and common areas of multifamily dwellings specified in 210.52 and 550.1 3 Guest rooms and guest suites of hotels, motels, and their common areas Child care facilities

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 408-SV.IJTCHBOARDS, Sv.TJTCHGEAR, AND PANELBOARDS ( 4) (5)

(6)

(7) (8)

Preschools and education facilities Business office s, corridors, waiting rooms and the like in clinics, medical and dental offices, and outpatient facilities Subset of assembly occupancies described in 518.2 to include places of awaiting transportation, gymnasiums, skating rinks, and auditoriums Dormitory units Assisted living facilities

408.3

that connections are to be performed in the following sequence and that d isconnection is in the reverse sequence: (a) Equipment grounding conductor connectors (b) Grounded circuit-conductor connectors, if provided (c) Ungrounded conductor connectors Informational Note: A single-pole locking-type separable connector is investigated in accordance with ANSI/ UL 1691-20 14, Single Pole Locking-1)1" Se/Htmble Connectors.

Informational Note No. I: This requirement would include receptacles identified as 5-15, 5-20, 6-15, and 6-20 in ANSI/ NEMA WD 6-20 16, Wiring Devices - Dimensional Specifications. Informational Note No. 2: Assisted living facilities are Institutional Use Group 1-1 per IBC 2015.

Exception to (1), (2), (3), (4), (5), (6), (7) and (8): Receptacles in the foll.owing locations shall no/ be required to be lamper resi5tant: ( 1) (2) (3)

( 4)

Receptacles located more than 1. 7 m (5 1/2 ft) above the floor Receptacles that are part of a luminaire or appliance A single receptacle, or a duplex receplacl.e for two appliances, located within the dedicated space for each appliance that, in normal use, i5 not easily moved from one place lo another and that is cord-and-plug-connected in accordance with 400.JO(A)(6), (A)(7), or (A)(8) Nongnnmding receptacles used for replacements as permitted in 406. 4(D)(2)(a)

406.13 Single-Pole Separable-Connector Type. Single-pole separable connectors shall be listed and labeled and shall comply with 406.1 3(A) through (D) . (A) Locking or Latching Type. Single-pole separable con nectors shall be of either the locking or latching type and marked with the manufacturer's name or identification and voltage and ampere ratings. (B) Identification. Connectors designated for connection to the grounded circuit conductor shall be identified by a whitecolored housing; connectors designated for connection to the grounding circuit conductor shall be iden tified by a greencolored housing.

ARTICLE408 Switchboards, Switchgear, and Panelboards

Part I. General

408.1 Scope. This article covers switchboards, switchgear, and panelboards. It does not apply to equipment operating at over 1000 volts, except as specifically referenced elsewhere in the Code. 408.2 Other Articles. Switches, circuit breakers, and overcurrent devices used on switchboards, switchgear, and panel boards and their enclosures shall comply with this article and also with the requirements of Articles 240, 250, 312, 404, and other articles that apply. Switchboards, switchgear, and panelboards in hazardous (classified) locations shall comply with the applicable provisions of Articles 500 through 517. 408.3 Support and Arrangement of Busbars and Conductors. (A) Conductors and Busbars on a Switchboard, Switchgear, or Panelboard. Conductors and busbars on a switchboard, switchgear, or panelboard shall comply with 408.3(A)(l ) a nd (A)(2) as applicable.

(C) Interchangeability. Single-pole separable connectors shall be permitted to be interchangeable for ac or de use or for different current ratings or voltages on the same premises, provided they are listed for ac/ dc use and marked in a suitable manner to identify the system to which they are intended to be connected.

(1) Location. Conductors and busbars shall be located so as to be free from physical damage and shall be held fir mly in place.

(D) Connecting and Disconnecting. The use of single-pole separable connectors shall be performed by a qualified person and shall comply with at Least one of the following conditions:

J,,xception: Conductors shall be permitted lo travel h01izontally through vertical sections of switchboards and switchgear where such conductors are isolated from busbars by a bmrier.

(1)

Connection and disconnection of connectors are only possible where the supply connectors are interlocked to the source, and it is not possible to connect or disconnect connectors when the supply is energized. (2) Line connectors are of the listed seq uential-in terlocking type so that load connectors are connected in the following sequence and that discon nection is in the reverse sequence: (a) Equipment grounding conductor connection (b) Grounded circuit conductor connection, if provided (c) Ungrounded conductor connection (3) A caution notice that complies with 110.21 (B) is provided on the equipment employing single-pole separable connectors, adjacent to the line connectors, indicating 2020 Edition

NATIONAL ELECTRJCAL CODE

(2) Same Vertical Section. Other than the required interconnections and control wiring, o nly those conductors that are intended for termination in a vertical section of a switchboard or switchgear shall be located in that section .

(B) Overheating and Inductive Effects. The arrangement of busbars and conductors shall be such as to avoid overheating due to inductive effects. (C) Used as Service Equipment. Each switchboard, switch gear, or panelboard, if used as service equipment, shall be provided with a main bonding jumper sized in accordance with 250.28(0) or the equivalent p laced within the panelboard or one of the sections of the switchboard or switchgear for connecting the grounded service conductor on its supply side to the switchboard, switc hgear, or panelboard frame. All sections of a switchboard or switchgear shall be bonded together using an equipment-bonding jumper or a su pply-side

70-271

408.3

ARTICLE 408 - SWlTCHBOARDS, S\.\7JT CHGEAR, AND PANELBOARDS

bonding jumper sized in 250.102 (C) (1) as applicable.

accordance

with

250.122 or

Exception: Switchboards, switchgem; and panelboards used as service equipment on high-impedance grounded neutral systems in accordance with 250.36 shall not be required to be provided with a main bonding jumpe1: (D) Terminals. In switchboa1~ds and switchgear, load terminals for field wiring shall comply with 408.lS(C). (E) Bus Arrangement.

(I) AC Phase Arrangement. Alternating-current phase arrangement on 3-phase buses shall be A, B, C from front to back, top to bottom, or left to right, as viewed from the front of the switchboard, switchgear, or panelboard. The B phase shall be that phase having the higher voltage to ground on 3-phase , 4-wire, delta-connected systems. Other busbar arrangements shall be permitted for additions to existing installations and shall be marked.

Exception: l!.quipment within the same single section or multisection switchboard, switchgea-1; or panelboard as the meter on 3-phase, 4-wire, delta-connected systerns shall be permitted to have the same phase configuration as the rnete1ing equipment. In formational Note: See 110.15 for requirements on marking the busbar or phase conductor having the higher voltage to ground where supplied from a 4-wire, delra-conneCLed system. (2) DC Bus Arrangement. Direct-current ungrounded buses shall be permitted to be in any order. Arrangement of de buses shall be field marked as to polarity, grounding system, and nominal voltage. (F) Switchboard, Switchgear, or Panelboard Identification. A

caution sign(s) or a label(s) provided in accordance with 408.3(F)(l) through (F)(5) shall comply with 110.2l(B). (I) High-Leg Identification. A switchboard, switchgear, or panelboard containing a 4-wire, delta-connected system where the midpo int of o ne phase winding is grounded sh a ll be legibly and permanently field marked as follows: "Caution

Phase H as

Volts to Ground"

(2) Ungrounded AC Systems. A switchboard, switchgear, or panelboard containing an ungrounded ac electrical system as permitted in 250.21 shall be legibly and permanently field marked as fo llows:

"Caution Ungrounded System Operating Between Conductors"

___ Volts

(3) High-Impedance Grounded Neutral AC System. A switc hboard, switchgear, o r panel board con taining a high-impedance grounded neutral ac syste m in accordance with 250.36 shall be legibly and permanently field marked as follows:

CAUTION: HIGH-IMPEDANCE GROUNDED NEUTRAL AC SYSTEM OPERATING VOLTS BETWEEN CONDUCTORS AND MAY OPERATE VOLTS TO GROUND FOR INDEFINITE PERIODS UNDER FAULT CONDITIONS (4) Ungrounded DC Systems. A switchboard, switchgear, or panelboard containing an ungrounded de electrical system in accordance with 250.169 shall be legi bly and permanently fi eld marked as fo llows:

70-272

CAUTION: UNGROUNDED DC SYSTEM OPERATING VOLTS BETWEEN CONDUCTORS (5) Resistively Grounded DC Systems. A switchboard, switchgear, o r panelboard containing a resistive connection between current-carrying conductors and the grounding system to stabilize voltage to ground shall be legibly and permanently field marked as follows:

CAUTION: DC SYSTEM OPERATING VOLTS BETWEEN CONDUCTORS AND MAY OPERATE VOLTS TO GROUND FOR INDEFINITE PERIODS UNDER FAULT CONDITIONS (G) Minimum Wire-Bending Space. The minimum wirebending space at terminals and minimum gutter space provided in switchboards, switchgear, and panelboards shall be as required in 312.6. 408.4 Field Identification Required. (A) Circuit Directory or Circuit Identification. Every circuit and circuit modification sh all be legibly identified as to its clear, evident, and specific purpose or use. The identification shall include an approved degree of d etail that allows each circuit to be distinguished from all oth ers. Spare positions that contain unused overcurrent devices or switches shall be described accordingly. The identification shall be included in a circuit directory that is located on the face, in side of, or in an approved location adjacent to the panel door in the case of a panelboard and at each switch o r circuit breaker in a switchboard or switchgear. No circuit shall be described in a manner that depends on transient conditions of occupancy. (B) Source of Supply. All switchboards, switchgear, and panelboard s supplied by a feeder( s) in other than one- or two-family dwellings shall be permane ntly marked to indicate each device or equipment where the power originates. The label shall be permane ntly affixed, of sufficient durability to withstand the environment involved, and not handwritten . 408.5 Clearance for Conductor Entering Bus Enclosures. , f!aratus is defined in Pan Ill of Article 100.

(9) (10)

Boxes and fitt ings shall be dusttight. Optical fiber cable Types OFNP, OFCP, OFNR, OFCR, OFNG, OFCG, OFN, and OFC shall be permitted to be installed in cable trays or any raceway in accordance with 506.1 5(C) . Optical fiber cables shall be sealed in accordance with 506.1 6. (11 ) Cable bus.

506.16 Sealing. , !\There necessary to protect the ingress o f combustible dust or ig nitible fibers/ flyings, or to maintain the type of protection, seals shall be provided. The seal shall be identified as capable of preventing the ingress of combustible dust o r ignitible fibers/ flyings and maintain ing the type of protection but need not be explosion proof or flameproof.

70-407

506.17

ARTICLE 510 -

HAZARDOUS (CLASSIFIED) LOCATIONS-SPECIFIC Informational Note: See NFPA 499-2017, Recommended Practice for Lhe ClassiflcaLion of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process A,ms, for minimum ignition tern peratures of specific dusts.

506.17 Flexible Cords. Flexible cords used in Zone 20, Zone 21, and Zone 22 locatio ns shall comply with all of the following:

(l ) (2) (3) (4) (5)

Be of a type listed for extra-hard usage Contai n, in addition to the conductors of the circuit, an equipment ground ing conductor complying with 400.23 Be connected to terminals or to supply conductors in an approved manner Be supported by clamps or by other suitable mean s in such a manner to minimize tension o n the terminal connectio ns Be terminated with a listed cord connector that ma intains the protection tech nique of the terminal compartment Informational Note: For further information on construction, testing, and marking of cables, cable fittings, and cord connectors, see ANSI/ UL 2225-2013, Cables and Cable-Fillings for Use in Hazardous (Classified) Locations.

506.20 Equipment Installation. (A) Zone 20. In Zone 20 locations, o nly equipment listed and marked as suitable for the location shall be permitted. Exception: Equipment listed for use in Class II, Division 1 locations with a suitable temperature class shall be permitted.

(B) Zone 21. In Zone 21 locations, o nly equipment listed a nd marked as suitable for the location sh all be permitted. Exception No. 1: Apparatus listed for use in Class II, Division 1 locations with a suitable temperature class shall be permitted.

506.25 Grounding and Bonding. Regardless of the voltage of the elecu·ical system, ground ing and bonding shall comply with Article 250 and the requirements in 506.25(A) and (B) . (A) Bonding. The locknut-bushing and double-locknut types of contacts sh all not be depended on for bonding purposes, but bonding jumpers with proper fittin gs or other approved means of bo nding shall be used. Such means of bonding shall apply to all intervening raceways, fittings, boxes, enclosures, and so forth, be nveen Zone 20, Zone 21, a nd Zone 22 locatio ns and the point of grounding for service equipment or point of grounding of a separately derived system. Exception: The specific bonding means shall be required onl.y to the nearest point where the grounded circuit conductor and the grounding electrode conductor are connected together on the line side of the building or structure disconnecting means as specified in 250.32(B) if the branch side overcurrent protection is located on the load side of the disconnecting means. (B) Types of Equipment Grounding Conductors. Liquidtight flexible metal conduit shall include an equipment bonding jumper of the wire type in compliance with 250.1 02.

Exception: In Zone 22 locations, the bonding jumper shall be permitted to be deleted where all of the following conditions are rnet: (1)

Exception No. 2: Presswized equipment identified for Class II, Division 1 shall be permitted.

(2)

(C) Zone 22. In Zone 22 locations, only equipment listed and marked as suitable for the location shall be permitted.

(3)

Listed liquidtight flexible rnetal conduit 1.8 m (6 ft) or less in lengtJi, with fittings listed for grounding, is used. Overcurrent protection in the circuit is limited to JO amperes m· less. The load is not a power utilization load.

Exception No. 1: Apparatus listed for use in Class II, Division 1 or Class II, Division 2 locations with a suitable temperature class shall be permitted. Exception No. 2: Presswized equipment identified for Cla.~5 II, Division 1 or Division 2 shall be permitted.

(D) Material Group. Equipment marked Group nIC shall be permitted for applicatio ns requiring IIIA or nm equipment. Simila rly, equipment marked Group nm shall be permitted for applications requiring IIIA equipment. (E) Manufacturer's Instructions. Electrical equipment installed in hazardous ( classified) locations shall be installed in accordance with the insu-uctions (if any) provided by the ma nufacturer. (F) Temperature. The

temperature marking specified 506.9(C)(2)(5) shall complywith (F)(l ) or (F)(2): (I)

(2)

in

For combustible dusts, less than the lower of either the layer or cloud ignition temperature of the specific combustible dust. For organ ic dusts that may dehydrate or carbonize, the temperature ma rking shall not exceed the lower of either the ignition temperature or 165°C (329°F). For ig nitible fibers/ flyings, less than 165°C (329°F) for equipment that is not subject to overloading, or 120°C (248°F) for equipment (such as motors or power transformers) that may be overloaded.

70-408

ARTICLE510 Hazardous (Classified) Locations Specific 510.1 Scope. Articles 5ll through 5 l 7 cover occupan cies or parts of occupan cies th at are or may be hazardous because of atmospheric concentratio ns of flammable liquids, gases, or vapors, or because of deposits or accumulatio ns of materials that may be readily ig nitible . 510.2 General. The general rules of this Code a nd the provisions of Articles 500 through 504 sh all apply to e lectrical wiring a nd equipment in occupancies within the scope of Articles 511 through 517, except as such rules are modified in Articles 5 11 thro ugh 517. Where unusual conditions exist in a specific occupancy, the a uthority havingjurisdiction shall judge with respect to the application of specific rules.

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 511 -COMMERCIAL GARAGES, REPAIR AND ST ORAGE

ARTICLE 511 Commercial Garages, Repair and Storage 511.1 Scope. These occupancies sh all include locations used for service and repair operatio ns in connection with selfpropelled vehicles (including, but not limited to, passenger automobiles, buses, trucks, and tractors) in which volatile flammable liquids or flammable gases are used for fuel or power. Informational Note: Text that is followed by a reference in brackets has been extracted from NFPA 30A-2018, Code for Motor Fuel Dispensing Facilities and Repair Garages. Only editorial changes were made to th e extracted text to make it consistent with this Code.

511.3 Area Classification, General. vVhere Class I liquids or gaseous fuels are stored, handled, or transferred, electrical wiring and electrical utilization equipment shall be designed in accordance with the requirements for Class I, Division 1 or 2 hazardous (classified) locatio ns as classified in accordance with 500.5 and 500.6, and this article . A Class I location shall not extend beyond an unpierced wall, roof, or other solid partition that has no openings. [30A:8 .3.l, 8 .3 .31 Where the term "Class I" is used with respect to Zone classifications within this article of the Code, it shall apply to Zone 0, Zone 1, and Zone 2 designations. Informational Note: The term "Class I" was originally included as a prefix to Zone 0, Zone 1, and Zone 2 locations and references as an identifier for flammable gases, vapors, or liquids to differentiate from Class II and Class Ill locations. Zone 0, Zone 1, and Zone 2 only apply to flammable gases, vapors, or liquids so the "Class I" prefix is redundant and has been deleted, except for texc chat is extracted from ocher documents or co remain consistent throughout chis article.

(A) Parking Garages. Parking garages u sed for parking or storage shall be permitted to be unclassified. Informational Note: For further information, see NFPA 88A-2019, Standard for Parking Structures, and NFPA 30A-2018, Code for Motor Fuel Dispensing Facilities and Repair

Gmnges.

(B) Repair Garages, with Dispensing. Major and minor repair garages that d ispense motor fuels into the fuel tanks of vehicles, including fla mmable liquids having a flash point below 38°C (100°F) such as gasoline, or gaseous fuels such as natural gas, hydrogen, or LPG, sh all have the d ispensing functions and components classified in accordance with Table 514.3(B) (I) in addition to any classification required by this section. vVhere Class I liquids, other than foels, are dispensed, the area within 900 mm (3 ft) of any fi ll or dispensing point, extending in all directions, shall be a Class I, Division 2 location . (C) Repair Garages, Major and Minor. \'\'here vehicles using Class I liquids or heavier-than-air gaseous fuels (such as LPG) are repaired, hazardous area classification guidance is found in Table 51 l.3(C) . Informational Noce: For additional information, see NFPA 30A-2018, Code for Motor Fuel Disf1ensi11g Facilities and Repair Garages, Table 8.3.2.

(D) Repair Garages, Major. \'\There vehicles using lighter-thana ir gaseous fuels (such as hydrogen and natural gas) a re

2020 Edition

NATIONAL ELECTRJCAL CODE

511.7

repaired or stored, hazardous area classification g uidance is found in Ta ble 511.3 (D) . Informational Note: For additional information see N FPA 30A-2018, Code for Motor Fu.el Dispensing Facilities and Rej,air Garages, Table 8.3.2.

(E) Modifications to Classification.

(1) Specific Areas Adjacent to Classified Locations. Areas adjacent to classified locations in which flammable vapors are not like ly to be released, such as stock rooms, switc hboard rooms, and other similar locations, shall be unclassified where mechanically ventilated at a rate of four or m ore air changes per hour, or designed with positive air pressure, or where effectively cut off by walls or partitions. (2) Alcohol-Based Windshield Washer Fluid. The area used for storage, handling, or d ispensing into motor vehicles of alcoholbased windshield washer fluid in repair garages shall be unclassified unless othe rwise classified b y a provision of 511.3. [30A: 8 .3 .1 , Exception l 511.4 Wiring and Equipment in Class I Locations. (A) Wiring Located in Class I Locations. Within Class I locations as classified in 511.3, wiring shall conform to applica ble provisions of Article 501. (B) Equipment Located in Class I Locations. W ithin Class I locations as defined in 511.3, equ ipment sh a ll conform to applicable provisions of Article 501. (1) Fuel-Dispensing Units. Where foel..ciispensing units (other than liquid petroleum gas, which is prohibited) are located within buildings, the requirements of Article 514sha ll govern . Where mechan ical ventilation is provided in the dispensing area, the control shall be interlocked so that the d ispenser cannot operate without venti lation, as prescribed in 500.5(B) (2) . (2) Portable Lighting Equipment. Portable lighting equipment shall be equipped with handle, larnpholder, hook, and substantial guard attached to the la mpholder or handle . All exterior surfaces that might come in contact with battery terminals, wiring terminals, or other object s shall be of nonconducting material or shall be effectively protected with insulation . La mpholders shall be of an unswitched type and shall not provide means for plug-in of attachm ent plugs. T he outer shell shall be of molded composition or other sui table material. Unless the lamp and its cord are supported or arranged in such a m a nner that they cannot be used in the locations classified in 511.3, they shall be of a type identified for Class I, Division 1 locations. 511.7 Wiring and Equipment Installed Above Class I Locations. (A) Wiring in Spaces Above Class I Locations. (1) Fixed Wiring Above Class I Locations. All fixed wmng above Class I locations shall be in m etal raceways, r igid nonmetallic conduit, electrical nonmetallic tubing, fl exible metal conduit, liquidtight flexible meta l conduit, or liquidtight flexible nonmetallic conduit, or shall be Type MC, AC, MI, manufactured wiring systems, or PLTC cable in accordance with Article 725, or Type T C cable or Type ITC cable in accordance with Article 727. Cellular meta l floor raceways or cellular concrete floor raceways sha ll be permitted to be used only for

70-409

511.7

ARTICLE 511 -

COMMERCIAL GARAGES, REPAIR AND ST ORAGE

Table 51 l.3(C) Extent of Classifie d Locations for Major and Minor Repair Garages with H eavier-Than-Air Fuel Class I Location Repair garage, major (where Class I liq uids or gaseou s fue ls arc transferred or d ispensed*)

Specific areas adjacent to classified locations

Repair garage, m inor (where Class I liquids or gaseous fue ls arc not transferred or d ispensed*)

Specific areas adjacent to classified locations

Division (Group D)

Zone (Group HA)

Extent of Classified Location Entire space with in any pit, belowgradc work area, or su bfloor work area that is not ventilated Entire space with in any pit, belowgrade work area, or su bfloor work area that is p rovided with ven tilation of at least 0.3 m 3/ m in/ m 2 (1 h 3/ min/ ft 2 ) of floor area, "~th suction taken from a p oint \1~t hin 300 mm (12 in .) of floor level Up to 450 mm (18 in .) above floor level of the room, except as n oted below, for entire floor area Up to 450 mm (18 in .) above floor level of the room where room is provided with ventilation of at least 0.3 m 3 / min / m 2 (1 f t3 / min/ h 2 ) of fl oor area, with suction taken from a poin t within 300 mm (l 2 in .) of floo1· level Within 0.9 m (3 ft) of any fill or dispensing p oint, extending in all directions Areas adjacent to classified locations where flammable vapors are not likely to be released, su ch as stock rooms, S\1~tchhoard rooms, and other sim ilar locations, where m echanically ven tilated at a rate of four or more air changes per hour or designed with positive air pressure or where effectively cut off by walls o r partitions

2

2

2

2

Unclassified

U nclassificd

2

2

Unclassified

U nclassificd

2

2

Entire space with in any pit, bclowgradc work area, or subfloor work area that is not ventilated

2

2

Unclassified

Unclassified

Up to 450 mm (18 in .) above floor level, extending 0.9 m (3 ft) horizon tally in all directions from opening to any p it, belowgrade work area, or subfloor work area that is not ventilated Entire space with in any pit, bclowgrade work area, or su bfloor work area that is provided \1~ th ven tilation ofat least 0.3 m 3/ m in/ m 2 (1 ft3/ min/ ft2 ) of floor area, \1~th suction taken from a p oint \1~t hin 300 mm (12 in .) of floor level

Unclassified

Unclassified

Areas adjacent to classified locations where flammable vapors are not likely to be released, su ch as stock rooms, S\1~ tchhoard rooms, and other sim ilar locations, where mechanically ven tilated at a rate of four or more air changes per hour or designed with positive air pressure, or where effectively cut off by walls or partitions

*Includes draining of Class I liquids from vehicles.

supplying ceiling outlets or extensions to the area below the floor, but such raceways sh al l h ave n o connections leading into or t h rou gh any C lass I location ab ove the floor.

(2) Pendant. For pen dants, flexible cord suitable for the type of service and listed for hard usage shall be used . (B) Electrical Equipment Installed Above Class I Locations. (1) Fixed Electrical Equipment. Electrical equipmen t in a fixed position sh all b e located above th e level of any defi ned C lass I location or shall be identified for the location. (a) Arcing l!.quiprnent. Eq uipmen t th at is less th an 3 .7 m (12 ft) ab ove the floor level and that may p rodu ce arcs, spa rks,

70-410

or particles of hot metal, su ch as cutouts, switches, charging panels, generators, motors, or oth er equip m ent (exclu ding receptacles, lamps, a n d lamph o lders) having m ake-and-break or slid ing contacts, shall be of the totally enclosed type or con structed so as to preven t th e escape of sparks or h ot metal particles. (b) Fixed Lighting. La m ps and la m p ho lders for fixed ligh ting that is located over lanes t h i-ou gh which vehicles are com monly driven or that may otherwise be exposed to physical damage shall b e located not less th an 3.7 m (12 ft) a bove fl oor level, unless of the totally enclosed type or constructed so as to preven t escape of sparks or hot metal particles.

NAT IONAL ELECTRJCAL CODE

2020 Edition

513.1

ARTICLE 513-AIRCRAFT HANGARS Table 511.3(D) Extent of Classified Locations for Major Repair Garages with Lighter-than-Air Fuel Class I Location

Division

2

2

Zone 3

Extent of Classified Location

2

Within 450 mm (18 in.) of ceili ng, except as noted below v\/ithin 450 mm (l 8 in .) of ceili ng where ventila tion ofat least 0.3 m3/ min/ m2 (1 f t3 / min/ ft2 ) of floor area, with suction taken from a poin t with in 450 mm (18 in .) of the h ighest poin t in the ceiling Areas adjacent to classified locations where flammable vapors arc not likely to be released, such as stock rooms, switchboard rooms, and other similar locations, where mechanically ventilated a t a rate of four or more air changes p er hour or designed with positive air pressure, or where effectively cut off by walls or partitions

Repair garage, major (where ligh ter-than-air gaseous fueled ' vehicles are repaired or stored)

Unclassified

Unclassified

Specific areas adjacent to classified locations

Unclassified

Unclassified

1

Includes fuels such as hydrogen and natural gas, but not L PG. For hydrogen (lighter than air) Group B, or natural gas Group D. ' For hydrogen (lighter than air) Group IIC or IIB+H2, or natural gas Group IIA. 2

511.8 Underground Wiring Below Class I Locations. Undergrou nd wiring shall be installed in threaded rigid m etal condu it or intermediate m etal con d uit.

511.12 Ground-Fault Circuit-Interrupter Protection Personnel. Ground-fault circwt-111terrupter protection personnel shall be provided as required in 2 10 .S(B) .

Exception: Type PVC conduit, Type R TRC conduit, and Type HDPE conduit shall be permitted where lnnied under not less than 600 mm (2 ft) of cove,: Where Type PVC conduit, Type R TRC conduit, or Type HDPE conduit is used, threaded rigid metal conduit or threaded steel intermediate metal conduit shall be used for the last 600 mm (2 ft) of the underground run to emergence or to the point of connection to the aboveground raceway, and an equipment grounding conductor shall be included to provide elect1ical continuity of the raceway system and for grounding ofnon-current-canying metal parts.

511.16 Grounding and Bonding Require ments.

511.9 Sealing. Seals complying wi th the req uirem ents of 501.1 5 and 501.15( B)(2) shall b e provided and shall apply to horizontal as well as vertical bou ndaries of th e defined Class I locations. 511.10 Special Equipment. (A) Battery Charging Equipment. Battery chargers and their control equip me nt, and batteries being ch arged, sh all not be located with in locatio ns classified in 511.3 . (B) Electric Vehicle Charging Equipmen t. (1) General. All electrical equi pment and w1 rmg shall be installed in accordance with Article 625, except as noted in 511.10(B)(2) and (B)(3) . Flexible cords shall b e ofa type identified for extra-hard usage.

for for

(A) Gen eral Grounding Requirements. All m etal raceways, th e metal armor or m etallic sh eath o n cables, and all n on-cu rren tcarrying metal parts of fi xed or portable electrical equi pmen t, regardless of voltage, sh all b e grou nded. (B) Supplying Circuits with Grounded and Grounding Conductors in Class I Locations. Ground ing in Class I locatio n s sh all com p ly with 501.30.

(1) Circuits Supplying Portable Equipment or Pendants. Wh ere a circu it supp lies porta bles o r pendan ts and inclu des a grou nded con ductor as provided in Article 200, receptacles, attachmen t plugs, connectors, and sim ilar devices sh all be of the grou nding type, a n d t he grounded condu ctor of th e flexible cord sh all be conn ected to th e screw shell of any lampholder o r to the grounded term inal of any u tilization equi pm ent supplied. (2) Approved Means. Approved m eans shall b e provided for maintaining continuity of the equip ment grou nding con ductor b etween the fixed wiring system a n d the non-current-carrying metal portion s of pendant lumina ires, portable lum inaires, and portable utilization equipment.

(2) Connecto r Location. No connector shall be located with in a Class I locatio n as defined in 511.3 . (3) Plug Connections to Vehicles. Where th e cord is suspended from overhead, it shal l be arranged so t hat the lowest point of sag is at least 150 mm (6 in .) above the fl oor. Where an automatic arrangement is provided to pull b oth cord and p lug b eyond the range of physical damage, no additional connector shall be required in the cable or at the outlet.

2020 Edition

NATIONAL ELECTRJCAL CODE

ARTICLE513 Aircraft Hangars 513.1 Scope. T h is article sh all apply to buildings or strucnires in any part of which a ircraft con tai ning Class I (flam mable)

70-411

513.3

ARTICLE 513 -AlRCRAIT HANGARS

liquids or Class II (combustible) liquids whose temperanires are above their flash points a1·e housed or stored and in which aircraft might undergo service, repairs, or alterations. It shall not apply to locations used exclusively for aircraft that have never contained fuel or unfueled aircraft. Informational Note No. I: For definitions of aircraft hangar and unfueled aircraft, see NFPA 409-2016, Standard on Aircraft Hangars. Informational Note No. 2: For further information on fuel classification see NFPA 30-2018, Flammable and Combustible Liquids Code.

513.3 Classification of Locations. Where the term "Class I" is used with respect to Zone classifications within this article of the Code, it shall apply to Zone 0, Zone 1, and Zone 2 designations. Informational Note: The term "Class I" was originally included as a prefix to Zone 0, Zone 1, and Zone 2 locations and references as an identifier for flammable gases, vapors, or liquids to differentiate from Class I I and Class Ill locations. Zone 0, Zone I, and Zone 2 only apply to flammable gases, vapors, or liquids so the "Class I" prefix is redundant and has been deleted, except for text that is extracted from other documents or to remain consistent throughout this article.

513.4 Wiring and Equipment in Class I Locations. (A) General. All wiring and equipment that is or may be installed or operated within any of the Class I locations defined in 513.3 shall comp ly with the applicable provisions of Article 501 or Article 505 for the d ivision oir zone in wh ich they are u sed. Attach ment plugs and receptacles in Class I locations shall be identified for Class I location s or shall be designed such that they cannot be energized while the connections are being made or broken . (B) Stanchions, Rostrums, and Docks. Electrical wmng, outlets, and equipment (including lamps) on or attached to stanch ions, rostrums, or docks th at a1·e located or likely to be located in a Class I location, as defined in 513.3(C), shall comply with the applicable provisions of Article 501 or Article 505 for the division or zone in which they are used.

513.7 Wiring and Equipment Not Installed in Class I Locations. (A) Fixe d Wiring. All fixed wiring in a hangar but not installed in a Class I location as classified in 5 13.3 shall be installed in metal raceways or shall be Type MI, T C, or MC cable.

(A) Below Floor Level. Any pit or depression below the level of the hangar floor shall be classified as a Class I, Division l or Zone l location that shall extend up to said floor level.

l'.xception: Wiring in unclassified locations, as described in 513.3(D), shall be permitted to be any suitable type wiring method recognized in Chapter 3.

(B) Areas Not Cut Off or Ventilated. The entire area of the hangar, including any adjacent and communicating areas not suitably c ut off from the hangar, shall be classified as a Class I, Division 2 or Zone 2 location up to a level 450 mm (18 in.) above the floor.

(B) Pendants. For pendants, flexible cord suitable for the type of service and identified for hard usage or extra-hard usage shall be used. Each such cord shall include a separate equipment grounding conductor.

(C) Vicinity of Aircraft.

(1) Aircraft Maintenance and Storage Hangars. The area within 1.5 m (5 ft) horizontally from aircraft power plants or aircraft fuel tanks shall be classified as a Class I, Division 2 or Zone 2 location that shall extend upward from the floor to a level 1.5 m (5 ft) above the upper surface of wings and of engine enclosures. (2) Aircraft Painting Hangars. The area within 3 m (10 ft) horizontally from aircraft surfaces from the floor to 3 m (10 ft) above the aircraft shall be classified as Class I, Division l or Zone l. The area horizontally from aircraft surfaces between 3.0 m (10 ft) and 9.0 m (30 ft) from the floor to 9.0 m (30 ft) above the aircraft surface shall be classified as Class I, Division 2 o r Zone 2. Informational Note: See NFPA 33-2015, Standard for Spray Aj,J,/ication Using Flammable or Corn.btistible Materials, for information on ventilation and grounding for static protection in spray painting areas.

(D) Areas Suitably Cut Off and Ventilated. Adjacent areas in which flammable liquids or vapors are not likely to be released, such as stock rooms, electrical control rooms, and other similar locations, shall be unclassified where mechanically ventilated at a rate of four or more air changes per hour, or designed with positive air pressure, or where effectively cut off from the hangar itself by walls or partitions.

70-412

(C) Arcing Equipment. I n locatio ns above those described in 513.3, equipment that is less than 3.0 m (IO ft) above wings a nd engine enclosu res of a ircraft and that may produce arcs, sparks, o r particles of hot metal, such as lamps and lampholders for fixed lighting, cutouts, switches, receptacles, charging panels, generators, motors, or other equipment having makeand-break or sliding contacts, shall be of the totally enclosed type or consu·ucted so as to prevent the escape of sparks or hot metal particles . l'.xception: Equipment in areas described in 513.J(D) shall be permitted lo be of the general-purpose type.

(D) Lampholders. lampholders of metal-shell, fiber-lined types sh all not be used for fixed incandescent lighting . (E) Stanchions, Rostrums, or Docks. Where stanchions, rostrums, or docks are not located or likely to be located in a Class I location , as defined in 513.3(C), wiring and equipment shall comply with 513.7, except that suc h wiring and equipment not more than 457 mm (18 in .) above the floor in any position shall comply with 513.4(B) . Receptacles and attachment plugs shall be of a locking type that will not readily disconnect.

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 513-AIRCRAFT HANGARS (F) Mobile Stanchions. Mobile stanch ions with electrical equipment complying with 5 13.7(E) shall carry at least one permanently affixed warn ing sig n with the following words or equivalent:

WARNING KEEP 5 FT CLEAR OF AIRCRAFf ENGINES AND FUEL TANK AREAS or WARNING KEEP 1.5 METERS CLEAR OF AIRCRAFT ENGINES AND FUEL TANK AREAS

(C) External Power Sources for Energizing Aircraft.

(1) Not Less Than 450 mm (18 in.) Above Floor. Aircraft energizers shall be designed and mounted such that all elecu·ical equipment and fixed wiring will be at least 450 mm (18 in. ) above floor level and sh all not be operated in a Class I locatio n as defined in 513.3(C) . (2) Marking for Mobile Units. Mobile energizers shall carry at least o ne permanently affixed warning sign with the following words or equivalent:

WARNING KEEP 5 FT CLEAR OF AIRCRAFf ENGINES AND FUEL TANK AREAS

513.8 Underground Wiring. (A) Wiring and Equipment Embedded, Under Slab, or Underground. All wiring installed in or under the h angar floor shall comply with the requirements for Class I, Division l locatio ns. \.\'here such wiring is located in vaul ts, pits, or ducts, adequate drainage shall be provided. (B) Uninterrupted Raceways, Embedded, Under Slab, or Underground. Uninterrupted raceways that are embedded in a hangar floor or buried beneath the hangar fl oor shall be considered to be within the C lass I location above the floor, regardless of th e point at which the raceway descends be low or rises above the fl oor. 513.9 Se aling. Seals shall be provided in accordance with 501.15 or 505.1 6, as applicable. Sealing requirements specified shall apply to horizontal as well as to vertical boundaries of the defined Class I locations. 513.10 Special Equipment. (A) Aircraft Electrical Systems.

or WARNING KEEP 1.5 METERS CLEAR OF AIRCRAFf ENGINES AND FUEL TANK AIU:AS (3) Cords. Flexible cords for a ircraft e nergizers and ground support equipment shall be identified for the type of service and exu·a-hard usage and shall include an equipment grounding conductor. (D) Mobile Servicing Equipment with Electrical Components.

(1) General. Mobile servicing equipment (such as vacuum cleaners, air compressors, air movers) having electr ical wiring and equipment not suitable for Class I , Divisio n 2 or Zone 2 locatio ns shall be so designed and mo unted that all such fixed wiring and equipme nt will be at least 450 mm (18 in. ) above the floo r. Such mobile equipment shall not be operated within the Class I location defined in 513.3(C) an d shall carry at least one permanently affixed warning sign with the following words or equivalent:

(1) De-energizing Aircraft Electrical Systems. Aircraft electrical systems shall be de-energized whe n the aircraft is stored in a hangar a nd, whenever possible, while the a ircraft is undergoing ma intenance. (2) Aircraft Batteries. Aircraft batteries shall no t be charged where installed in an a ircraft located inside or partially inside a hangar. (B) Aircraft Battery Charging and Equipment. Battery chargers and their control equipment shall not be located or operated within any of the C lass I locations defined in 513.3 and shall preferably be located in a separate building o r in an area such as defined in 513.3(0 ) . Mobile charge rs shall carry at least one permanently affixed warn ing sign with the following words or equivalent:

WARNING KEEP 5 FT CLEAR OF AIRCRAFT ENGINES AND FUEL TANK AREAS or WARNING KEEP 1.5 METERS CLEAR OF AIRCRAFT ENGINES AND FUEL TANK AREAS Tables, racks, trays, and wiring shall not be located within a Class I location a nd, in addition, shall comply with Article 480.

2020 Edition

NATIONAL ELECTRJCAL CODE

513.10

WARNrNG KEEP 5 FT CLEAR OF AIRCRAFf ENGINES AND FUEL TANK AREAS or WARNrNG KEEP 1.5 METERS CLEAR OF AIRCRAFfENGINES AND FUEL TANK AREAS (2) Cords and Connectors. Flexible cords for mobile equipment shall be suitable for the type of service and identified for extra-hard usage a nd shall include an equipment grounding conductor. Attachment plugs and receptacles shall be identified for the location in which they a re installed and shall provide for connectio n of the equipment grounding conductor. (3) Restricted Use. Equipment that is not identified as suitable for Class I, Division 2 locations shall not be operated in locatio ns wh ere mainte na nce operations likely to release flammable liquids or vapors are in progress.

(E) Portable Equipment. (1) Portable Lighting Equipment. Portable lighting equipment that is used within a hangar shall be identified for the location in which they are used. For portable lumi naires, fl exible cord suitable for the type of service and identifi ed for extra-hard u sage shall be used. Each such cord sha ll include a separate equipment grounding conductor.

70-413

513.10

ARTICLE 514-MOTOR FUEL DISPENSING FACILITIES

(2) Portable Utilization Equipment. Portable utilization equipment that is or may be used within a hangar shall be of a type suitable for use in Class I, Division 2 or Zone 2 locations. For portable utilization equipmen t, flexible cord suitable for the type of service and approved for extra-hard usage shall be used. Each such cord shall include a separate equipment grounding conductor. 513.12 Ground-Fault Circuit-Interrupter Protection Personnel. Ground-fault circu1t-111terrupter protection personnel shall be provided as required in 210.S(B) .

for for

513.16 Grounding and Bonding Requirements. (A) General Grounding Requirements. All metal raceways, the metal armor or metallic sheath on cables, and all 11011-currentcarrying metal parts of fixed or portable electrical equipment, regardless of voltage, shall be grounded. Grounding in Class I locations shall comply with 501.30 for Class I, Division 1 and 2 locations and 505.25 for Zone 0, 1, and 2 locations. (B) Supplying Circuits with Grounded and Equipment Grounding Conductors in Class I Locations.

differemiace from Class II and Class In locations. Zone 0, Zone 1, and Zone 2 only apply to flammable gases, vapors, or liquids so the "Class I" prefix is redundant and has been deleted, except for text that is extracted from other documents or to remain consistent throughout this article.

[See Figure 514.3.J (A) Unclassified Locations. Where the authority having jurisdiction can satisfactorily determine that flammable liqu ids having a flash point below 38°C (100°F), such as gasolin e, will not be handled, such location shall not be required to be classified. (B) Classified Locations. [See Figure 514.3(B) .J

(1) Class I Locations. Table 5 14.3(B)(l) shall be applied where Class I liquids are stored, handled, or dispensed and shall be used to delineate and classify motor foe! d ispensing facilities and commercial garages as defined in Article 511. Table 515.3 s hall be used for the pm-pose of delineating and classifying aboveground tanks. A Class I location shall not extend beyond an unpierced wall, roof, or other solid partition. [30A:8.1 , 8.2, 8.31

(1) Circuits Supplying Portable Equipment or Pendants. Where a circuit supplies portables or pendants and includes a grounded conductor, receptacles, attachment plugs, connectors, and similar devices shall be of the grounding type, and the grounded conductor of the flexible cord shall be connected to the screw shell of any lampholder or to the grounded terminal of any utilization equipment s upplied. (2) Approved Means. Approved means shall be provided for maintaining continuity of the equipment grounding conductor benveen the fixed wiring system and the non-current-carrying metal portions of pendant luminaires, portable luminaires, and portable utilization equipment.

0.5 m (18 in.)~

0.5m (18in.)

ARTICLE 514 Motor Fuel Dispensing Facilities

21 ~

j-6 m (20ft)

514.1 Scope. This article shall apply to motor fuel dispensing facilities, marine/motor foe! dispensing facilities, motor foe! d ispensing facilities located inside buildings, and fleet vehicle motor fuel dispensing facilities. Informational Note No. I: For li.irther information regarding safeguards for motor fuel dispensing facilities, see NFPA 30A-2018, Code for Molor Fu.el Dispensing Facililies and Repair Garages.

Below grade sump -

-

--

-"'

~

/ I

Informational Note No. 2: Text that is followed by a reference in brackets has been extracted from NFPA 30A-2018, Code for Molor Fuel Dispensi.ng Facililies and Repair Garages. Only edito rial changes were made to the extracted text to make it consistent with chis Code.

514.3 Classification of Locations. \/\There the term "Class I" is used with respect to Zone classifications within this article of the Code, it shall apply to Zone 0, Zone 1, and Zone 2 designations. Informational Note: The term "Class I" was originally included as a prefix to Zone 0, Zone 1, and Zone 2 locations and references as an identifier for flammable gases, vapors, or liquids to

70-414

'-- ~ Im Class I, Div. 2 or Class I, Zone 2 D Class I, Div. 1 or Class I, Zone 1

Note: Not to scale.

FIGURE 514.3 Classified Areas Adjacent to Dispensers. [30A: Figure 8.3.2(a)] NAT IO NAL ELECTRJCAL CODE

2020 Edition

514.3

ARTICLE 514-MOTOR FUEL DISPENSING FACILITIES

~

~,

..

~ "~ ,,

/ Dispenser Class I Division 2 or Class I, Zone 2

rw~ 0.5m

~

:L"=

f--- 6 m (20 ft) - - - - -

6 m (20 ft)

-W28~ 6 m (20 ft)

------..J

Note: Not to scale.

FIGURE 514.3(B)

Classified Areas Adjacent to Dispenser Mounted on Aboveground Storage Tank. [30A: Figure 8.3.2(b)]

(2) Compressed Natural Gas, Liquefied Natural Gas, and Liquefied Petroleum Gas Areas. Table 514.3(B) (2) shall be used to delineate and classify areas where CNG, LNG, compressed or liquefied h ydrogen, LP-Gas, or combinations of these, are dispensed as motor veh icle fuel s along with Class I or Class II liquids that are also dispensed as motor veh icle fuels. [30A:12.l l

Where CNG or LNG dispensers are installed beneath a canopy or enclosure, either the canopy or enclosure shall be designed to prevent accumulation or entrapment of ignitible vapors or all electrical equipment installed beneath the canopy or enclosure shall be suitable for Class I, Division 2 hazardous ( classified) locations. [30A:l 2.4 l

Dispensing devices for LP-Gas shall be located as follows: (l)

(2)

At least 3 m (10 ft) from any dispensing device for Class I liquids At least 1.5 m (5 ft) from any dispensing device for Class I liquids where the following conditions exist: a. The LP-Gas deliver nozzle and filler valve release no more than 4 c m 3 (0.1 oz) of liquid upon d isconnection. b. The fixed maximum liquid level gauge remains closed during the entire refueling process. [30A:I2.5.2l Informational Note No. I: Applicable requirements fo r dispensing devices for LP-Gas is found in NFPA 58-2017, Liquefied Petr1>le11 rn Gas Code. Informational Note No. 2: For information on classified areas pertaining to LP-Gas systems other than residential or commercial, see NFPA 58-201 7, Liquefied Petroleum Gas Code, and NFPA 59-2018, Utility LP-Gas Plant Code. Informational Note No. 3: See 514.3(C) for motor fuel dispensing stations in marinas and boatyards.

2020 Edition

NATIONAL ELECTRJCAL CODE

70-415

514.3

ARTICLE 514-

Table 514.3(B)(l) Qass I Locations Location

MOTOR FUEL DISPENSING FACILITIES

Motor Fuel Dispensing Facilities

Division (Group D)

Zone (Group IIA)

Dispensing Device (except Overhead Type) 2• 3 Under dispenser containmen t

Disp enser

2

2

Outdoor

2

2

Indoor - with mechanical ventilation

2

2

- with gravity ventilation

2

2

Dispensing Device - Overhead Type•

2

2

2

2

Remote Pmnp O utdoor

2

2

2

2

Indoor

Sales, Storage, Rest Rooms includ ing structures (such as the attendant's kiosk ) on or adjacent to dispensers

1

2

2

2

2

unclassified

unclassified

]

]

2

2

Tank, Aboveground Inside tank Shell, ends, roof; d ike area

Vent

0

2

2

2

2

1

1

2

2

Extent of Classifie d Location1

En tire space within and u nder d ispenser pit or containment Within 450 mm ( 18 in .) of disp enser enclosure or that portion of disp enser enclosure contain ing liquidhandling components, extending ho1izontally in a ll directions and down to grade level Up to 450 mm (18 in .) above grade level, extending 6 m (20 ft) ho1i zontally in a ll d irections from dispenser enclosure Up to 450 mm (18 in.) above floor level, extending 6 m (20 ft) ho1i zontally in all directions from dispenser enclosure Up to 450 mm (18 in .) above floor level, extending 7.5 m (25 ft) ho1i zontally in all directions from dispenser enclosure Space within disp enser enclosure and all electrical equipment integral with dispensing hose or nozzle Within 450 m m ( 18 in .) of disp enser enclosure, extending horizontally in all directions and down to grade level Up to 450 mm (18 in .) above grade level, extending 6 m (20 ft) ho1i zontally in a ll d irections from a point vertically below edge of dispenser enclosure En tire space within any pit or box below grade level, any part of which is within 3 m (10 ft) horizontally from any edge of p ump v\/ithin 900 mm (3 ft) of any edge of pump, extending horizontally in all d irections Up to 450 mm (18 in .) above grad e level, extending 3 m (JO ft) ho1i zontally in all directions from any edge of pump En tire space withi n any pit Within 1.5 m (5 ft) of any edge o f pum p, exten ding in all d irections Up to 900 mm (3 ft) above floor level, extending 7.5 m (25 ft) ho1i zontally in a ll direction s from any edge of pump Except as noted below En tire volume, if there is any o pening to room with in t he exten t ofa Division 1 or Zone I location En tire volume, if t here is any opening to room \\~th in t he exten t ofa Division 2 or Zone 2 location Entire inside volume En tire space withi n d ike, wh ere d ike heigh t exceed s d istance from tank sh ell to inside of d ike wall for more than 50 percent of tank circumference En tire space within d ike, wh ere d ike heigh t does not exceed d istance from tank shel I to inside of dike wall for more than 50 percent of tank circumference Within 3 m (] 0 ft) of shell, ends, or roof of tank Within 1.5 m (5 ft) of open end of vent, extending in all directions Be tween l .5 m and 3 m (5 ft and 10 ft) from open end of vent, extending in a ll directions (conlinues)

70-416

NAT IONAL ELECTRJCAL CODE

2020 Edition

514.3

ARTICLE 514-MOTO R FUEL DISPENSING FACILITIES Table 514.3(B)(l )

Continued

Location

Division (Group D)

Zone (Group IIA)

Extent of Classified Location'

1 l

0

2

2

1

1

2

2

Entire inside volume Entire space with in any pit or box below grade level, any part of wh ich is with in a Division 1 or Division 2 classified location or within a Zone 1 or Zone 2 classified location Up to 450 mm (]8 in .) above grade level, extending 1.5 m (5 fi.) horizontally in all directions from any Light-fill connection and extending 3 m (10 ft) ho1i zontally in all d irections from any loose-fi ll connection Within 1.5 m (5 ft ) of open end of vent, extendi ng in a ll directions Between 1.5 m and 3 m (5 ft and l Oft) from open end of vent, extending in all directions

Tank, Unde rgr0tmd Inside tank Fill Opening

Vent

Vapor Processing System Pits

Eq uipment in p rotective enclosures Eq uipment not with in protective enclosure

2

2

2

2

2

2

2

2

2

2

2

2

1

1

- EquipmcnL enclosu re

- Vacuum assist blower

Vault

Entire space with in any pit or box below grade level, any part of wh ich : (]) is with in a Division l or Division 2 classified location; (2) is within a Zon e l or Zone 2 classified location; (3) hou ses any equipment used to transfer or process vapors Entire space with in enclosure Within 450 mm (18 in .) of equipment contain ing flamm able vapors or liquid, extending horizontally in all d irections and down to grade level Up to 450 mm (]8 in .) above grade level with in 3 m (JO ft) horizomally of the vapor p rocessing equipment Entire space with in enclosure, if fl am mable vapor or liq uid is present under normal o perati ng conditions Entire space with in enclosure, if fl am mable vapor or liq uid is not presen t under norm al operating conditions Within 450 mm (18 in .) of blower, extending horizontally in all directions and down to grade level Up to 450 mm (18 in .) above grade level, extending 3 m (10 ft) horizontally in all d irections Entire interior space, if Class I liquids arc sLOrcd with in

1

For marine application, grade level means the surface of a p ier, extending down to water level. 2 Refer to Figure 514.3 and Figure 514.3( 8 ) for an ill ustration of classified location around dispensing devices. ' Area classification inside the d ispenser enclosure is covered in UL 87, Standard/or Power-O/iemled Disjiensing Devices for Petroleum Producls. ''Ceiling-mounted hose reel. [30A:Table 8.3.l ]

Table 514.3(B)(2) Electrical Equipment Classified Areas for Dispensing Devices Extent of Classified Area Dispensing Device

Class I, Division I

Compressed natural gas (CNG)

Entire space with in the dispenser enclosure

Liq uefied natural gas (LNG)

Entire space with in t he dispenser enclosure

Liq uefied petroleum gas (LP-Gas)

Entire space with in t he dispenser enclosure; 450 mm (18 in .) from the exterior surface of the d isp enser enclosure to an elevation of 1.22 m (4 fi:) above the base of the dispenser; the enti re pit or open sp ace beneath the d ispenser and within 6 m (20 ft) horizontally from any edge of t he dispenser when the pit or trench is not mechanically ventilated

Class I, Division 2 1.5 m (5 fl) in all d irections from d ispenser enclosure 3 m ( 10 ft ) in all d irections from the dispenser enclosure Up to 450 mm (18 in .) above ground and with in 6 m (20 fl) horizontally from any edge of Lhe dispenser enclosure, in cluding pi LS o r trenches with in th is area when p rovided \\~th adequate mechanical ventilation

[30A:Table 12.6.2]

2020 Edition

NATIONAL ELECTRJCAL CODE

70-417

514.3

ARTICLE 514- MOTOR FUEL DISPENSING FACILITIES

(3) Fuel Storage. (a) Abovegro und tanks sto ring CNG or LNG shall be separated fro m any adjacent property line that is or can be built u pon, any public way, and the nearest important build ing 0 11 the sa me property. r3oA: 12.3. ll

(C) Motor Fuel Dispensing Stations in Boatyards and Marinas.

Informational Note: The 1·elevant d istances are given in Section 8.4 of NFPA 52-20 19, Vehicular Natuml Gas Fuel Syswms Code.

(1) General. Elecu-ical wiring an d equip me nt located a t or serving moto r fue l dispensing locations shall be installed on the side of the wharf p ier, or dock opposite fro m the liquid p iping system.

(b ) Aboveground tanks storing hydrogen shall be separated fro m any acijace nt property line that is o r can be built u pon, a ny public way, and the nearest important bu ild ing on the same proper ty. [30A:1 2.3.2l Informational Note: T he relevant NFPA 2-2016, Hydrogen Technologies Code.

distances

g iven

in

(c) Aboveground tanks storing LP-Gas shall be separated from any adj acent property line that is or can be built u pon, any public way, a nd the nearest important build ing on th e same property. r3oA: 12.3.31 Informational Note: T he relevant d istances are given Section 6.3 of NFPA 58-2017, Liquefied Petroleum Gas Code.

in

(d) Abovegrou nd tanks storing CNG, LNG, or LP-Gas shall be separated from each othe r by at least 6 m (20 ft) a nd from d ispensing devices that d ispe nse liqu id or gaseous motor vehicle fue ls by at least 6 m (20 ft) . [30A:1 2.3.3l

Informational Note: For additional information, see NFPA 303-2016, Fi>r Protection Standard for Marinas and Boatyards, and NFPA 30A-2018, Code for Motor fii.Uil Disj1ensi11g Facilities and Repair Garages.

(2) Classification of Class I , Division I and 2 Areas. The following criteria shall be used for t he purposes of applying Table 514.3( B) (1) an d Table 514.3(B) (2) to motor fue l d ispensing equipment o n fl oating or fixed p ie rs, wharfs, or docks. (D) Closed Construction. Wh ere the constructio n of floating docks, piers, or wharfs is closed so that t he re is no space between the bottom of th e dock, pie r, or wha rf a nd the wate r, as in the case of concrete-enclosed expanded foam or similar con struction, and the consu-uctio n includes integral service boxes with supply ch ases, the following sh all apply:

(1)

(2)

Exception No. 1: The required separation shall not apply to tanks or dispensers storing or handlingJi.tels of the same chemical composition. Exception No. 2: The required separation shall not apply when both the gaseous fuel storage and dispensing equipment are at least 15 m (50 ft) Ji-om any other aboveground motar fuel storage or dispensing equipment. Informational Note: For furthe r information, see NFPA 52-2019, Vehicular Natural Gas Hie/ Systems Code, or NFPA 58-2017, Liquefied Petroleum Gas Code, as applicable .

(e) Dispenser Installations Beneath Canopies. Where CNG or LNG d ispensers are installed beneath a canopy or enclosu re, e ither th e canopy or enclosu re shall be design ed to preve nt accumulation o r e ntrapment of ign itible vapors or all e lectrical equipment installed beneath the canopy or enclosure shall be suitable for Class I, Division 2 h aza rdous (classified) locations. [30A:1 2.4] (f) Specific Requirements for LP-Gas Dispensing Devices. r30A:1 2.5l Dispensing devices fo r LP-Gas shall be located as fo llows: (1 ) (2)

At least 3 m (10 ft) fro m any d ispensing device for Class I liquids At least 1.5 m (5 ft) from a ny d ispensing device for Class I liq uids where the following conditio ns exist: a. The LP-Gas deliver nozzle more th an 4 cm 3 (0.1 oz) tion. b. The fixed maximu m liq uid d uring the e n tire refueling

Exception No. 1: Dock, pie1; or whmf sections that do not support fuel dispensers and abut, but are located 6.0 m (20 ft) or mare from, dock sections that support a fuel dispenser(s) shall be permitted to be Class I, Division 2 locations where documented air space is provided between dock sections to allow flammable liquids o,· vapors to dissipate without traveling to such dock sections. 17ie documentation shall comply with 500.4. Exception No. 2: Dock, piei; or whmf sections that do not support fuel dispensers and do not directly abut sections that support Ji.tel dispensers shall be pmnitted to be unclassified where documented air space is provided and where flammable liquids or vapors cannot travel to such dock sections. 17ze documentation shall comply with 500.4.

(E) Open Construction. Where t he construction of piers, wharfs, or docks is open, as in the case of decks built on stringers su pported by pilings, floats, pontoons, or similar construction, the followin g shall apply: (1)

and fi ller valve release no of liquid upon disconnec(2) level gauge remains closed process. r30A:12.5.2l

The space above th e su rface of the floating dock, p ie r, o r wha rf sh a ll be a Class I, Division 2 location with d istances as specified in Table 514.3(B ) (1) for dispenser and outdoor locatio ns. Spaces below th e surface of the fl oating dock, pier, or wha rf that have areas o r enclosures, such as tubs, voids, pits, vaults, boxes, depressions, fuel piping ch ases, o r similar spaces, where fl ammable liquid or vapor can accumulate sha ll be a Class I , Divisio n l location.

The area 450 mm (18 in .) above the surface of th e dock, pier, or wh arf a nd extendi ng 6.0 m (20 ft) h orizo ntally in all direction s from the o utside edge of the dispenser and down to the water level shall be a Class 1, Divisio n 2 locatio n. Enclosu res such as tubs, voids, pits, vaults, boxes, depressio ns, piping c hases, o r similar spaces where fl ammable liq uids or vapors can accumulate within 6.0 m (20 ft) of the d ispenser shall be a Class I, Division l location.

Ta bl e 514.3(B) (2) sh all be used to delineate an d classify a reas for th e purpose of installation of electr ical wiring a nd e lectrical utilization equipment.

70-418

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 514-MOTOR FUEL DISPENSING FACILITIES 514.4 Wiring and Equipment Installed in Class I Locations. All elecu·ical equipment and wiring installed in Class I locations as classified in 514.3 shall comply with the applicable provisions of Article 501. Exception: As permitted in 514.8. Informational Note: Fo r special requirements for conductor insulation, see .501.20.

514.7 Wiring and Equipment Above Class I Locations. Wiring a nd equipment above the Class I locations as classified in 514.3 shall comply with 511.7. 514.8 Underground Wiring. Underground wiring shall be installed in threaded rigid metal conduit or threaded steel intermediate metal conduit. Any portion of electrical wiring that is be low the surface of a Class I, Division l or a Class I , Division 2 location [as classified in Table 514.3(B) (l) and Table 514.3(B)(2)l shall be sealed within 3.05 m (10 ft) of the point of emerge nce above grade. Except for listed explosionproof reducers at the conduit seal, there shall be no union, coupling, box, or fittin g between the conduit seal and the point of emergence above grade. Refer to Table 300.5. Exception No. I: Type Ml cable shall be permitted where it is installed in accordance with Article 332. Exception No. 2: Type PVC conduit, Type RTRC conduit, and Type HDPE conduit shall be permitted where buried under not less than 600 mm (2 ft) of cove,: Where Type PVC conduit, Type RTRC conduit, or Type HDPE conduit is used, threaded 1igid metal conduit or threaded steel intermediate metal conduit shall be used for the last 600 mm (2 ft) of the underground run to emergence or to the point of connection lo the aboveground raceway, and an equipment grounding conductor shall be included to provide electrical continuity of the raceway system and for grounding ofnon-current-canying metal parts.

514.9 Sealing. (A) At Dispenser. A listed seal shall be provided in each conduit run entering or leaving a dispenser or any cavities or e nclosures in d irect commun ication therewith. The sealing fitting or listed explosionproof reducer at the seal shall be the first fitting after the conduit e merges from the earth or concrete . (B) At Boundary. Additional seals shall be provided in accordance with 501.15. Sections 501.15(A)( 4) and (B) (2) shall apply to horizontal as well as to vertical boundaries of the defined Class I locations.

2020 Edition

NATIONAL ELECTRJCAL CODE

514.16

514.11 Circuit Disconnects. (A) Emergency Electrical Disconnects. Fuel dispensing syste ms shall be provided with one or more clearly identified emergency shutoff devices or e lectrical disconnects. Such devices or disconnects shall be installed in approved locations but not less than 6 m (20 ft) or more than 30 m (100 ft) from the fuel dispensing devices that they serve. Emergency shutoff devices or elecu·ical disconnects shall disconnect power to all dispensing devices; to all remote pumps serving the d ispensin g devices; to all associated power, conu·ol, and signal circui ts; a nd to all other electrical equipment in th e h azardous (classified) locations surrounding the fuel dispensing devices. When more than o n e emergency shutoff device or elecu·ical disconnect is provided, all devices shall be intetTonnected. Resetting from an emergen cy shutoff condition shall require manual intervention and the manner of resetting shall be approved by the a uthority having jurisdiction. r30A:6.7l T he emergency shutoff device shall disconnect s imultaneously from the source of supply, all conductors of the circui ts, includ ing the grounded conductor, if any. Equipment grounding conductors sh all remain connected. E xception: Intrinsically safe electrical equipment need not meet this requirement. [30A:6. 7] (B) Attended Self-Service Motor Fuel Dispensing Facilities. At attended motor fuel dispensing facil ities, the devices or disconnects shall be readily accessible to the attendant. [30A:6.7. l) (C) Unattended Self-Service Motor Fuel Dispensing Facilities. At unattende d motor fuel d ispensing faci lities, the devices or disconnects shall be readily accessible to patrons and at least one additional device or d isconnect shall be readily accessible to each grou p of dispensing devices on an individual island. r3oA:6.7.2l

514.13 Provisions for Maintenance and Service of Dispensing Equipment. Each d ispensing device shall be provided with a means to remove all external voltage sources, includ ing power, communica tions, data, a nd video circuits and including feedback, during periods of maintenance and service of the dispensing equipment. The location of this means sha ll be permitted to be other than inside or adj acent to the dispensing device. The means sha ll be capable of being locked in the open position in accordance with 110.25 . 514.16 Grounding and Bonding. All metal raceways, the me ta l armor or metallic sheath o n cables, and all 11011-currentcarrying metal parts of fixed and portable electrical equipment, regardless of voltage, shall be grounded a nd bonded. Grounding a nd bonding in Class I locations shall comply with 501.30.

70-419

515.1

ARTICLE 515-BULK ST ORAGE PLANTS

ARTICLE 515 Bulk Storage Plants 515.1 Scope. This article covers a property or portion of a property where flammable liquids are received by tank vessel, pipelines, tank car, or tank vehicle and are stored or blended in bulk for the purpose of d isu·ibuting such liquids by tank vessel, pipeline, tank car, tank veh icle, portable tank, or container. Informational Note: Text that is followed by a reference in brackets has been extracted from NFPA 30-2018, Nammabw and Combustibk Liquids Code. Only editorial changes were made to the extracted text to make it consistent with this Code.

515.3 Classified Locations. vVhere the term "Class I" is used with respect to Zone classifications within this article of the Code, it shall apply to Zone 0, Zone 1, and Zone 2 designations. Informational Note: The term "Class I" was originally included as a prefix to Zone 0, Zone I, and Zone 2 locations and references as an identifier for flammable gases, vapors, or liquids to differentiate from C lass II and Class Ill locations. Zone 0, Zone I, and Zone 2 only apply to flammable gases, vapors, or liquids so the "Class I" prefix is redundant and has been deleted, except for text that is extracted from other documents or to remain consistent throughout this article.

Table 515.3 shall be applied where Class I flammable liquids are stored, handled, or dispensed and shall be used to delineate and classify bulk storage plants. The classified location shall not extend beyond a floor, wall, roof, or other solid partition that has no communicating openings. Informational Note No. 1: The area classifications listed in Table 515.3 are based on the premise that the installation meets the applicable requirements of NFPA 30-2018, Flammable and Combuslibk Liquids Code, Chapter 5, in all respects. Should th is not be the case, the authority having jurisdiction has the authority to classify the extent of the classified space. Informational Note No. 2: See .514.3(C) through (E) for gasoline dispensing stations in marinas and boatyards.

515.4 Wiring and Equipment Located in Class I Locations. All electrical wiring and equipment within the Class I locations defined in 515.3 shall comply with th e applicable provisions of Article 501 or Article 505 for the division or zone in which they are used.

Exception: As permitted in 515.8. 515.7 Wiring and Equipment Above Class I Locations. (A) Fixed Wiring. All fixed wiring above Class I locations shall be in metal raceways, Schedule 80 PVC conduit, Type RTRC marked with the suffix -XW, or Type MI, Type TC, or Type MC cable, or Type PLTC and Type PLTC-ER cable in accordance with the provisions of Article 725, including installation in cable tray systems or Type ITC and Type ITC-ER cable as permitted in 727.4. The cable shall be terminated with listed fittings.

70-420

(B) Fixed Equipment. Fixed equ ipment that may produce arcs, sparks, or particles of hot metal, such as lamps and lampholders for fixed lighting, cutouts, switches, receptacles, motors, or other equipmen t having make-and-break or sliding contacts, shall be of the totally enclosed type or be constructed so as to prevent the escape of sparks or hot metal particles.

(C) Portable Luminaires or Other Utilization Equipment. Portable luminaires or other utilization equipment and their flexible cords shall comply with the pmvision s of Article 501 o r Article 505 for the class of location above which they are connected or used. 515.8 Underground Wiring. (A) Wiring Method. Underground wiring shall be installed in threaded r igid metal conduit or th readed steel intermediate metal conduit or, where buried under not less than 600 mm (2 ft) of cover, shall be perm itted in Type PVC conduit, Type RTRC conduit, or a listed cable . Where Type PVC conduit or Type RTRC conduit is used, threaded rigid metal conduit or threaded steel intermediate metal conduit shall be used for not less than the last 600 mm (2 ft) of the conduit run to the conduit point of emergence from the underground location or to the point of connection to an aboveground raceway. vVhere cable is u sed, it shall be enclosed in threaded rigid metal conduit or th readed steel intermediate metal conduit from the point of lowest buried cable level to the point of connection to the aboveground raceway. (B) Insulation. Conductor insulation shall comply with 501.20. (C) Nonmetallic Wiring. \/{here Type PVC conduit, Type RTRC conduit, or cable with a nonmetallic sheath is used, an equipment grounding conductor shall be included to provide for elecu·ical continuity of the raceway system and for grounding of non-current-carrying metal parts.

515.9 Sealing. Sealing requirements shall apply to horizontal as well as to vertical boundaries of the defined Class I locations. Buried raceways and cables under defined Class I locations shall be considered to be within a Class I, Divisio n 1 or Zone 1 location. 515.10 Special Equipment Gasoline Dispensers. Where gasoline or other volatile flammable liquids or liquefied flammable gases are dispensed at bulk stations, the applicable provisions of Article 514 shall apply. 515.16 Grounding and Bonding. All metal raceways, the metal armor or metallic sheath on cables, and all 11011-currentcarrying metal parts of fixed or portable elecu·ical equipment, regardless of voltage, shall be grounded and bonded. Grounding and bonding in Class I locations shall comply with 50 1.30 for Class I, Division 1 and 2 locations and 505.25 for Zone 0, I , and 2 locations. Informational Note: For information on grounding for static protection, see 6.5.4 of NFPA 30-2018, Flammable and Com.bustibk Liquids Code.

NAT IO NAL ELECTRJCAL CODE

2020 Edition

ARTICLE 515 - BULKSTORAGE PLANTS

515.16

Table 515.3 Electrical Area Classifications Location Indoor equipment installed where flammable vapor-air mixtures can exist under nonnal operation (sec Informational Note)

Division

Zone

Extent of Classified Area

1

0

The entire area associated with such equipment where flammable gases or vapors are present continuously or for long periods of time

2

Outdoor equ ipment installed where flammable vapor-air mixtures can exist under nonnal operation

0

2

Tank storage installations inside buildings

2

2

I

I

2

2 0

Tank -aboveground, fixed roof

2

2

I I

0

2 Tank - abovegrou nd, floating roof With fixed outer roof v\/ith no fixed outer roof

I 2

0

Area within 1.5 m (5 fl) of any edge of such equipment, extending in all directions Area between l.5 m and 2.5 m (5 ft and 8 ft) of any edge of su ch equipment, extending in all directions; also, space up to 900 mm (3 ft ) above floor or grade level within l.5 m to 7.5 m (5 fi. to 25 ft) horizontally from any edge of su ch equipment' The entire area associated with such equipment where flammable gases or vapors are present continuously or for long periods of time Area within 900 mm (3 ft) of any edge of such equipment, extending in all directions Arca between 900 mm (3 ft) and 2.5 m (8 ft) of any edge of su ch equipment, extending in all directions; also, space up to 900 mm (3 ft) above floor or grade level within 900 mm to 3.0 m (3 ft to IO ft) horizontally from any edge of such equipment All equipment located below grade level Any equipment located at or above grade level Inside fixed roof tank Area inside dike where dike height is greater than the d istance from the tank to the dike for more than 50 percent of the tank circumference With in 3.0 m (] 0 ft) from shell, ends, or roof of tank; also, area inside d ike to level of top of d ike wall Arca inside of vent p iping or opening With in 1.5 m (5 ft) of open end of vent, extending in all d irections Area between 1.5 m and 3.0 m (5 ft and 10 ft) from open end of vent, extending in all d irections Arca between the floating and fixed roof sections and with in the shell Area above the floating roof and with in the shell

Tank vault- interior

Entire interior volume, if Class I liquids arc stored within

Underground tank fi ll opening

Any p it, box, or space below grade level, if any part is within a Division 1 or 2, or Zone 1 or 2 classified location Up to 450 mm (18 in.) above grade level within a horizontal radius of 3.0 m (IO ft) from a loose fi ll connection, and within a horizontc1l radius of l.5 m (5 ft) from a tight fi ll connection

Vent - discharging upward

2

2

1

0 l 2

Area insid e of vent p iping or opening With in 900 mm (3 ft) of open end of vent, exte nding in all d irections Area between 900 mm and l.5 m (3 ft and 5 ft) of open end of vent, extending in all d irections

0

Arca inside the drum or container

l 2 Drum and container fi lling indoors

outdoors or

Pumps, b leeders, withdrawal fittings Indoor

2

2

2

2

With in 900 mm (3 ft) of vent and fill openings, extending in all directions Area between 900 mm and 1.5 m (3 ft and 5 ft) from vent or fi ll opening, extending in all directions; also, up to 450 mm (18 in.) above floor or grade level \1~thin a horizontal radius of 3.0 m (IO ft) from vent or fi ll opening With in I.5 m (5 ft) of any edge of such devices, extending in all directions; also, up to 900 mm (3 ft) above floor or grade level with in 7.5 m (25 ft) horizontally from any edge of such devices (continues)

2020 Edition

NATIONAL ELECTRJCAL CODE

70-421

515.16 Table 515.3

ARTICLE 515 - BULK STORAGE PLANTS

Continued Location

Outdoor

Division

Zone

2

2

Pits and sumps Without mechanical ven tilation

Extent of Classified Area

Within 900 mm (3 ft) of any edge of such devices, extending in all d irections. Also, up to 450 mm (18 in.) above grade level with in 3.0 m (]0 ft) horizontally from any edge of such devices Entire area within a p it or sump if any part is within a Division l or 2 or Zone 1 or 2 classified location Entire area within a p it or sump if any part is within a Division l or 2 or Zone l or 2 classified location Entire pit or sump

With adequate mechanical ventilation

2

2

Containing valves, fittings, or piping, and not with in a Division l or 2 or Zone l or 2 classified location

2

2

2

2

Arca up to 450 mm (18 in.) above ditch, separator, or basin; also, area up to 450 mm ( 18 in.) above grade with in 4.5 m (l 5 ft) horizontally from any edge Same as pits and sump s

1

0

]

]

2

2

Arca inside of the tank Within 900 mm (3 ft) of edge of dome, extending in all directions Arca between 900 mm and 4.5 m (3 ft and 15 ft) from edge of dome, extending in all d irections

1

0

Drainage d itches, separators, impo unding basins Outdoor

Indoor Tank vehicle and tank car2 Loading through op en dome

Loading through bottom connections with atmospheric venting

]

Arca inside of the tank Within 900 mm (3 ft) of point of ven ting to atmosphere, extending in all directions Arca between 900 mm and 4.5 m (3 ft and 15 ft) from po int of venting to atmosphere, extending in all d irections; also, up to 450 mm (l 8 in.) above grade with in a horizontal radius of 3.0 m (10 ft) from point ofloadin g connection Within 900 mm (3 ft) of open end of vent, extending in all directions

2

2

2

2

Ar ca between 900 mm and 4.5 m (3 ft and 15 ft) from open end of vent, extending in all d irections; also, within 900 mm (3 ft) of edge of dome, extending in all directions

Loading through closed dome with vapor control

2

2

Bottom loading with vapor control or any bottom unloading

2

2

Within 900 mm (3 ft) of point of connection of both fi ll and vapor li nes extend ing in all d irections Within 900 mm (3 ft) of point of connections, extending in all d irections; also up to 450 mm (18 in.) above grade with in a horizontal radius of 3.0 m (l O ft) from poin t of connections

Loading through closed dome with a tmospheric venting

Storage and repair garage for tank vehicles

1

]

2

2

Garages for other than tank vehicles

Unclassified

Outdoor drum storage

Unclassified

Inside rooms or storage lockers used for the storage of Class I liquids

2

2

All p its or spaces below floor level Ar ca up to 450 mm (18 in .) above floor or grade level for en tire storage or repair garage If there is any o pen ing to these rooms within the extent of an outdoor classified location, the en tire room shall be classified the same as the area classification at the p oint of the opening.

Enti re room or locker (continues)

70-422

NAT IONAL ELECTRJCAL CODE

2020 Edition

516.1

ARTICLE 516-SPRAY APPLICATION, DIPPING, COATING, AND PRINTING PROCESSES Table 51 5.3

Continued

Location

Division

Zone

Extent of Classified Area

Indoor warehousing where there is no flammable liq uid trnnsfcr

Unclassified

If there is any opening to these rooms with in the extent of an indoor classified location, tl1e classified location shall extend through the opening to the same extent as if the wall, curb, or partition d id not exist.

Office and rest rooms

Unclassified

If there is any opening to these rooms witl1in the extent of an indoor classified location, tl1e room shall be classified the same as if tl1e wall, curb, or partition did not exist.

Piers and whan,cs

Sec Figure 515.3.

1

The release of Class I liquids can generate vapors to the extent that the enti re building, and possibly an area surrounding it, should be considered a Class I, Division 2 or Zone 2 location. 2 When classifying extent of area, consideration shall be given to the fact that tank cars or tank vehicles can be spoued at varying points. Therefore, the exu-em ities of the loading or unloading positions shall be used. [30:Table 7.3.3] Informational Note: See Section 7.3 of NFPA 30-2018, Flammable and Comhuslible Liquids Code, for additional information.

50ft~ j-25ft~

f . - 5 o ft r-25 ft +j

~

25 Open sump in deck for draining lines and hose

Operating envelope and stored position • of loading arms or hose

~

Key:

D

2 ft

FIGURE 5 15.3

D

Nonclassified

Area Classificatio n for a Marine Terminal H andling Flammable Liquids. [30:Figure 29.3.22]

ARTICLE 516 Spray Application, Dipping, Coating, and Printing Processes Using Flammable or Combustible Materials Part I. General 516.1 Scope. Th is article cove rs th e regular or frequent appl ication of flammable liquids, combustible liquids, and combustible powders by spray operations and the application of flammable liquids or combustible liquids at temperatures above their flashpo int by spraying, dipping, coating, printing, or other means.

2020 Edition

~ Division 2

Notes: (1) For SI unrts, 1 in.=25 mm; 1 ft = 0.3 m. (2) The •source of vapor" is the operating envelope and stored posrtion of the outboard flange connection of the loading arm (or hose). (3) The berth area adjacent to tanker and barge cargo tanks is to be Division 2 to the following extent: (a) 25 ft (7.6 m) horizontally in all directions on the pier side from the portion of the hull containing cargo tanks. (b) From the water level to 25 ft (7.6 m) above the cargo tanks at their highest position. (4) Addrtional locations can be classified as required by the presence of other sources of flammable liquids on the berth, or by Coast Guard or other regulations.

i.---50ft

I

Division 1

NATIONAL ELECTRJCAL CODE

Informational Note No. I: For further information regarding safeguards for these processes, such as fire protection, posting of warning signs, and maimenance, see NFPA 33-2018, Slandardfor Sfnny Af,plicalion Using Flammable or Combuslible Ma/iirials, and N FPA 34-2018, Standard for Dif'JJing, Coaling, and Prinling P,vcesses Using Flammable or Combustible Liquiuwd t:nergy Resources, and ANSI/ UL 9741, Bidi,~ctional Ei£ctric Vehicle (EV) Charging Syst,em Equijmumt; for vehicle interactive systems, see SAE J 3072, Standard for Interconnection RequimnenlS for On.board, Utility-Interaclive Inverter Syswms.

625.44 Equipment Connection. EVSE and WPTE shall be connected to the premises wiring system in accordance with one of the methods in 625.44(A) th rough (C) .

625.50 Location. The EVSE shall be located for d irect electrical coupling of the EV connectoi· (conductive or inductive) to the e lectric veh icle . Unless specifically listed and marked for the locatio n, the cou pling means of the EVSE shall be stored or located at a he ight of not less than 450 mm (18 in .) above the floor level for indoor lo cations or 600 mm (24 in.) above the grade level for outdoor locations. Thi s req ui rement does not apply to portable EVSE constructed in accordance with 625.44(A) .

(A) Portable Equipment. Portable equipmen t shall be connected to the premises wiring system by one or more of the following methods:

625.52 Ventilation. The ventilation requirement for charging an electri c vehicle in an indoor enclosed space shall be determin ed by 625.52(A) or (B) .

A nonlocking, 2-pole, 3-wire grounding-type receptacle o u tlet rated at 125 volts, single phase, 15 or 20 amperes A nonlocking, 2-pole, 3-wire ground ing-type receptacle outlet rated at 250 volts, single phase, 15 or 20 amperes A nonlocking, 2-pole , 3-wire or 3-pole, 4-wire ground ingtype receptacle outlet rated at 250 volts, single phase, 30 or 50 amperes A nonlocking, 2-pole, 3-wire ground ing-type receptacle outlet rated at 60 volts de maximum, 15 or 20 amperes

(A) Ventilation Not Required. ,!\There e lectric vehicle storage batteries are used or where t he e qui pment is listed for charging e lectric vehicles indoors without ventilatio n , mechanical ventilation shall not be required.

625.43 Disconnecting Means. For equipment rated more than 60 amperes or more than 150 volts to ground, the disconnecting means shall be provided and installed in a readily accessible location . The disconnecting means shall be lockable open in accordance with 110.25.

(1)

(2) (3)

( 4)

(B) Fastened-in-Place Equipment. Equipment that is faste ned in place shall be connected to the prem ises wiring system by one of the following methods: (1)

(2) (3) ( 4)

A nonlocking, 2-pole, 3-wire grounding-type receptacle o utlet rated 125 volts or 250 volts, single phase, up to 50 amperes A nonlocking, 3-pole, 4-wire grounding-type receptacle o utlet rated 250 volts, three phase, up to 50 amperes A nonlocking, 3-pole, 4-wire grounding-type receptacle outlet rated 250 volts, single phase, 30 or 50 amperes A nonlocking, 2-pole, 3-wire grounding-type receptacle o utlet rated 60 volts d e maximum, 15 or 20 amperes

(C) Fixed Equipment. All other EVSE and V1TJ'TE shall be permanently wired and fi xed in place to the supporting surface .

(B) Ventilation Required. Where th e equ ipment is listed for charging electric vehicles that require ventilation for indoor charging, mechanical ventilation, such as a fan, shall be provided. The ventilation shall include both su pply and exhaust equipment and shall be permanently installed and located to intake from , and vent directly to, th e outdoors. Positivepressure ventilatio n systems shall be perm itted o nly in vehicle charging buildings or a reas that have been specifically designed and approved for that application. Mechanical ventilation requirements shall be determined by one of the methods specified in 625.52(B)(l) through (B) (4) . (1) Table Values. For supply voltages and currents specified in Table 625.52(B) (l )(a) or Tabl e 625.52(B)( l )(b), the minimum ventilation requi remen ts shall be as specified in Ta ble 625.52(B) (I )(a) or Table 625.52 (B) (1 )(b ) for each of the total number of electric vehicles that can be charged at o ne time. (2) Other Values. For sup ply voltages and currents other than specified in Table 625.52(B)( l )(a) or Table 625 .52(B)(l)(b), the minimum ventilation requirements sh all be calculated by means of the following general formulas, as applicable:

625.46 Loss of Primary Source. Means shall be provided such that, upon loss of voltage from the utility or oth er e lectrical system(s) , energy cannot be back fed through the elecu·ic veh icle and the supply equipment to the premises wiring system unless perm itted by 625.48.

2020 Edition

NATIONAL ELECTRJCAL CODE

70-533

ARTICLE 625 - ELECTRIC VEHICLE PO\-VER T RANSFER SYSTEM

625.52

Table 625.52(B)( l)(a) Minimum Ventilation Required in Cubic Meters per Minute (m 3 / min) for Each of the Total Number of Electric Vehicles That Can Be Charged at One Time Branch-Circuit Voltage BranchCircuit Ampere Rating

15 20 30 40 50 60 100 150 200 250 300 350 400

Single Phase DC ~ 50V

0.5 0.6 0.9 1.2 1.5 1.8 2.9

3 Phase

120 V

208V

240Vor 120/ 240 V

1.1 l.4

1.8 2.4 3.6 4.8 6.l 7.3 12

2.1 2.8 4.2 5.6 7.0 8.4 14

2.l 2.8 3.5 4.2 7.0

208Vor 208Y/ 120V

240V

480 Vor 480Y/ 277 V

600Vor 600Y/347 V

4.2 6.3 8.4 10 13 21 31 42 52 63 73 84

4.8 7.2 9.7 12 15 24 36 48 60 73 85 97

9.7 15 19 24 29 48 73 97 120 145 170 195

12 18 24 30 36 60 91 120 150 180 210 240

Table 625.52(B)(l)(b) Minimllllil Ventilation Required in Cubic Feet per Minute (cfm) for Each of the Total Number of Ele ctric Vehicles That Can Be Charged at One Time Branch-Circuit Voltage Single Phase BranchCircuit Ampere Rating

15 20 30 40 50 60 100 150 200 250 300 350 400 (])

DC ~ 50V

120 V

15.4 20.4 30.8 41.3 51.3 61.7 102.5

37 49 74 99 123 148 246

3 Phase

208V

240 Vor 120/ 240V

208 Vor 208Y/ 120V

64 85 128 171 214 256 427

74 99 148 197 246 296 493

148 222 296 370 444 740 l llO

1480 1850 2221 2591 2961

Single-phase ac or de: Ventilatio n,,ngle-ptm,e (m 3/ m in) =

(2)

ae " ' de

in cubic meters per min u te

240V

480 Vor 480Y/ 277 V

600Vor 600Y/ 347V

17] 256 342 427 512 854 1281 1708 2135 2562 2989 3416

342 512 683 854 1025 1708 2562 3416 4270 5125 5979 6832

427 641 854 1066 1281 2135 3203 4270 5338 6406 7473 8541

T hree-phase ac: Ventila tio n 3."""'e (m 3/ m in ) =

in

cubic

meters

[625.52(B)(2)a] ( vo l ts )(ampe res)

1718

1718

ae o, d e

in cubic feet per min u te

minute

[625.52(B)(2)c] l .732(vo lts)(ampe res)

Ventilatio n,,ngle-phase (cfm) =

p er

Ventila tio n 3,phase in cubic feet p er min ute (d'm ) =

[625.52(B) (2)d] [625.52(B)(2)b] ( vo l ts )(amperes)

1.732( volts )(amperes)

48.7

48.7

70-534

NAT IONAL ELECTRJCAL CODE

202 0 Edition

ARTICLE 626- ELECTRIFIED TRUCK PARKING SPACES (3) Engineered Systems. For an equipment ventilation system designed by a person qualified to perform such calculations as an integral part of a building's total ventilation system, the minimum ventilation requirements shall be permitted to be determined in accordance with calculations specified in the engineering study.

626.1

625.102 Installation. (A) 1ype. The ch arger power converter, where integral to the

primary pad, shall comply with 625 .102(C) . The charger power converter, if not integral to the primary pad, sh all be provided with a minimum Type 3R enclostffe rating.

(4) Supply Circuits. The supply circuit to the mechanical ventilation equipment shall be electrically interlocked with the equipment and shall remain energized during the entire electric vehicle charging cycle. Equipment receptacles rated at 125 volts, single phase, 15 and 20 amperes sha ll be switched and the mechanical ventilation system shall be electrically interlocked through the switch supply power to the receptacle . Equipment supplied from less than 50 volts de shall be switched and the mechanical ventilation system shall be electrically interlocked through the switch supply power to the equipment.

(B ) General. lf the charger power converter is not integral to the pri mary pad, it shall be m ounted at a height of not less than 450 mm (18 in. ) above the floor level for indoor locations or 600 mm (24 in. ) above grade level for outdoor locations. The charger power converter shall be mounted in one of the following forms:

625.54 Ground-Fault Circuit-Interrupter Protection for Personnel. In addition to the requirements in 210.8, all receptacles installed for the connection of elecu·ic vehicle charging shall have ground-fault circuit-interrupter protection for personnel.

surface, embedded in the surface of the floor with its top flush with the surface, or embedded in the surface of the floor with its top below the surface. This includes primary pad constructions with the charger power converter located in the primary pad enclosure .

625.56 Receptacle Enclosures. All receptacles installed in a wet location for electric vehicle charging shall have an enclosure that is weatherproof with the attachment plug cap inserted or removed. An outlet box hood installed for this purpose shall be listed and shall be identified as extra duty. Other listed products, enclosures, or assemblies providing weatherproof protection that do not utilize an outlet box hood shall not be required to be marked extra duty.

(1)

625.60 AC Receptacle Outlets Used for EVPE. AC receptacles installed in electric veh icles and intended to allow for connection of oH~board utilization equipment shall comply with 625.60(A) through (D) . (A) 1ype. The receptacle outlet shall be listed.

(B) Rating. The receptacle outlet shall be rated 250 volts maximum, single phase 50 amperes maximum . (C) Overcurrent Protection. Electric vehicles provided with

receptacle outlets for power export shall be provided with overcurrent protection integral to the power export system. The overcurrent protection shall have a nominal rating sufficient for the receptacle it protects. The overcurrent protection sh all a lso be sufficiently rated for the maximum available fault current at the receptacle and shall be included in the interactive equipment evaluation . See 625.48. (D) GFCI Protection for P ersonnel. Ground-fault circuitinterrupter protection for personnel shall be provided for a ll receptacles. The ground-fault circuit-interrupter indication and reset shall be installed in a readily accessible location . Informational Note: There are various methods availab le to achieve ground-fault circuit-imerrupter protection.

Part IV. Wireless Power Transfer Equipment 625.101 Grounding. The primary pad base plate shall be of a non-ferrous metal and shall be grounded unless the listed WPTE employs a double-insulation system. The base plate sh all be sized to match the size of the primary pad enclosure.

2020 Edition

NATIONAL ELECTRJCAL CODE

(1)

(2) (3) ( 4)

Pedestal Wall or pole Building or structure Raised concrete pad

(C) Primary Pad. The primary pad shall be installed on the

If the primary pad is located in an area requiring snow

removal, it sh all n ot be located on or above the surface.

Exception: Where installed on private property where snow removal is done manually, the primary pad shall be permitted to be located on or above the swface. (2)

The enclosure shall be provided with a suita ble enclosure rating m inimum Type 3. If the primary pad is located in an area subject to severe climatic conditions (e.g., flooding), it shall be suitably rated for those conditions or be provided with a suitably rated enclosure.

(D) Protection of Output Cable. The outpu t cable to the primary pad shall be secured in place over its entire length for the purpose of restricting its move ment and to prevent strain at the connection points. If installed in conditions where driveover could occur, the cable shall be provided with supplemental protection . \!\There the charge•· power converter is a part of the primary pad assembly, the power supply cord to the primary pad shall also be protected. (E) Other Wiring Systems. Other wiring systems and fittings specifically listed for use on the WPTE shall be permitted.

ARTICLE 626 Electrified Truck Parking Spaces Part I. General 626.1 Scope. This article covers the electrical conductors and equipment external to the truck or transport refrigerated unit that connect trucks or transport refrigerated units to a supply of electricity, and the installatio n of equipment and devices related to electrical installations within an electrified truck parking space.

70-535

626.2

ARTICLE 626- ELECTRIFIED TRUCK PARKING SPACES

626.2 Definitions. The following definitions shall apply only within th is article. Cable Management System (Electrified Truck Parking Spaces). An apparatus designed to control and organize unused lengths of cable o r cord at electrified truck parking spaces. Cord Connector. A device that, by inserting it into a truck flanged surface inlet, establishes an electrical connection to the truck for the purpose of providing power for the on-board electric loads and may provide a means for information exchange. This device is part of the u·uck coupler. Disconnecting Means, Parking Space. The necessary equipment usually consisting of a circuit breaker or switch and fuses, and their accessories, located near the point of entrance of supply conductors in an electrified truck parking space and intended to constintte the means of cutoff for the supply to that truck. Electrified Truck Parking Space. A truck parking space that has been provided with an electrical system that allows truck operators to connect their vehicles while stopped and to use off-board power sources in order to operate on-board systems such as air conditioning, heating, and appliances, with out any engine idling. Informational Note: An electrified truck parking space also includes dedicated parking areas for heavy-ducy trucks at travel p lazas, warehouses, shipper and consignee yards, depot facilities, and border crossings. It does not include areas such as the shoulders of highway ramps and access roads, camping and recreational vehicle sites, residential and commercial parking areas used for automotive parking or other areas where ac power is provided solely for the purpose of connecting amomotive and other light electrical loads, such as engine block heaters, and at private residences.

Electrified Truck Parking Space Wiring Systems. All of the e lectrical wiring, equipment, and appurtenances related to electrical instal lations within an elecu·ified truck parking space, including the electrified parking space supply equipment. Overhead Gantry. A su·ucture consisting of horizontal framework, supported by vertical columns spann ing above electrified truck parking spaces, that supports equipment, appliances, raceway, and other necessary components for the purpose of supplying e lectrical, HVAC, internet, communications, and other services to the spaces. Separable Power Supply Cable Assembly. A flex ible cord or cable, including ungrounded, grounded, and equipment grounding conductors, provided with a cord connector, an attachment plug, and all other fittings, grommets, or devices installed for the purpose of delivering energy from the source of electrical supply to the truck or TRU flanged surface inlet. Transport Refrigerated Unit (TRU). A trailer or container, with integrated cooling or heating, or both , used for the purpose of maintammg the desired environment of temperan1re-sensitive goods or products. Truck. A motor vehicle designed for the transportation of goods, services, and equipment. Truck Coupler. A truck flanged surface inlet and mating cord connector. Truck Flanged Surface Inlet. The device(s) on the truck into wh ich the connector(s) is inserted to provide electric energy

70-536

and other services. This device is part of the truck coupler. For the purposes of this article, the truck flanged surface in let is considered to be part of the truck and not part of the electrified truck parking space supply equipment. 626.3 Other Articles. Wherever the requirements of other articles of this Code and Article 626 differ, th e requirements of Article 626 shall apply. Unless electrified truck parking space wiring systems are supported or arranged in such a manner that they cannot be used in or above locatio ns classified in 511.3 or 514.3, or both , they shall comply with 626.3(A) and (B) in addition to the requirements of this article. (A) Vehicle Repair and Storage Facilities. Electrified truck parking space electrical wiring systems located at facilities for the repair or storage of self~propelled vehicles that use volatile flammable liquids or flammable gases for fuel or power shall comply with Article 511. (B) Motor Fuel Dispensing Stations. Electrified truck parking space electrical wiring systems located at or serving motor fue l dispensing stations shall comply with Article 514. I nformational Note: For additional information, see NFPA SSA-2019, Standard for Parking Structmes, and N FPA 30A-2018, Code for M otor Ftwl DisjJensing Facilities and Repair Garages.

626.4 General Requirements. (A) Not Covered. This article shall not apply to that portion of other equipment in residential, commercial , or industrial faci lities that requires electric power used to load and unload cargo, operate conveyors, and for other equipment used on the site or truck. (B) Distribution System Voltages. Unless other voltages are specified, the nominal ac system voltages of 120, 120/ 240, 208Y/ 120, 240, or 480Y/277 shall be used to supply equipment covered by this article. (C) Connection to Wiring System. This article shall apply to the electrified truck parking space supply equ ipment intended for connection to a wiring system as defined in 626.4(B) .

Part II. Electrified Truck Parking Space Electrical Wiring Systems 626.10 Branch Circuits. Electrified truck parking space singlephase branch circuits shall be derived from a 208Y/ 120-volt, 3phase, 4-wire syste m or a 120/ 240-volt, single-phase, 3-wire system.

1',xception: A 120-volt distribution system shall be permitted to supply existing electrified truck parking spaces. 626.11 Feeder and Service Load Calculations. (A) Parking Space Load. The calculated load of a feeder or service shall be not less than the sum of the loads on the branch circuits. Electrical service and feeders shall be calculated on the basis of not less than 11 kVA per electr ified truck parking space. (B) Demand Factors. Electrified u·uck parking space electrical wiring system demand factors shall be based u pon the climatic temperature zone in which the equipment is installed. The demand factors set forth in Table 626.ll (B) shall be the minimum allowable demand factors that shall be permitted for

NAT IO NAL ELECTRJCAL CODE

2020 Edition

ARTICLE 626- ELECTRIFIED TRUCK PARKING SPACES calculating load for service and feeders. No demand factor shall be allowed for any other load, except as provided in this article. Informational Note: The U.S. Department of Agriculture (USDA) has developed a commonly used "Plant Hardiness Zone" map that is publicly available. The map provides guidance for determining the Climatic Temperature Zone. Data indicate that the HVAC has the highest power requirement in cold climates, with the heating demand representing the greatest load, which in turn is dependent on outside temperature. In very warm climates, where no heating load is necessary, the cooling load increases as the omdoor temperature rises. These demand factors do not apply to the portion of electrical wiring systems d,at supply d1e transport refrigerated units (TRUs) .

(C) Two or More Electrified Truck Parking Spaces. Where the electrified u·uck parking space wiring system is in a location that serves two or more electrified truck parking spaces, the equipment for each space shall comply with 626.11 (A), and the calculated load shall be calculated on the basis of each parking space .

(D) Conductor Rating. Truck space branch-circuit supplied loads shall be considered to be continuous. Table 626.1 l(B) Demand Factors for Services and Feeders Climatic Temperature Zone (USDA Hardiness Zone) (See Note) 1 2a 2b 3a 3b 4a 4b

5a 5b 6a 6b 7a 7b Sa Sb 9a

9b

10a 10b 11

Demand Factor (%)

70 67 62 59

57 55 51 47 43 39

34 29 24 21 20 20 20 21 23

24

Note: The climatic temperature zones shown in Table 626. 11 (B) correlate with those found on the "USDA Plant Hardiness Zone Map," and the climatic temperarnre zone selected for use with the table shall be determined duough d1e use of this map based on the installation location.

626.24

Part III. Electrified Truck Parking Space Supply Equipment 626.22 Wiring Methods and Materials. (A) Electrified Truck Parking Space Supply Equipment Type. The electrified truck parking space supply equipment shall be provided in one of the following forms: (1)

(2)

(3)

Pedestal Overhead gantry Raised concrete pad

(B) Mounting Height. Post, pedestal, and raised concrete pad types of electrified truck parking space supply equipment shall be not less than 600 mm (2 ft) aboveground or above the point identified as the prevailing highest water level mark or an equivalent benchmark based on seasonal or storm-driven flooding from the authority having jurisdiction. (C) Access to Working Space. All e lectrified truck parking space supply equipment shall be accessible by an unobsu·ucted entrance or passageway not less than 600 mm (2 ft) wide and not less than 2.0 m (6 ft 6 in. ) h igh.

(D) Disconnecting Means. A disconnecting switch or circuit breaker shall be provided to d isconnect one or more electrified truck parki ng space supply equipment sites from a remote location. The disconnecting means shall be provided and installed in a readily accessible location and shall be lockable open in accordance with 110.25.

626.23 Overhead Gantry or Cable Management System. (A) Cable Management. Electrified truck parking space equipment provided from e ither overhead gantry or cable management systems shall utilize a permanently attached power su pply cable in electrified truck parking space supply equipment. Oth er cable types and assemblies listed as being suitable for the purpose, including optional hybrid communications, signal, and composite optical fiber cables, shall be permitted. (B) Strain Relief. Means to prevent strain from being transmitted to the wiring terminals shall be provided. Permanently attached power supply cable (s) shall be provided with a means to de-energize the cable conductors and power service delivery device upon exposu re to strain that could result in either cable damage or separation from the power service delivery device and exposure of live parts. 626.24 Electrified Truck Parking Space Supply Equipment Connection Means. (A) General. Each truck shall be supplied from electrified truck parking space supply equipment through suitable extrahard service cables or cords. Each connection to the equipment shall be by a single separable power supply cable assembly. (B) Receptacle. All receptacles shall be listed and of the grounding type. Every truck parking space with elecu·ical supply shall be eq uipped with 626.24(B) (1) and (B) (2) .

(1)

A maximum of three receptacles, each 2-pole, 3-wire grounding type and rated 20 amperes, 125 volts, and two of the three connected to two separate branch circuits. Informational Note: For the non-locking-type and groundingtype 20-ampere receptacle confi guration, see ANSI/ NEMA WD 6-2016, Wiri11g Devices - Dimensional Sfiecif,calions, Figure 5-20.

2020 Edition

NATIONAL ELECTRJCAL CODE

70-537

626.24

(2)

ARTICLE 626- ELECTRIFIED TRUCK PARKING SPACES

One single receptacle, 3-pole, 4-wire ground ing type, single phase rated e ither 30 a mperes 208Y/ 120 volts or 125/250 volts. The 125/250-volt receptacle shall be permitted to be used on a 208Y/ 120-volt, single-phase circuit.

In formational Note: For various configurations of 30-ampere pin and sleeve receptacles, see ANSl/ U LI 686-20 12, Standard for Pin and Sleeve Configurations, Figure C2.9 or Part C3.

Exception: Where e!.ectrified truck parking space supply equipment provides the heating, air-conditioning, and comfort-cooling jimction without requiring a direct electrical connection at the truck, only two receptacles identified in 626.24(B)(l) shall be required. (C) Disconnecting Means, Parking Space. The electrified truck parking space supply equipment shall be provided with a switch or circuit breaker for d isconnecting the power supply to the electrified truck parking space. A disconnecting means shall be provided and installed in a readily accessible location and shall be lockable open in accordance with 110.25.

(D) Ground-Fault Circuit-Interrupter Protection for Personnel. In addition to the requirements in 210.8, the electrified truck parking space equipment shall be designed and constructed such that a ll receptacle outlets in 626.24 are provided with ground-fault circuit-interrupter protection for personnel. 626.25 Separable Power-Supply Cable Assembly. A separable power-supply cable asse mbly, consisting of a power-supply cord, a cord connector, and an attachment plug intended for connection with a truck flanged surface inlet, shall be of a listed type. The power-supply cable assembly or assemblies shall be identified and be one of t he types a nd ratings specified in 626.25(A) and (B) . Cords with adapters and pigtail ends, extension cords, a nd similar items shall not be used. (A) Rating(s).

(I) Twenty-Ampere Power-Supply Cable Assembly. Equipment with a 20-ampere, 125-volt receptacle, in accordance with 626.24(B) ( 1), shall use a listed 20-ampere power-supply cable assembly.

Exception: It shall be permitted to use a listed separable powei~supply cable assembly, either hard service or extra-hard service and rated 15 amperes, 125 volts, for connection to an engine block heater for legacy vehicles. (2) Thirty-Ampere Power-Supply Cable Assembly. Equipment with a 30-ampere, 208Y/ 120-volt or 125/250-volt receptacle, in accordance with 626.24(B) (2), shall use a listed 30-ampere ma in power-supply cable assembly. (B) Power-Supply Cord.

(I ) Conductors. The cord shall be a listed type with three or four conductors, for single-phase connection, one conductor of wh ich shall be identified in accordance with 400.23.

Exception: It shall be permitted to use a separate listed three-conductor separable power-supply cable assembly, one conductor of which shall be identified in accordance with 400. 23 and rated 15 amperes, 125 vol.ls for connection to an engine block heaterfor existing vehicles. (2) Cord. Extra-hard usage flexible cords and cables rated not less than 90°C (194°F) , 600 volts; listed for both wet locations and sunlight resistance; and having a n outer j acket rated to be resistant to temperanire extt·emes, o il, gasoline, ozone, abrasion , acids, a nd chemicals shall be permitted wh ere flexibility is

70-538

necessa1y between the electrified truck parking space supply equipme nt, the panel board, a nd fl a nged surface inlet(s) on the truck.

Exception: Cords Jor the separabl.e power supply cable assembly for 15and 20-ampere connections shall be pemiilted to be a hard service type. (3) Cord Overall Length. The exposed cord length shall be

measured fro m the face of the attachment plug to the point of entt·ance to the truck or the face of the flanged surface inlet or to the point wh ere th e cord enters the truck. The overall len gth of the cable shall not exceed 7.5 m (25 ft) unless equipped with a cable management system that is listed as suitable for th e purpose. (4) Attachment Plug. The attachment plug(s) shall be listed,

by itself or as part of a cord set, for th e purpose and shall be molded to or installed on th e flexible cord so that it is secured tig htly to the cord at the point where the cord enters the attachment plug. If a right-angle cap is used, the configuration shall be oriented so that the grounding member is farthest from the cord. Where a flexible co rd is provided, the attachment plug shall comply with 250.1 38(A) . (a) Connection to 20-Ampere Receptacl.e. A separable powersupply cable assembly for connection t o a truck fl anged surface inlet, rated at 20 amperes, shall have a no n-locking-type attachment plug that shall be 2-pole, 3-wii·e grounding type rated 20 a mperes, 125 volts and intended for use with the 20-ampere, 125-volt receptacle.

Exception: A separable power-supply cable assembly, pmvicled for the connection of only an engine block heater, shall have an attachment plug of the 2-pole, 3-wire grounding type, rated 15 amperes, 125 volts. Informational Note: For non-locking- a n d grounding-type 15- or 20-ampere p lug and receptacle configurntions, see ANSI/ NEMA WD 6-2016, Wiring Devices - Dimensional Sjiecificalions, Figure 5-15 or Figure 5-20.

(b ) Connection to JO-Ampere Receptacle. A separable powersupply cable assembly for connectio n to a truck fl anged surface inlet, rated at 30 amperes, shall have an attachment plug that shall be 3-pole, 4-wire grounding type rated 30 amperes, 208Y/ 120 volts or 125/250 volts, and intended for use with the receptacle in accordance with 626.24(B)(2) . The 125/ 250-volt attachment plug shall be permitted to be used o n a 208Y/ 120volt, single-phase circ uit. 1nformational Note: For various configurations of 30-ampere pin and sleeve p lugs, see ANSI/U L 1686-2012, Standard for Pin and Sleeve Config1.1rations, Figure C2. J Oor Pan C3.

(5) Cord Connector. T he cord connector for a separable powe1~supply cable assembly, as specified in 626.25(A) (1), shall be a 2-pole , 3-wire ground ing type rated 20 amperes, 125 volts. The cord connector for a separable power-supply cable assembly, as specified in 626.25(A)(2) , sh all be a 3-pole, 4-wire ground ing type rated 30 amperes, 208Y/120 volts or 125/250 volts. The 125/250-volt cord connector shall be permitted to be used on a 208Y/ 120-vo lt, single-phase circuit.

Exception: The cord connector for a separable power supply cable assembly, rated 15 amperes, provided for the connection of an engine block heater for existing vehicles, shall have an attachment plug that shall be 2-pole, 3-wire grounding type rated 15 amperes, 125 volts. 1nformatio nal Note: For various configuratio n s of 30-ampere

cord connectors, see ANSI/ UL 1686-2012, Standard for Pin and Sleeve Config1.1mtio11s, Figure C2 .9 or Part C3.

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 626- ELECTRIFIED TRUCK PARKING SPACES 626.26 Loss of Primary Power. Means shall be provided such that, upon loss of voltage from the utility or other elecu-ic supply system (s), energy cannot be back-fed through the truck and the u·uck supply equipment to the electrified u·uck parking space wiring system unless permitted by 626.27. 626.27 Inte ractive Systems. Elecu·ified truck parking space supply equipment and other parts of a syste m, either on-boa.rd or off~board the vehicle, that are identified for and intended to be interconnected to a vehicle and also serve as an optional standby system or an electric power production source or provide for bi-directional power feed shall be listed as suitable for that purpose. When u sed as an optional standby system, the requirements of Article 702 shall apply, and when used as an electric power production source, the requirements of Article 705 shall apply.

Part IV. Transport Refrigerated Units (TRUs) 626.30 Transport Refrigerated Units. Electrified u·uck parking spaces intended to supply u-ansport refrigerated units (TRUs) shall include an individual branch circuit and receptacle for operation of the refrigeration/ heating units. The receptacle associated with the TRUs shall be provided in addition to the receptacles required in 626.24(B) . (A) Branch Circuits. TRU spaces shall be supplied from 208volt, 3-phase, 240-volt, 3-phase, or 480-volt, 3-phase branch circuits and with an equipment grounding conductor. (B) Electrified Truck Parking Space Supply Equipment. The elecu·ified truck parking space supply equipment, or portion thereof, providing e lectric power for the operation of TRUs shall be independent of the loads in Part III of Article 626. 626.31 Disconnecting Means and Receptacles. (A) Disconnecting Means. Disconnecting means shall be provided to isolate each refrigerated unit from its supply connection . A disconnecting means shall be provided and installed in a readily accessible location and shall be lockable open in accordance with 110.25. (B) Location. The disconnecting means shall be readily accessible , located not more than 750 mm (30 in. ) from the receptacle it conu·ols, and located in the supply circuit ahead of the receptacle. Circuit breakers or switches located in power outlets complying with this section shall be permitted as the disconnecting means.

626.32 Separable Power Supply Cable Assembly. A separable power supply cable assembly, consisting of a cord with an attachment plug and cord connector, shall be one of the types and ratings specified in 626.32(A), (B), and (C) . Cords with adapters and pigtail ends, extension cords, and similar items shall not be used. (A) Rating(s). The power supply cable assembly shall be listed and rated in accordance with one of the following: (I )

(2) (3) ( 4) (5)

(I) (2) (3)

( 4) (5)

A 30-ampere, 480-volt, 3-phase, 3-pole, 4-wire receptacle A 60-ampere, 208-volt, 3-phase, 3-pole, 4-wire receptacle A 20-ampere, 1000-volt, 3-phase, 3-pole, 4-wire receptacle, pin and sleeve type A 60-ampere, 250-volt, 3-phase, 3-pole, 4-wire receptacle A 60-ampere, 480-volt, 3-phase, 3-pole, 4-wire receptacle Informational Note: Complete details of the 30-ampere pin and sleeve receptacle configuration for refrigerated containers (TRUs) can be found in ANSI/ UL 1686-2012, Standard for Pin and Sleeve Configurations, Figure C2.l l. For various configurations of 60-ampere pin and sleeve receptacles, see ANSI/ UL1686.

2020 Edition

NATIONAL ELECTRJCAL CODE

A 30-ampere, 480-volt, 3-pha.se assembly A 60-ampere , 208-volt, 3-pha.se assembly A 20-ampere, 1000-volt, 3-phase assembly A 60-ampere, 480-volt, 3-phase assembly A 60-ampere, 250-volt, 3-phase assembly

(B) Cord Assemblies. The cord shall be a listed type with four conductors, for 3-phase connection, one of wh ich shall be identified in accordance with 400.23 for use as the equipment grounding conductor. Extra-hard usage cables rated not less than 90°C (194°F) , 600 volts, listed for both wet locati o ns and sunlight resistance, and having an outer jacket rated to be resistant to temperature extremes, oil , gasoline, ozone, abrasion, acids, and chemicals, shall be perm itted where flexibility is necessary between the electrified truck parking space supply equipment and the inlet(s) on the TRU. (C) Attachment Plug(s) and Corel Connector(s). Where a flexible cord is provided with an attachment plug and cord connector, they shall comply with 250.1 38(A) . The attachment plug(s) and cord connector(s) shall be listed, by itself or as part of the power-supply cable assembly, for the purpose and shall be molded to or installed on the flex ible cord so that it is secured tightly to the cord at the point where the cord enters the attachmen t plug or cord connector. If a right-angle cap is used, the configuration shall be orie nted so that the gro unding member is farthest from th e cord. An attachment plug and cord con necto r for the connection of a u·uck or trailer shall be rated in accordance with one of the following:

(1)

(2)

(3)

(4)

(C) Receptacles. All receptacles shall be listed and of the

grounding type. Every e lectrified truck parking space intended to provide an elecu·ical supply for TRUs shall be equipped with one or more of the following:

626.32

(5)

30-ampere, 480-volt, 3-ph ase, 3-pole , 4-wire and intended for use with 30-ampere, 480-volt, 3-phase, 3-pole, 4-wire receptacles and inlets, respectively 60-ampere, 208-volt, 3-ph ase, 3-pole, 4-wire and intended for use with 60-ampere, 208-volt, 3-phase, 3-pole, 4-wire receptacles and inlets, respectively 20-ampere, l 000-volt, 3-phase, 3-pole, 4-wire and inte nded for use with 20-ampere, 1000-volt, 3-phase, 3-pole, 4wire receptacles and inlets, respectively 60-ampere, 480-volt, 3-ph ase, 3-pole , 4-wire and intended for use with 60-ampere, 480-volt, 3-pha.se, 3-pole, 4-wire receptacles and inlets, respectively 60-ampere, 250-volt, 3-ph ase, 3-pole , 4-wire and intended for use with 60-ampere, 250-volt, 3-ph ase, 3-pole, 4-wire receptacles and inlets, respectively Informational Note: Complete details of the 30-ampere pin and sleeve atrnchmem plug and cord connecwr configurations for refrigerated comainers (TRUs) can be found in ANSI/ UL 1686-2012, Slandard for Pin and Sleeve Configurations, Figures C2.12 and C2.l l. For various configurations of 60-ampere pin and sleeve attachmem plugs and cord connectors, see ANSI/ UL1686.

70-539

630.1

ARTICLE 630- ELECTRIC WELDERS the standard ampere ratin gs provided in 240.6 or where the rating or setting specified results in un necessary o pening of the overcurren t device, the next higher standard rating or setting shall be permitted.

ARTICLE 630 Electric Welders Part I. General 630.1 Scope. Th is article covers apparatu s for e lectric arc weld ing, resistance weld ing, p lasma cutting, and other similar weld ing and cutting process equipment that is connected to an electrical su pply system. 630.6 Listing. All welding and cutting power equipment under the scope of this article shall b e listed.

Part II. Arc Welders 630.11 Ampacity of Supply Conductors. The a m pacity of conductors for arc welders shall be in accordance with 630.11 (A) and (B) . (A) Individual Welders. The ampacity of the su pply cond uctors shall be not less than th e IietT value on the rating plate. Alternatively, if the 11.n is not g iven, the am pacity of the su pply conductors shall not be less than the cu rrent value determined by m ultiplying the rated primary cu rrent in a m peres g iven on the welder rating plate by the factor shown in Ta ble 630.11 (A) based on the d uty cycle of the welder.

(A) For Welders. Each welder shall h ave overcu rrent protection rated or set at n ot more th an 200 percent of / 1"'""' Alternatively, if the 11"'"" is not given , the overcurren t protection shall be rated o r set at not more th an 200 percent of the rated p rimary current of the welder.

An overcu rren t device shall not be required for a welder that has su pply conductors protected by an overcurrent device rated or set at n ot more than 200 percent of 11"'"-' or at the rated primary current of the welder. If the supply conductors for a welder are protected by an overcurren t device rated o r set at not more than 200 percent of / 1"'"" or at the rated primary cu rrent of the welder, a separate overcurren t device shall not be required.

(B) For Conductors. Conductors that su pply one or more welders sh all be protected by an overcurrent device rated or set at not more than 200 percent of the conductor a m pacity. l nfOrmational Note: / 1111,.x is the maxinn1m value of the rated supply current at maximum rated output. 1,.,rr is the maximum value of the effective supply current, calculated from the rated supply current (11) , the corresponding duty cycle (duty factor) (X), and the supply current at no-load (4,) by the following equation:

(B) Group of Welders. Minimum cond uctor a m pacity shall be based on the individual curre nts determined in 630.11 (A) as the su m of 100 percen t of t he two la rgest welders, plus 85 percent of the third largest welder, plus 70 pe rcent of the fou rth largest welder, plus 60 percen t of all remain ing welders. Exception: Percentage values lower than those given in 630.1 l (B) shall be permitted in cases where the work is such that a high-operating duty cycle for individual welders is impossible. Informational Note: Duty cycle considers welder loading based on the use to be made of each welder and the number of welders supplied by the cond uctors that will be in use at the same time. T he load value used for each welder considers both the magnitude and the duration of the load while the welder is in use.

630.12 Overcurrent Protection. Overcu rrent protection for arc welders shall be as provid ed in 630. I 2(A) and (B) . V.'here th e valu es as determ ined by th is sectio n do not correspond to

Table 630.11 (A) Duty Cycle Multiplication Factors for Arc Welders Multiplier for Arc Welders Duty Cycle

JOO 90 80 70 60 50 40 30 20 or less 70-540

Nonmotor Generator

Motor Generator

l.00 0.95 0.89 0.84 0.78 0.71 0.63 0.55 0.45

1.00 0.96 0.9] 0.86 0.81 0.75 0.69 0.62 0.55

[630.12(B)]

630.13 Disconnecting Means. A d isconnecting m eans sha ll be provided in t he su pply circuit for each arc welder that is not equi pped with a d isconnect mou nted as an integral part of the welder. The d isconnecti ng mean s identity sh all be marked in accordance with 110.22(A) .

The d iscon necting mean s shall be a switch or circuit breaker, and its rating sha ll be not less than that necessary to accom modate overcurrent protection as specified u nder 630.1 2. 630.14 Marking. A rating plate shall b e provided for arc welders giving the following information: (I)

(2) (3) (4) (5) (6) (7) (8)

Name of manufacturer Frequency N u mber of phases P rimary voltage 11"'"" a nd I 1.tT, or rated p rimary cu rrent Maximum open-circuit voltage Rated secondary current Basis of rating, such as the d u ty cycle

630.15 Grounding of Welder Secondary Circuit. The secondary circuit cond uctors of a n arc welder, consisting of the elecu·ode cond uctor a nd the work cond uctor, shall no t be con side red as premises wiring for the purpose of ap plying Article 250. I nformational Note: Connecting welder secondary circuits to grounded objects can create parallel paths and can cause objectionable current over equipment grounding conductors.

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 630 - ELECTRIC 'NELDERS Part III. Resistance Welders

630.31 Ampacit:y of Supply Conductors. The ampacity of the supply conductors for resistance welders shall be in accordance with 630.31 (A) and (B) . Informational Nore: The ampaciry of the supply conductors for resistance welders necessary ro limit the voltage drop ro a value permissible for I.he satisfactory performance of I.he welder is usually greater than rhar required ro prevent overhearing.

(A) Individual Welders. The ampacity of conductors for individual welders shall comply with the following: (I)

(2)

The arnpacit:y of the supply conductors for a welder that can be operated at different times at d ifferent values of primary current or duty cycle shall not be less than 70 percent of the rated primary curren t for seam and automatically fed welders, and 50 percent of the rated primary current for manually operated nonautomatic we lders. The ampacity of the supply conductors for a welder wired for a specific operation for which the actual primary current and duty cycle are known and rema in uncha nged shall not be less than the product of the actual primary current and the multiplier specified in Table 630.31 (A) for the duty cycle at which the welder will be operated.

(B) Groups of Welders. The ampacity of conductors that supply two or more welders shall not be less than the sum of the value o btained in accordance with 630.31 (A) for the largest welder supplied and 60 percent of the values obtained for all the other welders supplied . Informational Nore: Explanation of Terms ( l)

(2)

(3)

The rated fn'irnary cummt is the rared kilovolt-amperes (kVA) multiplied by l000 and d ivided by the rared primary voltage, using values given on rhe nameplate. The actual prirnar-y cur-mnl is die current drawn from the supply circuit during each welder operation at the particu lar hear rap and conu-ol setting used. The duly cycle is the percentage of the time during which the welder is loaded. For instance, a spot welder supplied by a 60-Hz system (216,000 cycles per hour) and making 400 15-cycle welds per hour would have a duty cycle of 2.8 percent (400 multiplied by 1.5, d ivided by 216,000, multiplied by 100) . A seam welder operating 2 cycles "on" and 2 cycles "oH~ wou ld have a duty cycle of 50 percent.

630.42

630.32 Overcurrent Protection. Overcurrent protection for resistance welders shall be as provided in 630.32(A) and (B) . Whe re the values as determined by this section do n ot correspond with the standard a mpere ratings provided in 240.6 or where th e rating or setting specified results in unnecessary opening of the overcurrent device, a higher rating or setting that does not exceed the next higher standard ampere rating shall be permitted. (A) For Welders. Each welder sha ll have an overcurrent device rated or set at not more than 300 percent of the rated primary cu rrent of the welder. If the supply conductors for a welder are protected by an overcurrent device rated or set at not more than 200 percent of the rated primary current of the welder, a separate overcurrent device shall not be requi red. (B) For Conductors. Conducro1-s that supply o ne or more welders shall be protected by a n overcurrent device rated or set at not more than 300 percent of the conductor ampacity. 630.33 Disconnecting Means. A switch or c ircuit breaker shall be provided by which each resistance welder and its control equipment can be d isconnected from the supply circuit. The a mpere rating of this d isconnecting means sha ll not be less than the supply conductor arnpacity determined in accordance with 630.31. The su pply circuit switch sh all be permitted as the welder disconnecting means where the circuit supplies only o ne welder. 630.34 Marking. A nameplate shall be provided for each resistance welder, giving the following information: (1) (2) (3) (4) (5) (6) (7)

Name of manufacturer Frequ ency Pr imary voltage Rated kilovolt-amperes (kVA) at 50 percent duty cycle Maximum and minimum o pen-circuit secondary voltage Sh ort-circuit secondary current at maximum secondary voltage Specified throat and gap setting

Part IV. Welding Cable 630.41 Conductors. Insulation of condu ctors intended for use in the secondary circuit of electric welders shall be flame retardant. 630.42 Installation. Cables shall be permitted to be installed in a dedicated cable tray as provided in 630.42(A), (B), a nd (C) .

Table 630.3l(A) Duty Cycle Multiplication Factors for Resistance Welders Duty Cycle (%)

50 40 30 25 20 15 10 7.5 5 or less

2020 Edition

NATIONAL ELECTRJCAL CODE

Multiplier 0.71 0.63 0.55 0.50 0.45 0.39 0.32 0.27 0.22

(A) Cable Support. The cable tray shall provide support at not greater than 150-mm (6-in. ) intervals. (B) Spread of Fire and Products of Combustion. The installation shall comply with 300.21.

(C) Signs. A permanent sign shall be attached to the cable tray at intervals not greater t ha n 6.0 rn (20 ft) . T h e sig n shall read as follows: CABLE TRAY FOR WELDING CABLES ONLY

70-541

640.1

ARTICLE 640 - AUDIO SIGNAL PROCESSING, AMPLIFICATION, AND REPRODUCTION EQUIPMENT

ARTICLE 640 Audio Signal Processing, Amplification, and Reproduction Equipment Part I. General

640.1 Scope. (A) Covered. This article covers equipment and wmng for audio sig nal generation, reco rding, processing, amplifi cation , a nd re pro duction; distribution of sound; public address; speech input systems; te mporary audio syste m installations; a nd electronic organs or other electronic musical instruments. This also includes a udio syste ms subject to Article 517, Part VI, a nd Articles 518, 520, 525, and 530. In fo rma tio nal Note: Exa mp les of permanently installed d istributed a ud io system locatio ns include, but are not limited to, restau rant, hotel, business office, commercial an d retail sales e nvi ro nme nts, chu rches, a nd sch ools. Both portable a nd permane ntly installed equip ment locatio ns include, b m are not limited to, residen ces, aud ito riums, th eaters, stadi u n1s, a nd movie a nd televisio n stud ios. Te mpo rary installatio ns include, bm a re not limited to, aud itoriums, t heaters, stadiums (which use both tempo rary and permanently installed systems), a nd ou tdoo r events su ch as fa irs, festivals, circu ses, public events, a nd concer ts.

(B) Not Covered. This articl e does not cover the installatio n a nd wiring of fire and burglary a larm sig n aling d evices. 640.2 Definitions. The following definitions shall apply only within this article. Abandoned Audio Distribution Cable. Installed audio distributio n cable that is not terminate d at equipment and not ide ntifie d for future use with a tag. Audio Amplifier or Pre-Amplifier. Electronic equipme nt that increases the current or vol tage, or both, of an audio sig na l inte nded for use by another p iece of audio equipment. Amplifier is the te rm used within this a rticle to denote a n audio amplifie r. Audio Autotransformer. A transform e r with a single winding a nd multipl e taps inte nded fo r use with an amplifier loudspeaker sig nal output. Audio Signal Processing Equipment. Electrically operated equipment that produce s, pro cesses, or both, electronic sig nals that, wh e n appropria tely a mplified a nd reproduced by a loudspeaker, produce an acoustic signal within the range of normal human h earing (ty pically 20- 20 kHz) . Within this article, the terms equipment a nd audio equipment are assumed to be equivale nt to audio signal processing equipme nt. Informatio nal Note: This equ ipme nt includes, bu t is not limited to, lo udspeake rs; headpho nes; pre-amplifiers; micropho nes a nd their power su pplies; mixers; MIDI (musical instrument digital inter face) equi p men t o r othe r d igital con trol systems; equa lize rs, com p resso rs, a nd othe r a ud io signal processing equi p men t; a nd au d io media record ing a n d p layback equi p me nt, including turn tables, tape decks and d isk players (aud io and multimedia), synthesizers, tone gen erators, a nd electronic o rgans. Electronic o rgans and synth esizers may h ave integral o r separate amplificatio n a nd lo udspeake rs. With th e exceptio n of a m p lifier ou tpu ts, virtua lly all such equipme nt is used to p rocess sign als (u tilizing

70-542

a nalog o r digital techniques) th at have n o nhazardou s levels of voltage o r curre nt.

Audio System. Within this article, the totality of a ll equipment and inte rconnecting wiring used to fabricate a fully functional audio sig nal processing, amplifi catio n , and reproduction system. Audio Transformer. A transformer with two o r more electrically iso late d windings and multiple taps intended for use with a n amplifi e r loudspeaker signal output. Equipment Rack. A fram ework for the suppo rt, enclosure, o r bo th, o f equipme nt; can be portable or sta tionary. Info rmatio nal Note: See EIA/ ECA 310-E-2005, Cabinets, Rachs, Panels and Associaled Equipment.

Loudspeaker. Equipment that converts an ac elec tric sign al into an acoustic sig nal. The term speaker is commonly used to mean loudspeaker. Maximum Output Power. The maximum power delivered by an a mplifie r into its rated load as determined under specifi ed test conditio ns. Info rmatio na l Note: The maximum output power ca n exceed the ma nufacture r 's rated outpm power for tl1e same am p lifie r.

Mixer. Equipme nt used to combine and level match a multiplici ty of electroni c sign a ls, su ch as from m icropho nes, electronic instrumen ts, and recorded a udio . Portable Equipment. Equipment fed with portable cords o r cables intended to be moved from o ne place to a nother. Rated Output Power. The amplifier m a nufacnirer's stated or marke d output p ower capability into its rate d load . Technical Power System. An electrical distribution system wh e re the equipment grounding conductor is isolated from the premises g rounded co nducto r and the premises e quipment grounding conductor except at a single grounded ter mination point within a branch-circuit pane lbo ard, at the o riginating (m a in breaker ) bran ch-circuit panelboa rd, or at the premises grounding electrode. Temporary Equipment. Portable wiring and equipme nt intended for use with events of a transient o r tempo rary nature wh e re a ll equipment is p resume d to b e re moved at the conclusio n of the event. 640.3 Locations and Other Articles. Circu its a nd e qui p ment shall comply with 640.3 (A) through (M), as a pplicable. (A) Spread of Fire or Products of Combustion. Sectio n 300.21 shall apply. (B) Ducts, Plenums, and Other Air-Handling Spaces. Sectio n 300.22(B) sh all apply to circuits a nd equipm ent installed in d u cts specifically fab r icated for e nvironmental air. Sectio n 300.22 (C) sh all apply to circuits and equipment installed in other spaces u sed for e nvironme ntal a ir (ple nums) . 1'.xception No. 1: Class 2 and Class 3 cables installed in accordance with 725.135(B ) and Table 725. 154 shall be permilled to be installed in ducts specifically fal1ricated f or environmental ai1: Exception No. 2: Class 2 and Class 3 cables installed in accordance with 725.135(C) and Table 725. 154 shall be permitted to be installed in other spaces used for environmental air (plenums ).

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 640-AUDIO SIGNAL PROCESSING, AMPLIFICATION, AND REPRODUCTION EQUIPMENT Informational Nore: NFPA 90A-2018, Standard for lhe Installation of Air-Conditioning and Ventilating Systems, 4.3 .11.2.6.5, permirs loudspeakers, loudspeaker assemblies, and their accessories listed in accordance with UL 2043-2013, Fire Test for Heal and Visi-

640.9

640.6 Mechanical Execution of Work.

(C) Cable Trays. Cable trays and cable tray systems shall be installed in accordance with Article 392.

(A) Installation of Audio Distribution Cables. Cables installed exposed on the surface of ceilings and sidewalls shall be supported in such a manner that the audi o disu·ibution cables will not be damaged by n ormal building use . Such cables shall be secured by straps, staples, cable ties, hangers, or similar fittings designed and installed so as not to damage the cable. The installatio n shall conform to 300.4 and 300.11 (A) .

Informational Nore: See 725.135(I-l ), 725.136(G), and Table 725.154 for rhe use of Class 2, Class 3, and Type PLTC cable in cable trays.

(B) Abandoned Audio Distribution Cables. The accessible portion of abandoned audio d istribution cables shall be removed.

(D) Hazardous (Classified) Locations. Equipment used in hazardous (classified) locations shall comply with the applicable requirements of Chapter 5.

(C) Installed Audio Distribution Cable Identified for Future Use.

(E) Assembly Occupancies. Equipment used in assembly occupancies shall comply with Article 518.

of sufficient durability to withstand the environment involved.

ble Smolw Release for Discret,e Producls and Their Accessories lnslalled in Ai1°Handli11g Spaces, ro be ins railed in other spaces used for em~-

ronmenral a ir (ceiling cavity p lenums).

(F) Theaters, Audience Areas of Motion Picture and Television

Studios, and Similar Locations. Equipment used in theaters, audience areas of motion picture and television sn1dios, and similar locations shall comply with Article 520. (G) Carnivals, Circuses, Fairs, and Similar Events. Equipment used in carnivals, circuses, fairs, a nd similar events shall comply with Article 525. (H) Motion Picture and Television Studios. Equipme nt used in motion picture and television studios shall comply with Article 530.

(I) Swimming Pools, Fountains, and Similar Locations. Audio equipment used in or near swimming pools, fountains, and similar locations shall comply with Article 680.

(J) Combination Systems. Where the authority having jurisdiction permits audio systems for paging or music, or both , to be combined with fire a larm systems, the wiring shall comply with Article 760. Informational Note: For installation requiremenrs for such combination systems, refer to Nl•PA 72-2016, Nalional Fire Alarm and Signaling Code, and N FPA 101-2018, Life Safety Code.

(K) Antennas. Equipment used in audio systems that contain a n audio or video tune1- and an antenna input shall comply with Article 810. Wiring other than ante n na wiring that connects suc h equipment to other audio equipment shall comply with this article. (L) Generators. Generators shall be installed in accordance with 445.10 through 4 45.12, 445.14 through 445.16, and 445.1 8. Grounding of portable and vehicle-mounted generators shall be in accordance with 250.34. (M) Organ Pipes. Additions of pipe organ pipes to an elec-

(1) Cables identified for future use shall be marked with a tag

(2) Cable tags shall have the following information:

(1) (2) (3)

Date cable was identified fot·future use Date of inte nded use Information related to the intended fi.mire use of cable

640.7 Grounding. (A) General. Wireways a nd auxiliary gutters s hall be connected to an equipment grounding conductor(s), to an equipment bonding jumper, or to the grounded conductor where permitted or required by 250.92(B)(l) or 250.142. Where the wireway or auxiliary gutter does not conta in power-supply wires, the equipment grounding conductor sh all not be required to be la rger tha n 14 AWG copper or its equivalent. Where the wireway or auxiliary gutter contains power-supply wires, the equipme n t grounding conductor shall not be smaller than specified in 250.1 22. (B) Separately Derived Systems with 60 Volts to Ground. Grounding of separately derived syste ms with 60 volts to ground shall be in accordance with 647.6. (C) Isolated Ground Receptacles. Isolated grounding-type receptacles shall be permitted as described in 250.146(0), and for the imple mentation of othe1· technical power syste ms in compliance with Article 250. For separately derived systems with 60 volts to ground, th e b ran c h-circuit equipment grounding conductor sh all be term inated as required in 647.6(B) . Informational Note: See 406.3(0 ) for g rounding-type receptacles and required identification.

640.8 Grouping of Conductors. Insulated conductors of different systems grouped o r bundled so as to be in close physical contact with each o ther in the same raceway o r other enclosure, or in portable cords or cables, shall comply with 300.3(C) (1) .

tronic organ shall be in accordance with 650.4 through 650.9.

640.9 Wiring Methods.

640.4 Protection of Electrical Equipment. Amplifiers, lo udspeakers, and other equipment shall be so located or protected as to guard against environmental exposu re or physical damage, such as might resu lt in fire, shoc k, or pe rsonal hazard.

(A) Wiring to and Between Audio Equipment.

640.5 Access to Electrical Equipment Behind Panels Designed to Allow Access. Access to equipment shall not be denied by an accumulation of wires and cables that prevents re moval of panels, including suspended ceiling panels.

2020 Edition

NATIONAL ELECTRJCAL CODE

(1) Power Wiring. Wiring a nd equipment from source of power to and between devices con nected to the prem ises wiring systems shall comply with the requi remen ts of Chapters 1 through 4, except as modified by this a rticle . (2) Separately Derived Power Systems. Separately derived syste ms shall comply with the a pplicable articles of this Code, except as modified by this articl e . Separately derived systems

70-543

640.9

ARTICLE 640-AUDIO SIGNAL PROCESSING,AMPLIFICATION, AND REPRODUCTION EQUIPMENT

with 60 volts to ground shall be permitted for use in audio system installations as specified in Article 647.

I nformational Note: See 680.27 (A) for installation of underwater audio equipmenL

(3) Other Wiring. All wiri ng not connected to the premises wiring system or to a wiring system separately derived from the premises wiring system sha ll comply with Article 725.

(A) Equipment Supplied by Branch-Circuit Power. Audio system equipment supplied by branch-circuit power shall not be placed horizontally within 1.5 m (5 ft) of the inside wall of a pool, spa, hot nib, or fountain, or within 1.5 m (5 ft) of the prevailing or tidal high water mark. I n addition to the requirements in 210.S(B), the equipment shall be provided with branch-circuit power protected by a ground-fault circuit interrupter where required by oth er articles.

(B) Auxiliary Power Supply Wiring. Equipment that has a separate input for an auxiliary power supply shall be wired in compliance with Article 725 . Battery installation shall be in accordance with Article 480. This section sha ll not apply to the use of uninterruptible power supply (UPS) equipment, or other sources of supply, that are intended to act as a direct replacement for the primary circuit power source and are connected to the primary circuit input. In formational Note: Refer to NFPA 72-2019, Nalional Fire Alarm and Signaling Code, where equipment is used for a fire alarm system.

(C) Output Wiring and Listing of Amplifiers. Amplifiers with output circuits carrying audio program signals shall be permitted to employ C lass 1, Class 2, or Class 3 wiring wh ere the amplifier is listed and marked for use with the specific class of wiring method. Such listing shall ensure the energy output is equivalent to the shock a nd fire risk of the same class as stated in Article 725. Overcurrent protection shall be provided a nd shall be permitted to be inherent in the amplifier.

Audio amplifier output circuits wired using Class I wiring methods shall be considered equivalent to Class 1 circuits and shall be installed in accordance with 725.46, where applicable. Audio a mplifier output circuits wired using Class 2 or Class 3 wiring methods shall be con sidered equivalent to Class 2 or Class 3 c ircuits, respectively. They shall use conductors insulated at not less than the requirements of 725.1 79 a nd shall be installed in accordance with 725.1 33 and 725.1 54. Informational Note No. I: ANSI/U L 1711-2016, Amf!lifiersforFire Proleclive Signaling Syslems, comains requirements for the listing of amplifiers used for fire a larm systems in compliance with NFPA 72-20 I9, Nalional Fire Alarm and Signaling Code. Informational Note No. 2: Examples of requirements for listing amplifiers used in residential, commercial, and professional use are found in ANSI/UL 8 13-1996, Comniercud Audio Equipmen~ ANSI/ UL 1419-2016, Professional Vid.eo and Audio Equijnnen~ ANSI/ UL 1492-1996 revised 201 3, AudirrVid.eo Producls and Accessories; ANSI/ UL 6500-1999 revised 2013, Audio/Video and Musical lnslrunienl AJJj>araltis for Hotisehold, Comniercial, and Similar Use-, and UL 62368-1-2014, Audio/Video, Information and Communicalion Technology Equijmienl - Pcirl 1: Safety Requirenienls.

(D) Use of Audio Transformers and Autotransformers. Audio transformers and autotransformers shall be used only for audio signals in a manner so as not to exceed the manufacnirer's stated input or output voltage, impedance, or power limitations. The input or output wires of an audio transformer or autou·ansformer shall be allowed to connect directly to the amplifier or loudspeaker terminals. No e lectrical terminal or lead shall be required to be grnunded or bonded. 640.10 Audio Systems Near Bodies of Water. Audio systems near bodies of water, either natural or artificial, shall be subject to the resu-ictions specified in 640.1 0 (A) and (B) .

Exception: 17iis section does not include audio systerns intended for use on boats, yachts, or other forms of land or water transportation used near bodies ofwate1; whether or not supplied by branch-circuit power.

70-544

(B) Equipment Not Supplied by Branch-Circuit Power. Audio system equ ipment powered by a listed Class 2 power supply or by the output of an amplifier listed as permitting the use of Class 2 wiring shall be resu·icted in placement only by the manufacturer's recommendations. I nformational Note: See 640.I0(A) for p lacement of the power supply or amplifier if supplied by branch-circuit power.

Part II. Permanent Audio System Installations 640.21 Use of Flexible Cords and Cables. (A) Between Equipment and Branch-Circuit Power. Power supply cords for audio equipment shall be suitable for the use and shall be permitted to be used whe1·e the interchange, maintenance, or repair of such equipment is facilitated through the use of a power-supply cord. (B) Between Loudspeakers and Amplifiers or Between Loudspeakers. Cables used to connect loudspeakers to each other or to an amplifier shall comply with Article 725 . Other listed cable types and assemblies, including optional hybrid communications, sig nal, and composite optical fiber cables, shall be permitted. (C) Between Equipment. Cables used for the d isu·ibution of audio signals between equipment shall comply with Article 725 . Other listed cable types and assemblies, including optional hybrid communications, signal, and composite optical fiber cables, shall be permitted. Other cable types and assemblies specified by the equ ipment manufacturer as acceptable for the u se shall be permitted in accordance with ll 0.3(B) . Informational Note: See 770.3 for the classification of composite optical fiber cables.

(D ) Between Equipment and Power Supplies Other Than Branch-Circuit Power. The following power supplies, other than branch-circuit power supplies, sh all be installed and wired between equipment in accordance with the requirements of this Code for the voltage and power delivered: (I)

(2) (3) (4)

Storage batteries Transformers Transformer rectifiers Other ac or de power supplies Informational Note: For some equipment, these sources such as in items (I) and (2) serve as the only source of power. These could, in turn, be supplied with intermittent or continuous branch-circuit power.

(E) Between Equipment Racks and Premises Wiring System. Flexible cords and cables shall be permitted for the electrical connection of permanently installed equipment racks to the premises wiring system to facilitate access to equipment or for the purpose of isolating the technical power system of the rack

NATIONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 640-AUDIO SIGNAL PROCESSING, AMPLIFICATION, AND REPRODUCTION EQUIPMENT from the premises ground. Connection shall be made either by using approved plugs and receptacles or by direct connection within an approved enclosure. Flexible cords and cables shall not be subjected to physical manipulation or abuse while the rack is in use. 640.22 Wiring of Equipment Racks and Enclosures. Metal equipment racks and enclosures shall be bonded and grounded. Bonding shall not be required if the rack is connected to a technical power ground.

,1\/'ires, cables, structural components, or other equipment shall not be placed in such a manner as to prevent reasonable access to equipment power switches and resettable or replaceable circuit overcurrent protection devices. Supply cords or cables, if used, shall terminate within the equipment rack enclosure in an identified connector assembly. The supply cords or cable (and connector assembly if used) shall have sufficient ampacity to carry the total load connected to the equipment rack and shall be protected by overcurrent devices. 640.23 Conduit or Tubing. (A) Number of Conductors. The number of conductors permitted in a single conduit or tubing shall not exceed the percentage fill specified in Table 1, Chapter 9. (B) Nonmetallic Conduit or Tubing and Insulating Bushings. The use of nonmetallic conduit or tubing and insulating bushings shall be permitted where a technical power system is employed and shall comply with applicable articles. 640.24 Wrreways, Gutters, and Auxiliary Gutters. The use of metallic and nonmetallic wireways, gutters, and auxiliary gutters shall be permitted for use with audio signal conductors and shall comply with applicable articles with respect to permitted locations, construction, and fill . 640.25 Loudspeaker Installation in Fire Resistance-Rated Partitions, Walls, and Ceilings. Loudspeakers installed in a fire resistance-rated partition, wall, or ceiling shall be listed and labeled, o r identified as speaker assemblies for fire resistance, or installed in an enclosure or recess that maintains the fire resistance rating. Informational Note: Fire-rated construction is the fire-resistive classification used in building codes.

Part III. Portable and Temporary Audio System Installations 640.41 Multipole Branch-Circuit Cable Connectors. Multipole branch-circuit cable connectors, male and female, for powersupply cords and cables shall be so constructed that tension on the cord or cable is not transmitted to the connections. The female half shall be attached to the load end of the power supply cord or cable. The connector shall be rated in amperes and designed so that differently rated devices cannot be connected together. Alternating-current multipole connectors shall be polarized and comply with 406.7(A) and (B) and 406. l 0. Alternating-current or direct-current multipole connectors utilized for connection benveen loudspeakers and amplifie rs, or between loudspeakers, shall not be compatible with nonlocking 15- or 20-ampere rated connectors intended for branch-circuit power or with connectors rated 250 volts or greater and of either the locking or nonlocking type. Signal cabling not intended for such loudspeaker and amplifier inter-

2020 Edition

NATIONAL ELECTRJCAL CODE

640.43

connection shall not be permitted to be compatible with multipole branch-circuit cable connectors of any accepted configuration . Informational Note: See 400.14 for pull at terminals.

640.42 Use of Flexible Cords and Cables. (A) Between Equipment and Branch-Circuit Power. Power supply cords for audio equipment shall be listed and shall be permitted to be used where the i nterchange, maintenance, or repair of such equipment is facili tated through the use of a power-supply cord. (B) Between Loudspeakers and Amplifiers, or Between Loudspeakers. Installation of flexible cords and cables used to connect loudspeakers to each other or to an amplifier shall comply with Part I of Article 400 and Parts I, II, III, and IV of Article 725, respectively. Cords and cables listed for portable use, either hard or extra-hard usage as defined by Article 400, shall also be permitted. Other listed cable types and assemblies, including optional hybrid commun ications, signal, and composite optical fiber cables, shall be permitted. (C) Between Equipment and/ or Between Equipment Racks. Installation of flexible cords and cables used for the distribution of audio signals benveen equipment shall comply with Parts I and II of Article 400 and Parts I, II, and III of Article 725, respectively. Cords and cables listed for portable use, either hard or extra-hard service as defined by Article 400, shall also be permitted. Other listed cable types and assemblies, including optional hybrid commun ications, signal, and composite optical fiber cables, shall be permitted.

(D) Between Equipment, Equipment Racks, and Power Supplies Other Than Branch-Circuit Power. Wiring between the following power supplies, other than branch-circuit power supplies, shall be installed, connected, or wired in accordance with the requirements of this Code for the voltage and power required:

(1) (2) (3) (4)

Storage batteries Transformers Transformer rectifiers Other ac or de power supplies

(E) Between Equipment Racks and Branch-Circuit Power. The supply to a portable equipment rack shall be by means of listed extra-hard usage cords or cables, as defined in Table 400.4 . For outdoor portable or temporary use, the cords or cables shall be further listed as being suitable for wet locations and sunlight resistant. Sections 520.5, 520.10, and 525.3 shall apply as appropriate wh en the following conditions exist:

(l)

(2)

,I\There equipment racks include audio and lighting and/ or power equipment \,\Then using or constructing cable extensions, adapters, and breakout assemblies

640.43 Wiring of Equipment Racks. Equipment racks fabricated of metal shall be bonded and grounded. Nonmetallic racks with covers (if provided) removed s hall not allow access to Class 1, Class 3, or primary circuit power without the removal of covers over terminals or the use of tools.

Wires, cables, su·uctural components, or other equipment shall not be placed in such a manner as to prevent reasonable access to equipment power switches and resettable or replaceable circuit overcurrent protection devices.

70-545

640.44

ARTICLE 645 - INFORMATION TECHNOLOGY EQUIPMENT

Wiring that exits the equipment rack for connection to other equipment or to a power supply shall be relieved of strain or otherwise suitably terminated suc h that a pull on the flexible cord or cable will not increase the risk of damage to the cable or connected equipment such as to cause an unreasonable risk of fire or electric shock. 640.44 Environmental Protection of Equipment. Portable equipment not listed for outdoor use shall be permitted only where appropriate protection of suc h equipment from adverse weather conditions is provided to prevent risk of fire or e lectric shock. \!\/here th e system is intended to remain operable during adverse weather, arrangemen ts shall be made for maintaining operation and ventilation of h eat-dissipating equipment. 640.45 Protection of Wiring. '"'here accessible to the public, flexible cords and cables laid or run on the ground or on the floor shall be covered with approved nonconductive mats. Cables and mats shall be arra nged so as not to present a tripping hazard. The cover require ments of 300.5 shall not apply to wiring protected by burial. 640.46 Equipment Access. Equipme nt like ly to present a risk of fire, electric shock, or phys ical injmy to the public shall be protected by barrie rs o r supe rvised by qualified pe rsonnel so as to prevent public access.

ARTICLE 645 Information Technology Equipment 645.1 Scope. This article covers equipment, power-su pply wiring, equipment in terconnecting wiring, a nd grounding of information technology equipment and systems in an information technology equipment room. In fo rmational Note No. I: For further information, see NFPA 75-2017, Standard for the Fire Prowclion of Information Technology Equipmen~ which covers the requirements for th e protection of info rmation technology equipmem and in formation technology equipment areas. Informational Note No. 2: Text that is followed by a reference in brackets h as been extracted from NFPA 75-20 l 7, Standard for the Fire Protection of lnformalion Technology t :quifmumt. Only edito rial ch anges were made to the extracted text to make it consistent with d1is Code.

645.2 Definitions. The following definitions shall apply only within this article. Abandoned Supply Circuits and Interconnecting Cables. Installed supply circuits and interconnecting cables that a re not terminated at equipment a nd not identified for future use with a tag. Critical Operations Data System. An information technology equipment system that requires continuous operation for reasons of public safety, emergency management, nationa l security, or business continuity. Remote Disconnect Control. An e lectric device a nd c ircuit that controls a disconnecting means through a relay or equivalent device.

70-546

Zone. A physically identifiable area (such as barriers or separation by d istance) within an information technology equipment room, with dedicated power and cooling systems for the informatio n technology equipment or syste ms.

645.3 Other Articles. Circuits and e quipment shall comply with 645.3(A) through (I), as applicable. (A) Spread of Frre or Products of Combustion. Sections 300.21, 770.26, a nd 800.26 sha ll a pply to penetrations of the fire-resistant room boundary. (B) Wiring and Cabling in Other Spaces Used for Environmen-

tal Air (Plenums). The following sectio ns and tables shall apply to wiring and cabling in other spaces used for environmental air (plenums) above an information technology equipment room: (l )

(2) (3) (4) (5) (6)

Wiring methods: 300.22(C) (l ) Class 2, Class 3, and PLTC cables: 725.1 35(C) and Table 725.154 Fire alarm syste ms: 760.53(B)(2), 760.135(C), and Table 760.154 Optical fiber cables: 770.l 13(C) and Table 770.1 54(a) Communications circuits: 800.ll 3 and Table 800.154(a) CATV and radio distribution systems: 800. ll 3 and Table 800.l54(a)

(C) Bonding and Grounding. The non-current-carrying conductive members of optical fiber cables in an information techno logy equipmen t room shall be b o nded and g rounded in accordance with 770.11 4. (D) Electrical Classification of Data Circuits. Section 725 .121 (A)( 4) shall apply to the electrical classification of listed information technology equipment signaling circuits. Sections 725.1 39(0 ) (] ) a nd 805.1 33(A)(l)(c) shall apply to the e lectrical classification of Class 2 and Class 3 circuits in the same cable with communicatio ns circuits. (E) Fire Alarm Cables and Equipment. Parts I, II, a nd III of Article 760 shall apply to fire a larm syste ms cables and e quipme nt installed in an information technology equipme nt room . Only fire alarm cables listed in accordan ce with Part IV of Article 760 and listed fire alarm equipment shall be permitted to be installed in an information technology equipment roo m. (F) Cable Routing Assemblies, Communications Wires, Cables, Raceways, and Equipment. Sectio ns 800.II 0, 800.ll3, and 800.1 54 shall apply to cable routing assemblies and communications raceways. Parts I, II, III, IV, a nd V of Article 805 shall a pply to communicatio ns wires, cables, a nd equipme nt installed in an information technology equipment room. Only communications wires and cables listed in accordance with 805.179, cable routing assemblies, and communications raceways listed in accordance with 800.182, a nd commun ications equipme nt listed in accordance with 805 .170 shall be permitted to be installed in an information technology equipment room. Article 645 shall apply to the powering of communications equipment in an information technology equipment room. Info rmational Note: See Part I of Article 100, Definitions, for a defin ition of communications equipment.

(G) Community Antenna Television and Radio Distribution Systems Cables and Equipment. Parts I, II, III, IV, a nd V of Article 820 shall apply to community antenna television and radio distribution systems cabl es and e quipme nt installed in an information technology equipment room. Only community

NAT IONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 645- INFORMATION TECH NOLOGY EQUIPMENT antenna television and radio distribution cables listed in accordance with 820.179 and listed CATV equipment shall be permitted to be installed in an information technology equipment room . Article 645 shall apply to the powering of community antenna television and radio distribution systems equipment installed in an information technology equipment room .

(H) Optical Fiber Cables. Only optical fiber cables listed in accordance with 770.1 79 shall be permitted to be installed in an information technology equipment room . (I) Cables Not in Information Technology Equipment Room. Cables extending beyond the information technology equipment room shall be subject to the applicable require ments of th is Code.

645.4 Special Requirements for Information Technology Equipment Room. The alternative wiring methods to Chapter 3 and Parts I and III of Article 725 for signaling wiring and Parts I and V of Article 770 for optical fiber cabling shall be permitted where a ll of the following conditions are met: ( l) (2)

Disconnecting means complying with 645.10 are provided. A heating/ventilati n g/ air-conditioning (H VAC) system is provided in one of the methods identified in 645.4(2) a orb. a . A separate HVAC system that is dedicated for information technology equipment use and is separated from other areas of occupancy; or b. An HVAC system that serves other occupancies and meets all of the followin g: (i) (ii) (iii)

Also serve s the information technology equipment room Provides fire/smoke dampers at the point of penetration of th e room b o undary Activates the damper operation upon initiation by smoke detector alarms, by operation of the disconnecting means required by 645.10, or b y both

Informational Note: F'or further information, see NF'PA 7.5-20 I 7, Standard for Lhe Nre Prolection of lnfonnation Technology Equipment, Chapter 10, 10.1, 10.1.1, 10.1.2, and 10.1.3.

(3) ( 4)

(5)

All information techn o logy a nd communications equipment installed in the room is listed. The room is occupied by, and accessible to, only those personnel needed for the maintenance and functional operation of the installed information technology equipment. The room is separated from other occupancies by fireresistant-rated walls, floors, a nd ceilings with protected openings. Informational Nore: F'or h.irther information on room construction requirements, see NF'PA 75-2017, Standardfor the Fire Protection of Information Technology .equipment, Chapter 5.

(6)

Only electrical equipment and wiring associated with the operation of the information technology room is installed in the room. Informational Note: HVAC systems, communications systems, and mon itoring systems such as telephone, fire alarm systems, security systems, water detection systems,

2020 Edition

NATIONAL ELECTRJCAL CODE

645.5

and other related protective equipment are examples of equipment associated with the operation of the information technology room.

645.5 Supply Circuits and Interconnecting Cables. (A) Branch-Circuit Conductors. The branch-circuit conductors supplying one o r more units of information technology equipment sh all h ave an ampacity not less than 125 percent of the total connected load. (B) Power-Supply Cords. I nformation technology equipment shall be perm itted to be connected to a branch circuit by a power-supply cord. (l ) (2)

P ower-supply cords shall not exceed 4 .5 m ( 15 ft) . P ower cords shall be listed and a type perm itted for u se on listed information technology equipment o r sh all be con structed of listed flexible cord and listed attachment plugs and cord connectors of a type permitted for information technology equipment.

Informational Note: One method of determining if cords are of a type permitted for the purpose is found in U L 60950-1-2007, Safety of Information Technology Equipment - Safety - Part 1: General Requirements; or UL 62368-1-2012, Audio/Video, information and Communication Technology Equifmtent - Part 1: Safety Requirements.

(C) Interconnecting Cables. Separate information techno logy equipment units shall be permitted to be interconnected by means of listed cables and cable assembl ies. The 4 .5 m (15 ft) limitation in 645.5( B) ( 1) shall not apply to interconnecting cables. (D) Physical Protection. Where exposed to physical damage, supply circuits and interconnecting cables shall be protected. (E) Under Raised Floors. Where the area under the fl oor is accessible and openings minimize the entrance of debris beneath the floor, power cables, communications cables, con necti ng cables, interconnecti ng cables, cord-and-plug con nection s, and receptacles associated with the informatio n technology equipment shall b e permitted under a raised floor of approved construction. The installatio n requirement shall comply with 645.5(E) (1) through (E) (3) . (l) Installation Requirements for Branch Circuit Supply Conductors Under a Raised Floor. (a) T he supply condu ctors shall be installed in accorda n ce with the requirements of 300.11. (b) In addition to the wirin g methods of 300.22(C), the following wiring m ethods shall also be permitted: (1) (2) (3) ( 4) (5) (6) (7) (8) (9) (10) ( 11 ) (12) (13) (14) (15)

Rigid metal conduit Rigid nonmetallic conduit Intermediate metal conduit Electrical metallic tubing Electrical n onmetallic tubi ng Metal wireway Nonmetallic wireway Surface m etal raceway with metal cover Surface nonmetallic raceway Flex ible metal conduit Liquidtight flexible metal conduit Liquidtight flexible nonmetallic conduit Type MI cable Type MC cable Type AC cable

70-547

645.5

ARTICLE 645 - INFORMATION TECHNOLOGY EQUIPMENT

(16) Associated metallic and nonmetallic boxes o r enclosures (17) Type TC power and control tray cable

connecting cables shall be removed unless contained in a raceway.

(2) Installation Requirements for Electrical Supply Cords, Data Cables, Interconnecting Cables, and Grounding Conductors Under a Raised Floor. The following cords, cables, and conductors shall be permitted to be installed under a raised floor:

(H) Installed Supply Circuits and Interconnecting Cables Identified for Future Use.

(1) (2) (3) ( 4)

Supply cords of listed information technology equipment in accordance with 645.S( B). Interconnecting cables enclosed in a raceway. Equipment grounding conductors. Where the air space under a raised floor is protected by an automatic fire suppression system, in addition to wiring installed in compliance with 725.135(C), Types CL2R, CL3R, CL2, and CL3 and substitute cables including CMP, CMR, CM, and CMG installed in accordance with 725.1 54(A) shall be permitted under raised floors. Informational Note: Figure 725.154(A) illustrates I.he cable substillltion hierarchy for Class 2 and Class 3 cables.

(5)

(6)

vVhere the air space under a raised floor is not protected by an automatic fire suppression system, in addition to wiring instal led in compliance with 725.1 35(C), substitute cable Type CMP installed in accordance with 725.154(A) shall be permitted unde1· raised floors. Listed Type DP cable having adequate fire-resistant characteristics suitable for use under raised floors of an information technology equipment room. Informational Note: One method of defining Jh~ resistance is by establishing that the cables do not spread fire to the top of the tray in I.he "U L Flame Exposure, Vertical Tray Flame Test" in UL 1685-2015, Standard for Safety for Vertical-Tray Fire-Propagation and Smoke-Re/ease Test for /!,/ectrical and Optical-Fiber Cab/es. The smoke measurements in the test method are not applicable. Another method of defining fire resistance is for the damage (ch ar length ) not to exceed 1.5 m (4 ft 11 in.) when performing I.he CSA "Vertical Flame Test - Cables in Cable Trays," as described in CSA C22.2 No. 0.3-2014, Test Methods for Ekct1ical Wiws and Cab/es.

(3) Installation Requirements for Optical Fiber Cables Under a Raised Floor. The installation of optical fiber cables shall comply with either of the following:

(1)

(2)

Where the air space under a raised floor is protected by an automatic fire suppression system, optical fiber cables installed in accordance with 770.11 3(C), Types OFNR, OFCR, OFN, and OFC shall be permitted under raised floors. Where the air space under a raised floor is not protected by an automatic fire suppression system, only optical fiber cables installed in accordance with 770.11 3(C) shall be permitted under raised floors.

(F) Securing in Place. Power cables; communications cables, connecting cables, interconnecting cables, and associated boxes, connectors, plugs, and receptacles that are listed as part of, or for, information technology equipment shall not be required to be secured in place where installed under raised floors. Informational Note: Securement requirements for raceways and cables not listed as part of, or for, information technology equipmem are found in 300.11.

(I) Supply circuits and interco nnecting cables identified for future use shall be marked with a tag of sufficient durability to withstand the environment involved. (2) Supply circu it tags and interconnecting cable tags shall have the following information: (1)

(2) (3)

Date identified for future use Date of intended use Information relating to the intended future use

645.10 Disconnecting Means. An approved means shall be provided to disconnect power to all electronic equipment in the information technology equipment room or in designated zones within the room. There shall also be a similar approved means to disconnect the power to all dedicated HVAC systems serving the room or designated zones and to cause all required fire/smoke dampers to close. The d isconnecting means shall comply with either 645.l 0(A) or (B) . Exception: Installations complying with Article 685. (A) Remote Disconnect Controls. (I) Remote disconnect controls shall be located at approved

locatio ns readily accessible in case of fire to authorized personnel and emergency responders. (2) The remote disconnect mea ns for the conu·ol of electronic equipment power and HVAC systems shall be grouped and identified. A single means to control both systems shall be permitted. (3) Where multiple zones are created, each zone shall have an approved means to confine fire or products of combustion to within the zone. (4) Additional means to prevent unintentional operation of remote disconnect controls shall be permitted. Informational Note: For further information, see NFPA 7.5-20 17, Standard for the Fire Prol.ection of Information Technology Equifmumt.

(B) Critical Operations Data Systems. Remote disconnecting conu·ols shall not be required for critical operations data syste ms when all of the following conditions are met:

(1)

(2)

(3)

An a pproved procedure has been established and main-

tained for removing power and a ir movement within the room or zone. Qualified personnel are continuo usly available to advise e mergency responders and to insu·uct th e m of disconnecting methods. A smoke-sensing fire detection system is in place. In formational Note: For further information, see NFPA 72-2019, National Fire Alarm and Signaling Code.

(4)

(5)

An approved fire suppression system suitable for the

application is in place. Cables installed under a raised fl oor, other than branchcircuit wiring, and power cords are installe d in compliance with 645.5 (E) (2) or (E)(3), or in compliance with Table 645.10(B)(5) .

(G) Abandoned Supply Circuits and Interconnecting Cables. The accessible portion of abandoned supply circuits and inter-

70-548

NAT IO NAL ELECTRJCAL CODE

2020 Edition

ARTICLE 646-MODULAR DATA CENTERS

646.1

Table 645.10(B)(5) Cables Installed Under Raised Floors Cable Type

Applicable Sections

Branch circuits under raised floors Supply cords oflistcd infom1ation technology equipmen t Class 2 and Class 3 remote control and PLTC cables in other spaces used for environmental air (plenums) Optical fiber cable in othe,· spaces used for environmental air (plenums) Commun ications wires and cables, cable routing assemblies, and communications raceways in other spaces used for environmental air (plenums) Coaxial CATV and radio distribution cables in other spaces used for environmental air (plenums)

645.5(E) (1) 645.5(E) (2) (a), 300.22(C) 725.l35(C) and Table 725.154

770.113(C) and Table 770.154(a) 800.11 3, 800.113(C), and Tables 800. l 54(a), (b), and (c)

800.113(C) and Table 800.154(a)

645.11 Uninterruptible Power Supply (UPS). U PS systems installed within the information technology equipment room, and their supply and output circuits, shall comply with 645.1 0, except for the following installations and constructions: ( 1) (2)

Installations complying with Article 685 Power sources limited to 750 volt-amperes or less derived either from UPS equipment or from battery circuits integral to e lectron ic equipment

The disconnecting means shall also disconnect the battery from its load. Informational Note: For information on product listings for e lectronic equipment d isconnecting means and backup battery power sources, see UL l 778-2014 (R20 17), Uninterruplible Power Systems, and UL 62368-1-2014, Audio/Vidm, Infomwtion and Communication Technol.ogy EquiJnnent - Part 1: Safety Requirements.

645.14 System Grounding. Separately derived power systems shall be installed in accordance with Parts I and II of Article 250. Power systems derived within listed information technology equipment that supply in formation technology systems through receptacles or cable assemblies supplied as part of this equipm ent shall not be considered separately derived for the purpose of applying 250.30. 645.15 Equipment Grounding and Bonding. All exposed noncurrent-carrying metal parts of an information technology system shall be bonded to the equipment grounding conductor in accordance with Parts I, V, VI, VII, and VIII of Article 250 or shall be double insulated. Where signal reference strucnires are installed, they shall be bonded to the equipment grounding conductor provided for the information technology equipment. Any auxiliary grounding electrode(s) instal led for information technology equipment shall be installed in accordance with 250.54. Informational Note No. I: The bonding requ irements in the product standards governing this listed equipment ensure that it com plies with Article 250. Informational Note No. 2: Where isolated grounding-type recep• tacles are used, see 250.146(0 ) and 406.3(0 ) .

645.16 Marking. Each unit of a n information technology system supplied by a branch circuit shall be provided with a manufacturer's nameplate, which sha ll also include the input

2020 Edition

NATIONAL ELECTRJCAL CODE

power requirements for voltage, frequency, a nd maximum rated load in amperes.

645.17 Power Distribution Units. Power distribution un its that are used for informat io n technology equipment shall be permitted to h ave multiple panelboards within a single cabine t if the power distribution unit is u t ilization equipment listed for information technology application. 645.18 Surge Protection for Critical Operations Data Systems. Listed surge protection shall be provided for critical operations data systems. 645.25 Engineering Supervision. As an alternative to the feeder a nd service load calculations required by Parts III and IV of Article 220, feeder and service load calculations for new or existing loads shall be permitted to be used if provided by qualified persons under e ng ineering supervision. 645.27 Selective Coordination. Critical operations data syste m (s) overcurrent protective devices shall be selectively coordinated with all supply-side overcurrent protective devices. Selective coordi nation shall be selected by a licensed professional engineer or other qualified persons e ngaged primarily in the design, installation, or maintenance of electr ical systems. The selection shall be documented and made available to those authorized to design, install, inspect, maintain, and o perate the syste m.

ARTICLE646 Modular Data Centers Part I. General

646.1 Scope. This article covers modular data centers. Informational Note No. l: Modular data centers include the installed information technology equipment ( !TE) and support equipment, electrical supply and distribution, wiring and protection, working space, grounding, HVAC, and the like, that are located in an equipment enclosure.

70-549

646.2

ARTICLE 646-MODULAR DATA CENTERS

Informational Note No. 2: For further information, see NFPA 75-2017, Slandard for lhe Proleclion of Informalion Technology Equifmienl, which covers the requiremems for the protection of information technology equipmem and systems in an information technology equipment room.

646.2 Definitions. The following definition shall apply only within this article. Modular Data Center (MDC). Prefabricated units, rated 1000 volts or less, consisting of an outer enclosure housing multiple racks or cabinets of information technology equipment (ITE) (e.g., servers) and various support equipment, such as electrical service and distribution equipment, HVAC systems, and the like. Informational Note No. I: A typical construction may use a standard ISO shipping container or other structure as the olller enclosure, racks or cabinets of ITE, service-entrance equipment and power distribution components, power storage such as a UPS, and an air or liquid cooling system. Modular data centers are imended for fixed installation, either indoors or ollldoors, based on their construction and resistance lO environmental conditions. MDCs can be configured as an all-in-one system housed in a single equipment enclosure or as a system with the support equipment housed in separate equipment enclosures. Informational Note No. 2: For information on listing requirements for both information technology equipment and communications equipment contained within a modular data center, see UL 60950-1-2014, Informrttion Technology Equipment - Safaty - Par/ I: General Requimuents, and UL 62368-1-2012, Audio/ Video, Informalion and Communication Technology EquiJmuml Part 1: Safety Requii~men.lS. In formational Note No. 3: Modular data centers as defined in this article are sometimes referred lO as comainerized data cemers. In formational Note No. 4: Equipmem enclosures housing only support equipment (e.g., HVAC or power distribmion equipment) that are not pan of a specific modular data center are not considered a modular data cemer as defined in this article.

646.3 Other Articles. C ircui ts and equipment shall comply with 646.3(A) through (N) as applicable. Wherever the requirements of other articles of this Code and Article 646 differ, the requirements of Article 646 shall apply. (A) Spread of Fire or Products of Combustion. Sections 300.21, 770.26, and 800.26 shall apply to penetrations of a fireresistant room boundary, if provided. (B) Wiring and Cabling in Other Spaces Used for Environmental Air (Plenums). The following sections and tables shall apply

members of optical fiber cables in an MDC shall be grounded in accordance with 770.114. Grounding and bonding of com munications protectors, cable shields, and non-currentcarrying metallic members of cable shall comply with Part IV of Article 805. (D) Electrical Classification of Data Circuits. Section 725 .1 21 (A) ( 4) shall apply to the electrical classification of listed information technology equipment signaling c ircuits. Sections 725.1 39(D )( l ) and 805.1 33(A)( l) (c) shall apply to the electrical classification of Class 2 and Class 3 circuits in the same cable with communications circuits. (E) Fire Alarm Equipment. Parts I, II, and III of Article 760 shall apply to fire alarm systems, cables, and equipment installed in an MDC, where provided. Only fire alarm cables listed in accordance with Part IV of Article 760 and listed fi re a larm equipment shall be permitted to be installed in an MDC. (F) Cable Routing Assemblies and Communications Wires, Cables, Raceways, and Equipment. Sections 800.11 0, 800.113, a nd 800.154 shall apply to cable routing asse mblies and com munications raceways. Parts I , II, III, IV, and V of Article 805 shall apply to communications wires, cables, and equipment installed in an MDC. Only communications wires and cables listed in accordance with 805 .179, cable routing assemblies and communications raceways listed in accordance with 800.1 82, and communications equipment listed in accordance with 805.170 shall be permitted to be installed in an MDC. Informational Note: See Part I of Article l00 for a definition of communications equipment.

(G) Community Antenna Television and Radio Distribution Systems Cables and Equipment. Parts I, II, III, IV, and V of Article 820 shall apply to commun ity antenna television and radio distribution systems equipment installed in an MDC. Only commun ity antenn a television and radio distribution cables listed in accordance with 820.1 79 a nd listed CATV equipment shall be permitted to be installed in an MDC. (H) Storage Batteries. Installation of storage batteries shall comply with Article 480.

Exception: Batteries that are part of listed and labeled equipment and installed in accordance with the listing requirements.

(I) Surge-Protective Devices (SPDs). ½There provided, surgeprotective devices shall be listed and labeled and installed in accordance with Article 242.

to wiring and cabling in other spaces used for environmental air (plenums) within a modular data center space:

0) Lighting. Lighting shall be installed in accordance with Article 410.

(1) (2)

(K) Power Distribution Wiring and Wiring Protection. Power disu·ibution wiring and wiring protection with in an MDC shall comply with Article 210 for branch circuits.

(3) (4) (5) (6)

Wiring methods: 300.22(C)(l) Class 2, Class 3, and PLTC cables: 725.1 35(C), and Table 725.1 54 Fire alarm systems: 760.53(B)(2), 760.1 35(C), and Table 760.1 54 Optical fiber cables: 770 .11 3(C) and Table 770.1 54(a) Communications circuits: 800.11 3 and Table 800.1 54(a) CATV and radio disu·ibution systems: 800.11 3 and Table 800. l 54(a) In formational Note: Environmentally controlled working spaces, aisles, and equipmem areas in an MDC are not considered a plenum.

(C) Grounding. Grounding and bonding of an MDC shall

comply with Article 250. The non-current-carrying conductive

70-550

(L) Wiring Methods and Materials.

(1)

Unless modified elsewhere in this article, wiring methods and materials for power distribution shall comply with Chapter 3. Wiring shall be suitable for its use and installation and shall be listed and labeled.

Exception: This requirement shall not apply to wiring that is part of listed and labeled equipment.

(2)

The following wiring methods shall not be permitted: a. Integrated gas spacer cable: Type IGS (Article 326)

NATIONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 646-MODULAR DATA CENTERS b. c. d. e.

Concealed knob-and-tube wiring (Article 394) Messenger-supported wiring (Article 396) Open wiring on insulators (Article 398) Outdoor overhead conductors over 600 volts (Article 399) Wiring in areas under a raised floor that are constructed and used for ventilation as described in 645.5(E) shall be permitted to use the wiring methods described in 645.5(E) if the conditions of 645.4 are met. Installation of wiring for remote-control, signaling, and power-limited circuits shall comply with Part III of Article 725. Installation of optical fiber cables shall comply with PartV of Article 770. Alternate wiring methods as permitted by Article 645 shall be permitted for MDCs, provided that all of the conditions of 645.4 are met.

(2)

(M) Service Equipment. For an MDC that is designed such

( 4)

(3)

( 4)

(5) (6)

that it can be powered from a separate electt·ical service, the service equipment for control and protection of services and their installation shall comply with Article 230. The service equipment and their arrangement and installation shall permit the installation of the service-e ntrance conductors in accordance with Article 230. Service equipment shall be listed and labeled and marked as being suitable for use as service equipment. (N) Disconnecting Means. An approved means shall be provided to disconnect power to all electronic equipment in the MDC in accordance with 645.10. There shall also be a similar approved means to disconnect the power to all dedicated HVAC systems serving the MDC that shall cause all required fire/smoke dampers to close. 646.4 Applicable Requirements. All MDCs shall be listed and labeled and comply with 646.3(N) and 646.5 through 646.9, or comply with this article. Informational Note: For information on listing requirements for MDCs, see UL Subject 2755, Oulli1u of Invesligalion for Modular Dau, Cenlers.

646.5 Nameplate Data. A permanent nameplate shall be attached to e ach equipment e nclosure of an MDC and shall be plainly visible after installation. The nameplate sh all include the information in 646.5(1) through (6), as applicable: (1)

Supply voltage, number of phases, frequency, and follload current. The full-load current shown on the nameplate shall not be less than the sum of the full-load currents required for all motors a nd other equipment that may be in ope.-ation at the same time under normal conditions of u se. , .\There unusual type loads, duty cycles, and so forth, require oversized conductors or permit reduced-size conductors, the required capacity shall be included in the marked full-load current. Vl'here more than one incom ing supply circuit is to be provided, the nameplate shall state the preceding information for each circuit. Informational Note No. I: See 430.22(E) and 430.26 for duty cycle requiremems.

646.7

For MDCs powered by a separate service, the short-circuit current rating of the service equipment provided as part of the MDC. Informational Note: This rating may be part of the service equipment marking.

(3)

For MDCs powered by a separate service, if the required service as determined by Parts III and IV of Article 220 is less than the rating of the service pan el used, the required service shall be included on the nameplate. Informational Note: Branch circuits supplying !TE loads are assumed to be loaded not less than 80 percent of die branchcircuit rating with a I 00 percent duty cycle. As an alternative to the feeder and service load calculations required by Parts III and IV of Article 220, feeder and service load calculations for new, future, or existing loads may be permitted to be used if performed by qualified persons under engineering supervision .

(5)

(6)

Electrical diagram number(s) or the number of the index to the electrical drawings. For MDC equipment enclosures that are not powered by a separate service, feeder, or branch circuit, a reference to the powering equipment. Manufacturer's name or trademark.

646.6 Supply Conductors and Overcurrent Protection. (A) Size. The size of the supply conducto r shall be such as to have an ampacity not less than 125 percent of the full-load current rating. Informational Note No. I: See the 0- 2000-volt ampacity tables of Article 310 for ampacity of conductors rated 600 \I and below. Informational Note No. 2: See 43 0.22(E) and 430.26 for dmy cycle requirements.

(B) Overcurrent Protection. ,~'here overcurrent protection for supply conductors is furn ished as part of th e MDC, overcurrent protection for each supply circuit shall comply with 646.6(B)(l) through (B)(2) .

(I) Service Equipment Overcurrent Protection. Service conductors shall be provided with overcurrent protection in accordance with 230.90 through 230.95. (2) Taps and Feeders. Where overcurrent protection for supply conductors is famished as part of the MDC as permitted by 240.21, th e overcurren t protection shall comply with the following: (1)

(2) (3)

The overcurrent protection shall consist of a single circuit breaker or set of fuses. The MDC shall be marked "OVERCURRENT PROTECTION PROVIDED AT MDC SUPPLY TERMINALS." The supply conductors s hall be considered e ither as feeders or as taps and be provided with overcurrent protection complying with 240.21 .

646.7 Short-Circuit Current Rating. (A) Service Equipment. The se1·vice equipment of an MDC that con nects directly to a service shall have a short-circuit current rating not less than the available fault current of the service.

Informational Note No. 2: For listed equipment, the full-load currem shown on the nameplate may be the maximum, measured, 15-minute, average full-load currenL

2020 Edition

NATIONAL ELECTRJCAt. CODE

70-551

646.7

ARTICLE 646-MODULAR DATA CENTERS

(B) MDCs Connected to Branch Circuits and Feeders. Modular data centers that connect to a branch circuit or a feeder circuit shall have a short-circuit current rating not less th an the available fault current of the branch circuit or feeder. The short-circuit current rating of the MDC sh a ll be based on the short-circuit current rating of a listed and labeled MDC or the short-circuit current rating established utilizing an approved method.

Exception: This requirement shall not apply to listed and labeled equipment connected to branch circuits located inside of the MDC equipment enclosure. In formational Note: UL 508A-2013, Standard for Industrial Control Panels, Suj,j,knwnl SB, is an example ofan approved method.

(C) MDCs Powered from Separate MDC System Enclosures. Modular data center equipment enclosures, powered from a separate MDC system enclosure that is part of the specific MDC system, shall have a short-circuit current rating coordinated with the powering module in accordance with 110.1 0. In formational Note: UL 508A-2013, Slandardfor Industrial Control Panels, SttfJ!Jlemenl SB, is an exam pie of an approved method for determining short-circuit current ratings.

646.8 Field-Wiring Compartments. A fi e ld-wiring compartment in wh ich service or feeder connections are to be made shall be readily accessible a nd comply with 646.8(1) through (3) as follows: (1) (2) (3)

Permit the connection of th e supply wires after the MDC is installed Permit the connection to be introduced and readily connected Be located so that the connections may be read ily inspected after the MDC is installed

646.9 Flexible Power Cords and Cables for Connecting Equipment Enclosures of an MDC System. (A) Uses Permitted. Flex ible power cords and cables shall be permitted to be used for connections between equipment enclosures of an MDC system where not subject to physical damage. Informational Note: One example of flexible power cord usage for connections between equipment enclosures of an MDC system is between an MDC enclosure containing only servers and one containing power dist ribution equipment.

(B) Uses Not Permitted. Flexible power cords and cables shall not be used for connection to external sources of power. Informational Note: Exam pies of external sources of power are electrical services, feeders, and premises branch circu its.

(C) Listing. Where flexible power cords or cables are used, they shall be listed as suitable for extra-hard usage. Where used outdoors, flex ible power cords and cables shall also be listed as suitable for wet locations and shall be sunlight resistant.

(D) Single-Conductor Cable. Single-conductor power cable shall be permitted to be used only in sizes 2 AWG or larger.

Part II. Equipment 646.10 Electrical Supply and Distribution. Equipment used for e lectrical supply and distribution in an MDC, including fittings, devices, luminaires, apparatus, machinery, and the like, shall comply with Pa rts I and II of Article 110. 70-552

646. 11 Distribution Transformers. (A) Utility-Owned Transformers. Utility-owned transformers shall not be permitted in an MDC.

distribution

(B) Non-Utility-Owned Premises Transformers. Non-utilityowned premises distribution transformers installed in the vicinity of an MDC shall be of the dry type or the type filled with a noncombustible dielectric medium. Su ch transformers shall be installed in accordance with the requirements of Article 450. Non-utility-owned premises d istribution transformers shall not be permitted in an MDC. (C) Power Transformers. Power transformers that supply power only to the MDC shall be permitted to be installed in the MDC equipment enclosure. Only dry-type transformers shal l be permitted to be installed in the MDC equipment enclosure . Such transformers shall be installed in accordance with the requirements of Article 450. 646.12 Receptacles. At least one 125-volt ac, 15- or 20-ampererated duplex conven ience outlet shall be provided in each work area of the MDC to facilitate the powering of test and measurement equipment that may be required during routine maintenance and servicing, without having to route flexible power cords through or across doorways or around line-ups of equipment, or the like. 646.13 Other Electrical Equipment. Electrical equipment that is an integral part of the MDC, including information technology equipment, lighting, control, power, HVAC (heatin g, ventilation, and ai1~conditioning), emergency lighting, alarm c ircu its, and so forth, shall comply with the requirements for its use and installation and shall be listed and labeled. 646.14 Installation and Use. Listed and labeled equipment shall be installed and used in accordance with any instructions or limitations included in the listing.

Part III. Lighting 646.15 General Illumination. Illumi nation shall be provided for all workspaces and areas that are used for exit access and exit discharge. The illumination shall be arranged so that the fai lure of any single lighting unit does n ot result in a complete loss of illumination . I nformational Note: See Nf'PA 101-2018, Life Safely Code, Section 7.8, for information on illumination of means of egress.

646.16 Emergency Lighting. Areas that are used for exit access and exit d ischarge shall be provided with emergency lighting. Emergency lighting systems shall be listed and labeled equipment installed in accordance with the manufacturer's instructions. Informational Note: See Nf'PA 101-2018, Life Safety Code, Section 7.9, for information on emergency lighting.

646.17 Emergency Lighting Circuits. No appliances or lamps, other than those specified as required for emergen cy use, shall be supplied by emergency lighting c ircuits. Branch circuits supplying emergency lighting shall be installed to provide service from storage batteries, generator sets, UPS, se parate service, fuel cells, or un it equipment. No o ther equipment shall be connected to these circuits unless the emergency lig hting system includes a backup system where only the lighting is supplied by battery circuits under power failure conditions. All

NATIONAL ELECTRJCAL CODE

2020 Edition

ARTICLE 647 -SENSITIVE ELECTRONIC EQUIPMENT boxes and enclosures (including transfer switches, generators, and power panels) for emergency circuits shall be marked to identify them as components of an emergency circuit or system. Part IV. Workspace 646.18 General. Space comply with 110.26.

about

electrical

equipment

shall

646.19 Entrance to and Egress from Working Space. For equipment over 1.8 m (6 ft) wide or deep, there shall be one entrance to a nd egress from the required working space not less than 610 mm (24 in. ) wide and 2.0 m (6 ½ ft) high at each end of the working space. Doors shal l o pen in the direction of egress and be equipped with listed panic hardware or listed fire exit hardware. A single entrance to a nd egress from the req uired working space shall be permitted where either of the cond itions in 646. I 9(A) or (B) is met. (A) Unobstructed Egress. Where the location permits a continuous and unobstructed way of egress travel, a single entrance to the working space shall be permitted. (B) Extra Working Space. v\7here the depth of the working space is twice that required by 110.26(A) (1 ), a single entrance shall be permitted. It shall be located such that the distance from the equipment to the nearest edge of the entran ce is not less than the minimum clear d istance specified in Table 110.26(A) (1) for equipment operating at that voltage and in that condition . 646.20 Working Space for ITE. (A) Low-Voltage Circuits. The working space abo ut ITE where any live parts that may be exposed during routine servicing operate at not greater than 30 volts rms, 42 volts peak, or 60 volts de shall not be requi red to comply with the workspace requirements of646.1 9. (B) Other Circuits. Any areas of ITE that require servicing of parts that are greater than 30 volts nns, 42 volts peak, or 60 volts de shall comply with the workspace requirements of 646.1 9. Informational Note No. 1: For example, fie ld-wiring compartments for ac mains connections, power distribution units, and so forth. Informational Note No . 2: It is assumed that ITE operates at vo ltages not exceeding 1000 volts.

647.4

ARTICLE647 Sensitive Electronic Equipment 647.1 Scope. This article covers the installation and wiring of separately derived systems operating at 120 volts line-to-line and 60 volts to ground for sensitive elecu·onic equipment. 647.3 General. Use of a separately derived 120-volt singlephase 3-wire system with 60 volts on each of two ungrounded conductors to an equipment grounding conductor shall be permitted for the purpose of reducing o bjectionable n oise in sensitive e lectronic equipment locations, provided the following conditio ns apply:

(]) (2) (3)

The system is installed only in commerc ial o r indusu·ial occupancies. The system's use is restricted to a reas under close supervision by qualified personnel. All of the requirements in 647.4 th rough 647.8 are met.

647.4 Wiring Methods. (A) Panelboards and Overcurrent Protection. Use of sta nda rd single-phase panelboards and d istribution equipme nt with a higher voltage ratin g shall be permitted. The system shall be clearly marked o n the face of the panel or on the inside of the panel doors. Common trip two-pole circuit breakers or a combination two-pole fused disconnecting means that are identified for use at the system voltage shall be provided for both ungrounded conductors in all feeders and bran ch circuits. Branch circuits a nd feeders sh all be provided with a means to simultaneously d isconnect all ungrounded conductors. (B) Junction Boxes. All junction box covers shall be clearly marked to indicate the disu·ibution panel and t he system voltage. (C) Conductor Identification. All feeders a nd branch-circuit conductors installed under this section shall be ide n tified as to system at all splices and terminations by color, marking, tagging, or equally effective mean s. The means of identification shall be posted at each branch-circuit panelboard a nd at the disconnecting means for the build ing. (D) Voltage Drop. The voltage drop on any branch circuit shall not exceed 1.5 percent. The combined voltage drop of feeder and branch-circuit conductors shall not exceed 2.5 percent.

646.21 Work Areas and Working Space About Batteries. Working space about a batte ry system shall comply with 110.26. Working space shall be measured from the edges of the battery racks, cabinets, or u·ays.

(1) Fixed Equipment. The voltage drop on branch circuits supplying equipment connected using wiring methods in Chapter 3 shall not exceed 1.5 percent. The combined voltage drop of feeder and branch-circu it conductors shall not exceed 2.5 percent.

646.22 Workspace for Routine Service and Maintenance. Workspace sh a ll be provided to facili tate routine servicing and ma in tenance (those tasks involving operations that can be accomplished by employees and where extensive d isassembly of equipment is not required) . Routine servicing and ma intenance shall be a ble to be performed without exposing the worker to a risk of e lectric shock or personal injury.

(2) Cord-Connected Equipment. The voltage drop on bra nch circuits s upplying receptacles sh a ll not exceed I percent. For the purposes of making th is calculatio n, the load connected to the receptacle outlet shall be considered to be 50 percent of the branch-circuit rating. The combined voltage drop of feeder and branch-circuit conductors sha ll not exceed 2.0 percent.

Informational Note: An example of such routine maintenance is cleaning or replacing an air filter.

Informational Note: The purpose of this provision is to limit voltage drop to 1.5 percent where portable cords may be used as a means of connecting equipment.

2020 Edition

NATIONAL ELECTRJCAL CODE

70-553

647.5

ARTICLE 650-PIPE ORGANS

647.5 T hree-Phase Systems. Where 3-phase power is supplied, a separately derived 6-phase "wye" system with 60 volts to ground installed under this anicle shall be co nfigured as three separately derived 120-volt single-phase systems having a combined total of no more than six disconnects.

Exception: Receptacles and attachment plugs rated 125-volt, singll}phase, 15- or 20-amperes, and that are identified for use with grounded circuit conductors, shall be permitted in machine rooms, control rooms, equipment rooms, equipment racks, and other similar locations that are restricted to use by qualified personnel.

647 .6 Grounding.

(B) Isolated Ground Receptacles. Isolated ground receptacles shall be permitted as described in 250.146(D); however, the branch-circuit equipment grounding conductor shall be terminated as required in 647.6(B) .

(A) General. The transformer secondary center tap of the 60/120-volt, 3-wire system shall be g rounded as provided in 250.30. Grounding Conductors Required. Pennanently wired utilization eq uipment and receptacles shall be grounded by means of an equipment grounding conductor run with the circuit conductors and connected to an equipment grounding bus prominently marked "Techn ical Equipment Ground" in the branch-circuit panel board. The equipment grounding bus shall be connected to the grounded conductor on the line side of disconnecting means supplied by the separately derived system. The e quipment grounding conductor shall n ot be smaller than that spec ified in Table 250.122 a nd run with the feeder conductors. The technical equipment grounding bus shall not be required to be bonded to the panelboard enclosure. Other equipment gro unding methods authorized elsewhere in this Code shall be permitted where the impedance of the equipment grounding return path does not exceed the impedance of equipment grounding conductors sized and installed in accordance with this article . (B) Equipment

647.8 Lighting Equipment. Lighting equipment installed under th is article for the purpose of reducing elecu·ical noise originating fro m lig hting e quipment shall meet the conditions of 647.S(A) through (C) . (A) Disconnecting Means. All lumina ires connected to separately derived systems operating at 60 volts to g round, a nd associated conu·ol equipment if provided, shall have a disconnecting means that simultaneously opens a ll un grounded conductors. The disconnecting means shall be located within sig ht of the luminaire or be lockable ope n in accordance with 110.25. (B) Luminaires. All luminaires shall b e perma nently installed and listed for connectio n to a separately derived system at 120 volts line-to-line and 60 volts to gro und.

(C) Screw She ll. Luminaires installed under this section shall not have a n exposed lamp screw shell.

Info rmational Note No. I: See 250.122 for equipment grounding conductor sizing requirements wh ere circu it conductors are adjusted in size to compensate for voltage drop. Informational Note No. 2: These requirements limit the impedance of the ground fat~t return path wh ere only 60 volts apply to a fault condition instead of the usual 120 volts.

ARTICLE 650 Pipe Organs

647.7 Receptacles. (A) General. Where receptacles are used as a means of connecting equipment, the fo llowing conditions shall be met: (1 )

(2)

All 15- a nd 20-ampere receptacles shall be GFCI protected. All receptacle outlet strips, adapters, receptacle covers, a nd faceplates shall be marked with the following words or equivalent: WARNING-TECHNICAL POWER Do not connect to lighting equipme nt. For electronic equipment u se only. 60/ 120 V. l upply Cords Portab le P ower Cable General-Use Snap Switches Enclosed and Dead-From Swi tches Open-Type Switches Knife Switc hes Plug-In Lockino- Type Ph otocomrols for Use wit h Area Lightin g o nindustria l Pho toelectric Switch es for Lighting Control Clock-O perated Sw itches Pull o uLSwitches Anachmem Plugs and Recep tacles Plugs , Receptacles, and Cable Con nec to rs, of the Pin and Sleeve Type Panel boards Switchboards Meta l-Enclosed Low-Voltage Power Circuit Breaker Switchgear Low-Voltage Swi tchgear and Comro lgea r - Part I : General Ru les Low-Voltage Swi Lchgear an d Contro lgear - Pan 4-1: Co n tac tors and Mo tor-Starters - Electromechan ical Co m ac tors a nd Mo to r-Starters Voltage Switcl1gear and Co n tro lgear - Part 4-2: Contactors a nd Motor-Starters - AC Sem ico nducto r Mo tor Comro llers and Staners Low-Vohage Switc hgea r and Comro lgea r - Part 5-1: Co n trol Circuit Devices and Switch in g Elements Elec Lromechanical Co n trol CircuiL Devices Low-Vo ltage Switchgear and Co mro lgear - Part 5-2: Control Circuit Devices and Switchi ng Elements - Prox im ity Switches Low-VolLage Switchgear And Contro lgear - Pa rt 7-1: Ancilla ry Equi p mem - Term in a l Blocks for Copper ond uctors (continues)

NATIONAL ELECTRI CAL CODE

70-7 11

Annex A: Product Standards Article

Standard Number UL 60947-7-2

UL 60947-7-3 409 4 10

411

422

424

70-71 2

UL 508 U L 508A UL 65 UL 153 UL 496 UL 542 UL588 UL935 UL 1029 UL Subject L029A UL 1574 UL 1598 UL 15988 UL 1598C UL 1993 UL 2388 U L 8750 UL 8752 UL8753 U L 8754 UL Sul:>ject 8800 UL234 UL 1838 UL 2L08 UL 22 UL 73 UL 122 UL 141 UL 174 UL 197 UL 283 UL 399 UL 430 UL474 U L 507 UL 574 UL 62 1 U L 70.5 UL 710B UL 749 UL 75 1 UL 763 UL 858 UL 875 UL921 UL 923 UL962 UL 962A UL 101 7 UL 1026 UL 1278 UL 1453 UL 1727 U L 1776 UL 603 35-2-40 UL 603'15-2-24 UL 499 UL 834 UL 873 U L 1042 UL 1673 UL 1693

INFORMATIVE ANNEX A Standard Title Low-Voltage Switchgear and Con u·olgear - Part 7-2: Ancill ary Equipmem - Protective Con ductor Term in al Blocks for Coppe r Cond uctors Low-Voltage Swi tchgear and Con trolgear- Part 7-3: Ancillary Equipmem- Safety Requiremen ls for Fuse Terminal Blocks lnd ustrial Comrol Equ ipment Industrial Con trol Panels Wired Cab inets Portab le Electric Luminaires Lamp holders Fluorescent Lamp Starters Seasonal and Hol iday Decora ti ve Prod ucts Fluorescem-Lamp Ba ll asts Hi gh-lmen ity-Di scharge Lamp Ballam lgnito rs and Re lated Auxiliaries for HID Lamp Ballasts Track Lig htin g Systems Luminai res Lumin aire Reflector Kits for Installation o n Previously Insta ll ed .Fluorescent Luminaires, Supplememal Requi reme n ts Liglu-Emi tting Diode (LED) Retrofit LLLminaire Co nver ion Kits Self-Ballasted Lamp and Lamp Adapters Flexible Li gh ting Products Li gh t Emitting Diode (LED) Equipment fo r Use in Lighti ng Proclucts Organic Li gh t Emitting Di ode (OLED) Panels Field-Rep laceable Li ght Erni u.in g Diode (LED ) Ligh t Engines Ho lders, Bases and Co nnectors for So li d-Sta te (LED ) Light Engines and Arrays Horticultural Lighting Equipm e n t Low-Vo ltage Li gh Li n g Fixtures fo r Use in Recreat.ional Veh icles Lo1v-Vo ltage Landscape Lighti n g Systems Low-Vo ltage Li ghtin g Systems AmLLSemem and Gaming Machines Moto r-Operated Applia nces Ph otogra phi c Equipment Carm em Fi ni sh in g Appliances Household El ectric Swrage Tank Water Hea te rs C',nmmerc ial Electric Cooking Appliances Air Fresheners and Deodorizers Drinking Wa ter Coolers Waste Dispose rs D eh umidifiers El ect ric Fans Electric Oil H ea ters Ice Cream Make rs Power Vent.ilators Recirculatin g Systems Household Dishwashers Vending Machines Motor-Operated Commercial Food Preparin g Mach in es H ousehold El ectric Ra nges El ectric Dry-Bath Heaters C',nmmerc ial Dishwashers Microwave Cookin g Appli ances HoLLSehold and Comm e rc ial Furnish in gs Fu rniwre Power Distributio n Un its Vacuum Cleaners, Blower Clea ners, and Ho usehold Floor Finishing Machines H oLLSehold Electric Cooki ng an d Food Serving Appli ances Movab le and Wall- or Ce iling-Hung Electric Room Heaters Electric Booste r and Commercial Storage Tan k Water Heaters C',nmmerc ial Electric Persona l Grooming Appliances Hi gh-Pressure Cleani n g Machines Household and Simi lar Elec ui cal Appliances, Pan 2: Particul ar Requirements for Hea tin g and Coolin« H ousehold and Simi lar Electri cal Appliances, Pan 2: Particul ar Requi rements for Refrigeratin g Appliances, IceCream Applia nces, and Ice-Makers Elect ric Healin g Appliances Heati ng, Water Supply, and Powe r Bo ilers - Electric Tem peratu re-I ndi cati n g and -Regulating Equipm e m Electric Baseboard Heating Equipm e m Elecu·ic Space Heating Cables El ect ric Radiant Heating Pane ls a nd H eatin g Pa nel SeL~ (continues)

NATIONAL ELECTRICAL CO DE

2020 Edition

INFORMATIVE ANNEX A Article

426 427

430

440

44.5 450

460 480

490

500

Standard Number

UL19% UL 1996 UL 2021 UL Subject 1588 IEEE 515 UL .515 UL Subject 2049 UL 508C UL845 UL 1004-1 UL 1004-2 UL 1004-3 UL2111 UL 1004-6 UL 1004-7 UL 1004-8 UL 1004-9 UL 60034-1 UL250 UL 412 UL416 UL427 UL 47 1 UL484 UL .54 1 UL563 UL 1004-4 UL 2200 UL506 UL 5085-1 UL 5085-2 UL 1062 UL 156 1 UL 1562 UL8 10 UL 810A UL 1642 UL 1973 UL 1989 UL 20.54 UL347 UL Subject 347!\ UL Subject 347 8 UL Subject 347C ANS I/ ISA 12.l2.0l ANSI / ISA-12.27.01

.50 1

504

UL698A UL844 UL 1203 UL 2075 UL 2225 UL 60079-29-1 UL 60079-15 UL60079-0 UL60079-7 UL 60079-1 UL 60079-.5 UL60079-6 UL913

505

UL 60079-1 1 UL 60079-18

506

UL 61241-18

2020 Edition

Annex A; Product Standards

Standard Title

Healing a nd Coolin g Equ ipm en L Electric Duct Heaters Fixed a nd Location-Dedicated Elec tric Room H eaters Roof a nd C u uer De-Icing Cable Units Electrica l Resis tance Heat Traci ng for Indus trial Appli caL ions Electrica l ResisLance Heal Traci ng for Commerc ial a nd Indus tria l Applications Resid ential Pipe Healing Cable Powe r Conversion Equ ipme nt Motor Co n u·ol Cen te rs RoLati n g Electri cal Machines - General Req uire me nts tm pedance Protec Led Mo Lo rs Th e m1 ally Pro teCLed Mo tors Ove rh eatin g Protec tion for MOLors Sen,o and Stepper Mowrs Electro ni cally Pro LecLed MoLors In ve rte r Du ly Mo tors Medium Voltage and Form v\lounrl Motor Rota tin g Electrical Machines Household Refrigerators and Freezers Refrigeration UnjL Coole rs Refrigerated Med ica l Equ ipm em Refrigeratin g Units Commercia l Refrigerators and Freezers Room Air Cond ition ers RefrigeraLed Vending Machines Ice Makers Electric Generators Stationary Eng in e CeneraLor A~sem bli es Specially Tra nsformers Low Voltage Transformers - Pan 1: General Requ irements Low Vol tage Transfom1ers - Part 2: General Purpose Tra nsfo rmers UniL Subs tations Dry-Type Ge ne ra l Purpose an d Power Transformer Transfonners, Disuibution , Dry-Type - O ver 600 Vo lts Capacitors Electroc hem ical CapaciLOrs Lithium BaLteries Batteries for Use in Stationary, Veh icle Auxili ary Powe r and Li ghL Elec t ric Rail (LER) Applications SLandby Baueries Household and Commerc ial Batteries Medium-Voltage AC Contacwrs, Conu·ollers, an d Co ntrol Centers Medium Voltage Power Co n version Controllers Medium Voltage Mowr Controllers, Up Lo 15kV Medium VolLage So lid State Res istive Load Controllers, Up LO 15kV No n incendive Electrical Equi pment for Use in Class I and II , Divisio n 2 and Class Ill, Divisio ns I and 2 Hazardous (Classified) Locations Req ui rements for Process Seali n g Be rween ElecLrical SysLem and PoLentiall y Flammable or Comb ustible Process Fluids Industria l Control Panels Relating LO Hazardo us (Classified) Loca ti ons Lurni naires fo r Use in Hazardous (Classified) Locations Exp losionproofa nd Dust-lgnition-ProofE lec Lrical Equip ment for Use in Hazardous (Classifi ed) Locatio ns Gas and Vapor Detenors and Sensors Cable a nd Cab le Fiuing. for Use in Hazard o us (Classified ) Locati o ns Exp losive Aunosphe res - Pan 29-1: Gas D etectors - Per formance Requirements of DeLectors for Flammable Cases Electrica l Appara tus fo r Explosive Gas Atmosphe res - Pan 15: Type of Pro tec Lion " n" Exp losive Gas Atmospheres - Pan 0: Eq uip ment- General Requireme nts Exp losive Gas Atmosphe re - Pan 7: In creased Safety "e" Exp losive Gas Atmospheres - Pan I: Type of Protection - Flam eproof "cl" Exp losive Gas Atmosp heres - Pan 5: Type of PrOLecLion - Powd er Filling "q" Exp losive Gas Au11ospheres - Pan 6: Type o f ProLecLion - Oil Immersion "o" In trinsically Sate ApparaLus and Assoc iated ApparaLu fo r Use in Class I, II , and Ill , Divisio n I, Hazardo us (Classified) Locations Exp losive Atmosphe res - Pan I J: Equ iprnem Protectio n by l mrin ic Safety "i" Electrica l Appara Lus fo r Use in Class I, Zone l Hazardous (C lassified) Locations Type of Pro Lec ti on EncapsulaLion "m" Electrica l Appara Lus fo r Use in Zone 20, Zone 21 , and Zone 22 Hazardo us (Classified) Locations - Prmec Lio n by Encapsulation "mD" (continues)

NATIONAL ELECTRI CAL CODE

70-713

Annex A: Product Standards Article

INFORMATIVE ANNEX A

Standard Number UL 61241-1

Standard Title El ect rical Apparatus for Use in Zo ne 21 and Zone 22 Hazardo us (Classifi ed) Loca tions- Protectio n by Enclosure

UL 61241-0

Elect rical Apparaws for Use in Zone 20, Zone 21, and Zone 22 Hazardo us (Classi fi ed) Local.ions - General Req ,ii rem e n ts El ectrical Apparatus for Use in Zone 20, Zone 21, and Zon e 22 Hazardous (Classi fi ed) Locations -Protection by lntrinsic Safety "iD" El ectrical Apparaws for Use in Zone 21 and Zone 22 Hazardo us (Classified) Loca tions - Protection by Pressmi zation "pD" Garage Equ ipment In dustria l Bauery Chargers Line Isolation Mon ito rs lsola ted Power Systems Eq ui pmem Medi cal Electrica l Equ ipmem- Pan l: Ge neral Requirements for Safety 171eater Li gh ting Dis tribut.ion and Comro l Equipment Stage and Studio Lumin aires and Connector Strips Portab le Power-Distribution Equjpment Mobile Home Pipe Heatin g Cable Power OuLleLS Electric Signs Gas-Tube-Sign Cab le Electric Si gn Compone nLS LED Sign and Sign Re tro fi t K.iLS Polyme ric Enclosure Systems for the Splice Between Neon Tubing Electrod e Leads a nd GTO Cable, and the CTO Ca ble Leading LO th e Splice Neon Transformers and Power Supplies Manufactured Wi1ing Systems Office Furnishings H ou ehol d and Commerc ial Furn(~hings Festoon Cable El ectric Vehicle (EV) Cha rging System Equipment Pe rson nel Protection Systems for Electri c Vehicle (EV) Suppl y Circuits; Part l: General Requirements Pe rson nel Protection Sys tems for Elec ui c Vehicle (EV) Suppl y Circuits; Part 2: Particu lar Requireme nts for Protect io n Devices for Use in Chargin" Systems Plugs, Receptacles and Co uplers for Elec trical Ve hi cles Batteries for Use in Electri c Veh icles El ectric Vehicle Su pply Equipmem Bidirec tional Electric Vehicle (EV) Chargin g System Equ ipme m Pin and Sleeve Co n figura tions Transfo1mer-Type Arc-We lding Mach in es Commerc ial Audio Equipme nt Professional Video and Audio Equipmem Audio-Video Prod ucts and Accessories Amplifier for Fi re Pro tec ti ve Signaling Systems Audio/ Video and Mnsical Instrum en t Apparatus for H o use hold, Commercial, and Si mi lar Genera l Use Audio, Video anrl Similar Electron ic Ap paratus -Safety Requirements Audio/ Video, Inform ation and Commun ication Techno lo 6'Y Equipment - Pan 1: Safety Requirements Data-Processing ab le Uni merrupt.i ble Powe r Systems In format io n Tec hn olO!,'Y Equipmem Safe ty - Part 1: General Req uireme n ts ln forn1a1io n Techn o logy Equipment Safe ty - Part 21: Re mo Le Power Feeding ln forn1atio n Tec hn o logy Equip men t SaleLy - Part 22: EquipmenL LO be In stal led O mdoors In forma tio n Technology EquipmenL Safety - Part 23: Large Data Storage Equipm enL Modular Data Cen ters Adju stable Speed Electrical Power Drive Systems - Pan .5-l : Safety Requirements - Elecu;cal, T hermal and Energy Power Units fo r Foumain, Swimming Pool, and Spa Lu minaires UnderwaLer Luminaires and Submersible.Junction Boxes Pollin g Com pound s for Swimming Pool, Foumain, and Spa Equipmem Swimm in g Pool Pumps, Fi lters, and Chlorinato rs lsolaLed Power Systems Equipmen t El ectric Water Heaters for Pools and Tubs Elect ric Spa, Equipment Assemblies, and Associated Equipme m H ydromassage BaLhtubs Enclosed and Dead ~From Switches fo r Use in Photovolta ic Systems Molded-Case Circ uit Breakers, Molded-Case Switches, and Circui t-Breaker Enclosures for Use \\~Lh Ph otovolta ic (PV) Systems Manual Disconnec t witches Intended for Use in Photovo ltai c Syste ms Ph otovo lta ic D C Arc-Fault Ci rcuit Protection (continues)

"ill "

UL 6124 1-11 UL 6124l-2 511 517

520

5.50 5.51 600

604 60.5 fil0 625

UL 20 l UL 1564 UL 1022 UL 1047 UL 60601- 1 UL Subject 334 UL 1573 UL1 640 UL Subject 1462 UL 231 UL48 UL 814 UL 879 U L 879A UL Subject 879B U L 2161 UL 183 UL 1286 UL 962 UL Subject 2273 UL 2202 UL 223 1-1 UL 223 1-2

626 630 640

645

646 670 680

690

UL 22.5 l UL 2580 UL 2594 UL Subject 9741 UL 1686 U L 55 1 UL 8l3 UL 141 9 U L 1492 UL 1711 UL 6500 UL 60065 UL 62368-l UL 1690 UL 1778 UL 60950-1 UL 609.50-21 UL 60950-22 UL 60950-23 UL Sul:>ject 2755 UL 6l800-5-l UL 379 UL676 UL 676A U L 1081 UL 124 1 UL 126 1 UL 1563 UL 1795 UL 98B UL 489B UL Sul:>ject 508 1 UL Subject l699B

70-71 4

NATIONAL ELECTRICAL CO DE

2020 Edition

INFORMATIVE ANNEX A Article

694

695

700

706 72.5

727 728 750 760

770 800

810 820

2020 Edition

Standard Number UL 1703 UL 174 1

UL Sul:lject 2579 UL Subject 3703 UL Subject 3730 UL4703 UL6703 UL Subject 6703A UL Sul:lject 8703 UL Subject 9703 UL62109-l UL3003 UL 61 730-1 UL 61730-2 UL3741 UL ubj ect 489C UL Su hj ect 6 140 UL 6141 UL6142 UL 218 UL448 UL448B UL 448C UL 1004-5 UL924 UL 1008 UL 1008A UL 2200 UL9540 UL5C UL 13 UL 1012 UL 1310 UL 1666 UL 1685 UL 5085-3 UL Subject 9990 UL 2250 UL Subject 1724 UL 2196 UL916 UL268 UL 268A UL 4978 UL 1424 UL 1425 UL 1480 UL 165 1 UL 2024 UL444 UL489A UL497 UL497A UL 497C UL Subject 497E UL Subject 523 UL 1863 UL 150 UL452 UL 16.55

Annex A; Product Standards

Standard Title Fla t-Plate Photovolta ic Modul es and Panels In e rters, Conveners, Comrollers and Interconnection System Equ ipment for Use with Disuibuted Energy Resources Low-Voltage Fuses - Fuses for Photovo ltaic Syste ms Solar Trackers Ph otovolta ic_] unctio n Boxe.~ Ph0tovo lta ic Wire Con neno rs for Use in Pho Lovol raic Systems MulLi-Po le Co nn ecLOrs for Use in Photovoltaic Systems Concen u·ator Photo oltaic Mod ules and Assemblies Distrib uted Wiring Harnesses Powe r Conve n e rs fo r use in PhoLOvolta ic Power Systems - Part 1: Genera l Requirements Disuibmed Gene ration Cables Photovolta ic (PV) Module Safety Q ualification - Pan l: Requirements for Co nstrnction Ph otovolta ic (PY) Modu le Safety Q ual ification - Pan 2: Req uirements for Test ing Ph o Lovoha ic H azard Con trol Molded-Case CircuiL Breakers a nd Mo lded-Case Switches for Use "~th Wind Turbines Wind Turbin e Generating Sys tems Wind Turbin es Perm iLLing Entry of Personne l Wind Turb in e Generating Sy Lems - Sma ll Fire Pump Co ntro llers Ce nu·ifuga l StaLionary Pumps for Fire-Pro Lection Service Resid ential Fire Pumps Intended for One- and Two-Fam ily D, e ll in gs and Man ufactured Homes Sta ti ona ry, Ro tary-Type, Positive-Displacemem Pumps for Fire Pro Lec tion Service Fire Pump Motors Emergency Lightin g an d Power Eqn ipmem Transfer S"~tc h Equipmen t Medium-Voltage Transfer Sw iLches Stationary Eng in e Generator Assemblies En e rgy Storage Systems and Equ ipment Su,face Raceways an d Fi llin gs for Use with Data , Signal an d Co mro l Circ uits Power-Limited Ci rcui t Cables Power Un its Oth e r T ha n Class 2 Class 2 Power U nits Tes Lfor Flame Propagatio n Height ofElecLrical a nd Optica l-Fi ber Cables ln sLal led Vertically in ShafLs Verti cal-Tray Fire-PropagaLion and Smoke-Release Test for Elec trical a nd Optica l-Fiber Cab les Low Voltage Transformers - Pan 3: Class 2 and Class 3 Transformers ln forma Lion and Comm unica tio n Techn ology (JCT) Power Cables lnsu·urn e ntatio n Tray Cable Fire Tests for Electrical Circu it PrOLecti e Systems Tests fo r Fi re-Resistive Cables En ergy Ma nagement Eq,1ipm e nL Smoke D etectors for Fire Alarm Sig nal in g Systems Smoke D etectors fo r Duc LApplica tio n Protectors for Data Co mmun ica ti on a nd Fire J\larm Circuits Cab les for Power-Li mited Fire-Alarm Circu its Ca bles for Non-Powe r Li mited Fire-Alarrn Circuits Speakers for Fire Alarm and Signali ng Systems, Incl uding Accessories Optical Fiber Cable Optical Fiber and Comm uni cati on Cable Raceway Comm uni cations Ca bles Circuit Brea kers for Use in Comm unica tio n Equiprnem Protectors for Paired-Conductor Comm uni cations Circnits Secondary Pm teCLo rs for Comm uni cati o ns Circui ts Protecto r for Coaxial Comm u n icatio ns CircuiL~ Protectors for Amenna Lead-In Conductors Telepho ne Serv ice Drop Wire Comm uni catio n Circ LLi l Accessories Amen na Ro Latnrs Anten na-Disc ha rge Uni Ls Comm unity-Amen na Te levision Cab les

NATIONAL ELECTRI CAL CODE

0

70-715

Annex B: Ampacities

INFORMATIVE ANNEX B

Informative Annex B Application Information for Ampacity Calculation This informative annex is not a part of the requirement of this NFPA docmnent but is included for informational fJuiposes only.

B.l Equation Application Information. This informative annex provides app lication information for ampacities calculated under engineering supervision. B.2 Typical Applications Covered by Tables. Typical ampacities for conductors rated O through 2000 volts a re shown in Table B.2(1) through Table B.2 (10). Table B.2(11) provides the adj ustmem factors for· more than th1·e e current-ca rqrin g conductors in a raceway or ca bl e with load clive1·sity. Underground electrical duct bank configu1·ations, as detailed in Figure B.2(2 ), Figure B.2 (3 ), and Figure B.2(4) , are utilized for conductors rated O through 5000 volt5. In FigLu-e B.2(1) th rough Figure B.2(4), where adjacent duct banks are used, a separation of 1.5 m (5 ft) between the cemerlines of the closest ducts in each bank or 1.2 m (4 ft) between the ext remities of the concrete envelopes is sufficient to prevent derating of the conductors due to mutual heating. These ampacities were calculated as detailed in the basic arnpacity paper, AJEE Paper 57-660 , The Calculation of the Temperature Rise and Load Capability of Cable Systems, by J. H. Neher and M. H. McGrath. For additional information concerning the application of these ampacities, see IEEE STD 835, Standard Power Cable Ampacity Tables. Typical values of thermal resistivity (Rho) are as follows: Average soi.I (90 pe1·cent of USA) = 90

v\/here the burial depth of direct burial or elecu·ical duct bank ci.rcuits are modified from the values shown in a figure or table , ampacities can be modified as shown in (a) and (b) as follows. (a) Where burial depths are increased in part( ) of an elecu·ical duct run to avoid underground obsu·uctions, no dec1·ease in ampacity of the cond uctors i needed, provided the total length of part~ of the duct nm increa~ed in depth to avo id obsu·uctions is less than 25 percent of the total run length. (b) Where burial depths are deeper than shown in a specific underground ampacity table or figure, an ampacity derati.ng factor of 6 percent per i.ncrea~ed 300 mm (foot) of depth for all values of Rho can be utilized. No rating change is needed where the bmial depth i"~ decreased.

B.4 Electrical Ducts. The term electrical duct(s) is defined in 311.2. B.5 Table B.2(6) and Table B.2(7). (a) To obtain the ampacity of cables installed in two electrical ducts in one horizontal row with 190-mm (7.5-in .) centerto-center spacing between elecu-ical ducts, similar LO Figure B. 2 (1), Detail 1, multiply the ampacity shown for one duct in Table B.2(6) and Table B.2(7) by 0.88. (b) To obtain tJ1e ampac ity of cables installed in four e lecu-ical duct5 in one horizontal row with 190-mm (7.5-in. ) center-to-center spacing between electrical ducts, similar to Figme B.2(1), Detail 2, multiply the ampacity shown for three e lecu·ical dum in Table B.2 (6) and Table B.2(7) by 0.94.

Concrete = 55 Damp soi l (coastal areas, hi.gh water table) = 60 Paper insulation = 550 Polyethylene (PE) = 450 Polyvinyl chloride (PVC) = 650 Rubber and rubber-like = 500 Very dry soi.I (rocky or sandy)= 120 Th ermal resistivity, as used in this informative annex, refers to the heat transfer capabil ity through a substance by conduction . It is the reciprocal of thermal conductivity and i.s normally expressed in the units Gcm/ watt. For additional information on determining soil thermal resistivity (Rh o), see IEEE STD 442, Guide for Soil Thermal Resistivity Measurements. 0

B.3 Criteria Modifications. \r\lhere values of load factor and Rho are known for a particular electrical duct bank instal lation and they are different from those shown in a specific table or figure , the ampacities shown in the table or figure can be modified by the application of factors derived from the use of Figme B.3. Where two different ampacities apply to adjacent portions of a circuit, the higher ampacity can be used beyond th e poim of transition, a distance equal to 3 m (10 ft ) or 10 percent of the circuit length calculated at the higher ampacity, wh ichever is less.

70-716

B.6 Electrical Ducts Used in Figure B.2(1). lf pacing between e lecu-ical ducts, as shown in Figw·e B.2 ( 1), is less than as specified where electrical ducts ente1· equipment enclosures from underground , tJ1e ampacity of conductors contai.ned with.in such electrical ducts need not be reduced. B. 7 Examples Showing Use of Figure B.3 for Electrical Duct Bank Ampacity Modifications. Figure B.3 is used for interpolation or extrapolation for va lues of Rho and load factor for cables installed in elecu-ical duel~ - The upper family of curves shows the variation in ampacity and Rh o at unity load factor in terms of 11, the ampacity for Rho = 60, and 50 percem load factor. Each curve is designated for a particular ratio l,/ 11, whe1·e I.,_ is tJ1e ampacity at Rh o = 120 and 100 pet-cent load factor. The lower family of curves shows the relationship between Rho and load factor tJ1at will g ive substantially the same ampacity as the indicated value of Rho at 100 percent load factor.

As an example, to find the ampacity of a 500-kcmil copper cable circuit for six electrical ducts as shown in Table B.2 (5) : At the Rh o= 60, LF = 50, 11 = 583; for Rho= 120 and LF = 100, 12 = 400 . The ratio 12/ 11 = 0.686. Locate Rho = 90 at the bottom of the chart and follow tJ1e 90 Rho line to d1e intersection witJ1 100 percent load factor where the equivalent Rho= 90. Then follow the 90 Rho line to 12 / 11 ratio of 0.686 where F = 0.74. The desi.red ampacity = 0.74 x 583 = 43 1, which agrees witJ1 tJ1e table for Rho = 90, LF = 100.

NATIONAL ELECTRICAL CODE

2020 Edition

Annex B: Ampacities

INFORMATIVE ANNEX B

To determ ine the ampac ity for the same circuit where Rho= 80 and LF = 75, using Figure B.3, the equivalent Rho= 43, F = 0.855, and the desired ampacity = 0.855 x 583 = 498 amperes . Values for lL5ing Figure B.3 are found i.J1 the electrical duct bank ampacity tables of this informative annex .

Example I Calculate the ampacity Limit for twelve 14 AV•/ G THWN cm-rent-carrying conductors (75°C) in a raceway that contains 24 conductors that may, at different times, be current-carrying.

v\There the load factor- is less than 100 percent and can be verified by measw·emen t or calculation., the ampacity of elecu-ical duct bank instal lations can be modified as shown . Different va lues of Rho can be accommodated in the same manner.

[B.7h]

,~(o_. 5)_(2_4) x 9_o( 0.1,., ) 12

Informational Note: The ampacity limit for 10 through 85 currem-carrying conducwrs is bas ed on the following equation.

14 amperes (i.e ., 50 pe rce nt d iversity )

For more than 85 conducwrs, special calcu lations are required that are beyond th e scope of this rnbl e.

Example 2 [B.7a]

~

v~

= [ {o.5iV X (A , )]

. eve r or A ,, which

.IS less

Calculate the ampacity limit for e ighteen 14 AWG THWN cturent-carrying conductors (75°C) in a raceway that contains 24 conductors that may, at different times, be current-carrying. [B.7c]

where: A1

N

ampacity from Table 310.16, Table 310.18, Table B.2(1), Table B.2(6), or Table B.2(7) multiplied by the appropriate adj ustment factor from Table B. 2(11). tota l number of conductors used to select adjusU11ent factor from Table B.

(0 5)(94 ) ·

18

-

x20 (0 .7) = 11.5 am peres

2(11)

E

A2

2020 Edition

number of conductors carrying current simultaneously in the raceway or cable ampacity Li.Jnit fo1· the current-carrying conductors in the raceway or cable

NATIONAL ELECTRICAL CODE

70-717

Annex B: Ampacities

INFORMATIVE ANNEX B

Table B.2(1) Ampacities of Two or Three Insulated Conductors, Rated OThrough 2000 Volts, Within an Overall Covering (Multiconductor Cable), in Raceway in Free Air Based on Ambient Air Temperature of 30' C (86'F)* Temperature Rating of Conductor. [See Table 310.4(A).] 60' C (140 °F)

Size (AWG or kcmil)

TypesTW, UF

75'C ( 167°F)

TypesRHW, THHW,THW, THWN, XHHW, ZW

90°c

60 °C

75°c

(194'F)

(140°F)

(167 °F)

TypesTHHN, THHW, THW-2, THWN-2, RIIB,

TypesTHHN, THHW, THW-2, THWN-2,

RHH,RWH-2, USE-2, XHHW, XHHW-2, ZW-2

COPPER

90 'C (194°F)

TypeTW

TypesRHW, THHW, THW, THWN,XHHW

RWH-2, USE-2, XHHW, XHHW-2, ZW-2

ALUMINUM OR COPPER-CLAD ALUMJNUM

Size (AWG or kcmil)

14** 12** 10** 8

20 27 36

18 24 33 43

21 27 36 48

16 21 28

18 25 33

21 28 37

14 12 10 8

6 4 3 2 l

48 66 76 88 102

58 79 90 105 121

65 89 102 ll9 137

38 51 59 69 80

45 61 70 83 95

51 69 79 93 106

6 4 3 2

1/ 0 2/ 0 3/ 0 4/ 0

l 21 l 38 158 l 87

145 166 189 223

163 186 214 253

94 108 124 147

11 3 129 147 176

127 146 167 197

1/ 0 2/ 0 3/ 0 4/ 0

250 300 350 400 500

205 234 25° 274 315

245 281 305 328 378

276 317 345 371 42 7

160 185 202 218 254

192 221 242 261 303

217 250 273 295 342

250 300 350 400 500

600 700 750 800 900 1000

343 37(j 387 397 415 448

413 452 466 479 500 542

468 514 529 543 570 617

279 310 321 331 350 382

335 371 384 397 421 460

378 420 435 450 477 521

600 700 750 800 900 1000

16

l

*Refer m 3 10.15 for the ampacity correction facto rs where the a mbi em tempera ture is other than 30"C (86' F). **Refer to 240.4(0) for con ductor ove rc urrem proteclion limitations.

70-718

NATIONAL ELECTRICAL CO DE 2020 Edition

Annex B: Ampacities

INFORMATIVE ANNEX B

Table B.2(3) Ampacities of Multiconductor Cables with No t More Than Three Insulated Conductors, Rated 0 Through 2000 Volts, in Free Air Based on Ambient Air Temp erature o f 40°C (104°F) (for Types TC, MC, MI, U F, and USE Cables) * Temperature Rating of Conductor. [See Table 310.4(A) .]

Size (AWG or kcmil)

60°C (140 °F)

75°c (167 °F)

85°C (I85 °F)

90°c (194°F)

75 °c (167°F)

85°C (I85°F)

90°c (I94°F)

ALUMINUM OR COPPER-CLAD ALUMINUM

COPPER

-

-

-

18 21 28 39

21 28 36 50

24 30 56

16 25 32 43 59

6 4 3 2 1

52 69 81 92 107

68 89 104 ll8 138

75 100 116 132 154

79 104 121 138 161

1/ 0 2/ 0 3/ 0 4/ 0

124 143 165 190

160 184 213 245

178 206 238 274

186 215 249 287

250 300 350 400 500

212 237 261 281 321

274 306 337 363 416

305 341 377 406 465

600 700 750 800 900 l 000

354 387 404 415 438 461

459 502 523 539 570 601

513 562 586 604 639 674

18 16 14** 12** 10** 8

60 °C (140°F)

41

Size (AWG or kcmil)

-

-

-

-

18 21 30

21 28 39

24 30 44

25 32 46

41

53 70 81 92 108

59 78 91 103 120

61 81 95 108 126

6 4 3 2 l

129 149

125 144 166 192

139 160 185 214

145 168 194 224

l/0 2/ 0 3/ 0 4/ 0

320 357 ::194 425 487

166 186 205 222 255

214 240 265 287 330

239 268 296 317 368

250 280 309 334 385

250 300 350 400 500

538 589 615 633 670 707

284 306 328 339 362 385

368 405 424 439 469 499

410 462 473 490 514 558

429 473 495 513 548 584

600 700 750 800 900 1000

11

54 63 72 84 97 111

18 16 14 12 10

8

*Refer Lo 3 10.15 for cJ1e ampac ity correction factors where th e ambi e nt tempe ratLlre is other man 40°C (I 04°F). ** Refer to 240.4(0) for conduc r.or ove rcurre nt protection limitations.

2020 Edition

NATIONAL ELECTRICAL CODE

70-7 19

Annex B: Ampacities

INFORMATIVE ANNEX B

Table B.2(5) Ampacities of Single Insulated Conductors, Rated OT hro ugh 2000 Volts, in Nonmagnetic Unde rground Electrical Ducts (One Cond uctor per Electrical Duct), Based on Ambient Earth Temperature of 20°C (68°F), Electrical Duct Arrangemen t in Accordance with Figure B.2(1), Conductor Temperature 75°C (167°F) 3 Electrical Ducts 6 Electrical Ducts 9 Electrical Ducts 3 Electrical Ducts [Fig. B.2(1 ), Detail 2 ) [Fig. B.2(1) , Detail 3) [Fig. B.2(1) , Detail 4) [Fig. B.2 (1 ), Detail 2)

Types RHW, THHW, THW,THWN, XHHW, USE

Types RHW, THHW, THW,THWN, XHHW,USE

RllO 60 LF 50

RIIO 60 LF 50

Size (kcmil)

250 350 500 750 1000 1250 1300 1750 2000

Types RHW, THHW, THW,THWN, XHHW, USE

RJIO 120 LF 100

410 503 624 794

344 418 640

327 396 484 603

936

745 832 907 970 1027

700 781 849 907 959

105.'\

1160 1250 1332

5ll

9 Electrical Ducts [Fig. B.2( 1), Detail 4)

Types RHW, THHW, Types RHW, THHW, Types RHW, THHW, THW,THWN, THW, THWN, THW,THWN, XHHW, USE XHHW, USE XHHW, USE

COPPER RIIO 90 LF 100

6 E lectrical Ducts Fig. B.2(1), Detail 3)

ALUMINUM OR COPPER-CLAD ALUMINUM

RIIO 90 LF 100

RllO 120 LF

JOO

RIIO 60 LF 50

386 472 583 736

295 3:>5 431 534

275 330 400 494

864 970 I 063 1142 1213

617 686 744 793 836

570 632 685 729 768

R.110 90

RlIO 60 LF

RllO 120 LF 100

RJIO 60 L..F :;o

RllO 90 L..F

50

RJIO 90 L..F 100

JOO

RHO 120 LF 100

R.110 60

Size (kcmil)

L..F 100

RllO ]20 L..F 100

369 446 545 674

270 322 3 7 469

252 299 360 434

320 393 489 626

269 327 401 .,;05

256 310 379 475

302 369 457 581

2 30 277 337 421

21 4 258 313 389

288 350 430 ,,38

21] 2~2 305 375

]97 235 284 347

2.'\0 350 500 750

776 854 918 975 1030

533 581 619 651 683

493 536 571 599 628

744 848 941 1026 I l03

593 668 736 796 85 0

557 627 689 74:, 794

687 779 863 937 1005

491 551 604 651 693

453 508 556 598 636

629 703 767 823 877

432 478 517 550 :>81

399 441 477 507 535

lOOO [250 1500 I 750 2000

L..F 50

RllO 90 LF 100

RIIO 120 L..F 100

Ambient Temp. (· C)

6-10 l 1- 15 16-20 21-25 26-30

70-720

Ambient Temp. (•F)

Correctiou Factors

l.09 1.04 l.00 0.95 0.90

l.09 1.04 1.00 0.9 5 0.90

1.09 1.04 1.00 o.9.o 0.90

1.09 1.04 1.00 0.95 0.90

1.09 1.04 l.00 0.95 0.90

1.09 1.04 1.00 0.95 0.90

NATIONAL EL£CTRJCAL CO DE

43-50 52-59 61-68 70-77 79-86

2020 Edition

Annex B: Ampacities

INFORMATIVE ANNEX B

Table B.2(6) Ampacities of Three Insulated Conductors, Rated 0 Through 2000 Volts, Within an Overall Covering (Three-Conductor Cable) in Underground Electrical Ducts (One Cable per Electrical Duct) Based on Ambient Earth Temperature of 20°C (68°F), Electrical Duct Arrangement in Accordance with Figure B.2(1), Conductor Temperature 75°C (167°F)

Size (AWG or

I Electrical Duct [Fig. B.2(1 ), Detail I)

3 Electrical Duels [Fig. B.2 (1), Detail 2)

6 Electrical Duels [Fig. B.2( l ), Detail 3)

I Electrical Duel [Fig. B.2 (1) , Detail I)

3 Electrical Duels [Fig. B.2 (1) , Detail 2]

6 Electrical Duels [Fig. B.2 (1 ), Detail 3]

1)pes RHW, THHW, THW, THWN, XHHW, USE

1)pes RHW, THHW, THW,THWN , XHHW, USE

1)pes RHW, THHW, THW,THWN, XHHW, USE

1)pes RHW, THHW, THW,THWN, XHHW, USE

Types RHW, THHW, THW, THWN , XHHW, USE

Types RHW, THHW, THW,THWN, XHHW,USE

RII O 60 LF 50

RJIO 60 LF 50

RJIO 60 LF 50

RJI O 60 LF 50

kcmil)

COPPER RHO 120 LF 100

100

RJIO 120 LF 100

I

132 154

54 71 93 121 140

:~3 69 91 118 136

56 74 96 126 146

48 63 81 l03 12 1

46 60 77 100 ]14

53 70 91 119 137

42 54 69 89 102

39 51 65 83 95

l/ 0 2/ 0 3/ 0 4/ 0

177 203 233 268

[ 60 183 210 240

156 178 204 232

168 192 221 253

137 156 178 202

130 147 158 190

157 179 20?, 234

11 6 131 148 l 68

250 350

297 363 444 552 628

265 321 389 478 539

256 3 10 375 459 5 18

280 340 414 511 579

222 267 320 388 435

209 250 299 362 405

258 312 377 462 522

184 219 261 314 35]

8

58 77

6 4 2

;;oo

750 1000

JO ]

RJ IO 90 LF

ALUMINUM OR COPPER-CLAD ALUMINUM

RII O 90 LF 100

RIIO 90 LF 100

RJIO 120 LF 100

RII O 90 LF 100

RIIO 120 LF 100

60 78 103 120

42 55 72 94 109

41 54 71 92 106

43 57 75 98 114

37 49 63 82 94

36 47 60 78 89

!07 121 137 155

138 158 182 209

125 143 164 187

122 139 159 182

131

JO]

172 198

[07 122 [39 158

169 202 240 288 321

233 285 352 446 521

207 252 308 386 447

201 244 297 372 430

219 267 328 4-13 480

174 209 254 314 36 1

45

RIIO 60 LF 50

HO

RllO 90 LF 100

RJIO 120 LF 100

RJIO 60 LF 50

RJIO 90 LF 100

RIIO 120 LF 100

41 54 71 92 107

32 42 ,H 70 79

30 39 51 65 74

l I"> 13] 149

122 140 160 183

90 102 116 131

84 95 107 12]

1/ 0 2/ 0 3/ 0 4/ 0

163 196 237 293 336

202 245 299 374 433

144 172 207 254

132 158 190 233 266

250 350 500 750 !000

29]

Ambient ( OC )

2020 Edition

8 6 4 2 l

Ambient

Temp.

6-JO ll-15 16-20 21-25 26-30

Size (AWG or kcmil)

Temp (OF)

Correction Factors

l.09 1.04 l.00 0.95 0.90

l.09 1.04 l.00 0.95 0.90

NATIONAL ELECTRI CAL CODE

l.09 l.04 1.00 0.9.; 0.90

1.09 1.04 1.00 0.95 0.90

l.09 1.04 l.00 0.95 0.90

1. 09 1.04

1. 00 0.95 0.90

43-50 52-59 6 1-68 70-77 79-86

70-721

Annex B: Ampacities

INFORMATIVE ANNEX B

Table B.2(7) Ampacities of Three Single Insulated Conductors, Rated OThrough 2000 Volts, in Underground Electrical Ducts (Three Conductors per Electrical Duct) Based on Ambient Earth Temperature of 20°C (68°F), Electrical Duct Arrangement in Accordance with Figure B.2 (1), Conductor Temperature 75 °C (167°F)

Size

(AWG or kcmil)

I Eleclrical Duel [Fig. B.2(1 ), Delail I ]

3 Electrical D ucls [Fig. B.2 (1) , Delail 2]

6 Electrical Du els [Fig. B.2( 1), Detail 3]

I Electrical Duct [Fig. B.2(1), Detail I]

3 Electrical Duels [Fig. B.2 (I), Detail 2]

6 Electrical D ucls [Fig. B.2(1), Delail 3]

Types RHW, THHW, THW, THWN, XHHW,USE

Types RHW, THHW, THW,THWN, XHHW, USE

Types RHW, THHW, TUV.1, THWN, XHHW, USE

Types RHW, THHW, THW, THWN, XHHW, USE

Types RHW, THHW,

Types RHW, THHW, THW,THWN, XHHW, USE

RJIO 60

RIIO 60

RJIO 120

RJI O 60

COPPER

LF

:;o

63 84

RII O 90

ALUMINUM OR COPPER-CIAO ALUMINUM

RII O 90 LF 100

Rll O 120 LF 100

Rll O 60

RJIO 120

RJ IO 90 LF 100

LF

LF

LF

LF

50

JOO

JOO

50

57 75 98 11 3 128 148

61 80 105 122 139 161

51 67 86 99 11 2 128

49 63 81 94 !06 121

57

44

75 98 113 129 149

56 73 83 93 106

8 6 4 3 2 1

129 147 171

58 77 100 116 132 153

1/ 0 2/ 0 3/ 0 4/ 0

197 226 260 301

175 200 228 263

169 193 220 253

185 212 243 280

146 166 189 2L)

137 L'i6 177 21ll

170 194 222 255

121 136 H4 175

250 300 350 400

334 373 409 442

290 321 351 376

279 308 337 361

3 10 344 377 394

236 260 283 302

220 242 264 280

281 3 10 340 368

500 600 700 75 0

503 55 2 602 632

427 468 509 529

409 447 486 505

460 5ll 5.'>3 574

34 1 37 ] 402 417

3 16 343 371 385

4 12 457 492 :\09

800 900 1000

654 692 730

544 57:i 60:'\

520 549 576

597 628 659

428 450 472

395 4 15 435

527 554 38 1

Ill

THW,THWN, XHHW,USE

LF

LF

100

50

41 53 67 77 86 98

49 66 86

RIIO 90 LF 100

4.'i

RJIO 120

LF JOO 44

RllO 60 LF 50

RII O 90

Rl lO 90

RJIO 60 LF

100

Rl!O 120 LF 100

:;o

100

Rl! O 120 LF 100

47 63 79 83 I08 126

40 52 67 77 87 100

38 49 63 73 82 94

45 59 77 84 JOI 116

34 44 57 6.'i 73 83

32 41 52 60 67 77

8 6 4 3 2 l

11 4 130 147 168

107 121 138 ]';7

133 151 173 199

94 !06 121 137

87 98 126

1/ 0 2/ 0 3/ 0 4/ 0

LF

LF

60

.·s 76 89

11.o 133

78 91 103 119

126 14 2 16 1

153 176 203 235

136 156 178 20">

132 151 172 198

144 165 189 219

192 210 228 243

176 192 209 223

261 293 321 349

227 276 297

218 242 26:i 284

242 272 296 321

185 204 222 238

172 190 207 220

220 245 266 288

150 [65 179 191

137 151 164 174

250 300 350 400

273 296 319 330

249 270 29 1 30 1

397 446 48 .'\08

338 373 408 425

323 356 389 405

364 408 443 461

270 296 32 1 334

2:'iO 274 297 309

326 365 394 409

216 236 255 26.'\

197 215 232 241

"iOO 600 700 750

338

308 323 338

530 .'\63 .'i97

439 466 494

41

481 :,JO 338

344 36:i 385

3 18 337

427 450 475

273 288 304

247 261 276

800 900 1000

35:i 372

]I ]

IO I

252

JOO 11 5

444 471

35_·

lll

Ambienl Temp.

Ambient Temp.

c·q

&-IO

11 - 15 16-20 21 - 25 26-30

70-722

Size (AWG or kcmil)

(°F)

Correction Factors

1.09 1.04 I.OD 0.95 0.90

l. 09 l. 04 l. 00 0.95 0.90

l.09 l.04 l.00 0.95 0.90

1.09 1.04 l.00 0.9,; 0.90

1.()9

1.04 1.00 0.95 0.90

1.09 1.04 l.00 0.95 0.90

NATIONAL EL£CTR1CAL CO DE

43-5 0 52-59 61-68 70-77 79-86

2020 Edition

Annex B: Ampacities

INFORMATIVE ANNEX B

Table B.2(8) Ampacities of Two or Three Insulated Conductors, Rated O Through 2000 Volts, Cabled Within an Overall (Tuo- or Three-Conductor) Covering, Directly Buried in Earth, Based on Ambient Earth Temperature of 20°C (68 °F), Electrical Duct Arrangement in Accordance with Figure B.2(1), 100 Percent Load Factor, Thermal Resistance (Rho) of 90 l Cable [Fig. B.2(1), Detail 5] 60 °C (140°F)

2 Cables [Fig. B.2(1), Detail 6]

75°c (167°F)

60 °C (140 °F)

75°c (l 67 °F)

l Cable [Fig. B.2(1), Detail 5] 60 °C (140°F)

75°c (167 °F)

TYPES RHW",

RHW,

RHW,

RHW,

THHW, TH\V, TH\VN, XHHW, USE

THHW, TH\V, TH\VN, XHHW, USE

THHW, TH\V, TH\VN, XHHW, USE

USE

UF

UF

UF

ALUMINUM OR COPPER-CIAO ALUMINUM

COPPER

128 145

51 68 83 107 12]

59 75 97 126 142

ll3

70 91 ll7 132

208 236 269 304

165 188 213 241

193 220 250 282

138 157 179 203

162 184 210 238

129 146 166 188

151 171 195 220

l/0 2/ 0 3/ 0 4/ 0

333 401 481 585 657

-

308 370 442 535 600

-

261 315 381 473 545

-

241 290 350 433 497

250 350 500 750 1000

l

75 100 125 161 182

1/ 0 2/ 0 3/ 0 4/ 0

177 201 229 259

250 350 500 750 1000

-

60 81 HJ()

Ambient Temp. (°C)

47 60 78 llO

55

Correction Factors

2020 Edition

1.12 1.06 1.00 0.94 0.87

1.09 l.04 1.00 0.95 0.90

NATIONAL ELECTRI CAL CODE

1.12 l.06 1.00 0.94 0.87

1.09 1.04 1.00 0.95 0.90

l.12 l.06 1.00 0.94 0.87

8 6 4 2 l

Ambient Temp. (OF)

1.1 2 1.06 l.00 0.94 0.87 Note: For a rnpac ities of Type UF cable in u nd e rgrou nd elec trical ducts, multiply th e arnpacitie shown in the table by 0.74. 6-10 ll - 15 16-20 21-25 26-30

Size (AWG or kcmil)

70 95 117 150 170

64 85 107 137 155

8 6 4 2

75 °c (167°F)

THHW,

XHHW,

Size (AWG or kcmil)

60 °C (l40°F)

TYPES

TH\V, TH\VN,

UF

2 Cables [Fig. B.2(1), Detail 6]

l.09 l.04 l.00 0.95 0.90

l.09 l.04 l.00 0.95 0.90

43-50 52-59 61-68 70-77 79-86

70-723

Annex B: Ampacities

INFORMATIVE ANNEX B

Table B.2(9) Ampacities of Three Triplexed Single Insulated Conductors, Rated 0 Through 2000 Volts, Directly Buried in Earth Based on Ambient Earth Temperature of 20'C (68°F), Electrical Duel Arrangement in Accordance with Figure B.2(1), 100 Percent Load Factor, Thermal Resistance (Rho) of 90 See Fig. B.2(1), Detail 7 60°C (140 °F)

See Fig. B.2(1), Detail 8

75°c (167°F)

60 °C (140 °F)

75 °c (167 'F)

See Fig. B.2(1), Detail 7 60 °C (140°F)

75°c (167°F)

1YPES Size (AWG or kcmil)

UF

See Fig. B.2 (1) , Detail 8 60 °C (140 °F)

75°c (167"F)

1YPES

USE

UF

USE

COPPER

UF

USE

UF

USE

ALUMINUM OR COPPER-CLAD ALUMINUM

Size (AWG or kcmil)

84 107 139 179 203

66 84 109 140 159

77 99 128 164 186

55 72 92 119 135

65 84 108 139 158

51 66 85 109 124

60 77 100 128 145

8 6 4 2

l

72 91 119 153 173

1/ 0 2/ 0 3/ 0 4/ 0

197 223 254 289

231 262 298 339

181 205 232 263

212 240 272 308

154 175 199 226

180 205 233 265

141 159 181 206

165 187 212 241

1/ 0 2/ 0 3/0 4/ 0

250 350 500 750 1000

-

370 445 536 654 744

-

336 403 483 587 665

-

289 349 424 525 608

-

263 316 382 471 544

250 350 500 750 1000

8 6 4 2

-

-

Ambient Temp. (° C)

6-10 11-15 16-20 21- 25 26-30

70--724

-

-

Ambient Temp. (' F)

Correction Factors

1.12 1.06 1.00 0.94 0.87

1.09 1.04 1.00 0.95 0.90

l.1 2 l .06 1.00 0.94 0.87

1.09 1.04 1.00 0.95 0.90

1.12 l .06 1.00 0.94 0.87

l

1.09 l .04 1.00 0.95 0.90

1.12 1.06 1.00 0.94 0.87

1.09 1.04 1.00 0.95 0.90

NATIONAL ELECTRICAL CODE

43-50 52-59 61-68 70-77 79-86

2020 Edition

Annex B: Ampacities

INFORMATIVE ANNEX B

Table B.2( I 0) Ampacities of Three Single Insulated Conductors, Rated 0 Through 2000 Volts, Directly Buried in Earth Based on Ambient Earth Temperature of 20°C (68°F), Electrical Duct Arrangement in Accordance with Figure B.2(1 ), 100 Percent Load Factor, Thermal Resistance (Rho) of 90 See Fig. B.2(1), Detail 9 60 "C (140°F)

See Fig. B.2 (1), Detail IO

75 °c (167°F)

60"C (140"F)

75•c (167°F)

See Fig. B.2(1), Detail 9 60"C (140"F)

75•c (167°F)

1YPES Size (AWG or kcmil)

UF

UF

USE

COPPER

l

98 126 163 209 236

1/ 0 2/ 0 3/ 0 4/ 0

230 261 297 336

250 350 500 750

-

1000 1250 1500 1750 2000

-

-

-

60"C (140°F)

1s·c (167°F)

1YPES

USE

84 107 139 178 201

8

6 4 2

See Fig. B.2 (1), Detail IO

USE

UF

UF

USE

ALUMINUM OR COPPER-CLAD ALUMINUM

78

129 146

72 92 118 151 171

8 6 4 2

210 239 272 307

165 188 213 241

194 220 250 283

1/ 0 2/ 0 3/ 0 4/ 0

335 403 490 605

-

308 370 552

250 350 500 750

706 787 862 930 990

-

642 716 783 843 897

1000 1250 1500 1750 2000

130 165 187

92 118 152 194 219

66 84 108 139 157

98 127 163 184

270 306 348 394

212 241 274 309

249 283 321 362

179 204 232 262

429 516 626 767

-

394 474 572 700

-

887 979 1063 1133 1195

-

808 891 965 1027 1082

-

]OJ

-

-

61 78

77

-

-

JO]

-

-

l

448

Ambient Temp.

6-10 l 1-15

16-20 21-25 26-30

Ambient Temp. (OF)

Correction Factors

(°C)

1.1 2 .06 1.00 0.94 0.87 l

1.09 1.04 1.00 0.95 0.90

l .12 1.06 1.00 0.94 0.87

1.09 1.04 1.00 0.95 0.90

Size (AWG or kcmil)

1.12 1.06 1.00 0.94 0.87

1.09 1.04 1.00 0.95 0.90

1.1 2 1.06 1.00 0.94 0.87

1.09 l .04 1.00 0.95 0.90

43-50 52-59 61-68 70- 77 79-86

Table B.2(11) Adjustment Factors for More Than Three Current-Carrying Conductors in a Raceway or Cable with Load Diversity

umber of Conductors*

4-6 7- 9 10-24 25- 42 43-85

Percent of Values in Tables as Adjusted for Ambient Temperature if Necessary

80 70 70** 60** 50**

*Number of cond uctors is the tota l n umber of conductors in the raceway o r cab le acijusted in acco rdance with 310.15(D) and (E) . **T hese fac tors includ e th e effects ofa load diversity of50 perce nt.

2020 Edition

NATIONAL ELE:CTRI CAL CO DE

70-725

Annex B: Ampacities

INFORMATIVE ANNEX B C:

ii'i

t:. E E a a,

'I

Detail 1 290 mm x 290 mm (11 .5 in. x 11.5 in.) Electrical duct bank One electrical duct

E..-,-

190 mm (7.5 in.)

E--:-

E .S

E .S

OIO

OIO

~t;.

~!S

Detai l 2 475 mm x 475 mm (19 in. x 19 in.) Electrical duct bank Three electrica l ducts or

190mm (7.5 in.)

190 mm (7. 5 in.) Detail 3 475 mm x 675 mm (19 in. x 27 in.) Electrical duct bank Six electrical ducts

Detail 4 675 mm x 675 mm (27 in. x 27 in.) Electrical duct bank Nine electrical ducts

or

190mm (7.5 in.)

190mm (7.5 in.)

675mm x290mm

(27 in . x 11.5 in.) Electrical duct bank Three electrical ducts

190mm (7. 5 in.)

E--:-

E .S ~~-

-

190mm (7.5 in.)

190 mm (7.5 in.)

675 mm x 475 mm (27 in. x 19 in.) Electrical duct bank

!

•

Detail 5 Buried 3 cond uctor cable 190mm (7.5 in.)

600mm (24 in.) Detail 6 Buried 3 conductor cables

190mm (7.5 in.)

rI1

Detail 9 Buried single-conductor cables (1 circuit)

l

600mm (24in.)

•••

Detail 7 Buried triplexed cables (1 circuit) 190 mm (7.5 in.)

190 mm (7.5 in.)

rI I

Detail 8 Buried triplexed cables (2 circuits)

600mm (24 in.)

Note 2: For two and four elect rical duct installations with electrical ducts installed in a single row, see B.5.

70-726

190 mm (7.5 in.)

I I 1

Detail 10 Buried sing le-conductor cables (2 circuits)

Note 1: Min imum burial depths to top electrical ducts or cables shall be in accordance with 300.5. Maximum depth to the top of electrical duct banks shall be 750 mm (30 in.) and maximum depth to the top of direct-buried cables shall be 900 mm (36 in.)

FIGURE B.2(1) Table B.2(10).

190 mm (7.5 in.)

Legend Backfil l (earth or concrete) Electrica l duct •

Cable or cables

Cable Installation Dimensions for Use with Table B.2(5) Through

NATIONAL ELECTRICAL CO DE

2020 Edition

Annex B: Ampacities

INFORMATIVE ANNEX B Surface

Surface

N and

N and

EGC

EGC Cl,.

.0.

I

.

~ Ca)(a)(a) 190 mm (7.5t ( ; ) 190 mm (7.5 in.)

'

0

~~ (a)

L::,,.

,

.L(a)(a) , :. 'l

,:,.

600 mm (24 in .)

Cl

I

A0 250 mm(1 0 in.)

750 mm (30 in.)

0

0

p

(a) (a), (;), (a) ·

±-~-

o

"l

1

..

,:,.

600 mm (24 in.)

,

(-+--:_, ;) ~ -+--~-~_.o_.·-•-~+-,:,.~• j950 mm (3 8 in.)

2 50 ~~ 1

I

190 mm (7.5 in.)

o

~(a)A.

(Ty pical 190 mm~ for all ) (7.5 in.)

250mm (10 in.)

+ 675 mm (27 in.)

0

O

250 mm (10 in.)

\

250mm (1Din.)

1. 1 m (44 in.) Design Criteria Number of Cables per Phase = 9 Rho Concrete= Rho Earth - 5 Rho PVC Duct = 650 Rho Cable Insulation = 500 Rho Cable Jacf510 mm--,a:;635 mm (>20 in.-s25 in.)

~510 mm (s20 in.) ~

,r------,i■

(b)

FIGURE J.4

Vertical Clearance. FIGURE J.6.2

Obstructed High Forward Reach.

J.7 Side Reach.

J.5 Required Clear Width. Protruding o bjects shall not reduce the clear width required for accessible routes.

J.6

Forward Reach.

J.6.1 Unobstructed. V\Tl-1ere a forward reach is unobstructed, the hig h forward reach s hall be 1220 mm (48 in. ) maximum, and the low forward reach shall be 380 mm (15 in.) minimum a bove the finish fl oor or ground. (Se,e Figurej.6.1.) J.6.2 Obstructed High Reach. Where a hig h forward reach is over an o bstruction, the clear floor space sh all extend beneath the element for a distance n ot less than the required reach depth over the obstruction. The high forward reach shall be 1220 mm (48 in. ) maximum where the reach depth 1s 510 mm (20 in.) maximum. Where the reach depth exceeds 510 mm (20 in. ), the high forward reach shall be 11 20 mm (44 in. ) maximum, and the reach depth shall be 635 mm (25 in. ) maximum. (SeeFigurej.6.2.)

J.7.1 Unobstructed. Where a clear floor or g round spac_e allows a parallel approach to an e lement, a nd the side reach 1s unobstructed, t he hig h side reach sha ll be 1220 mm (48 in. ) maximum, a nd the low side reach shall be 380 mm (15 in. ) min imum above the finish floor or ground. (See Figure]. 7.1.) Excepti1m No. 1: An obstruction shall be permitted between the clear floor or ground space and the element where the depth of the obstruction is 255 mm ( 10 in. ) maximum. Exception No. 2: Operable parts ofJiiel dispensers shall be permitted to be 1370 mm (54 in.) maxirnurn, measured from the swface of the vehicular way where Jiiel dispensers are installed on existing curbs.

J.7.2 Obstructed High Reach. \-\'here a clear fl oor or ground space allows a parallel approach to an element and the high side reach is over a n obstruction, the h eight of the o bstructio n shall be 865 mm (34 in.) maximum , and the depth of the obstruction shall be 610 mm (24 in. ) maximum. The high side reach shall be 1220 mm ( 48 in. ) m aximum for a reach depth of 255 mm (10 in. ) maximum. Where the reach depth exceeds 255 mm (10 in. ), the high side reach shall be 1170 mm (46 in. ) maximum for a reach depth of 610 mm (24 in. ) maximum. (Se,e Figure]. 7.2.) Exception No. 1: The top of washing machines and clothes d1yers shall be pennitted to be 915 mm (36 in.) maximum above the finish jlom: Exception No. 2: Operable parts ofJiiel dispensers shall be permitted to be 1370 mm (54 in.) maxirnurn, measured from the swface of the vehicular way where Jiiel dispensers are installed on existing curbs.

I

7 ~ 1220 mm (~48 in.)

~1220 mm (~48 in.)

----t ~380mm (~15 in.)

s255 mm (~1 O in.)

FIGURE J.6.1

2020 Edition

Unobstructed Forward Reach.

NATIONAL ELECTRJCAL CODE

FIGURE J.7.1

T Unobstructed Side Reach.

70-843

Annex J: Accessible D esign

INFOIU-.1ATIVE ANNEXJ

7 ,S:865 mm (,s:34 in.)

L

L..........-~

,,;255 mm (,s:1 0 in.)__,-+

70-844

(;.,!!2.._}

>255 mm--,S:610 {>10 in.- "24 in.)

(a)

FIGURE J.7.2

,S:1170 mm ("46 in.)

,S:865mm (,S:34 in.)

(b)

Obstructed High Side Re ach.

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

Index Copyright© 2019 Natio n al Fire P rotection Associatio n. All Rights Reserved. T he copyrig h t in this index is separate and distinct from the copyrig h t in the document that it indexes. The licen sing provisio n s set forth for the document are not applicable to this index . This index may n o t be reproduced in w hole or in part by a ny means without the express w ri tten permissio n ofNFPA. -AAC and DC conductors in same enclosure, 300.3(C) ( 1), 725.48 AC armored cable, see Armored cable (Type AC) Access and working space, see also Wo rking space Audio sig nal processing, amplification, and reproductio n equipment, 640.46 Cranes and hoists, 610.57

Electrified truck parking space supply equipment, 626.22(C) ElevaLOr machine room, 620.71 Induction a nd d ie lectric h eating equipment, 66.5 .22 Manholes, 110.72, 110.73, 110.75 Not over l000 volts, 110.26 O ver 1000 volts, ll0--111 Portable substations, 530.62 Switchboards, 408.18 Transformers, electric sig n, 600.21 (D) Vaults a nd tu nne ls, ll0.76 Accessible Air-conditioning and refrigeration disconnects, 440.14, 440.63 Arc-fault circuit-interrupter protection, 210.12 Attics a nd roof spaces Armored cable, 320.23 Knob-a nd-mbe wiring, 394.23 Open wiring o n insulators, 398.23 Cable trays, 392. 18( E), 392. l 8(F) Condui t bodies,j unction, pull, and outlet boxes, 3 14.29, 3 14.72(D) C ritical operations power systems, 708.50 De finition, Art. 100 Electric sig ns and lights, 600.42( B) Ground-fau lt circuitinterrupters, 210.8 Grounding electrode connectio n, 250.68(A) Hydro massage bathtubs, 680.73

2020 Edition

Luminaires a nd

lampholders, 410.5, 410.24(B), 410.137(A) Motor d isconnects, 430.107 Overcurrent devices, 240.24 (A) Pa nels, electrical equipment installed behind, 300.23, 368.l 0 (B), 725.21, 760.2 1, 770.21,800.2 1 Readily De finit io n, Art. 100 Recreational vehicles site supply equipment, 551. 77(C) Sealing fittings, 50 l. I 5(C)( I ), 502. 15, 505.1 6( D)( l ); see also Hazardous (classified) locations Service overcurrent protection, 230.92 Services, 230.70(A)( l ) Site-isolating device, 547.9(A) (8) Splices and taps Auxi liary gutters, 366.56(A) Wireways, 376.56(A), 378.56 Theaters, stage switchboards, 520.21 (2) Transfo rmers, sig ns a nd omlet lighting, 600.21 (A) Transformers a nd vaults, 450.1 3 Accessible design, ADA standards for, Annex j AC Marking, 404.20 MoLOrs, 430.83(C) Pa nelboards, use in, 408.36(A) Ratings, type loads, 408.36(A) AC general-use snap switch, 404. l 4(A); see also AC-DC gen e ral-u se snap switch es AC modules and &-ystems, solar photovoltaic systems, IN Fig. 690.l (b), 690.4( B), 690.6, 690.13 (C), 690.51 De finitions, 690.2 AC resistance and reactance conversion, C hap. 9, Table 9 AC systems Co nducLOr to be grounded, 250.26 Grounding connection s, 250.24(A), 250.25

NATIONAL ELECTRJCAL CODE

Grounding elecu-ode conductor, 250.66 Ground ing of, 250.20, 250.30 Systems not required to be gro unded, 250.21 In same metallic e nclosu res, 215.4(B), 300.20 ADA standards for accessible d esign, Annexj Adjustable speed drive and drive &-ystems, 430 .88, 430--X Definiti o ns, Art. 100 Administration and enforcement, Annex H Adoption of; Annex H 80 ..5 Application of, Annex H 80.9 Autho ri ty, Ann ex H 80.13 Connection LO electric ity supply, Annex H 8 0.25 Definitio ns, Annex H 80.2 Effective date, Annex H 80.35 Elecu-ical board, Annex H 80.15 Inspector's qualificatio ns, Annex H 80.27 Liability fo r damages, Annex H 80.29 Notice of violations, penalties, Annex H 80.23 Occupancy of building o r structure, Annex H 8 0.1 1 Pe rmits and approvals, Annex H 80.19 Plans review, Annex H 80.21 Records and reports, Annex H 80.17 Repeal of conAicting a cts, Annex H 80.33 T itle of; Annex H 80.7 Validity of article, Annex H 80.3 l Aerial cables Communicatio ns system s, 800.44 Communi ty a n ten na television and radio d istributio n systems, 820.44 Ide n tificatio n, 200.6(A) Messenger-supported wiring, Art. 396 Network-powered broadba nd communications systems, 830.44 Optical fi ber cables, 770.44 Agricultural buildings, Art. 547

Bo nding, 547.9, 547. 10 Definitions, 547.2 Disconnecting means, 547.9 Distribution point, electrical supply to buildings or strucmres from, .547.9 Equipotential planes, bonding, 547.10 Feeder and service loads, calculation of; 220- V Grounding, 547.9 Luminaires, 547.8 Motors, 547.7 Overcurrent protection, .547.9 Surface temperatures, 547.4 S,vitch es, receptacles, circuit breakers, conu-o llers, and fuses, 547.6 Wiring methods, 547.5 Air conditioners, room, 440--VII Bra nch-circuit require ments, 440.62 Defini tion , 440.60 Disconnecting means, 440.63 G rounding, 440.6 l Nameplate marking, 220.82(C), 440.4 Air-conditioning and refrigerating equipment, Art. 440 Arc-fault circuit-interrupter protectio n, 440.65 Branch circuits Conductors, 440- IV Arnpacicy, determination of; 440.6 Combination loads for, 440.34, 440.35 General, 440.3 1 Multimowr equipment for, 440.35 Several motor-compressors for, 440.33 Sing le motor-compressor for, 440.32 Omlets, 210.63(A) Selection current Definiti o n, 440.2 Marking o n nameplate, 440.4(C) Short-circuit and ground-fault p rotection, 440--111 Eq uipmen t, for, 440.22(8)

70-845

NATIONAL ELECTRICAL CODE

Individual moLOr-compressor, fo,; 440.22(A) Controllers for, 440-V Marking, 440.5 Rating, 440.41 DefiniLions, 440.2, 551 .2 Disconnecting means, 440-11 Cord-connected equipme nt, 440.13 Ratings and imerrupting capacity, 440.12 Room a ir conditioners, 440.63 Hermetic refrigerant motorcompressor, see Hermetic refrigerant motor-compressors Leakage-curre nt deLecLorimerrupte ,; 440.65 Definition, 440.2 Load, 220.82(C), 220.83 Mobile homes, 5.50.20 NameplaLe requiremenLS, 440.4 Overload protection, 440-VI Application and selection of; 440.52 Branch-circuit conductors fo,; 440.52( B) Motor-compressors, 440.52(A) On 15- or 20-ampere branch circuiLS, 440.54 Park trailers, 552.48( P), 552.59(B) Rated-load current Definition, 440.2 Marking on nameplate, 440.4 (A) Recreational vehicles, 551.47(Q) Room air conditioners, see Air

conditione rs, room Single machine, when conside red, 440.8 Trucks transporting refrigeraLed uni LS, see Electrified truck parking space equipme m Aircraft hangars, An. 5 13 Aircraft baueries, 5 13 .10 Ai rcratt e lectrical systems, 5 13 .l0 (A) Classification of locations, 513.3 Equipmen t, 513.4, .513 .7, 5 13.8, 513 .10 Ground-fault circuit imerrupte rs, 513 .12 Grounding a nd bonding, 513. 16 Mobile equipment, 513 .7(F), 513. 10(0) Painting hangar, 513.3(C) (2 ) Definition, An. 100 Portable equipment, .51 3.1 0(E) Sealing, 5 13.9

70-846

Stanchions, rostrums, and docks, 513.7(E)

Wiring, 513.4, 51 3.7, 513.8 Air ducts, see DucLS Air plenums, see Plenums Air terminals, see Surge arresters Alarms Burglar, see Remote-control, signaling, and powerlimiLed circuiLS Fire, 230.82 (5), 230.94 Ex. 4. See also Fire alarm systems Alarm systems, see Fire alarm systems Alternate power source, see Power source, Alternate Alternating-current power distribution box, 530. 18(E) De finition , 530.2 Alternators, see Generators Aluminum conduit, see Rigid metal conduit Aluminum siding, grounding of, 250.11 6 IN Ambient temperature, 310.14(A) (3) IN No. 1, 310.14 (B), Table 3 I0.15( B) ( I), Table 310.15( B)(2), 311.60( 0 )(4), Table 311.60( 0 ) (4); see also Tern peramre limitations Ambulatory health care centers, see also Health care facilities Essential electrical sysLems, 517.45 Amb ula to ry heal th care occupancies DefiniLion, 517.2 Ampacities, see also Am paci ties,

under entries for specific wiring and equifimenl Conductors, 3 10.14 through 310.21, Tables 31 l.60(C) (67 ) through 311.60 (C) (86), Tables B.2(1 ) through B.2( 10) Amusement auractions, 522.22 Auxiliary guuers, 366.23 Crane and hoist, Table 610. 14(A) Ene rgy storage systems, 706.30 (C) Fire alarm systems, 760.51 Interconnected electric power production sources, 705.28( B) Motors, moLOr circu iLs, and controllers, 430.6 Remote comrol, signaling, and powe1°limi ted Class 2

and Class 3 circuits, Table 725.144

Dwelling uniLs Disconnecting means, 422.34

Solar phoLOvolmic systems, 690.8(B) Wind electric systems, 694.12(B) Definition, Art. I00 Feeders, 310.1 2(C) Fixmre wires, 402 .5 Grounding, 250. 122

OmleLs, 210 .52 Fixed, 550.12 (0 ), 550.13(C), 55 1.42 Definition, 550.2, 551 .2 Floating bu ildings, 555.56(B) Ground-fau lt circuiL-ime rrupter protection, 210.8(0 ), 422.5

Medium vollage cable (Type MV), 3 11-IV

Grounding, 250-VI, 550 .16, 55 1.54 Hazardous (classified ) locations, see Hazardous (classified) locations Household cooking, demand facLOrs and loads for, 210.21 (B) (4), Table 220.55 Installation, 422-II Listing, 422.6 Live parLS, 422.4 Load calw lations, 220.14, 220.52 through 220.56, Table 220.55 Marking, 422- V Mobile ho mes, in, 550 .12 (B}, 550.12( 0 ), 550.14, 550.150 ), 550.18 Motor-driven , 422.l 0 (A) Disconnecting means, 422.31 (C) Load, 220. 18(A) Marking, 422.62

Tab les, 0- 2000 vol LS, Annex B Amusement attractions, control systems for permanent, Art. 522 Comrol circuiLS, 522- II Comrol circuiLS wiring methods, 522-III Definitions, 522 .2 Maintenance, 522.7 Voltag·e limiLations, 522.5 Analgesia, relative Definition, 517.2 Anesthetizing locations, 517-IV. See also Health care faci lities Definition , 517.2 Flammable, 517 .60(A)(l), 517.60( B) (2 ) Ex., .517.6 1(F),.5 17.64(F) IN Definition, 517.2 Annexes, informative, 90 .5( 0 ), Annexes A throughj Antenna discharge units, 810.20, 810.57 Antenna systems, radio and television, see Community amenna television and radio distribution (CATV) systems; Radio and television equipmem Apparatus, see also Associated apparams; lnu-insically safe apparatus; Simple apparatus Associated nonincendive field wiring, 500.8(C) (6) De finition, Art. 100 Nonincendive fi eld wiring, 508.8(C) (6) Defin ition, An. 100 Appliances, Art. 422. See also Motors BatLery-powered, 517.64(E) Branch circuits, see Branch

circuits, appliances ConsLructio n, 422-IV Cords, see Cords, fl exible Definition , An. 100 Disconnecting means, 422- III

Overload protection, 422.11 (G) OmleLs, 210.50(C), 210.52 O ver cu rrem proLection, 422 .11 Park trailers, 552.l0(E) (3), 552.20(0), 552.46(B}, 552.47, 552.56(F) , .552.58 Portable, 550.18(A) (2) Definition, 550.2 Recreational vehicles, 551. 20(0 ), 55 1.41 (C) Ex. 1,551.42, 55 l.55(F}, 55 1.57 Sig na l transmissio n between, 5 17.82 Small, 210.11 (C}( l ), 210.52( B}, 220.52 (A), 550. 12(B), .550. I8, .552 .46 (B} (2), 552.47(A) Subject to imme rsion, 422.41 Terminals, ide ntification of, 200. I0(E) Approval, approved Definition , Art. 100 Equipment and maLerials, 90.4, 90.7, 110.2, 500.8(B), 680.3, 680.81, 691.5,

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

705.6, 710.6, Annex H 80.19

Artificially made bodies of water, see Natural and

anificially made bod ies of water, electrical wiring and equipment for

Arc-fault circuit interrupters, 210 .12

Definition, An. 100 ProLecLion, 440.65, 550.25 Receptacle replacements, 406.4(0 ) (4) Solar photovoltaic systems, 690.11 Arc fault protection, direct current microgrids, 712.57 Arc-flash hazard warning, 110.16 Arcing parts, 240.4 1

Enclosure of, 110.18, 430.14( 8 ), 511.7 ( B) ( I ), 513.7 (C), 515.7(8 ), 516.7(8), 517.61 (B) (2) Arc lamps, portable

Motion picmre smdios, 530.17 Stage equipment, 520.61 Arc-welder motors, see Welders, e lectric Arc welders, see Welders, eleCLric Arenas, 410.l 0(E), Art. 518, An. 520 Emergency lighting system, An. 700 Armored cable (Type

AC) , Art. 320 Accessible attics, 320.23 Ampacity, 320.80 Bends, 320.24 Boxes and fittings, 320.40 Conductor type, 320. I 04 Construction, 320--III De finition, 320.2 Equipmem grounding, 320.108 Equipmem grounding conductor installation, 250.120(A) Exposed work, 320.15 Installation, 320--11 Marking, 320.120 Support, 320.30 Through o r parallel lO fram ing members, 320.17 Uses not permiued, 320.12 Uses permitted, 320.10 Armories, An. 518 Emergency lighting system, An. 700 Array, solar photovoltaic systems, IN F'ig. 690.l(a},

690.7(C), 690.12(A), 690.1 2(8), 690.3 1(F ), 690.41 (A); see also Solar p hotovoltaic systems Definition, 690.2 Arres ters, surge, see Surge arresters

2020 Edition

Askarels

Defin ition, Art. 100 Transformers, 4.50.2.5 Assembly occupancies, 410.l0 (E),

Art. 518 Classifications, 518.2 Emergency lighting system, An. 700 Supply, 5 18.5 Theaters, audience areas, Art. 520 Wiring meLhods, 518.4 Associated apparatus

Defin ition, ArL 100 Grounding of, 504.50(A) IN, 504.50(8) Installation, 504.10 Listed, 504.4 Marking, .500.8(C} (6), .50.5.9(C) (2) Ex. 1, 505 .9(C) (2) Ex. 3, Table 505.9(C) (2) (4), Table 506.9(C) (2) (3), 506.9(C) (2) Ex. Pe rmiued equipment, 500.8( 8)(2) Associated nonincendive field wiring apparatus

Defi nition, An. 100 Marking, .500.8(C) (6) Atmospheric groups, see Hazardous (classified) locations Attachment fittings, 2 10.8(A) ( I0) Ex., 210.8( 8 ) ( 10) Ex., 314.27(E), 422.22, 422.33(A) Definition, Art. 100 Attachment plugs (caps), see also Hazardous (classified) locations; Receplacles, cord connectors, and attachmem plugs (caps) Construction ot; 406.7 De finition, An. 100 Flex ible cords on, 210.50(8), 400.l0(B), 400.24 Grounding lype, 406.1 0 Polarized, terminal identification, 200.l0( B) Attics

Armo red cable, 320.23 Knob and tube, 394.23 LighLing outlets required, 210.70(C) Metal-clad cable, 330.23 Nonmetallic extensions, 382.12( 1)

NATIONAL ELECTRJCAL CODE

Nonmetallic-sheatl1ed cable, 334.23 Open ,-,~ring, 398.23 Sign transformers in, 600.21 (E) Audio signal processing, amplification, and reproduction equipment, Art. 640

Access, 640.5, 640.46 Conduit or tubing, 640.23 Definitions, 640.2 Environmental protection, 640.44 Flexible cords, use ot; 640.21, 640.42, 640.45 Grounding, 640.7 Grouping of conductors, 640 .8 Locations, 640.3 Loudspeakers Definition, 640.2 In fire-resistant construction, 640.25 Mechanical execution of work, 640.6 Motion picn,re projectors, 540.50 Permanem installations, 640--II Portable a nd temporary installations, 640-III Protection of electrical equ ipment, 640.4 Thealers, 520.4 Transforme rs, 640.9( 0 ) Definition, 640 .2 Underwater, 680.27(A), 680.35(D), 680.43(G), 680.45(0 ) Water, near, 640. I 0 Wireways, guuers, auxiliary guuers, 640.24 Wiring methods, 640.9 Wiring of equipmem racks, 640.22, 640.43 Auditoriums, An. 518, An. 520 Emergency ligh ting system, An. 700 Authority having jurisdiction, 90.4; see also

Approval, approved Definition, An. 100 Automatic

Definition, Art. 100 Autotransformers, see

Transforme rs Auxiliary gutters, An. 366

Conductors Ampacities, 366.23 Clearance, bare live pans, 366. I00 ( E) Insulated, 366.58 Number ot; 366.22

Construction specifications, 366III Covers, 366.I00(D) Definitions, 366.2 Extension beyond equipmem, 366.12 Grounding, 366.60 Indoors Listing, 366.6(8 ) Marking, 366.120(8) Uses permiued, 366.l0(A) (1), 366. 10(8}(2} Installation, 366-11 Listing, 366.6 Marking, 366.120 Metallic Conductors, 366.22 (A), 366.23(A) Definition, 366.2 Securing and supporting, 366.30(A) Uses permitted, 366.l0(A) Nonmetallic ConduCLors, 366.22(8 ), 366.23(8) Definition, 366.2 Marking, 366.120 Securing and

supporting, 366.30(B) Uses permiued, 366.l0(B) Omdoors Listing, 366.6(A) Marking, 366.120(A) Uses permiued, 366.l 0(A) (1), 366. I0(B)( I) Sound reco rding, similar equ ipment, 640.7(A), 640.24 Splices and taps, 366.56 Support, 366.30 Uses not perm itted, 366.12 Uses permitted, 366.10 -BBack-fed devices, 408.36( 0 ) Backfill, 300.5(F'), 3 00.50(E) Balconies, outdoor, receptacles for, 210.52 (E) (3) Ballasts, electric discharge lamps, 4 10--XII, 410- XIII

Protection in fluorescent fixrnres, 410.130(E) Protection in recessed HID fixrnres, 4l0.1 30(F') Bare conductors

Ampacities, 3 10.1 5( 0 ) Auxiliary guuers, 366.56(8) Bond ing jumpers, 250.1 94(A) Contact conductors, cranes and hoists, 610--III

70-847

NATIONAL ELECTRICAL CODE

Defini tion, Art. 100 Equipment grounding conductors, l 10.54(B), 225.4 Ex., 250.118(1), 250. I I 9,250.120, 250.187( 0 ) Grounded conductors, 225.4 Ex., 230.22 Ex., 230.30(A) Ex., 230.41. Ex. Lighting systems operating at 30 volts or less, 411.6(C) Raceways, 22.5.27, 230.30(A) Ex. Service entrance, Types SE, USE, 338.100 Sizing conduits for, Chap. 9 Underground conduits, grounded neutral, 230.30(A) Ex., 230.4 1 Ex. Barriers, 368.234(B) Basements (cellars) Lighting outlets required, 210.70(C) Nonmetallic extensio ns, 382.12(1) Nonmetallic sh eath ed cable, 334.15 (C) Receptacles in, 2 I0.8(A) (5), 2I0.52(G) Basic care space, 5 17.29 (A) Definitio n, 5 17.2 Bathrooms, see also Bathwbs Branch circuits for, 210.ll (C)(3) Definition, Art. 100 Disconnecting means, 230.70(A) (2)

Fixed electric space-h eating equipment cables, 424.44(E) Lighting outlets required, 2 I 0.70(A) (I), 210.70(B) Overcurrent d evices, 240.24( E) Receptacles in, 210.8(A) (1), 210.8(B)(l), 210.52( 0 ), 406.9(C), .5.50.12(E) , 550.13(0 ) through (F), 551 .41 (C), 552.41 (F) Bathtubs Hydromassage, 680--\/11 Definit io n, 680.2 Fixed electric space-h eati ng equipment cables, 424.44 ( E) Lu minaires, 4 10.10 (0 ), 550.14(0 ), 551.53(B), 552.54(B) Receptacles, 210 .8(A) (9), 406.9(C), 550.1 3( F), 552.4 1 (F) Switches, 404.4(C) Batteries, see also Storage batteries

70-848

Aircraft, 513.10 Flow, 706-V

Carnivals, circuses, fairs, and sim ilar events, 525-1\/

Definition, 706.2 Installations, Art. 480

CATV and radio distributio n systems, 820.l 00 Communications circuits, 800.1 00, 800. 106(B) Cranes and hoists, 6 10- VI I Definition, Art. 100 Electrolytic cells, 668.30 (E) Elevat0rs, 620- IX Equipotential p lane, 547.10, 680.26, 682.33 Flexible metal conduit (Type FMC), 348.60 Garages, commercial, 511.16

Marking, 480.7(F), 480.7(G) Nominal voltage Definition, 480.2 Sealed Definition, 480.2 Vems, 480.11 (B) Terminal, see Te rminals Battery charging equipment, 51 1.10 (A) Aircraft hangars, 513. I0( B) Battery system, see also Storage batteries Definition, Art. 100 Bedrooms Arc-fault circuit-i nterrupter protection, 2 10.12(A) Bell circuits, see Remote-control, sig naling, and powerlimited circu its Bends, 300.34, Chap. 9, Table 2; see alsospecific wiring system Berths Definition, 555.2 Bipolar circuits, 690.7 (C), 690.3I(E) Definition, 690.2 Block (city, town, or village) Communication wires Protective devices, 805. 90 (A) Underground block distribution, 805.47(B) Definition, 800.2 Network-powered broadband communications systems, protection, 830.90(A) Boathouses and boat hoists, ground-fault circuit interrupters, 2 10.8(A) (8)

Boatyards, see Marinas, boatyards, floating buildings, a nd docking facilities Bodies, conduit, see Conduit bodies Boilers Electrode-type 600 volts o r less, 424-\/111 Over 1000 volts, 490--V Resistance-type, 424-\/11 Bonding, 250--V Agricu lmral buildings, 547.9, 547. 10 Aircraft hangars, 513.1 6 Bulk storage p lants, 5 1.5. 16 Cable trays, 392.60

Grounding-type receptacles, 250.146 Hazardou s (classified) locations, see Hazardous (classified) locations Health care facilities, .517. 13( B), 517.19( 0 ), 517.l 9(E) Induction and dielectric heating equipment, 665.26 Information technology equipmem, 645. 15 lntersystem bonding term ination, 54.5.27, 770.I 00(B) Defi nition, Art. 100 Intrinsically safe systems, 504.60 Irrigatio n machines, 675.14 Liquidtig ht flexible metal conduit (Type LFMC), 350.60 Liquidtight flexible nonmetallic conduit (Type LFNC), 356.60 Loosely jointed raceways, 250.98 Manufacmred bui ld ings, 545 .1 1 Marinas and boatyards, .555. 13 Metal boxes, 3 14.4 Mobile homes, 5.50. I 6(C) Motor fuel dispensing faci li ties, 514. 16 Namrally and a rtificially made bodies of water, electrical equipment for, 682- 1II Optical fibe r cables, 760.180, 770. 100, 770.1 06(B) Otl1er enclosures, 250.96 Outside raceway, 250.1 02(E) Over 250 vol LS, 250.97 Over I 000 volts, 490.74 Panelboards, 408.40, 517.1 4 Park trailers, .552 ..57 Piping systems and exposed strucmral steel, 250.104 Raceways, see Raceways

Radio and television equipment, 810.2 1, 810.58 Receptacles, 250.1 46 Recreational vehicles, 5.5 l..55(A), 55 1.55(B), 551.56 Relocatable structures, 545.26, 54.5.27 Sepa rately derived systems, 250.30(A) (8), 250.30(B)(3), 250.104(0) Service equipment, 250.92, 250.94 Sig ns and outline ligh ting, 600.7(B), 600.33( 0 ) Subs muons, fences and othe r metal structures enclosing, 250. 194 Swimming pools, see Swimming pools Tunnels, I 10.54 Wind electric systems, 694-V Bonding conductors, 517.1 9(0 ), 545.26, 547.!0(B), 55 I..56(C), 552.57(C), 680.74(B), 760. 180, 770.100, 800.100, 810.21, 8 I 0.58, Chap. 9, Note 3 Bonclingjumpers, seeJ umpers, bonding Bored holes through studs, joists, 300.4(A) (I ) Bowling alleys, ArL .5 18

Emergency lighting system, Art. 700 Boxes (outlet, device, pull, and junction), Art. 314. See also Hazardous (classified) locations Accessibility, 314 .29, 3 14.72(0) Agricultural buildings, 547.5(C) Alternating-current power distributio n box, 530.18( E) Defin ition, 530.2 Community antenna television and radio distribution systems, 820.l 33(A) ( I ) Concealed work, 314.20 Conductors, number in box, 314.16 Emering boxes, conduit bodies or fittings, 314.17 Constructio n specifications, 3 14111 Covers, 3 14.25, 314.28(C), 3 I 4.41 , 3 I 4.42, 314.72(E) Cutout, see Cabinets, cutout boxes, and meter socket enclosures

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

Damp locations, 314.15 Depth, minimum, 314.24 Drop (cheaters, ecc.), 520.44, 520.46 Definition, 520.2 Enclosures, handhole, 314.29, 3 14.30 Fill calcu lations, 314.16(8 ) Fire pumps, 695.6(H), 695.6(1) Fire resistive system, 728.5 (E) Floor, for receptacles, 314.27(8 ) Flush-mounted installations, 3 14.19 Grounding, 250.148, 250-\11 Guners, auxiliary, used as, 366.58( 8 ) Insulating, see Boxes, nonmetallic J unction, pull, seeJ unction boxes Lighting (luminaires) omlets, see Lighting omlets Marking, 314.44 Metal Construction, 314.40, 314-III Grounding and bonding, 314.4 Installation, 314-11 Wireways used as pu ll boxes, 376.23(8 ) Mobile homes, 550.15(1) Multioutlet assemblies used as pull boxes, 380.23(8) Neon transformer enclosu res used as, 600.5( 0 )(2) Network-powered broadband comn1unications

systems, 830.133(A)(l) Nonmetallic, 314.3, 314.17(C), 314.43, 334.40 Receptacles installed in, 406.3(D) (2) Wi rewa ys used as p u II boxes, 378.23(8 ) Not required, 590.4(G) Ex . I Optical fiber cables in, 770.133(8) Over 1000 voltS, 314-IV Park trailers, 552.48, 552.56( 0 ) Plugging, see Plugging boxes, motion picture stud ios Portable Rides, tents, and concessions, 525.22 Theaters, 520.62 Recreational vehicles, 551.47 Repairing noncombustible surfaces, 314.2 I Required location, 300.1 5 Round, 3 14.2

2020 Edition

Securing and supporting, 300.1 1, 314.23, 392.1 8(G) Snap switches over 300 voltS, not ganged, 404.8(8) Solar photovoltaic systems, 690.34 Surface extensions, 3 14.22 Temporary installations, 590.4(G) Unused openings, closed, 110.12 (A) Vertical raceway runs, 300.19 Volume calct~ations, 3 14.16(A) Wall or ceiling, 314.27(A) Wet locations, 314.15 Branch circuits, ArL 210, Art. 220 Air conditioners, 440--IV, 440-VII Appliances, 210.23, 422-II Calculations, 220-II Definition, An. 100 Small, 210.11 (C)( I) Arc-fault circuit-interrupter protection, 210.12 Audio equipment, 640. I0(A), 640.41, 640.42(E) Bathrooms, 210.ll (C)(3) Breakom assembly, 520.68(A) (6) Definition, 520.2 Busways as branch circuits, 368.17 (C) Calculation of loads, 220-II, Annex D Co lor code, 210.5 Common area, 210.25(8) Conductors, minimum ampacity and size, 210.19 Critical, 517.34, 517.44 Definitio n, 517.2 Critical operations power systems, 708-11, 708.30 Defin ition, Art. 100 Electric veh icle supply equipment, 625.40, 625.4 1, 625.47 Electroplating, 669.5 Elevators, durnbv,raiters, escalators, etc., 620.13 Emergency lighting transfer switch, 700.25 Definition, 700.2 Emergency systems, 700.12 (I) (2), 700.15, 700.17, 700.18, 700.25 Energy management systems, 750.30(C) Fire alarm systems, 760.41 (B), 760. 121 (B) Fixed e lectric space-heating equipment, 424.4

NATIONAL ELECTRJCAL CODE

Boilers, 424.82 Low-voltage equ ipment, 424.104 Radiant heating panels, 424.95, 424.96 Fixed resistance and electrode industrial process heating equ ipment, 425.4, 425.22(A), 425.22(D) Electrode-type boilers, 425.82 Resistance-type boilers, 425.72(D) General-purpose Definition, ArL 100 Guest rooms or suites, 210.6(A), 210.17 Health care facilities, 517.18(A), 517.63(8), 5l 7.63(C), 517.73(A) ( I) Individual Definition, Art. 100 Overcurrent protection, 210.20 Permissible loads, 210 .22 Rating or setting, 430.52 Required, 490.72, 600.5, 605.9(8), 620.22 tl1rough 620.25 Information technology equ ipment, 645.5 Irrigation machines, 675.9, 675.10 Isolated power systems, 5 17.160 Low-voltage suspended ceiling power distribution systems, 393.21 (B) Marinas, boatyards, fl oating buildings, and dockyards, 555.32(A) (3), 555.34(8) (2), .555.35(A) (3), 555.37(0 ), 555.53 Maximum loads, 220. 18 Mobile homes, 550.11, 550.12 Modular data centers, 646.7(8) Motor, on individual branch circuit, see Motors Multiple, 210.7 Multiple-outlet, 210.23, 210.24, Table 21 0.24 Multiwire, 210.4, 393.21 ( 8 ) Definition, Art. I 00 Outside, set Outside branch circuits and feeders Overcurre nt device, 240.24(8) (2)

Definition, Art. 100 Overcurrent p rotection, 210.20, 240.4, 250.32(8)(2), 250.32(C)(2), 520.52 Park trailers, 552.42, 552.46 Patient bed location, 517.18(A), 517.!9(A)

Permissible loads, 210.22, 210.23 Piers, 682.15(8) Ratings, 210--II Recreational vehicles, 551.42 RequirementS for, 210.24, Table 210.24 Selection current, 440.4(C) Definition, 440.2 Shore power, 55.5.33(A)(3) Small-appliance, 210 .ll(C)(l) Stage or set, 530.23 Swimming pools, 680.23(F) Taps from, 210.19 (A), Table 210.24, 240.4(E), 240.5(8)(2) Through luminaires, 4I0.64 (C) Voltage drop, 210.19(A) IN No. 3 Voltage limitations, 210.6 X-ray equipment, 517- V, 660.4, 660.6(A) Branch-circuit selection current Definition, 440.2 Marking on nameplate, 440.4(C) Building Definition, Art. 100 First fl oor of; 362.10 Building component Definition, 545.2 Building system Definition, 545.2 Building wire, see Con cl uctors Bulkhead Definition, 555.2 Bulk storage plants, An. 515. See also Hazardous (classified) locations Class I locations, 515 .3 Gasoline dispensing, 515.10 Grounding and bonding, 515.16 Sealing, 515.9 Underground wiring, 515.8 Wiring and equipment, 515 .4, .515.7 Bull switches, 530.1 5(0) Definition, 530.2 Burglar alarm systems, see Remote-control, signaling, and powerlimited circuits Busbars Aboveground wiring methods, 300.37 Definition, 393.2 Industrial control panels, 409. 102 Interco nnected electric power production sources, 705.12 ( 8 ) (3) Motor control centers, 430.97

70-849

NATIONAL ELECTRICAL CODE

Portable distribution or terminat ion

boxes, 525.22(B) Portable stage equipment, .520.62 (C) Switchboards, 408 .3, 408.51 Bushings Corel, luminaire, 410.84 Electrical no nmetallic tubing, 362.46 Fiber, 320.40 Fire alarm systems, 760.3(K) Ge ne rato rs, 445. 16 High density polyethyle ne conduit, 353.46 Insulated, 300.4(G), 312.6(C) Lampholders attached to flexible cord, 410.62(A) Securing fittin gs o r raceways, 300.4(G) Intermediate metal conduit, 342.46 Motors, 430.1 3 Outlet boxes, conduit bodies, and outlet fittings, 314.42 Rein forced thermosetting resin conduit, 355.46 Rigid metal con cl ui t, 344.46 Rigid polyvinyl chloride conduit, 352.46 Snow-melring and deicing equipme nt, 426.22 (C) Underground installa tio ns, 300.5 (H ) Use in lie u of box o r termina l fitting, 300.16( B) Busways, Art. 368 Barrie rs, fire, 368.234(B) Branc hes from, 368.56 Connections, 368.238 Constructio n, 368--lll Dead e nds closed, 368.58 De finitio n, 368.2 Drains, 368.236 Extension through walls and floors, 368.l 0(C) Feeder o r branch circuits, 368. 17 Gro unding, 368.60 Over 1000 volts, 368.260 Installatio n, 368--11 Luminaires connected to, 410.36(F) Manu factured wiring systems, 604. I00(A) ( 4) Marking, 368.1 20, 368.320 Ove rcurre nt protectio n, 368.17 Over 1000 volts, 368--IV Reduction in size, 368.17(B) Seals, vapor, 368.234(A)

70-850

Storage battery, d isconnection means, 480.7(E) Su ppo n , 368.30 Terminations, 368.238 Under 1000 volts, 368.240 Through walls and floors, 368. I0 (C) Uses not permitted, 368.1 2 Uses permitted, 368. IO Ventilated e nclosures, 368.237 Bypass isolation switch, 700.5 (B), 70l.5( B), 708.24 De finition , Art. I00 -CCabinets, cutout boxes, and meter socket enclosures, An. 312 Construction specifications, 3 1211 Damp and wet locations, 3 12.2 De finitio ns, Art. 100 Deflectio n of conductors, 3 I 2 .6 Installation, 312-1 Insulation at bushings, 300.4(G), 312.6(C) Ma rking, 230.66 (B) Positio n in walls, 3 12.3 Switch enclosures, splices, taps, 312.8 Unused openings, I I0.12 (A) Wire-bending space at terminals, 3 I2.6( B) Wiring space, side or back, 312.9 Cable bending, see type of cable Cablebus, Art. 370 Conductors, 370 .20 Ampacity, 370.80 O vercurre nt protection, 370.23 Te rminatio ns, 370.20(B), 370.42(3) Constru ction specifications, 370111

De finitio n, 370.2 Equipment grounding conductor installation, 250. I20 (A) Fittings, 370.42 G rounding, 370.60 Installa tion, 370-11 Ma rking, 370. 120 Securing a nd supporting, 370.30 Support and extension through walls and floors, 370.18 Uses not p e rm ittecl, 370---12 Uses permitted, 370. IO Cable connectors De finitio n, 324.2 Theater, 520.67

Cable end fittings, changing from cable to knob-andtube, 300.1 6(A) Cable management system, 62.5.17 (C), 626.23, 626.25 ( B) (3) Definitio n, 625.2, 626.2 Cable routing assembly, 800.26, 800.110, 800.113, 800.1 54, 800.182, 805.1 33(A)( l ) Coaxial cables, 820.l33(A) (1)

Definition, Art. 100 Netwo rk -powered broadband communicatio ns systems, 830.l 33(A) (l) Premises-powered broadband commun icatio ns systems, 840.170 (0 ) Cables Abandoned, 640.6(B) Aud io distribution, 640.2 Communications, 800.25 De finition, 800.2 Fire a larm, 760.25 De finiti o n, 760.2 Interconnecting De finition, 645.2 Optical fi ber, 770.25 De finition, 770.2 Pre mises-powered broadband communicari o n, 840.25 Remote-control, signa ling, and power-limited circuits, 725.25 De finition, 725.2 Adjustment factors fo r m ore th a n three currentcarrying conductors in, Table B.2( 11 ) Aerial, see Aerial cables Armored (Type AC), see Armo red cable (Type AC) Border ligh ts, tl1eater, 520.44(C) Bundled De finitio n, 520.2, 725 .2 Cable trays, installatio n in, see Cable trays CATV, Art. 820 Circuit integri ty, 725.179(F), 760.24( 8 ), 760. l 79(G), 770. I 79(E) Communicatio ns, 805 .1 79(C) Defin itio n, 80.5 .2 Coaxial, Art. 820,840.1 IN, 840.47(C), 840.48(C), 840.93(C), 840.I0l (A) De finitio n, Art. 100 Continuity, 300.12 Definition, 805.2

Festoon, 610.13(C) Definiti o n, 610.2 Flat cable assemblies (Type FC), see Flat cable assemblies (Type FC) Flat con cl uCLo r (Type FCC), see Flat conductor cable (Typ e FCC) Flexible, see Cords, Flexible Grouped, .520.2.54 (C), 620.21 (A) Definiti o n, 520.2 Heating, Art. 424 Installation in cable trays, see Cable trays Installed in g rooves, 300.4(F) Instrumen tatio n tray (Type ITC), see In strumentatio n tray cable (Type IT C) Integra ted gas spacer cable (Type IGS), see Integrated gas spacer cable (Type !GS) Interconnecting, 645.5 Definitio n, 645.2 Manufactured wiring systems, 604. I 00(A) Medium voltage cable (Type MV), see Medium voltage cable (Type MV) Metal-clad cable (Type MC), see Metal-clad cable (Type MC) Mineral-insulated metalsh ea tl,ecl (Type Ml), see Mineral-insulated metalsh eatl1ecl cable (Type Ml ) Multicond uctor cables, ide ntification of conductors in, 250.J 19( B) Nonmetallic extension, see Nonmetallic extensions Nonm etallic-sheathed (Types NM, NMC, and NM$), see Nonmecallicsh eatl1ecl cable (Types NM, NMC, and NM$) Nonmetallic underg ro und conduit with conductors, see Nonmetallic underground conduit with conductors Optica l fibe r, see Optical fi ber cables Od1er types of, see systems, e .g. Co mmunity antenna te levision a nd radio distributio n (CAT V) systems

NAT IO NAL ELECTRJCAL CODE

2020 Edition

INDEX

Point of e nu-ance De finition, 770.2, 800.2 Porcable, see Cords, flexible Po rtable power cables, ma rinas and boatyards, 555.34(A) (2), 555.34( B)(3) Power and control tray cable (Type TC), see Power and control u-ay cable (Type TC) Preassembled in no nmetallic conduit, see Nonmetallic undergro und conduit with conductors Protection against physical da mage, 300.4 Sealing, 50l.l.5( D), .501.15( E), 505.16(A)(2), 505.16(B) (5) through (B)(7) , 50.5 .16(C) (2) Secured, 300.11 , 314.l 7 (B) Service, see also Service-entrance cable (Types SE a nd USE) De finition, An. 100 Service-enu-a nce (Types SE and USE), see Ser vicee ntrance cable (Types SE and USE) Splices in boxes, 300.15 Stage, 530.18 Support, l 10.12(C), 392.l S(G) Through studs,joists, rafters, 300.4 Traveling, elevator, 620.l l ( B), 620.12 (A), 620--V Two-fe r, 520.69 De finitio n, 520.2 Type P, see Type P cable Unde rground, 230- III, 300.5, 300.50, 770.47 Unde rg round feeder and b ranch circ uit Type UF, see Unde rground feeder and branchcircuit cable (Type UF) Vehicle supply equipment, 625 .17, 626.23 diro ugh 626.25 De finitio ns, 625.2, 626.2 Weld ing, 630-IV Cable sheath De finition , 770.2, 800.2 Cable suspension, 300.19 Cable trays, Art. 392 Accessibili ty, 392.18(E), 392.18(F) Ampacity, 320.80( B), 392.80 Be nds, 392.lS(A) Bo nding, 392.60 Bushed conduit a nd nibing, 392.46

2020 Edition

Cable and conductor installation, 392.20 Cable fill, 392.22 Class I circuits, 725.48(B)(4), 725.5 [ Communications circuits in, 800.1 10, 800. I 13( H) Co mmunity antenna television and radio distribution systems, 820. 133(A) ( I ) Consu-uction specifications, 392111

Covers, 392.18(C) De finitio n, 392.2 Equipment grounding conducto r installation, 250.120(A) Exposed, 392.18( E) Fire alarm system conductors, 760.51 (C), 760.133, 760.1 39 Fire resistive system, 728.5 (D) Grounding, 392.60 Installation, 392- 11 Ma rking, 392.1 8( H) Maximum number of cables in, Tables C.14 through C.20 Network-powered broadband communica tion s

systems, 830.133(A) ( I ) Optical fiber cables, 770. l 13(H ), 770.133, Table 770.154 (a) Outdoo rs, 725.1 35( H ) Over 1000 volts, cables rated, 392.20 Over 2000 volts, cables rated, 392.80 (B) Photovoltaic system s, 690.31(C) (2) Plenums, 300.22 (C) (2) Securing and suppo rting, 392.30 Splices, cable, 392.56 Support fo r raceways, cables, boxes, and conduit bodies, 392.18(G) Thro ugh partitions and walls, 392 .18(D) Uses not permiued, 392.12 Uses permitted, 230.44, 392.10 Ve ntilated, 392.22 Wiring methods, 392.IO (A), Table 392.l 0 (A) Calculations, Annex D; see also Loads Camping trailer, see also Recreational vehicles (camping trailers, motor ho mes, park traile rs, travel trailers, truck campers)

NATIONAL ELECTRJCAL CODE

Definition, 551.2 Canopies Boxes and fi ttings, 314.25 Live parts, exposed, 410.5 Lum inaires fixtures Conductors, space for, 410.20 Cover At boxes, 410 .22 Combustible finishes, covering required between canopy and box, 410.23 Capacitors, Art. 460. See also Hazardous (classified) locations Definitio n, 460.2 Enclosing a nd guarding, 460.3 Induction and dielecu-ic heating, 665 .24 Installation, Art. 460 Motors, 430.27, 460.9 l 000 volts a nd under, 460- 1 Conductors, 460.8 Grounding, 460.10 Marking, 460. 12 Means of d ischarge, 460.6 Overcurrent protection, 460.8(B) Rating o r setting of motor overload device, 460.9 Over l 000 volts, 460-11 Grounding, 460.27 Identification, 460 .26 Means for discharge, 460.28 Overcurrent protection, 460.25 Switc hing, 460.24 Phase converters, 455.23 Safe zone Definition, 460.2 X-ray equipme nt, 51 7.76, 660--111 Caps, see Attachme nt plugs Carnivals, circuses, fairs, and similar events, Art. 525 Conductor overhead clearance, 525.5

Definitions, 525.2 Grounding and bonding, 525- IV Equipment bonding, 525.30 Equipment grounding, 525.31, 525.32 Grounding conductor continui ty assurance, 525.32 Power sources, 525- 11 Multiple sources of supply, 525.1 1 Se,v ices, 525.10 Protection of electrical e quipment, 525.6, 525.23 Wiring methods, 52.5- 111

Concessions, 525.21 Ground-fau lt circuitinterrupte r protection, 525.23 Portable distribution or terminal boxes, 525.22 Rides, 525.21 Tents, 525 .21 Cartridge fuses, 240--VI Disconnectio n, 240.40 CATVsystems, seeCommunity antenna television and

radio distribution (CATV) systems Ceiling fans, 680.22(B), 680.43(B) Suppo rt, 314.27(C), 422. 18 Cell Cellula r concrete floor raceways Definitio n, 372.2 Cellula r metal floor raceways Definition, 374.2 Electrolytic, see Elecu-olytic cells Fuel, Art. I00; see also Fue l cell systems lnte rcell connecto rs, 480.4(B) Definitio n, 480.2 lnte rtier connectors, 480.4(B) Definitio n, 480.2 Sola,; IN Fig. 690.l (a) Definition, 690.2 Storage baueries, 480.4, 480.1 l (B) Definition , 480.2 Cellars, see Basemen ts Cell line, electrolytic cells, see Elecu-olytic cells Cellular concrete floor raceways, Art. 372 Ampacity of conductors, 372.23 Connectio n Lo cabinets and oth er enclosures, 372.18( B) Definitions, 372.2 Discontinued outlets, 372.58 Header, 372.18(A) Installation, 372- 11 J unction boxes, 372.1 8(C) Markers, 372.18(E) Number of conductors, 372 .22 Size of conducrnrs, 372.20 Splices and taps, 372 .56 Uses not perm itted, 372 .12 Cellular metal floor raceways, Art. 374 Am pacity of conductors, 374.23 Connection to cabinets and extensio n from cells, 374.1 8(A) Construction, 374-111 Definiti ons, 374.2

70-851

NATIONAL ELECTRICAL CODE

Discontinued omlels, 374.58 lnsens, 374.18(C) lnstallalion, 374-11 Junc tion boxes, 374.18(8 ) Marke rs, 374.18( 0 ) Number of conducwrs, 374.22 Size ofconduclOrs, 374.20 Splices and taps, 374.56 Uses nol permiued, 374. 12 Chairlifts, see ElevalOrs, dumbwaiters, escalators,

moving walks, plalform lifis, and stairway chairlifls Charge controllers

De finition, An. 100, 694.2 Ene rgy swrage syslems, 706.33 So lar photovoltaic systems, 690.72 Charger power converter, 625.102 Definition, 625.2 Child care facility

Definilion, 406.2 Ta mper-resistam receptacles in, 406.1 2(3) Churches, An..518 Cinder fill

Eleclrical me tallic lubing, 358.l 0(C) High density polyelhyle ne conduit, 353.10(3) lnlermediate or rigid metal conduilS and e leClrical metallic tubing, in or under, 342.I0 (C), 344. I0(C) Nonmetallic unde rground conduil wilh conductors, 354.10 (3) Reinforcing lhermoselling resin conduil, 355. IO (C) Rigid polyvinyl chlo ride conduil, 352.I0 (C) Circuit breakers, An. 240. See also Hazardous (classified) locations Accessibility and grouping, 404.8(A) Agriculmral build ings, 547.6 Arc e ne rgy reductio n, 240.87 CircuilS over l000 volls, 490.21, 490.45, 490.46 Damp o r wet locations, in, 404.4 De finition, An. 100 DisconneClio n o f grounded circuilS, 404.2(8 ), 5 14. 11 (A) Enclosures, 404.3 Fixed eleClric healing equipme m for pipelines and vessels, 427.55(A)

70-852

Fixed resistance and elecrrode induslrial process heating equipmem, supply conducwrs, 425.2 1 General, 110.9, 240- 1 Indicati ng, 240.81, 404.7, 422.35, 425.21 Ma rkings, 240.83, 240.86(A) Mobile ho mes, 550.11 (C) Overcurrem proleclio n, 230.208, 240--1, 240--VII Generawrs, 445 .12 Molors, 250.122( 0 ), 430.52, 430.58, 430.111, 430.225(C) (1) Transformers, 450.3 Panelboards, 408--lll , 408.54, 408.55 Ex. I Raring Fixed-rrip circuil breakers, 240.6 (A), 240.83(C), 240.86 Molor branch circuilS, 430.58 Service disconnecting means, 230.70, 230.205 Service overcurrem protection, 230.90, 230.9 1 Stand-alone systems, 710. 15 (F) Switches, use as, 240.83( 0 ), 404.11 , 4 10.14 1(A) Swilching d evices, over 1000 volts Definilion, An. 100 Circuit directory, panelboards, 408.4 Circuit integrity cables, 725. I79 ( F),

770. I79(E) Communicatio ns, 805.l 79(C) De finitio n, An. l00, 760.2, 805.2 Fire alarm systems, 760.24(8 ), 760.53( 8 ) (2), 760.154, 760.176 (F), 760.179(G) Circuit interrupters, groundfault, see Ground-fault

circuit ime rrupters Circuits

Abandoned supply circuils, 645.5(G) Definition, 645.2 Anesthetizing locations, 517.63 Branch, see Branch circuilS Burglar alarm, see Rem otecomro l, signaling, and powe1°limiled circu ils Cemral statio n, see Fire a larm systems Communication, see Communicarjons circuits

Conrrol, see Contro l circuits

Different inrrinsically safe, 504.30( 8) Definition, An. 100 Elecrrical circuil proleclive system, 250. I 20(A) IN, 300.19(8 ) De finition , Art. 100 Fire alarm, see Fire alarm systems Fue l cell system s, see Fue l cell systems Grounding, Art. 250 Impedance, 110.10 Information technology equipment, 645.5 Inte rconnected electric power production sources, 705.28 lmrinsically safe, 504.30 Inverte r inpm and o mpm circuits, 690.1 , 690.8(A)(I), 690. 10 Less than 50 vollS, Art. 720 Class I, 725- 11 Grounding, 250.20(A) Modular data cente rs, 646.6 through 646.8, 646.17, 646.20 Moto r, 430- 11 MolOr control, 430--VI Number ot; in enclosures, 90.8( 8 ) Output, see Output circuilS Over 600 vollS, see Over 600 volts Over l 000 voks, see O ver l 000 volts Phowvoltaic syslems, 690.6, 690--1 I, 690--IV De finitio ns, 690.2 In verte r circ uilS, 690.6 Output circ ui lS, 690.1 , 690.6(8 ), 690.7 lhrough 690.9, 690.31 De finition, 690.2 Source circuits, 690.1, 690.7 through 690.9, 690.31, 690.53 De finiti o n, 690.2 Power-limited, see Remotecontrol, signaling, a nd power-limited circuits Premises communications De finition, 840.2 Premises community ante nna

television (CATV), 840 .170(F) Pre mises community antenna

lelevision (CATV) circuits

De finitio n, 840.2 Protectors required, communications

circuilS, 800.100, 800.106, 805.9 0, 805 .170, 830.90 Remote-comrol, see Remolecont rol, signaling, and

power-limited circui lS Sig nal, see Remote-control, sig naling, and powerlimiled circuils Telegraph, see Communicatio ns circuilS Telephone, see Communications circuits

Underground, see Co mmunica tio ns circ uilS Ungrounded, 210.10, 2 15.7, 410.93; see also Co nductors Wind electric systems, 694-11, 694.30(C) Definition s, 694.2 Circuses, see Carnivals, circuses, fairs, and sin1ilar events Clamp fill, boxes, 314.16(8 ) (2) Clamps, ground, 250.10, 250.70 Class I , 2, and 3 circuits, see Re mote-control, sig na ling, and powerlimited circuits Class I, n, and IH locations, see Hazardous (classified) locations Clean s urfaces, grow1ding conductor connections, 2.50 .12 Clearan ces, see also Enclosures;

Space Antennas, 810.1 3, 810.1 8, 8 10.54 Community antenna

systems, 820.44(8 ), 820.47, 820.133(A) Conductors Open, omside branch circuilS and feeders, 225.18, 22.5. 19 O verhead service, 230. 24, 230.26, 55 1. 79 Elevators, dumbwailers, escalawrs, etc., 620 .5 Fixed resistance and electrode indusrrial process heating equ ipme nt, supply conductors, 42.5.13 Live parlS Auxiliary gutters, 366.100 (E) CircuilS over I 000 volts, 110111 Lumina ires, 4 10.116, 410.136 Nelwork-powered broadband communicati ons

systems, 830.44 Swimming pools, 680.9

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

Switchboards, 408.5, 408.18 Wind electric systems, 694.7(G) Climbing space, line conductors on poles, 225.14( 0 ) Clothes closets

Definition, Art. 100 Heating, 424.38(C) Luminaires, 410.16 Overcurrent devices, 240.24( 0 ) Clothes dryers

Calculations for, 220.54 Feeder demand factors, Table 220 ..54, 220.82(B) Grounding, 250.11 4, 250.140 Mobile homes, 550.l5(E), .550.l 6(A), 550.l6( B)(3) Clothing manufacturing plants, 500.5(0 ), Art.

503, An. 506. See at.so Hazardous (classified) locations CO/ ALR

Receptacles, 406.3(C) Switches, 404.l4(C) Collector rings, 490.54, 675.11 Defin ition, 67.5.2 Collectors, cranes and hoists, 610.22 Color code

Branch circuits, 210.5 Conductors, 3 11.14, 410.69, 504.S0(C), 647.4(C) Extra-hard-usage

cables, 520.44(C) (3) Grounded conductor, 200.6, 200.7, 400.22, 520.44(C) (3), 520.54(.l )( l ) Grounding conductor, 250.119, 3 11.14, 400.23, .520.44(C) (3) Isolated power systems, 5l7.l 60(A)(5) Ungrounded, 210.5(C), 215 .12(C), 311.14 Higher voltage to ground Sensitive electronic equipment, 647.4(C) Service-entrance conductors, 230.56 Combustible dusts, Art. 502, Ar t. .506; see also Hazardous (classified) locations Defin ition, Ar t. 100 Combustible gas detection systems, 500.7(K),

505.8(1) De finition, Art. 100 Combustib le-liquid produced vapors, see Hazardous

(classified) locations

2020 Edition

Commercial garages, see Garages, commercial Common grounding electrode, 250.58 Common neutral

Feeders, 215.4 Outside wiring, 225.7( B) Communications circuits, Art. 800, Art. 805; see also Commun ications systems; Community antenna television and

radio distribution (CATV) systems; Premises-powered broadband communication systems; Rad io and television equipment Bonding, 800.1 00, 800.106( B), 805.93 Within buildings, 805-II Cable substitution, 805.154 Essential electrical systems, 517.33(D), 517.43( D) Grounding, 800-III, 805.93 Hybrid power and communications

cables, 805 .l 79(F) Limited-power circuits, 725.1 2l(A) Listing of equipment, 805.18, 805- V Protection, 80.5-III Devices, 805.90 Grounding, 800.100, 800.106(A) Mobile homes, g rounding and bonding at, 800.l 06 Primary p rotectors, 800.100, 800. 106, 80.5.50, 80.5.90, 805.170(A), 830.90 Secondary protectors, 805.90(0), 805.170(B) Raceways, 800.110, 800.113, 800.154, 800.182, 805.133(A) (1), 840. 170( D) Definition, An. 100 Underground circuits entering buildings, 805 .47 Un listed cables entering bu ild ings, 805 .48 Communications equipment

Definition, Art. 100 Communications service provider

Defin ition, 800.2 Communications systems, see also Commun ications circuits

Abandoned cables, 800.25 Definitio n, 800.2

NATIONAL ELECTRJCAL CODE

Access to electrical equ ipment, 800.21 Build ings, with in, 800.l00(B), 800--IV Cable marking, 800.1 79, 800. 182 Cable roming assemblies, 800. 182 Critical operations power systems, 708.14 Definitions, 800.2 Dwelling unit commun ications outlets, 800.1 56 Health care facilities, 517.33( D), 5l 7.43(O) , 517-VI Installation, 800--IV Lightning conductors, 800.53 Listing of equ ipment, 800.l 13(A), 800.1 79, 800--V Mechanical execmion of work, 800.24 Mobile homes, 800.1 06 Multifamily dwellings, 800. l 13( K) One- and two-fam ily dwellings, 800. l 13( L) Overhead wires and cables, 800.44 Types of cable, 800. 179 Commw1ity antenna television and radio distribution (CATV) systems, Art.

820; see also Radio and television equ ip ment Cables Aerial entrance, 820.44 Witl1in buildings, 820-V Entering buildings, 820.47, 820.48 Listing, 820.154, 820-VI Outside, 820.44 Underground, 820.47 Energy limitations, 820.15 Ground ing, 820--IV Cables, 820.93, 820.100 Equipment, 820. 103 Installation of cables and equ ipment, 820--V Locations, 820-II Marking, 820.179 Premises community ante nna television (CAT V) circuit Definition, 840.2 Premises con1nn1nity antenna

television (CATV) circuits, 840.170(F) Definition, 840.2 Protection, 820- III, 820 .100 Raceways, 820. I 33 Unlisted cables entering buildings, 820.48

Compressors, refrigeration, Art.

440 Computer rooms, see Information

technology equipment Concealed

Definition, Art. 100 Electrical metallic tubing, 358. I0(A) Electrical nonmetallic tubing, 362.10(4) Fixed ind us trial process duct heate rs, 425.45 Knob-and-tube wiring, see Knoband-tube wiring Low-voltage suspended ceiling power distribution systems, 393.12(4) Metal wireways, 376.10 (4) Nonmetallic extensions, see Nonmetallic extensions Surface metal raceways, 386.12(5) Concentric knockouts, see Knockouts Concrete

Boxes Enclosures, 314.23(G) Flush-mounted installations of, 3 14.20 Cellula r concrete floor raceways, Art. 372 Direct-buried cable, conduit, or raceways, cover

requirements, Table 300.5 Electrical metallic tubing in, 358.10, 358 .42 Electrical nonmetallic tubing in, 362.10 Electrodes encased in, 250.50 Ex., 250.52(A) (3), 250.66(B), 250.68, 250.70 Flexible metal conduit, 348.12(6) Heating cables, installation in concrete fl oors of; 424.44 Hig h dens ity polyetl1ylene conduit in, 353.1 0 Intermediate metal conduit, 342.10, 342.42(A) Liquidtight flexible metallic conduit, 374.18(A) Liquidtight flexible nonmetallic conduit, 356.10(7), 356.42, 374. 18(A) Metal raceways and equipment in, 300.6 (A) (3), 300.6(B) Mineral-insulated, metalsheamed cable in, 332.10(6)

70-853

NATIONAL ELECTRICAL CODE

Nonmetallic-;;heathed cable in, 334. I0 (B) (3), 334.12, 334.15(B) Nonmetallic underground conduit with conductors, 354.10(2) Rigid metal conduit, 344.10, 344.42(A) Rigid polyvinyl chlo ride conduit, 3.52.I0(G) Slabs, raceways under, Table 300.50 Underfloor raceways, 390.10 Underground feeder and branch-circuit cable, type UF, 340.12 (8) Walls, cabinets installed in, 312.3 Conductive surfaces, exposed, 51 7.1 I Definition, 517.2 Conductor fill Audio systems, 640.23(A) Auxiliary gutters, 366.22 Boxes, 3 14. I 6( B) ( I ), 314.16 (B) (5) Cable trays, 392.22 Cellula r concrete floor raceways, 372 .22 Cellular metal floor raceways, 374.22 Control circuits, 5 17.74(A) Electrical metallic tubing, 3.58.22 Electrical nonmetallic tubing, 362.22 Elevat0rs, 620.32, 620.33 Fixture wire, 402.7 Flexible metal conduit, 348.22 Flexible metallic tubing, 360.22 General installations, 300.17 Hazardous (classified) locatio ns, sealing

fittings, 50l.l5(C) (6), 505.16(0 ) (5) High density polyethylene condu it, 353.22 Intermediate m etal

condu it, 342.22 Liq uidtigln flexible metal conduit, 350.22 Liqu idtight flexible nonmetallic conduit, 356.22 Maximum permitted, 300.17 Nonmetallic underground condu it with conductors, 354. 100( 0 ) Outlet boxes, etc., 314. 16 Reinforc ing thermosetting resin conduit, 35.5.22 Remote control circuits, 725.51 Rigid metal conduit, 344.22

70-854

Rigid polyvinyl chlo ride conduit, 352.22 Signs, 600.31 (C) Strut-type channel raceway, 384.22 Surface raceways, 386.22, 388.22 Theaters, 520.6 Unde rfloor raceways, 390.22 Wireways, 376.22, 378.22 Conductors, see also Cords, flexible; Fixtu re wires Aluminum, 250. I 20 ( B) Ampacities, Table 3 1 l.60(C) (68), Table 3 1 l.60(C) (70), Table 31 l.60(C) (72), Table 31 l.60(C) (74), Table 31 J.60(C) (76), Table 31 l.60(C) (78), Table 3 1 l.60(C) (80), Table 31 I.60(C) (82), Table 31 l.60(C) (84), Table 3 1 l.60(C) (86) Properties of; Chap. 9, Table 8 Arnpacities, 310.14 through 310.21, Tables 31 l.60(C) (67) through 3 11 .60(C) (86), Annex B, Tables B. 2(1) through B.2(10) Amusement attractions, 522.20 through 522.24 Applications and insulatio ns rated 600 volts, Table 310.4(A) Armored cable, Type AC, see Armored cable (Type AC) Bare, see Bare conductors Bending radius, 300.34 Bo nding, see Bonding conductors Boxes and fittings, junction, 314.16, 314.17 Branch circui ts, Art. 210. See also Branch circuits Bundled, in theaters, etc. Definition, 520.2 Buried, 310.I0( E) Busways, see Bu sways Cabinets and clllolll boxes, 312.5 through 312.7 Cablebus, see Cablebu s Calculations, examples, Annex D Capacit0 rs, 460.8 Cellular concrete floor raceways, see Cellular concrete fl oor raceways Cellular metal floor raceways, see Cellular metal floor raceways

Circu it Communications, Art. 800

Control, h ealth care facilities, 517.74 Fire alarm, Art. 760 Less than 50 volts, Art. 720 Over l000 volts, Art. 490 Signal, remote-control, powerlimited , Art. 725 Combinations, Chap. 9, Table I Communications circu its, 800- 11 Concealed knob-and-tube, see Knob-and-mbe wiring Conduit or tubing, number in, 342.22, 344.22, 348.22, 350.22, 352.22, 353.22, 354.22, 356.22, 358.22, 360.22, 362.22, Chap. 9 Tables, Annex C Cooling of electric equipment, I IO. 13( B) Copper, 110.5, 505. 18(A), 760.49(C) Ampacities, Table 3 I I .60(C) (67), Table 31 l.60(C) (69), Table 31 l.60(C) (71 ), Table 31 l.60(C) (73), Table 31 l.60(C) (75), Table 3 1 l.60(C) (77), Table 31 l.60(C) (79), Table 31 l.60(C) (8 1), Table 3 1 l.60(C) (83), Table 31 l.60(C) (85), Tables B.2( 1) through B.2( lO) Properties, Ch ap. 9, Table 8 Copper-clad aluminum De finirion, Art. 100 Equipment-grounding conductors, 2.50. I 20(B) Cords, flexible, see Co rds, flexible Corrosive conditions, see Corrosive conditions Covered Defin ition, Art. 100 Crane and hoists, 6 10-1I, 610-111, 610.41 Damp locations, 3 10. I0( B) Definitions, Art. 100 Deflection of Auxiliary glllters, 366.58(A) Cabinets and cutout boxes, 312.6 Different systems, 300.3(C), 725.48 Dime nsions of; Chap. 9, Table 4 Dry locations, 310. I0 (A) a nd (B) Electrical metallic mbing, see Electrical metallic tubing Electrical nonmetallic tubing, see Electrical nonmetallic tubing

Elevators, dumbwaiters, escalators, etc., 620- 11 through 620-IV Enclosure, grounding, 250-IV Grounding electrode conducto rs, 250.64(0), 250.64(E) Equipment grounding, see Equipment grounding conductors Feeder, Art. 215 Fire alarm systems, 760.3, 760.48, 760.49, 760.130 Fire pumps, 695 .6 Fixed resistance and electrode industrial process h eating equipment, supply conductors, 425.11 , 42.5.22(0), 425.22(E) Fixture wires, Art. 402 Gages (AWG), gen eral provisions, 110.6 General wiring, Art. 310 Generators, size, 445.13 Grounded, see Grounded conducto rs Grounded power systems in anestl1etizing locations, 5 17.63 Grounding, see Grounding conductors Grounding e lectrode, see G rounding electrode conducto rs Grouped, 520.54(C) , 620.21 (A), 620.44, 640.8, 650.6, 690.3 1( B)(2) Defi nition, 520.2 Identification, 310.8, 3 11.14, 31 l.l 6, 410.69 Induction and dielectric h eating equipment, ampacity of supply, 665.10 Industrial control panels, 409.20 Installation, 310-III Other systems, with, 300.8 Insulated, Art. 310 At bushings, 4 AWG and la rger, 300.4(G), 312.6(C) Construction and application, 311.10 Definition , Art. I 00, 396.2 Elevators, dumbwaiters, escalators, etc., 620 .11 Fire alarm systems, 760.49(B) Fix.nires, 410.52, 410.117 (A) Grounded conductors, 200.2 (A), 55 I.54(C), 552.55(C)

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

H azardo us (classified) locations, 501.20, 505.18(B) Identification, 311.14, 410.69 Line-type fire deLecLors, 760.1790) Low-voltage suspended ceiling power distribution systems, 393.14 (B) Motion p icnire p rojectors, 540.1 4 Outside branch circuits and feede rs, 225.4 Park traile rs, 552.55 (C) Reinforced thermosetti ng resin conduit, 355 .10(1) Service conductors, 230.22, 230.30 (A), 230.41 Splices and joints, I I0.14( B), 400.13, 530.1 2(B), 590.4(G) Switch boards, 408 . I9 Theaters, 520.42 Inte rconnected e lectric power p roduction sources, 705.11 ( B) Intrinsically safe, 504.30, 504.50 Len g th in boxes, 300.14 Le ng th in surge protective devices, 242.28 Lightning rods, spacing from, 250. 106 IN No. 2, 800.53 Liquidtigh t flexib le m etal conduiL, see LiquidtighL flexible metal conduit Liquidtight flexible nonmetallic conduiL, see Liquidtigh L flexible nonmetallic conduit Low-voltage su spended ceiling power distribution sysLems, 393.104 Marking, 311.1 6 Material, 31 1.1 2( B) Metal-clad cable, see Metal-clad cable Metal enclosures, spacing from ligh tning rods, 250.1 06 IN No. 2 Metal wireways, 376.56(B) (5) Mine ral-insulated metalsheaLhed cable, see Mine ral-insulated m e talsh eath ed cable (Type M I)

Minimum size, 230.31, 230.42, 311.12 (A), 5 17.74(-8), 620. I 2, 6.50.6(A), 660.9, 72.'i.49(A), 760.49(.A), 760.142, 8 10 .17, 810.53

Modular d ata centers, supply conducto rs, 646.6, 646.9(D) Motion picture projectors, 540. 13 Motor circuits, 430.6, 430-II Multioutlet assembly, see Multioutlet assembly Multiple, 250.102(C) , 250. l22(F), 300.5( 1) Ex. I , 300.20, 310.I0 (G), 392.20(C), 520.27(A) (2), 620. 12(A) ( I) Neutral, se.e Neutral Nonmetallic exten sions, see Nonmetallic exten sions Nonmetallic sh eath ed cable, Types NM, NMC, and NMS, see Nonmetal licsh eath ed cable (Types NM, N MC, and NMS) Number of, in, see Conductor fill Organs, 650.6, 650.7 Outdoor overhead conductors over !000 volts, An. 399 Outlet boxes, temperature limits, 4 10.2 1 Outside wiring, Art. 225 O vercurrent protection, 240.4 Cablebus conductors, 370.23 Fixed resistance and electrode indusLrial process h eatin g equip me nt, 425.72(E), 425.72(F) Grounded conducto rs, 230.90(B), 240.22 Service-entran ce conducto rs, 230.90, 230.91, 230.208 Overhead service, see Overhead service conduCLors O ver IO00 volts, Art. 490 Outdoor overhead conducto rs, Art. 399 Paralleled, 250.30 (A)(3), 250. !02 (C), 250.122(F), 250.186(A) (2), 250.186(B) (2), 300.3( B) ( ! ), 300.5(1) Ex. I , 300.20, 310. I 0(G), 366.20, 376.20, 392.20(C), 520.27(A) (2), 620. 12(A) ( I); see also Flat cable assemblies (Type FC) Pendant fixmres, 410.54 Properties of; Chap. 9, Table 8 Raceways, number of co nductors in, see Conductor fill Radio and televisio n equipme nt and antenna

systems, 81 0.1 3,

2020 Edition

NATIONAL ELECTRJCAL CODE

8 10.16(A), 8 10.17, Art. 820 Railway, power and lighL from, 110.19 Recreatio nal vehicle site feeder circuiL, 551.73, 551.80 Definition , 55 1.2 Remote-control circuits, Art. 72.'i Rigid metal conduit, see Rigid metal conduit Sam e circuit, 300.5 (I) Selection of, examples, Annex D Service, see also Overhead service conductors; Servicee nmmce cable (Types SE and USE); Servicee ntrance conduCLors Definitions, Art. 100 Underground service, 300.5( 0 )(3) Service-en trance, see Service-

entrance conductors Sig nal circuits, Art. 725, Art. 760 Signs and outline lighting, 600.31, 600.32, 600.33 Single, 392.J 0( B) (I ), 392.20(D ), 392.22(B), 392.80 Sizes, I I0.6, .540.13, 8 !0. 16(A), Table 8 10.16(A), 8 10.17, 8 10.53, Chap. 9, Tables 5 a nd 5A; see also Minimum s ize

Spliced, 230.33, 230.46 SLranded, 311.12 (C), Ch ap.9, Table 10 Support of, I IO. I2(C), 300. 19 Surface raceway, see SLrlll-type c ha nnel raceway; Surface metal racev.iays; Surface no nmetallic raceways

SwiLch boards and panelboards, 408.3(A), 408. 19, 520 ..53(E), 520.54 Te mpe rani re, limitations o f, 310. 14(A)(3), 338.I0(B) (3) Theaters, portable stage e quipmem , 520.68 Tunnels, 110.53, 110 .54 Underfloor raceway, see U nderfloor raceways Underground feede r and branc h-circuit cable, se.e Underground feeder a nd branch-circuit cable (Type UF) Underground service, 300.5( 0 )(3) Definition , Art. JOO Un gro unded Disconnection of, 230.70

Flat conductors, no nmetallic extensio ns, 382.104(A) Grounding separaLely d erived systems, 250.30(B) Identification, 2 10 ..'i(C), 215.12(C) Lampholders, 4 10.93 Multiple branch circuits, 210.7 O vercurrent protection, 240 .15 Services, 230.90(A) Tapped from grounded system, 210.10 Welders, electric Ampacicy of supply, 630.1 1, 630.31 O vercurrent protection, 630.12( B), 630.32(B) Wet location s, 225.4, 310.J0(C) VVireways, see V\lirevm.ys, metal; Wireways, nonmetallic X-ray equ ipment, 517- V, 660.6 th rough 660.9 Conduit bodies, se.e also Boxes (omlet, device, pull, and junction) Definiti on , Art. JOO Marking, 314.44 Number of conductors, 31 4.l 6(C) O ver 1000 volts, 314--IV Pull andjuncLion box, 31 4.28 Sh ore radius, 3 14. I6(C) (3) Support Cable trays, 392 .1 8(G) By reinforcing thermosetting resin conduit, 355.I0(H) By rigid n onmetallic conduiL, 352.J0( H) Conduit fill, se.e also Conductor fill Equipment grounding conductors, Ch ap. 9, Note 3 Grounding conductor, 310.15(F) Conduit nipples, Chap. 9, Note 4 Conduits Boxes supporting, 314.23(H ) (2) C ircuits, physical proLection of re mote

control, 725.3 I (B) Conductors, number in, Chap. 9, Table I, Annex C, Tables C. l Lhrough C.13(A) Dime nsions, C hap. 9, Table 4 Electrical metallic tubing, see Electrical metallic tubing Electrical nonmetallic m bing, see Electrical nonmetallic mbing Flexible metal, see Flexible meLal conduit

70-855

NATIONAL ELECTRICAL CODE

High density polyethylene conduit (Type HOPE), see High density polyethylene conduit (Type HOPE) Intermediate metal, see Intermediate metal conduit Liquidtigh t flexible metal, see Liquidtight flexible metal conduit Liquidtigh t flexible nonmetallic, see Liquidtight flexible nonmetallic conduit Manufacntred \Viring systems, 600.100(2) Metallic, ground ing runs 7.5 m (25 ft), 250.86 Ex. l Number of fixture wires in, 402.7 Outside wiring, 225.10 Rigid metal, see Rigid metal conduit Rigid polyvinyl chloride, see Rig id polyvinyl chlo ride conduit Connections

Aluminum, copper conductors, 110.14 Busways, 368.238 Cellular metal floor raceways to cabinets and extensions, 374.18(A) Electric vehicle supply equipment, 625.44 Essential electrical systems, 5 17.32, 5 17.35, 517.43, 517.44 Fixed electric space-heating equipment, 424.45(C), 424.99(8) (2) Fuel cell systems to other circuits, 692-\111 Grounding conductor, 250-1 1I, 250-\11 High-impedance grounded neutral

system, 250.187 (C) Integri ty of, 110.12(8) Interconnected power produc tion sources, 705.11 (D) Multiple circu it connections, grounding, 250.144 Splices, 110.14(8 ) Switches, 404.2 Te mperature limitatio ns, 110.14(C), 11 0.40 Terminals, 110.14(A), 110.14( 0 ) X-ray installatio ns, 5 17.71 Co,mectors

Armored cable, 320.40

70-856

Boxes, 314.17 Breakout assembly, 520.68(A) (6)

Equipment grounding conductors, 250.124

Definition, 520.2 Cabinets and cutout boxes, 312 .5 (C) Cable Definition, 324.2 Theater, 520.67 Connector strip, 520.44, 520.46 Definition, 520.2 Electrical metallic tubing, 358.42 Electric vehicle, 625.17 (8), 625.50 Definition, 625.2 Flexible metal conduit, 348.42 lntercell, 480.4(8) Definition, 480.2 Intermediate metal conduit, 342.42 Intertier, 480.4( 8 )

Grounded conductors, 200.2(8) Gutters, aux iliary, 366. 100(A) Metal raceways and cables, 250.92( 8 ), 250.96, 250.97, 300.10 Wireways, 376.l00(A) Grounding, metal boxes, grounding-type receptacles, 250.148 Mechanical Gutters, auxiliary, 366. 100(A)

Definition, 480.2 Liqu id tight flex ible metal conduit, 350.42 Liq uid tight flexible nonmetallic condu it, 356.42 Low-voltage suspended ceiling power distribution systems, 393.40(A) Definitions, 393.2 Pressure (solde rless), 250.8(3), 250.70 Definition, Art. 100 Rigid metal conduit, 344.42 Single-pole separable, 520.53(C), .520.54(1), 52.5.22(0), 530.22 Definition, Art. 100 Solar photovoltaic systems, 690.32, 690.33 Constant-voltage generators, Art. 445

Overcurrent protection for, 445.12 (A) Construction, closed, 545.4 (B), .545.9(8) Definitio n, 545.2 Cons truction, types of, Annex E Construction s ites

Assured equipment grounding conductor program, 590.6(8 ) (2) Extension co rd sets, 590.6(A), 590.6(8 )(2) G round-fault protection, 590.6 Container, s torage battery

Definitio n, 480.2 Continuity

Electrical Cable trays, 392.60(A)

Charge controllers Defin ition, Art. l 00, 694.2

Raceways and cables, 300.10, 300.12 Conductors, 300.13 Grounded conductor of 1nultiwire

circuits, 300.1 3( 8 ) Wireways, 376. I00(A) Continuous duty

Definition, Art. 100 Motors, see Motors, Continuous duty Continuous industrial processes

Coordination, electrical system, 240.12 Ground-fault protection, 230.95 Ex. Orderly shutdown, 430.44 Power loss hazard, 240.4(A) Continuous load

Applications, 2 10.19(A), 210.20(A), 215.2(A) Definition, Art. I 00 Control, see also Hazardous (classified) locatio ns Definition, 750.2 Remote Circuits, see Remote-control, signaling, and powerlimited circuits Induction and dielectric heating equipment, 665.7 X-ray equipment, 517- \1, 660--11 Control circuits, 230 .82(7), 430--VI Amusement attractions, 522-11, 522- 111 Definition, Art. 100 Control drawing, 504. I0(A)

Definition, Art. 100 Controllers, see also Hazardous (classified) locations Agriculn,ral buildings, 547.6 Air-conditioning and refrigerating equipment, 440.5, 440--V Cases, g rounding, 250.112(0)

Energy storage systems, 706.33 Solar photovoltaic systems, 690.72 Definition, Art. 100 Diversion load controllers, 694.7(C) Defi nitio n, 694.2 Enclosures, grounding, 250.112(0) Fire pumps, 695 .12, 695. l 4(D), 695.l4(E) Motion, 610..51 ( B), Fig. 0 9, Fig . 010 Defi nitio n, 620.2 Moto r, see Moto r controllers Operation, 620.22(A), 620.5l(C)(l), Annex D, Ex. 09, Fig. 0 9, Fig. 010 Definition, 620.2 Ratings, 430.83 Resistors and reactors, see Resisto rs and reactors Control panels, see Industrial control panels Control room

Branch circuits, lig hting and receptacles, 620.23 De finition , 620.2 Wiring, 620.21 (A) (3), 620.37 Control space

Branch circuits, lig hting a nd receptacles, 620.23 Definition, 620.2 Wiring, 620.21 (A) (3), 620.37 Control system

Definition, 620.2 Convenience outlets, see

Receptacles Conversion table, AC conductor resistances and reactances, Chap. 9,

Table 9 Converters, see also DC-to-DC

converters; Electronic powe r converters; Phase converters Charger power, 625.102 Definiti o n, 625.2 Definition, 551.2 Voltage, 551.20, 552.20 Definition, 551.2 Cooking unit, countermounted, see also Ovens,

wall-mounted; Ranges Branch circuits, 2 10. l 9(A) (3), 210.23(C), 220.55 Definition, Art. 100 Feeders, calculation of load, 220.82( 8 ) (3)

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

Grounding, 250.140 Cooling of equipment, 110.l 3( B) Coordination, electrical systems, 240.12 Feeders, 240.l00(C), 517. l 7(B) Overcurrent protective devices Critical operations power systems, 708.54 Health care fac ilities, 517.3 I (G) Information technology equipment, 645 .27 Legally required standby systems, 70 I .32 Selective, 620.62, 645.27, 695.3(C)(3), 700.l0(B), 700.32, 701.32 Definition, An. 100 Copper-clad alwninum conductors Definition, An. 100 Equipment-grounding conductors, 250.120( B) Copper conductors, see Conductors, copper Cord connectors, 626.25( B)(5); see also Receptacles, cord connectors, and

attachment p lugs (caps) Definition, Art. 100, 626.2 Cords, see also H azard ous (classified ) locations Audio signal processing, amplification, and reproduction equipment power supply cords, 640.2 1, 640.42 Electric-discharge luminaires, 410.62(C) (1) Electrified truck parking space power-supply, 626.25(B), 626.32 Flexible, An. 400,422.16, 422.43 Air conditioner, 440.64 Ampacities, Tables 400.5(A) (1) through 400.5(A) (3) Anesthetizing locations, 517.6 I (A ) Audio sig nal processing, amplification, and reproduction equipment, 640.21, 640.42, 640.45 Bending radii, min imum, 400.34 Conslruction specifications, 400-II Electrified truck parking space supply equipment, 626.2.5 (B) (2 ), 626.32(C) Emergency systems, 700.12(1)(2)

2020 Edition

Equipment grounding conductors Identification, 400.23 Over 600 volts, 400.31 (B), 400.32, 400.33 Size of, 250.122(E) Fittings, 400.35 Hazardous (classified) locations, 505.17, 506. 17 Identified conductors within, 200.6(C), 250.119(C) , 400.22, 400.23 Insu lation, Table 400.4, 400.21 (B) Interconnected electric power production sources, 705.25(B) Labels, 400.20 Lampholders, insulating bush ings, 410.62(A) Manufactured wiring systems, 604.100(A)(3) Marking, 400.6 Modular data center equipment enclosures, 646.9 Motion p icmre projectors, 540.15 Office furn ishing, 605.9 (A) Outlets Covers, 3l4.2.5(C) Required, 210.50(B) Overcurrent protection, 240.5, 400.16 Over 600 volts, 400-III Power-limited and signal circuits, remoteconlrol, 725.49(A) Pu ll atjoints and terminals, 400. 14 Repair of, hard service, 400.13 Showcases, wall cases, 410.59 Sola r photovoltaic signs, 600.34(C) Solar photovoltaic system s, 690.31 (C) (4) Splices and taps, 400.13, 400.36, .530. l 2 Construction sites, 590.4(G) Stage equipment, portable, 520.68(A) (l ) Swimm ing pools, fountains, and sim ilar installations, 680.8, 680.2 1(A) (3) , 680.23(B) (3), 680.35(A), 680.42(A), 680.55 (B) , 680.56 Types, 400.4, Table 400.4 Uses not permitted, 400. 12 Uses p ermiued, 400.10

NATIONAL ELECTRJCAL CODE

Wind e leclric systems, 694.30(B) Heater, Table 400.4, 422.43(A) Information power-supply cord, 645.5(B) Mobile home power-supply cord, 550. IO Office furnishings power-supply cord, 605.9(A) Park trailer power-supply cord, 552.43(B), 552.44 Recreational vehicle powe, supply cord, 551.31, 5.51.46 Solar photovoltaic signs, 600.34(C) Submersible or floating e qu ipment, for bodies of water, 682. 14 Tinsel Overcurrent protection, 400.16 Types, Table 400 .4 0

Vehicle supply equ ipment power-supply cord, 625.17 (A), 625.l 7(C) Definition, 625 .2 Cord sets, see Extension cord sets Correction factors, ambient temperature, 310.15(B), Table 310.15(B) (1 ), Table 3 10. l 5(B) (2), Table 31 l.60(D ) (4) Corrosion protection, see Protection, corrosion Corrosive conditions Agricultural buildi ngs, v.riring

in , 547.5(C)(3) Armored cable, 320. I 2( 4) Bushings, 430.13 IN Cablebus, 370.10(3) Conductors and conductor insulation, 300.6, 3 10. l0(F), 50.5.l 8(B) High density polyeth ylen e conduit, 353.10(2) Rigid polyvi nyl chloride conduit, 352.l0( B) Deterio rating agents, 110 .11 Eleclrical nonmetallic tubing, 362.10(3) Fire alarm systems, 760.3(D) Flat cable assemblies, 322. l 2( I) Flat conductor cable, 324.12 (2), 324.101 Low-vohage suspended ceilin g power distribution systems, 393. l 2(2) Lum inaires in stalled in, 410. I0(B) Metal wireways, 376. I 2 (2)

Mineral-insulated, metalsheatl1ed cable, 332.10( 10) Nonmetallic-sheathed cable, 334. I0(B)(l), 334. 12(B)( l ) Nonmetallic wireways, 378. l 0(2) Open ,,viring on insulawrs, 398.15(B) Reinforcing thermosetting resin conduit, 355.10 Surface metal raceways, 386.12(3) Undergro und feeder and branch-circuit cable, 340.l 0(3) Corrosive environment, 680.7, 680.1 4, 680.2l (A)(l), 680.23(F)( I ), 680.25(A) Definition, 680.2 Countertops, outle ts, 210.52(A) ( 4 ), 2 I 0.52(C), 406..5 (E) Couplings Electrical metallic tubing, 358.42 Fire resistive system, 728.5(C) Flexible metal conduit, 348 .42 Inte rmediate metal cond ui l, 342.42 Liquidtight flex ible metal conduit, 350.42 Liquidtigh t fl exible nonmetallic conduit, 356.42 Rigid metal cond uil, 344.42 Running threads at, 342 .42( B), 344.42(B) Threaded and threadless, 250.92(B) Cove lighting, space for, 410.18 Covers Auxiliary guuers, 366.I00(D) Boxes and fittings, 3 14.25, 3l4.28(C), 314.41 , 314.42, 314.72(E) Cable, 650.6(D) Cable trays, 392 .18 (C) Faceplates, see Faceplates Luminaires fixmres, omlet boxes for, 410.22, 410.23 Pool cove,; electrically operated, 680.27 (B) Definition, 680.2 Strut-type c hannel raceways, 384. 100 (C) Wireways, 376.2, 376.56(B) (4), 376. I 00( D), 378.2 Cranes, Art. 610; see also Hoists Bond ing, 610-Vll Cond ucrors, 610-III Control, 610- Vl D efin i tion, 555.2

70-857

NATIONAL ELECTRICAL CODE

Disconnecting means, 430.112 Ex., 610--IV Electrolytic cells, 668.32 Flexible cords, 400.l0(A) (5) Gro unding, 250.22 ( I), 250.11 2( E), 250.11 6(1), 610- Vll Hazardous (classified) locations, 503.155, 610.3(A) Marinas and boatyards, 555.8 Motors and controlle rs, disconneCLing means, 430.1 12 Ex. Nameplates, 61 0.l 4(G) Overcurre nt protection, 610--V, 610.53 Wiring, 610--11 Critical branch, 5 17.25, 5 l 7.29 IN, 517.31, 517.34 Definitio n, 5 17.2 Essential electrical systems, 5 17.35 Critical care space, 5 17. I 9, 517.29(8 ), 5 17.34 (A), 517.40(B), 5 17.45(C) De finitio n, 517.2 Nu rsing homes a nd limited care facilities, .517.40 IN No. I Critical operations data system, 645.l 0(B) Definition, 645.2 Critical operations power systems, Art. 708, Annex F Availabili cy and reliabili cy for, Annex F-1 Circuit wiring and equipme nt, 708-11 Commissioning, 708.8 Definit io n, 708.2 Definitions, 708.2 Developme nt a nd imple me ntation of func tional pe r formance tests (FPTs), Annex F- 11 Emergency operatio ns plan , 708 .64 Grounding, 708.20 (C) Overcurrem protectio n, 708-IV Physical securicy, 708.5 Power sources and connection, 708-lll Risk assessme m , 708.4 System performance and analysis, 708-V Testing and maintenance, 708.6, 708.8 Cross sectional areas Conductors, Chap. 9, Tables 5 through 8 Conduits, Ch ap. 9, Table 4

70-858

Current-carrying capacities, see Ampacities Current-limiting devices, see also Circuit breakers; Fuses De finitio n, 240.2 Curtain machines, theaters, 520.48 Cutout bases, stt Fuseholders Cutout boxes, see also Cabinets, cuto ut boxes, and n1eter socket e nclosures De finitio n, Ar t. 100 Cutting tables, motion picture, 530-IV -D-

Dampers (flue), control

Critical operations power systems, 708.20(F) (4) Fixed stage equipmem, smoke ventilator contro l, 520.49 Transforme r vaults, ventilating openings, 450.45(E) Damp or wet locations, I 10. l I. Stt also Wet locations Agricu ltural buildings, .547.5(C)(2) Armored cable, 320.12 Boxes and fittings, 314.15 Busways, 368.12 (0 ) Cabinets and cutout boxes, 312.2 Cablebu s, 370.10(3) Conductors, types, 3 10.l0(B), 3 10.I0(C) De finitio n, An. 100 Electrical nonmetallic tubing, 362.l 0(4), 362.10(7) Electric sig ns a nd outline lighting, 600.l0 (C), 600.42(G), 600.42(H )(2) Fire alarm systems, 760.3( 0 ) Fixed electric space-h eating equipment, 424.12( 8 ) Fixed resistance and electrode industrial process h eating equipment, supply conductors, 425.12( 8 ) Flat conducrnr cable, 324.l 0 (E), 324.12( l ) Lampholders, 4 l0.96 Low-volrage su spended ceiling power distribution systems, 393.12(1) Luminaires, 4 l0. l0 (A) Metal-clad cable, 330. l 0(A) Mineral-insulated , metalsh eathed cable, 332.10(3) Non metal Iic-shea thed cable, 334.l0( B) (1), 334. 12( 8 ) (4)

Open wiring, 398.15(8) Overcurrent protection, enclosure, 240.32 Panelboards, 408.37 Receptacles, 210.8(A)( l l ), 406.9 Reinforcing th ermosetting resin conduit, 355.1 0(0), 3.55. I0( E) Rigid polyvi nyl chlo ride conduit, 355.1 0(0), 355.l 0 (E) Switc hboa rds, 408.16

and snow-melting equipment D elta breakers, 408.36(C) D elta-connected Grounding separately d erived systems, 250.30 (A) (3) Identifying hig h-leg, 3-phase supply, 4-wire, l l0. l5, 230.56, 408 .3(E) ( l ), 408.3(F), 4 09. 102 D emand factor, see also Loads De finition , Art. 100

Switches, 404.4 Dance halls, Art. 5 18 Data centers, modular, see Modular d ata centers Data processing systems, see Information technology equipment DC combiners, 600.34(A), 690.4 (8 ) Definition , 690.2 DC systems, 250--Vlll; St£ also Direct currem microgrid systems Bra nch circuits, ide ntificatio n of, 210.5 (C) (2) Grounding, 250.1 62, 250.1 64 Lumina ires, installation of, 410.134 Solar photovolta ic systems, see Solar photovoltaic systems DC-to-DC converters, IN Fig. 690.l (a), 690.4(8), 690.7(8 ), 690.8(A) ( l), 690.1 5, 690.4l( B), 706.30(A) (5), 706.33 (C) Definitio ns, Art. 100,690.2 Dead ends Busways, 368.58 Cableb us, 370.42(2) Flat cable assemblies, 322.40(A) Wireways, 376.58, 378.58 Dead front, 110.26(A) (l) Definition , Art. I 00, 55 l.2 Instrumen ts, meters, a nd relays on, 250. 174( 8 ) Park trailers, 552.45(C) Recreatio nal vehicles, 551.45 (C) Wo rking spaces abou t, l 10.26 (A )(l) Decks, receptacles for, 210.52(E)(3) Definitions, Art. I 00 Deflection of conductors Auxiliary gutte rs, 366.58(A) Cabinets a nd cutout boxes, 312.6 Deicing installations, see Fixed o utdoor electric deicing

Dental office (medical office) De finition , 517.2 D esignated critical operations area, see also Cri ti ca I operations power systems De finition , 708.2 D etached buildings, oil-insulated transformers in, 450.26 Ex.5 D eteriorating agents, 110.11 Device , see also Receptacles; Switc hes De finitio n , An. l 00 D evice or equipment fill for boxes, 314.16(8 ) (4) Diagnostic equipment, 5 17.73 (A) Diagrams Adjustable speed dri ve control, Fig . D.l0 Autotransformer overc urrem protection, Fig . 450.4 Cable installation dimensions, undergro und, Figs. B.2( l ) through B.2(4) for use with Tables B. 2(5) through B.2( 10) Cable substitutio n hierarchy Com municatio ns systems, Fig . 805.154 Cornmunicy antenna TV and radio d istributio n systems, Fig . 820.154 Optical fiber cables, Fig . 770. 154 Remote control, sig n aling, an d power limited circuits, Fig . 725. 154 (A) Communications system, bonding conductor in, Fig. IN 800.I00(B)(l), Fig . IN 800.l00 (B) (2) Elevators, dun1bwahers, escalators, etc. Conu·ol system, Fig. 620.2 Single line d iagram, Fig. 620.13 Feeders, 2 15.5 Generator fi eld control, Fig . D.9

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

Hazardous (classified) locations adjacent to dispe nsers, Fig. 514.3, Fig. 514.3(B) Luminaires, clo set storage

space, Fig. 410.2 Marine te rminal handling flammable liquids, Fig. 515 .3 Mobile homes, receptacle a nd aLtachment

plug, Fig. 550.l0(C) Motor feeder and branch circui tS, Fig. 430. l Park trailers, receptacles and attachment p lugs, Fig. 5.52.44(C) ( I) Recreational vehicles, receptacles and attachn1ent plugs, Fig. 551.46 (C) ( 1)

Remote contro l, signaling, and powe r limited circuits, Class 2 and 3 circuitS, IN Fig. 725.121 Services, Fig. 230.l Solar photovoltaic systems, identification of compone ntS, Fig. 690.l (a), Fig. 690.l (b) Spray application, dipping, coating, and printing, Fig. 516.4, Fig. 516.5( 0 ) ( 1), Fig. .5 16..5( 0 )(2), Fig. 516 .5(D )(4), Fig . 516 .5( 0 )(5), Fig . 516.18, Figs. 516.29(a) through (d)

Swimming pools, clearance from pool structures, Fig. 680.9(A) Dielectric heating, see also Induction and dielectric h eating equipme nt De finitio n, 665.2 Different systems, conductors in same enclosure, 300.3(C), 725.48, 725.136(B), 760.48, 760.1 36, 805.47 (A), 805.1 33(A), 810.18(C), 820. 133(A) Dimensions Conductors, C hap. 9, Tables 5 th ro ugh 8 Conduits and tubing, Ch ap. 9, Table 4 Dimmers Eme rgen cy ligh ting circuits, 700.23 Solid-state-type, 520.25 (C) De finition, 520.2 Stage switchboard, 520.25

2020 Edition

Switches, 404.9 (B), 404. 14(E); s~ also Snap switches Dip tanks, An. 516 Direct burial Ampacities, modification of, 3 10.16 CATV coaxial cables, 820.47(B) Corrosion p rotection Aluminum metal equipment, 300.6(B) Ferrous metal equipment, 300.6(A) (3) Electrical nonmetallic tubing, 362.1 2( 4) Flex ible metallic tubing, 360.12( 4) Grounding conductor connection, 250.68(A) Ex. l , 250. 70 High density polyethylene conduit, Table 300.50, 353.10 ( 4) Integrated gas spacer cable, 326.10 Inte rmediate metal conduit, Table 300.5, Table 300.50 Liquid tight flexible metal conduit, 350. !0(3), 350. 120 Liquid tight flexible no nmetallic conduit, 356.10( 4 ), 356.10 (7) Medium voltage cable, 311.36 Metal-clad cable, 330.l0(A) (5), 330. 12(2) Nonmetallic unde rground conduit with conducto rs, 354. 10 ( I) Optical fiber cables, 770.47(B) O ver !000 volts, 300.50 Premises-powered broadband communica tion, optical

fibe r cables for, 840.47 (A) (2 ) Re inforced thermosetting resin conduit, Table 300.50 Rigid metal condui t, Table 300.5, Table 300.50, 344.l0(A) (2), 344.l0 (B) Rigid polyvinyl c hloride conduit, Table 300.50, 352. I0(G) Bulk storage p lants, 515.8 Motor fuel d ispen sing facilities, 514.8 Ex. 2 Underground feeder a nd branch-circuit cable, 340.10( l ) Underground service cable, 230.30 (A) Ex., Table 300.5, 310.l0(E)

NATIONAL ELECTRJCAL CODE

Underground service-entrance conducto rs, 230.41 Ex. Direct current microgrid systems, Art. 712 Circuits, 7 12- II Definitions, 712.2 Disconnecting means, 712-III Fuel cell system installation, 692.4( B)(2) Marking, 7 I 2- V Primary DC source Definition, 712.2

Directory, 7 12 .10 Protection, 7 12-VI Systems over 1000 volts, 712- VII Wind electric systems, 694.50(B) Wiring metho d s, 712-IV Disconnecting means, see also Overcurrent protection Agricultu ral buildings, 547.9 Air-conditioning and refrigeratin g e quipment, 440-II , 440.63 Appliances, 422- III Branch circuits,

multiwire, 210.4( B) Capacito rs, 460.8 (C) Carnivals, circuses, fairs, and

similar events, 525.21 (A) Cranes, 430. 112 Ex., 610-IV Definitions, Art. 100, 551.2 Direct curre nt microgrid systems, 712-III Electric deicing, snow-melting equ ipme nt, 426.50 Electric p ipeline, vessel h eating equipment, 427.55 Electric space h eating equipment, 424--III Electric vehicle charging system e quipment, 625.43 Electrol ytic cells, 668. 13 Electroplating systems, 669.8 Elevators, 620-VI, 620.91 (C) Emerge ncy systems, 700.15 (0 ) Energy storage systems, 706--II Fire pumps, 695.4(B) Fixed electric heati ng equipment for pipelines and vessels, 427.55 Fixed outdoor electric deicing a nd snow-melting equipment, 426.50 Fixed resistan ce a nd electrode indusu·ial p rocess h eating equipment, supply conductors, 425.19, 425.65

Fuel cell systems, see Fuel cell systems Fuses, 240 .40 Gen erators, 445.1 8 Health care facilities, 517.l 7(B), 517.l 7 (C), 517.72 Id entification, I 10.22, 230.70(B), 620.51 (D) Inductio n and dielectric heating equipment, 665.12 Industrial control panels, 409.30 Industrial machinery, 670.4(B) Information technology equ ipment, 645.4( I), 645.1 0 Interconnected electric power production sources, 705.l2(A), 705.20 Irrigation machines, 675 .8 Legally required standby sys tems, 70 1.1 2(G) Lockable, 110.25 Low-voltage susp e nded ceiling power distribution systems, 393.21 Luminaires, 410.1 30(G), 410.141 (A) Marinas and boatyards, 5.55.36 Mobile homes, 550 .11 Motors and controlle rs, 430.75, 430.95, 4 30- IX, 430.1 28, 430.227 Naturally and artificia lly made bodies of water, electrical equipment for, 682.14 Omside branch circu its and feeders, 225.31, 225.51, 225.52 O ver !000 volts, 240-IV, 240.67(B), 240.83(0 ), 368.239 Mobile and portable equipme nt, 490.51 ( D) Parking space, 626.22( D), 626.24(C), 626.31 Definition, 626.2 Phase conven ers, 455 .8, 455.20 Pools, spas, and hot tubs, 680.13, 680..57(0 ) Portable equipment, 517.l 7 (C) Receptacles, cord connectors and attachment p lugs (caps), 422.33, 440.63 Recreational vehicle parks, 5.5 1.77(B) Recreation al vehicles, 551.45(C) Relocatable strucwres, 545.24(A) Sensitive elecu·onic equipment, lighting

equip ment, 647.8(A)

70-859

NATIONAL ELECTRICAL CODE

Separate building o n same premises, 250.32( 0 ) Services, 230-VI, 250.64( 0 ) Connections, ahead of; 230.82 Emergency, 230.85 Over IO00 volts, 225.51, 225 .52, 230.205, 230.206 Sho re power connections, 555.36 Signs and outli ne lighting, 600.6, 680.57(0 ) So lar photovoltaic signs, 600.34(E), 691.9 So lar photovoltaic systems, 690-111, 690.53, 690.54, 690.56 Stage switchboard, 520.27(A) (3) Standby systems, optional, 702.1 2 Storage batteries, 480.7 Switching devices, over l000 volts, 240.83( 0 ), 249.67(8 ), 368.239 Definit io n, Art. 100 Temporary circuits, 590.4( E) Transformers, 450.14 Tunnels, 1 10.58 Welders, 630.13, 630.33 Wind electric systems, 694-111 X-ray equipme n t, 51 7.72, 660.5, 660.24 Discontinue d outlets, see Omlets, discontinued Dissimilar metals, see Metals, dissimilar Distribution panelboards , see

Panelboards Distribution point, .547.9 Definition, 547.2 Divers ion charge controlle r, 706.33( B)

De fini tio n, 694.2, 706.2 Divers ion load, 694.7(C)

Definition, 694.2 Divers ion load controlle r, 694.7(C)

De finition, 694.2 Docking facilities, commercial and nonco1n1ne rcial, see

Marinas, boatyards, floating build ings, and clocking facilities Doors

Automatic, .5 17.33(H) Transformer vaults, 450.43 Dormitory units

Arc-fau lt circuit-interrupter protection, 2 10.12(8 ), 210.12(0 ) Definitions, Art. l 00 Outlets, 210.60

70-860

Double insulate d

Applia nces and tools, 250.114 Ex., 422.16(8 ) (1) Ex., 422.16( 8 ) (2) Ex. Pool pumps, 680.21(8), 680.3 1 Double locknuts, see Locknms, double, required Drainage

Busways, 368.236 Equipment, 50 l. 15(F), 505.16(E) Oil-i nsulated outdoor transformers, 450.27 Raceways, 225.22, 230.53 Transformer vaults, 450.46 Dressing rooms

Motion picture studios, 530-III Theaters, 520- VI Drip loops

Conductors entering buildings, 230.24(8) ( I), 230.52, 230.54(F), 398.15( 8 ) Service heads, 230.54( F) Driveways

Clearance of conductors, 225 .1 8 Overhead se,v ice conductors, 230.24(8) Drop

Service Co nnections, service h ead, 230.54 Definition, Art. 100 Voltage and volts Branch circuits, 2 I 0. I 9(A) IN No . 3 Conductors, 310.14(A) (1) IN No . l Sensitive electronic equipment, 647.4( 0 ) Dryers, clothes, see Cloth es dryers Dry location, 110. 11; see also Damp o r ,,vet locatio ns

Armored cable, 320. 10(3) Conductors, types, 3 IO. I0(A), 310.I0(B) Definitio n, Art. 100 Electrical nonmetallic tubing, 362.10( 4) Electric sig ns and omline lighting, 600.42 (H)(l) Portable or mobile, 600.10( 0 ) Flexible metallic tubing, 360. I 0( I) Low-voltage suspended cei ling power d istribution systems, 393. 10(2) Medium voltage cable, 311.32(1) Metal-clad cable, 330.1 0(A) ( 10)

Mineral-insulated, metalsh eath ed cable, 332.l 0(3) Nonmetallic extensions, 382. IO(B) Nonmetallic-sheathed cable, 334. I 0 Open wiring, 398. l.5(A) Reinforcing thermosetting resin conduit, 355.l 0(E) Rigid polyvi nyl chloride conduit, 352.I0(E) Surface raceways, 386.1 0( 1), 388. 10( 1) Switchboards, 408.20 Underground feeder and branch-circuit cable, 340.10(3) Dry-type transforme rs , 450.1 Ex . 2, 450.8( 8 ), 450.21, 450.22 Dual-voltage motor, locked-rotor rating , 430.7( 8 )(3) Duc t heaters, installation

of,424-VI Ducts

Bonding, 550.16(C) (3), 551.56( F), 552.57(F) Electrical, Tables 3 I I.60 (C) (77) through 31 I.60(C) (80), Annex B, Table B.2(5) De finition , 3 11.2 Fixed industrial process h earers in, 425- V Luminaires in, 410.l0(C) Wiring in, 300.21, 300.22, 725.1 35(8 ), Table 725. 154, 760.3( 8 ), 760.53( 8 )( 1), 760. 135(8 ), 770.26, 770.113(8 ), Table 770.1 54(a), 800.113(8 ), Tables 800.154(a) through (c), Fig . B.3 Dumbwaiters, see Elevators, dun1bwaiters, escalators,

moving walks, platform lifts, and stainvay chairlifts Dust-ignitionproof, 500.7(8), 502.1 5, 506.8(A) Definition, Art. I 00 Dusts, combustible, see also

In termittent duty, 430.22(E), 430.33 Shon-time duty, 430.22(E), 430.24( 4) Ex. I , 430.33 Varying duty, 430.22 (E ), 430.24 Ex. No. 1, 430.33 Duty cycle, welding, 630.31, Table 630.3 I(A) Dwellings, see also Appliances; Boxes; Grounding, and similar general categories Arc-fault circuit-interrupter protection, 210.12(A), 210.12(0) Branch-circuit voltages, 210 .6(A) Commun ications circuits, 800.l 13(G), 800. 113(K), 800. 113(L) Definitions, Art. 100 Energy storage systems, 706.20(8) Farm, services, 220.102(A), 220.103 Feeder load, calculations for, 220.14(.l), 220.16(A), 220.82 through 220.85, Annex D Fire alarm circuits, power-

limired, 760.1 35(G) Ground-fault circuit interrupter protection, 210.8(A) Lighting outlets required, 210.70(A) Lum ina ires, 4 10.135, 410.140(8); see also Luminaires

Optical fiber cables and racev.rays,

installation, 770. l 13(G) Panel boards as ser vices, 408.36 Ex. 3 Receptacles Circuits, 210. 11 Outlets, 2 I0.8(A), 210..52 Tamper-resistam, 406.12 Remote-control, signaling, and

power-limited circuit cables, installation, 725. 135(G), 725.135( L), 725.135(M) -E-

Hazardous (classified) locations Definition, Art. I 00 Dusttight, 500.7 (C), 500.8(C) (6), 506.8(0 ) Definition, Art. I00 Duty, types, see also Motors, Continuous duty Definitions, Art. 100

Eccentric knockouts , see

Knockouts Effective ground-fault current path

Definitio n, Art. 100 Elbows, metal, protection from corrosion, 300.6 Electrical datum plane , 5.5.5.3

Definition, An. 100 Electrical ducts, see Ducts

NAT IO NAL ELECTRJCAL CODE

2020 Edition

INDEX

Electrical life support equipment, 517.45 (B)

De finitio n, 517.2 Electrically operated pool covers, see Covers Electrical metallic tubing (Type EMT), Art. 358 Be nds, 358.24, 358.26, Chap. 9, Table 2 Connectors a nd couplings, 358.42 Constructio n specificatio ns, 358-III De finitio n, 358.2 Dime nsio ns, Chap. 9, Table 4 Expa nsio n fi ttings, 300.7 (B) IN Grou nding, 358.60 Installatio n, 358---II Listing, 358.6 Marking, 358.120 Maximum number of conductors a nd fix ture wires in, Tables C.l and C.l A Number of conducto rs, 358.22, Chap. 9, Table I Reaming a nd threading, 358.28 Sec uring a nd sup por ting, 314.23 (E), 358.30 Size, 358.20 Splices and taps, 358.56 Uses not permitted, 358.12 Uses permitted, 3.58. 10 Electrical noise, 647.3. See also Sensitive electronic equip ment Ground ing, 250.l46( D) Receptacles, 406.3( D) Electrical nonmetallic tubing (Type ENT) , Art. 362 Be nds, 362.24, 362.26, Cha p. 9, Table 2 Bus hings, 362.46 Constructio n specificatio ns, 362- III De finitio n, 362.2 Dime nsio ns, Chap. 9, Table 4 Grounding, 362.60 Installatio n, 362-1 1 J o ints, 362.48 Listing, 362.6 Marking, 362.120 Maximum nu mber of conductors a nd fixture wires in, Tables C.2 and C.2A Number of conducto rs, 362.22, Chap. 9, Table l Sec uring a nd su p porting, 362.30 Size, 362.20

2020 Edition

Splices and ta ps, 362.56 Temperature limitations, 362.10(9) Thro ugh metal framing mem bers, 300.4(B) Trimming, 362.28 Uses not permitted, 362. l 2 Uses permiued, 362.10 Electrical resistance trace heating "60079-3()..)", 505.8 () ), 506.8 ()) De fini tio n, Ar L 100 Electric-discharge lighting, Art. 41 0 Co nnection of lumina ires, 410.24, 410.62(C) De finitio n, Ar L 100 Eme rgency systems, 700.15 (C) Hazardo us (classified) Class I locatio ns, 50 l. 130 (B)(6) Lamp auxilia ry equi p ment, 410.104 Ma rking, 4 10.146 1000 volts o r less, 4 10- XII Over l000 volts, 4 10-XIII Signs and oucline lig hting, Art. 600 Electric h eating equipment, fixed , see Fixed elecu·ic heating equipme nt fo r pipelines and vessels; Fixed e lectric spaceheating equip m ent; Fixed outdoo r electric d eicing and snowmelting equi p ment Electric power production and distribution n etwork De finitio n, Art. 100 Electric power production sources,

see Generators;

Interconnected electric power p roduction sources; Sola r p hotovoltaic systems; Wind electric systems Electric signs, see Sig ns, electric Electric supply stations De finitio n, 691.2 Large-scale solar p hotovoltaic system s, Ar t. 691 Electric vehicle power export equipment (EVPE), 625.48, 625.60 De finition, 625.2 Electric vehicle power transfer system, ArL 625 Co rds and cables, Table 400.4, 625.17 De finitio ns, 625.2 Disconnecting means, 625.43

NATIONAL ELECTRJCAL CODE

Equi p men t constructio n, 625-11 Installation, 625- 1II Inte ractive system, 625.48 Listed, 625.5 Locatio n, 625.50 Pe rsonnel p rotection system, 625.22, 62.5 .54, 625.60(D) Definiti o n, 625 .2 Primar y source, loss of, 625.46 Rating, 625.42 Ve ntilation, 625.52 Vo ltages, 625.4 Wireless power transfer equip ment, 625- IV Electric vehicles Definiti o n, Art. 100 Electric vehicle supply equipment Definiti o n, 625.2 Equi p me nt connectio n, 625.44, 625.52(B) (4) Fastened in place, 625.17 (C) (2), 625.44(B) Definiti on, 625.2 Fixed in place, 625.44(C) Definiti on, 625 .2 Interactive systems, 625.48 Inte rconnecting cabling systems, 625.l 7 (0 ) Locatio n, 625.50 Overcurrent p rotectio n, 625.41 Po rtable equipment, 625.17(C)( l ) Definiti on, 625 .2 Electric welders, see Welders, e lectric Electrified truck parking space equipment, Art. 626 Definiti o ns, 626.2 Ge nera l requirements, 626.4 Supply equipme nt, 626--III Transport refri gerated unit, 626--IV Wiring system s, 626--1I Definition, 626.2 Electrode industrial process heating equipment, see Fixed resistance a nd e lectrod e ind ustrial process heating equipme nt Electrodes, grounding, 250.64( F); see also Ground ing electrode cond uctors Aluminum, 250..52( B)(2) Common, 250.58 Concrete-e ncased, 250.50 Ex., 250.52(A) (3), 250.66(B), 250.68(A) Ex. 1,250.70 Definiti o n, ArL 100

Fuel cell systems, 692.47 Gas piping as, 250.52(B) (1) Intrinsically safe apparatus, 504.50 (C) Metal fra me of building as, 250.30(A) (8), 250.52(A) (2), 250.68(C) Metal water piping system, 250.30 (A) (4 ), 250.30(A) (8), 250.52(A) (1), 250.68(C) Separately derived systems, 250.30(A) (4), 250.30(B)(2), 250.30(C) System installa tion, 250.53 Wind electric systems, 694.40( B) Electrolytes, 480.9 Definiti on, 480.2 Flow battery e nergy systems, 70 6--V Electrolytic cells, A rt. 668 Auxilia ry nonelectric connectio ns, 668.31 Cell line cond uctors, 668.1 2 Cell line wo rking zone, 668. 10 Definitio n, 668.2 Cranes and ho ists, 668.32 DC cell line p rocess power su pply, 668.11 Defini tions, 668.2 Disconnecting mea ns, 668.13 Enclosures, 668.40 Fixed electrical equip ment, 668.30 Ground ing, 668.1 5 Portable electrical equ ip me nt, 668.20, 668.21, 668.30 Shunting means, 668.14 Electronically actuated fuse, 240.67 (B), 240.I0l (A), Table 450.3(A) Note 4 Defini tion, Art. I 00 Electronically protecte d motors, 430.7(A)( l 6), 430.32(A) (2), 430.32( B) (2)

Definiti on, 430.2 Electronic computer/ data processing equipment, see Info rmatio n techno logy equipment Electronic lighting control switches, 404.22 Electronic power converters, 690.4 (F), 690.8(A)(2), 690.9(A), 690..53 Definiti on, 690.2 Electroplating systems, A rt. 669

70-861

NATIONAL ELECTRICAL CODE

Branc h-drcuit conductors, 669.5 Disconnecting means, 669.8 Overcurrent protection, 669.9 Warning signs, 669.7 Wiring methods, 669.6 Electrostatic equipment, spraying and detearing paint, 516.6(E), 516.10 Elevators, dumbwaiters, escalators, moving walks, platform lifts, and stairway chairlifts, An. 620

Cables Flexible, Table 400.4, 400.10(A)(4), 620.21 Traveling, 620.ll (8 ), 620.12(A), 620-V Clearances, working, 620.5 ConduCLors, 620-11 through 620-IV Definitions, 620.2 Disconnecting means and control, 620- Vl, 620.91 (C) Emergency and standby power systems, 620- X Essential electrical systems, 5 17 .33 (G), 517.43(F) Grounding, 250.112(E), 250.116, 250. 136, 620-IX Live parts, 620.4 Machine room, 620-VIII Overcurrent protection, 620-Vll Voltage limitatio ns, 620.3 Wiring, 620-111 Working clearances, 620.5 Emergency systems, Art. 700; see also Exits, emergency lighting for; Legally required standby systems; Optional standby systems Capacity and rating, 700.4 Circuits for lighting and power, 700-IV, 700-V Circuit wiring, 700-11 Connections at services, 230.82 Control, 700- V Definitions, 700.2 Elevators, dumbwaiters, escalators, etc., 620-X Grounding, 700.7( 8 ) Overcurrent protection, 700.10(8), IN Fig. 700. l 0(B)(a), IN Fig. 700.10(8) (b), 700- Vl Service disconnecting means, 230.72(8) Services, 230.2(A)

70-862

Signals, 700.6 Signs, 700.7 Sources of power, 700.3(F) , 700-III Tests and maintenance, 700.3 Transfer equipment, 700.5 Unit equipment, 700. 12(1) Wiring, 700.10, IN Fig·. 700.10(8) (a), IN Fig. 700. IO(B) (b) Enamel, coating of General equipment, indoor use only, 300.6(A) (l ) Metal boxes, 3l4.40(A) Removing for grounding connections, 2.50.96(A) Rigid metal conduit, 344. I0(A) (3) Encapsulation "m", 505.8(G), 506.8(E) Definition, Art. l00 Enclosed Definition, Art. I00 Enclosures, see also Hazardous (classified) locations Arcing parts, I IO. 18,515.7(8), 516.7(8) Bonding, 250.96, 250.146 Busways, 368.237 Cabinets and cutout boxes, 312.7 through 312.9, 312. ll (D) Circuits in, number of, 90.8( 8 ) Cranes, h o ists, resistors, 610.3(8) Definition, Art. 100 Electrolytic cells, 668.40 Elevators, dumbwaiters, escalators, etc., 620.4, 620-VIII Entrances, 110.33(A) Exits, 300.25 Fire alarm circuits and conductors, 760.48, 760.49(A), 760.53(A) (I), 760. 130(8) ( I), 760. 133, 760.136, 760.139 G rounding, 250.64(0 ), 250.64(E), 250-IV Handho le enclosures, 314.29, 3 14.30, 3 14-IV Definition, Art. 100 High-intensity discharge lamp awdliary equipment, 4 I0. !04 (A) Indoor use, for, Table 110 .28 Induction and dielectric heating, 665.20 Industrial control panels, 409. I00

Installations over l000 volts, I 10.31 Intrinsically safe systems, 504.I0(C), .504.30(A) (2), 504.50 (A) Low-voltage suspended ceiling power distribution systems, 393.40( 8 ) Membrane Defi nition, Art. 100 Spray application operations in, 516-IV Modular data centers, 646.7(C), 646.9 Neon transformer, as pull boxes, 600.5(0 ) (2) Outdoor use, for, Table 110.28 Overcurrent protection, 230.208(8), 240-111, 312.8 Panelboards, 408.38 Portable stage equipment, 520.62(A) Pressurized e nclosure "p", 505.8( 8 ), 506.8(H) Defin ition, Art. 100 Protection by enclosure "t", 506.8(G) Defin ition, Art. 100 Radio equipment., 81 0.7 I (A) Resistors and reactors over l000 volts, 470.18(8) Signs, 600.8, 600.42( H) Switches, 312.8, 404.3, 404. 12, 404.28, 450.8(C) Types, 110.28 Underground, 110.59; see also Manholes; Vaults Energized Definition, An. 100 Energized parts, see also Live parts Fire pumps, 695 .12 (0) M otors, motor circuits, and

controllers, 430-X II Energy management systems, A rt. 7 50 Alternate power sources, 750 .20 Definitions, 750.2 Field markings, 750.50 Load management, 750.30 Energy storage systems, Art. 706 Charge control, 706.33 Circuit requirements, 706-IV Connection to other e nergy sources, 706.16 Definitions, 706.2 Directory, 706.2 I Disconnecting means, 706-11 Flow battery systems, 706- V Installation requirements, 706-II I

Multiple systems in single building, 706.6 Nameplates, 706.30(A) (l) Other systems, 706-VI Overcurrent protection, 706.3 I Enforcement of, 90.4, 510.2, Annex H Engineering supervision, 310.14(8), 64.5.25 Entertainment devices Definition, 522.2 Equipment, see also specific types of equip ment Approval, see Approval, approved Cooling of, 110.1 3(8 ) Definition, Art. 100 Examinatio n of; 90.7, 110.3 Grounding, 250-VI I nstallation, general

provisions, Art. I 10 Less than 50 volts, Art. 720 Mo re than I 000 volts, Art. 490 Mounting, seeMountingof equipment Sealable Defi nitio n, An. 100 Service, see Service equipment Signa l, see also Audio signal processing, amplification, and reproduction equipmenr; Signaling circuits

Definition, 620.2 Equipment bondingjurnpers, see .Jumpers, bonding Equipment branch, 517 .25, 517.29 IN, 517.31 (A), 5 17.40 I N No. 2, .5 l 7.42(A), .517.43, 517.44 Definitio n, 517.2 Equipment grounding conductor fill and boxes, 314.16(8) (5)

Equipment grounding conductors Agricultural buildings, 547 ..5( F) Armored cable (Type AC) as, 320.108 Cable trays as, 392. 10(8 ) (I), 392.60 Capacitor cases connected to, 460.10, 460.27 Carnivals, circuses, fairs, equipment at, 525.30, 525.31 , 525.32 Commun ity antenna television and radio disu·ibution systems, 820. 100 Ex. Connections at ou tlets, 250.146, 250. 148, 400.33

NAT IO NAL ELECTRJCAL CODE

2020 Edition

INDEX

De finition, Art. 100 Fire alarm systems, 760.3(0 ) Fire resistive cable systems, 728 .60 Fixed outdoor electric deic ing and snow-melting equipment, 426.44 Fuel cell systems, 692.44, 692.4.5 Hazardous (classified) locations, 50 l.30(B), 502.30(B), 503.30(B ), 506.25(B)

Sensitive electronic equipment, 647.6(8) Signs and oulline lighting, 600.7(A) Sizing, 2.50. 122, 250. l 90(C)(3) Snap switches, generaluse, 404.9(8 ) Solar photovoltaic systems, 690.43 through 690.47

Heallh care faciliLies, 517.13, 5 17. 19(E), 5 17. 19(G) Id entificatio n, 210.5( 8 ), 250.11 9, 311.14, 400.23, 520.44(C) (3) Information technology equipment, 645 ..5(E) (2), 64.5.1.5 Installation, 215.6, 250.120, 250.1 30

Spas and tubs, 680.8(8 ) Swimming pools, 680.8(8), 680.23( B) (3), 680.23(8) (4), 680.23( F) (2), 680.23(F)(3) Switchboard, stage, 520.51 Switch enclosures connected to, 404.12 Switchgear and control assemblies frames connected to, 490.36, 490.37

Intrinsically safe apparatus connected to, 504.50 (A) Luminaires, 410.42, 410.44, 410.46 Marinas, boatyards, floating buildings, and docking fac ilities, 555.37, 555.56(8 )

Systems and circuits over l kV, 250.l 90(C) Temporary inscallations, 590.4( D), 590.4( F), 590.4(G) Ex. No. l, 590.6 (A) Ex., 590.6(8 )(2) Tunnels, 110.54( 8 )

Messenger-supported wiring, 396.30(C) Mecal-clad cable (Type MC) as, 330.108 Mineral-insulated metalsh eath ed cable (Type Ml) as, 332 . I08 Mobile homes, 550. 16 (8 ) Motio n picture and television studios, 530. 11 , 530.20, 530.22 (A), 530.64(B) Motor contro l centers, 430 .96 MoLOr terminal housings, 430.12( £ ) Nonmecallic sheathed (Type NMS) cable as, 334.108 Panelboards, 408.40 Parallel, 3 l 0. l 0 (G )(5 ) Park traile rs, inte rior equipment, 552..56(8 ) Po rtable cables over 600 vol LS, 400.31 (8 ), 400.32, 400.33 Recepcacles and cord connecLOrs, 406.3( D) (1), 406 .4, 406.10 Recreatio nal vehicles, 55 1.5 4, 551.55 Resistor and reactor cases/ e nclosures connected to, 470.19 Restricted use, 250. 121

2020 Edition

Type P cable as, 337.108 Types recognized, 250.1 18, 250.120, 250.134 Underground feeder and branch-circuit cable, 340.108 Wind electric systems, 694.40 Equipment racks, 640.21 ( E), 640.22, 640.42, 640.43 De finition, 640.2 Equipotential plane, 547.10, 680.26, 682.33 De finition, ArL 100, 547.2 Escalators, see Elevators, dum b,vaite rs, escalators,

moving walks, p latform lifLS, and stairway chairlifts Essential electrical systems, health care facilities, see Health care faci lities Examples (calculations), Annex D Exciters Leads in enclosure wil11 o mer conducLO rs, 300.3(C) (2) (b)

Overcurrent protectio n for, 445 .12 (A) Exhaust ducts, see DucLS Exit enclosu res Stair towe rs, 300.25 Exits, emergency lighting for, 517.33(A),

NATIONAL ELECTRJCAL CODE

5 17.33(8 ), 517.43(A), 5 17.43(8 ), 646.16, 646.17, 700.12( 1) (2), 700.16 Exit signs Health care facilities, 517.33( 8 ), 517.43(8) Expansion joints (fittings), 250.98, 300.7 (8 ), 352.44, 355.44, 366.44, 368.244, 424.98(8 ), 424.99( 8 ) (1), 426.20(E) , 426.21 (C), 426.22(D), 427. I 6 Explanatory material, IN , 90.5(C) Explosionproof equipment, 500.7(A), 501.10(8 ) (4 ), 502 ..5, 505.16(8 )(2) Definition, ArL 100 Explosive atmospheres, gases, liquids, dusts, ignitible fibers/ flyings, and lint, see Hazardous (classified) locations Exposed, see also Enclosures Cable trays, 392 .18(E) Conductive surfaces, 5 17.11 Definition, 5 17.2 Definition, 770.2, 800.2

Deicing and snow-melting equipment, 426.21 Electrical metallic tubing, 358.10 (A) Hazardous (classified ) locations, 501.25, 502.25, 503.25, 505 .19 Live parts, I I0. 26 Definiti on, Art. 100 Luminaire parLS, 410.5, 4 10.42, 410.46 Mera! wireways, 376.10 (1) Nonmetallic exten sions, 382 .10 (8 ) Receptacle term inals, 406.5( 1) Recreatio nal vehicle site supply equipment, 551.76(8) Structural metal, grounding, 250.52(A) (2) Transforme rs, 450.8(C) Wiring metho d s Definition, Art. 100 Open wiring on insulaLOrs, 398. 15 Extension cord sets On constructio n sites, 590.6(A), 590.6(8) (2) Overcurre nt p ro tection, 240.5 Te mpo rary inscallations, 590.40) , 590.6(A), 590.6( 8 ) (2) Extensions Aux iliary gutters, 366.12

Cellular metal floor raceways, 374.18(A) Flat cable assemblies, 322.40(D ) Lighting systems operating at 30 vol LS or less, conductors for, 411.5 (A) Nonmetallic, see Nonmecallic extensions Surface, boxes and fittings, 314.22 Surface raceways, 386.10 ( 4), 388.l 0(2) Wireways, 376.70, 378.10(4), 378.70 Externally operable Definition , Art. 100 -FFaceplates Grounding, 404.9(8 ), 406.6(8), 550.15(D )

Mate rial, 404.9(C) , 406.6 Minimum th icknesses for, 404.9 (Cl, 406.6(A) Mobile homes, 550 .1 5(0 ) Mounting surfaces,

against, 404.9(A} , 406.5, 406.9 (E) Fairs, see Carnivals, c ircuses, fairs, and similar even rs Fans, ceiling, sm Ceiling fans

Farm buildings, feeder calculations, 220. 102. See also Agricultural buildings Fastened in place, 625. l 7 (C) (2), 625.44(8) Definition , 625.2 Fault current, I 10.24 (A) Available, Fig . l 00.1, 110.24 Definitio n , Art. 100 Definition, Art. 100 Fault protection device, 830.44( F) (3) Ex., 830.47 (C) Ex. Definition , 830.2 Fault-tolerant external control circuits, 695.14(A) Definition , 695.2 Feeder assembly, mobile homes, 550.l0(A) Definiti on s, 550.2 Feeders, Art. 2 15, Art. 220 Ampacities, 310.12(C) 8usways, 368.17 Calculation of loads, see Loads Critical operatio n s power systems, 708-11, 708.52(8 ) Definition, Art. I00

70-863

NATIONAL ELECTRICAL CODE

Electric vehicle supply equipment, 625.41, 625.47 Elevators, dun1 bwaiters,

escalators, ere., 620.13, 620.37(C) Emergency systems, 700.10(8), IN Fig. 700. 10(8) (a), IN Fig. 700.10(8)(b), 700.10(0) Energy management sys rems, 750.30 (C) Equipment grounding conductors, 250.122(G) Farm buildings, for, 220. 102 Fire pumps, 695.3, 695.4( 8 ) (1), 695 ..5(C), 695.6(A)(2) Ground-fault circuil interrupters, with, 215.9 Grounding means, 21.5.6 Identification, 225.37, 225.52( F), 230.2(E) Interconnected electric power production sources, 705.12 (8) (1) Kirche n equipment, commercial, 220 ..56 Loads, see Loads, feeders Marinas, boatyards, floating buildings, and docking facilities, 555.6, 555 .34(8 ) (2), 555.35(A)(3), 555.37 (E) , 555.51, 555.53 Mobile homes and parks, 550.l0(A), 550-111 Modular data centers, 646.6(8 ) (2), 646.7(8), 646.8 Motion p icture studios, 530.18(8) Motors, 430-11 Outside, see Outside branch circuits and feeders Overcurrent protection, 21.5.3 Accessibility, 240.24(A) Motor, 430-V Park trailers, 5.52.43(A) Piers, 682.15(8) Pools, permanenrly installed, 680.25 Recreational vehicle sites, 551. 73, 551.80 Relocatable structures, 545 .22 (A) Restaurants, 220.88 Services, 220- 111 Stage switchboard, 520.27 Taps, 240.21( 8 ), 240.92(8), 430.28, 646.6(8 ) (2), 725.45(8) Television studio sets, 530.19

70-864

X-ray equipment, 660.6( 8 ) Feed-through conductors, 312.11 ( 0 ) Fences, grounding and bonding of, 250. I 94, 69 I.I I Ferrous metals, see also Rigid metal conduit (Type RMC) Induced currents in enclosures or raceways, 300.20 Pro recrion from corrosion, 300.6(A) Festoon cable, 610.13(C)

Definition, 610.2 Festoon lighting Conductor size, 225.6(8) De finition , Art. 100 Insulation, 22.5.4 Portable stage equipment, 520.65 Festoon wiring, portable stage equipment, 520.65 Fiber bushings, AC cable ends, 320.40 Fibers/ flyings, lint, ignitible, Art. 503, Art. 506; see also Hazardous (classified) locations Field evaluation body (FEB) Definition, Art. 100 Field labeled Definition, Art. 100 Interactive inverters, 705.6 Phorovolraic equipment, 690.4(8), 690. 12( 8 ) (2), 691.5(2) Service equipment, 230.66 Stand a lone systems, 7I0.6 Wind electric systems, 694.7(8 ), 694.7(F) Figures, see Diagrams Films, motion picture, see also Projection rooms, motion picture Storage vaults, 530-V Viewing, cutting, patch ing rabies, 530-IV Finish rating, 334. I 0(3), 362 . 10, 518.4(C) Definition, 362.10(2) IN Fire alarms, 230.82(5), 230.94 Ex. 4; see also Fire alarm systems Fire alarm ~ystems, A rt. 760 Abandoned cables, 760.25 Definition, 760.2 Access to electrical equipment, 760.21 Cables, 760.3, 760.48, 760.176, 760.179, 840.47(A) (1)

Circuits extending beyond one building, 760.32 Connections at services, 230.82 (5), 230.94 Ex. 4 Critical operations power systems, Arr. 708 Definitions, 760.2 Grounding, 250.112 (I ) Health care facilities, 5 l 7.33(C), 517.43(C), 517- VI Identification, 760.30 Installation, 760.32 Location, 760.3 Mechanical execmion of work, 760.24 Non power-limited circuits, 760-I I Cable marking, 760.176 Conductors, 760.49(8) Different circuits in same raceway, etc., 760.48, 805.47(A) Number of conducrors in racevvay, etc., and

derating, 760.51 Definition, 760.2 Listing, 760.176 Marking, 760.176 Mulliconducror cable, 760.53 Optical fiber cables, 760.3( F) , 840.47(A) (1) Overcurrent protection, 760.43, 760.45 Pov.rer source

requirem ents, 760.41 Requirements, 760.35(A) Wiring method, 760.46, 760.53(A) Power-limited circuits, 760-111 Cable markings, 760. 179 Circuit markings, 760.124 Conductors Separation, 760.136 Size, 760. 142 Support, 760.143 De finition, 760.2 Installation, 760.133, 760.139 Line-type fire detectors, 760 .145, 760. 1790) Listing, 760.179 Marking, 760.179 Overcurrem prorecrion, Chap. 9, Tables 12(A) and 12(8) Power sources, 760.121 Requirements, 760.35( 8 ) Wiring methods and materials Load side, 760.130

Supply side, 760.127 Fire de tectors, linetype, 760.179 (1 ) Fire pumps, Art. 695 Connection ar services, 230.72 (A) Ex., 230.72(8), 230.82(5), 230.94 Ex. 4 Continuity of power, 695.4 Control wiring, 695.14 De finitions, 695 .2 Emergency power supply, Art. 700 Equipment location, 695. 12 Grounding, 250.l 12(L), 250. l 12 (M) Listing, 695.6(H), 695.10 Motor, overcurrent protection, 430.31 On-sire standby generator, 695.3( 8 ) (2), 695.3(0 ), 695 .4( 8 ), 695.6(C) Ex. 2 Definition, 695.2 Over current protection, service equipment, 230.90(A) Ex.4 Power sources ro electric moro1° driven, 695.3 Power wiring, 695.6 Rem ore-control circuits, 430.72(8) Ex. I Services, 230.2(A) (1), 230.9 0 (A) Ex .4 Supervised connection, 695.4 Transforme rs, 695.5 Voltage drop, 695.7 Fire-resistive cable systems, Art. 728 De finition , 728.2 Equipment grounding conductors, 728.60 Insrallarion, 728.5 Marking, 728.120 Fire spread Prevention of; wiring methods, 300.21, 760.3(A), 770.26, 800.26, 840.26 Fire-sto pped partitions, 300.21; see also Firewalls Firewalls, wiring through, 300.21 Fittings, An. 314; see also Chap. 3, Wiring Methods and Materials Conduit bodies, 314.16 Cords, fl exible, 400.35 De finition , Art. 100 Expansion, see Expansion joints (fitti ngs)

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

Flat cable assemblies, installed with, 322.40 (C) l nsulmion, 300.4 (G) Imegrated gas spacer cable, 326.40 Fixed electric heating equipment for pipelines and vessels, An. 427 Continuous load, 427.4 Control and protection, 427-Vll Controls, 427.56 Disconnecting means, 427.55 O vercurrent p rotection, 427.57 Defin itions, 427.2 Impedance h eating, 427-IV Definition, 427.2 Grounding, 427.29 Induced currents, 427.28 Isolation transforme r, 427.26 Pe rsonnel protection, 427.25 Secondary conductor sizing, 427.30 Voltage limi tations, 427.27 Induction h eating, 427-V De finition, 427.2 Induced current, 427.37 Personnel protection, 427.36 Scope, 427.35 Installation, 427-1 1 General , 427.1 0 Id entification, 427.13 The rmal protectio n, 427.12 Use, 427.11 Resistance heating e le me nts, 427-III De finition, 427.2 Electrical connections, 427. 19 Equipment protection, 427.22 Expansio n and contraction, 427. 16 Flexural capabili ty, 427.17 Grounded conductive covering, 427.23 Marking, 427.20 Not in di rect contact, 427. 15 Power supply leads, 427.18 Secured, 427.14 Skin effect h eating, 427- VI Conductor a mpacity, 427 .45 De fini tio n, 427.2 G rounding, 427.48 Pull boxes, 427.46 Single co ndu ctor in e nclosure, 427.47 Fixed electric space-heating equipment, An. 424 Branch circuits fo r, 424.4 Boile rs, 424.82

2020 Edition

Low-voltage equipmen t, 424.104 Radiant heating panels, 424.95, 424.96 Cables, 424- V Area restrictio ns, 424.38 Ceilings Clearances, 424.36 Finished, 424.42 Clearances, wiring Ceilings, 424.36 Other objects, openings, 424.39 Construction, 424.34 Installation In con crete or poured masonry floo rs, 424.44 Nonheating leads, 424.43 Marking, 424.35 Splices, 424.40, 424.41 (D) Tests and inspectio ns, 424.46 Co ntrol a nd protection, 424- III Controllers, 424.20(A) Disconnecting means, 424.19 through 424.2 I, 424.65 Ind icating, 424.21 Overcurrent protection, 424.22, 424.72, 424.82 De finitio ns, 424.2 Duct heaters, 424- VI Airflow, 424.59 Conde nsation, 424.62 Disconnecting means, location, 424.6.5 Elevated inlet temperature, 424.60 Fan circuit interlock, 424.63 Ide ntificatio n, 424.58 Installation, 424.6 1, 424.66 Limit controls, 424.64 Electrode-type boile rs, 424-VIII Installation, 424-11 Locatio n Damp or wet locations, 424.12(B) Exposed w physical damage, 424.12(A) Low-voltage equipment, 424. 103 Spacing, combus tible materials, 424.1 3 Special permission, 424. 10 Supply conductors, 424. 11 Listed, 424.6 Load , 220.51, 220.82(C), 220.83 Low-voltage, 424-X Marking, 424-IV Boilers, 424.86

NATIONAL ELECTRJCAL CODE

Cables, 424.35, 424.47 Heating elem en ts, 424.29 Nameplates, 220.82(C), 424.28 Radiant heating panels a nd h eating panel sets, 424. 92 Overcurrent protection for, 424.22, 424.72, 424.82 Radiant h eating panels and h eatin g panel sets, 424-IX, 427.23(8) Clearances, wi ring Ceilings, 424.94 Walls, 424.95 Connection, 424.96 Insrallation , 424.93, 424.98, 424.99 Markings, 424.92 Nonh eating leads, 424.97 Resistance-type boile rs, 424-VI I Fixed equipment, grounding, 250. 110, 250.1 12, 250. 116, 250.134, 250.136, 250.190 Electric space-h eatin g equ ipmem, 424.45(F), 424.99( 8 ) (6) Patient care a reas, 517.1 3 Fixed in place, 625.44(C) Definition, 625.2 Fixed outdoor electric deicing and snow-melting equipment, A rt. 426 Branch circu its for, 210.19(A)(4) Ex. l (5) Connections, 426.24 Continuo us load, 426.4 Control and protection, 426-VI Cord-and-plug• connected, 426.50( B), 426.54 Definiti o ns, 426.2 Disconnecting means, 426.50 Ground-fault circuit interrupters, 210.8(A) (3) Ex . Ground ing, 426.22(A), 426.27, 426.44 Ide n tification of, 426. 13 Impedance heating, 426-IV Definition, 426.2 Induced currents, 426.33 Isolatio n tra nsforme,; 426.3 1 Personnel protection, 426.30 Voltage limitatio ns, 426.32 Installation, 426-1I Marking, 426.2.5 Nonheating leads, installatio n of, 426.22, 426.23

Protection Corrosion, 426.26, 426.43 Exposed equipmem, nonheating leads for, 426.23( 8 ) Ground fault, 210.8(A) (3) Ex., 426.28 The rmal, 426. 12 Res istan ce heating elements, 426-III Definitio n , 426.2 Embedded, 426.20 Exposed, 426.2 1 Skin effect heating, 426-V Conductor ampacity, 426.40 Definition, 426.2 Pull boxes, 426.41 Sing le conductor in enclosure, 426.42 Special permission, 426.14 Thermostats for, 426.51 Use of, 426. 11 Fixed resistance and electrode industrial process heating equipment, An. 425 Boilers Electrode-type, 425-VII Resistan ce-type, 425- VI Control and protection , 425-III , 425 .65 Du ct h eaters, 425- V Installation, 425- 11 Marking, 425-IV Conductors, overcu rrem protective devices, 425.72(E), 425.72(F) Duct heaters, 425.58 Electrode-type boilers, 425.81, 425 .86 Resistan ce-type boilers, 425. 71 Fixtures, see Lu1ninaires Fixture wires, An. 402 Ampaci ties, 402. 5 Grounded conducwrs, identification, 402.8 Marking, 402.9 Minimum size, 402.6 Number in con duits or tubing, 402.7 O vercurrem protection, 240.5, 402.12 Types, 402 .3 Uses n ot permi tted, 402 .11 Uses permitted, 402 .10 Flameproof "d", 505.8(A) Definiti on , An. I 00 Flame spread, see Fire spread

70-865

NATIONAL ELECTRICAL CODE

Flammable anesthetics, see also

Anesthetizing locations DefiniLion, 517.2 Flammable gases, see H azardous (classified) locations Flammable-liquid produced vapors, see Hazardous

(classified) locations Flammable liquids, see Hazardous

(classified) locations Flashers, time switches, etc., 404.5,

600.6(B) Flat cable assemblies (Type FC), An. 322

Boxes and fittings, 322.40 Branch-circuit rating, 322. IO( I) ConduCLor insulations for, 322.1 12 Conductor size, 322.104 Construction, 322-111 Dead ends, 322.40 (A) Definition, 322.2 Extensions from, 322.40(0) Fittings for, 322.40(C) Identification of grounded conductor, 322.120(B) Installation, 322-11 Luminaire hangers, 322.40(B) Marking, 322.120 Number of conductors in, 322.100 Size of conductors in, 322.104 Splices, 322..56 Support, 322.30 Te rminal block identification, 322.120(C) Uses not permitted, 322.12 Uses permitLed, 322.10 Flat conductor cable (Type FCC), Art. 324

Branch-circuiL rating, 324.l0(B) Cable connections and ends, 324.40(A) Construction, 324--111 Conductor identification, 324.120( B) Insu lation, 324.1 12 Markings, 324.120(A) Receptacles and housings, 324.42 Shields, 324.l 00(B) Definitions, 324.2 Transition

assemblies, 324.56( B) Definition, 324.2 Definitions, 324.2 Ground ing, 324.60 Installation, 324--11 AILerations, 324.56(A) Boxes and fittings, 324.40

70-866

Cable connections and insulating ends, 324.40(A) Connections to othe r systems, 324.40( 0 ) Crossings, 324.18 Floor coverings, 324.41 Heated floors, 324. IO(F) Metal shield connectors, 324.40(E) Receptacles and housings, 324.42 Shie lds, 324.40(C}, 324.40(E) Definition, 324.2 Support, 324.30 System he ig h t, 324.l0(G) Insulating ends, 324.40(A) Definition, 324.2 Listing req uirements, 324.6 Po larization, 324.40(B) Splices and taps, 324.56 Systems alterations, 324.56(A) Uses not permitted, 324.12 Uses permiued, 324.10 Flatirons

Cords, 422.43(A) Signals, 422.42 Stands fo ,; 422.45 Temperawre-lim iting means, 422.42, 422.46 Flexible cords, see Cords, flexible Flexible metal conduit (Type FMC), An. 348

Bends, 348.24, 348.26, Chap. 9, Table 2 Couplings and connectors, 348.42 Definition, 348.2 Dimensions, Chap. 9, Table 4 Grounding and bonding, 348.60 Installation, 348- 11 Liqu id tight, see Liquid tight flexible metal conduit Listing, 348.6 Maximum number of conductors and fixmre wires in, Tables C.3 and C.3A Number of conductors, Chap. 9, Table I Number of conductors in, 348.22 Securing a nd supporting, 348.30 Size, 348.20 Splices and taps, 348.56 Trimming, 348.28 Uses not permitted, 348.12 Uses permitted, 348.10 Flexible metallic tubing

Bends, Chap. 9, Table 2

Number of conductors, Chap. 9, Table I Flexible metallic tubing (Type FMT}, Art. 360

Bends, 360.24 Construction specifications, 360-111 Definition, 360.2 Grounding, 360.60 Installation, 36(}-I I Listing, 360.6 Marking, 360.1 20 Number of conductors, 360.22 Sizes, 360.20 Splices and taps, 360.56 Uses not perm itted, 360. 12 Uses permitted, 360.10 Floating buildings, see Marinas, boatyards, floating bu ildings, and docking facili ties Floor pockets, 520.46 Floors, see also Underfloor raceways

Busways through, 368. l 0(C) (2) Cablebus support and extension th rough, 370.18 Flat conductor cable (Type FCC) in/ on, 324.l0(C) Floor coverings, 324.4 1 Heated floors, 324. l 0(F) Insulating e nds, 324.41 Masonry o r concrete floors, installation of heating cables in, 424.44 Radiam heating panels, installation of, 424--IX Receptacles, 210.52(A) (3), 250.146(C) , 314.27(B), 406.9(0 ) Surface metal raceways Extension through floors, 386.10 (4) Under raised floors, 386.10(3) Surface nonmetallic raceways, 388.10(2) Flue damper control, see Dampers (flue), control Fluo rescent luminaires, 410-XII, 410-XIII Amotransformers in ballasts, 220.18(B}, 410.1 38 Auxiliary equ ipmem, 410.1 04, 410.1 37 Ballast protection required, 410.130(E) Circuit breakers used to switch, 240 .83(0) Connection of, 410.24, 410.62(C)

Disconnecting means, 410.130(G) Load calculations, branch circuits, 210.23 Raceways, 4 10.64 Snap switches for, 404.14(A) (5), 404. 14( B)(4) Surface-mounted or recessed, 410.16(A), 410. I6(C) The,·mal protection, 410.130(E) Fluoroscopic e quipment, see X-ray equipment Flyings, ignitible, Art. 503, Art. 506; see also Hazardous (classified) locations Footlights, theaters, 520.43 Definition, 520.2 Disappearing, 520.43 (C) Fo rmal interpretations, 90.6 Forming shells, underwater pool luminaires, 680 .23(B),

680.24, 680.26(B) (4), 680.27(A) (3) Definition, 680.2 Fountains, see Swimming pools, fountains, and similar installations Foyers, receptacles in, 210..52(1) Frame, recreational vehicle

Definition, 551.2 Free air, 310.21

Ampacities of conductors in, 310.1 7, Table 310.17, 310.19, Table 310.19, Table 310.2 1 Definition, An. 100 Fuel cell &ystems, A rt. 692 Circuit requirements, 692- 11 Connection at services, 230.82(6) Connection to other ci rcuits, 692- VII Identified imeractive equipment, 692.60 Loss of interactive system power, 692.62 Outpm characteristics, 692.61 Point of connection, 692.65 Transfer switch, 692.59 Unbalanced imerconnection, 692.64 Critical operaLions power systems, 708.20(H ) Definitions, Art. 100,692.2 Disconnecting means, 692-111 All conductors, 692.1 3 Switch or circuit breaker, 692.17 Emergency systems, source of power for, 700.1 2(G)

NAT IO NAL ELECTRJCAL CODE

2020 Edition

INDEX

Grounding, 692- V Equipment grounding conducLOr, 692.44, 692.45 Grounding e lectrode system, 692.47 System grounding, 692.4.1 Health care facilities, 517.30 (8 ) (2) Marking, 692-VI Fuel cell power sources, 692.53 Fue l shmoff; 692.54 Stored e ne rgy, 692.56 Overcurrent protection, 692.9 Standby systems, legally required, 701.l 2( H ) Wiring methods, 692-IV Full-load current motors Allernating c urre nt Single-phase, Table 430.248 Three-phase, Table 430.250 Two-phase, Table 430.249 Direct current, Table 430.247 Furnaces, 422.12 Fuseholders Cartridge fuses, 240-VI O ver 1000 volts, 490.2 1(8 ) Plug fuses, 240-V Rating, motor controllers, 430.90 Size, motor branch circuit protection, 430.57 Type S, 240.53, 240.54 Fuses, Art. 240. See also Hazardous (classified) locations Canridge, 240- VI Disconnection, 240.40 Con11nunicatio ns circuits,

p rotectors for, 805. 90(A) (2)

Disconnecting means, 240.40 Electronically aclllated , 240.67(8), 240.I0l (A), Table 450.3(A) Note 4 Definition, Art. 100 Enclosures, 240-111 Energy storage systems, 706.31 (E) Generators, constant-

voltage, 445.12(A) Group installation of motors, 430.53(C) Location in circui t, 240.21 Location on p remises, 240.24 Markings, 240.60(C) Motor branc h circuit p rotection, 430- IV Motor overload protectio n, 430.4 Ex.,

2020 Edition

430.28 Ex., 430.225(C) (I ) Multiple, see Multiple fuses Network-powered b roadband communication s circuits,

protectors for, 830.90(A) (2) Over l000 volts, 490.2 1(B) De finit io n, Ar t. 100 In parallel, not permitted, 240.8, 404.27 Plug, Edison-base type, 240-V Potential (voltage) transformers, 450.3(C) Ratings, 240.6 Service equip men t, 230.95(8) Services over 1000 volts, 230.208 Switches, arrangemem on panelboards with, 408.39 Type S, 240.53, 240.54 Wind electric systems, 694.26 Future expansion and convenience, 90.8(A) -GGages (AWG), conductors, I I0.6 Garages, commercial, Art. 511 Battery cha rging equipmem, 5 11. I0(A) Classificatio n of locatio ns, 51 1.3 Definitio ns, Art. 100 Electric vehicle cha rging, 51 I.I 0(B) Elevators, dumbwaiters, escalaLOrs, etc., 620.38 Equipmem, 511.4, 511 .7 Ground-fault circuit-ime rru pter protection, 2 10.8(8 )(8), 5 11.12 Grounding, 250.11 2(F) Grounding a nd bonding, 5 11.1 6 Locatio ns, 511.4 Major repair, 51 1.3 De fini tio n, An. 100 Minor repait; 511.3 Definition, Art. 100 Sealing, 511.9 Special equipment, 511.10 Vemilation, 511.3(C) thro ugh (E), Table 5 l l.3(C), Table 5 l l.3(D) Wiring, 511.4, 51 1.7 Gases, see Hazardous (classified) locatio ns Gasoline bulk storage plants, see Bulk sto rage pla n ts; Hazardous (classified) locations Gasoline dispensing and service stations, see Mo tor fuel dispen sing facilities

NATIONAL ELECTRJCAL CODE

Gas pipe As grounding e leetrode, 250.52(8 ) (1) General care space, 517 .18, 5l 7.29(A), 5 17.40 Definition, 517.2 General provisions, installation of wiring and equipment, Art. 110 General requirements for wiring m ethods, Art. 300. See also Wiring meth ods Boxes, conduit bodies, o r fittin gs, wh ere

required, 300.15 Changing raceway or cable to open wiring, 300.1 6 Conductors, 300.3 Different systems, 300.3(C) Installation with oth er systems, 300.8 Insulated fittings, 300.4(G) Number and sizes of; in raceways, 300.17 Supporting of conductors in ver tical raceways, 300. 19 Exhaust and ventilating ducts, wiring, 300.22 Expansion joints, raceways, 300.7(8) Free le ngth of wire at o utlets, junction and switch poims, 300.14 Induced curre n ts in ferrous metal enclosures, 300.20 Mech anical a nd e lectrical cominui ty, conducto rs, raceways, cables, 300.10, 300.1 2, 300. 13 Over l 000 volts, 110- 111, 300- II, Art. 490 Protection against

Corrosion, 300.6 Physical da mage, 300 .4 Raceway installations, 300.1 8 Raceways and cables wit h oth er systems, 300.8 Raceways and fi ttings, metric designator and trade size, 300.1 (C) Raceways as a means of suppon, 300.1 1 (C) Raceways exposed to differe m temperam res, 300.7 Raceways in wet locatio ns above grade, 300.9 Sealing, raceways, change in temperature, 300.7(A) Securing and supporting, 300.11 Spread of fi re o r products of combustio n, 300.2 1

Temperature limitations, 310 .14 (A) (3) T hrough smds,joists, rafters, 300.4 Underground installations, 300.5, 300.50 Voltage limitation s, 300.2 Wiring in ducts, p lenums, airhandling spaces, 300.22 G ene ral-use snap switches, see Snap switches Generating capacity Definition, Art. I00 G ene rating station Definition, 691.2 G ene rators, Art. 445 Bushings, 445 .16 ConducLOr, ampacity of, 445.1 3 Critical operatio n s power systems, 708.20(F) Disconnecting means, 445.18 Emergency systems, 700. I2(D) Essential electrical systems, cask illumination, 517.33(E ), 5 I 7.33(F), .5 I 7.43(E) Ground-fau lt circuit imerrupte rs, 445.20 Grounding, 250.34, 250 .35 Guards for attendan ts, 445.15 Hazardous (classified) locatio ns, 501.125, 502. I 25, 503.125, .505. I 6(E) (2), .505.22 Health care fac ilities, 517.30( 8 ), 517.33(E), 517.33(1'), 517.41 lmerconnected electric power production sources, 705.6, 705.1 4, 705.30(8 ), 705.30(0 ) Legally req uired standby systems, 70 1.1 2(D) Listing, 445.6 Location, 445.10 Marking, 445.11 Overcurrent p rotection, 445.12 Po rtable, 250.34, 702.12, 708.12, 708.20(F) Protection of live parts, 445.14 Recreation al vehicles, 551.30 Standby systems, Art. 701, 702 Fire pump, on-site, 695.3(8 ) (2), 695.3(D), 695.4(8 ), 695.6(C) Ex. 2 Terminal h ous ings, 445.17 Goosenecks, service cables, 230.54 Grid bus rail, 393.104(8 ) Definition, 393.2 Grooves, cables and raceways installed in, 300.4 (F)

70-867

NATIONAL ELECTRICAL CODE

Ground

Definitio n, Art. 100 Vollage to Definition, Art. 100 Ground clam ps, 250.10, 250.70 Grounde d

Definition, Art. l00 Functionally, 712.52(B), 712.55 Definit io n, 690.2, 7 l 2.2 Reference-grounded DC system, 712.30, 712.35, 712.52(B), 7 12 ..55 Definit io n, 712.2 Resistively, 712.30, 712.35 So lidly, l 10.54(A) Definit ion, Art. 100 Three-wire DC system, 712.35 Definit io n, 7l 2.2 Two-wire DC system, 712.35 Definit io n, 712.2 Grounded conductors, see also

Neutral Alternating current systems, 250.24 through 250.26 Identification, 200.6, 200.7, 210.5(A) Continuity of, 300. l 3( B) Definitio n, Art. 100 Different systems, 200.6 (0 ) Electrode-type boilers, over 1000 volts, 490.72(E) Energy storage

systems, 706.30 (C) Flat conductors, nonmetallic extensions, 382.1 04(B) Fuses in , 430.36 Insulated, 200.2(A), 5.5 l.54(C), 552.55(C) Minimun1 rating and

size, 215.2(A) (2) Mobile homes, 550.16(A) Motor contro llers, 430.85 Overcurrent protection , 230.90(B), 240.22 Pane lboards, termination

in, 408.41 Park trailers, 552 .55(C) Recreational vehicles, 55l.54(C) Recreational vehicle site supply equipment, .551.76(0 ) Separately derived systems, 250.30(A) Services Disconnection of; 230.7.5 Ground-faulL circuit conductor, 250.186(A) Overcurrent protection, 230.90(B)

70-868

Single-phase dwellings, 310.12(0 ) Switch es, disconnection, 404.2 (B) Use and identification, Art. 200 Ground fault

Definitio n, Art. 100 Gro und-fault circuit conductors, 250.186 Gro und-fault circuit interrupters

Accessory buildings, dwelling units, 210.8(A) (2) Aircraft hangars, 5 l3. l 2 Appliances, 2 10.8(0 ), 422.5 Bath tubs, hydromassage, 680.71 Carn ivals, circuses, fairs, and simila r events, 525.23 De finition, Art. 100 Electrically operated pool covers, 680 .27 ( B) (2) Electric signs, portable o r mobile, 600.10 (C) (2) Electric vehicle c harging systems, 625 ..54, 625.60( 0 ) Electrified truck parking space supply equipment, 626.24( 0 ) Elevators, dumbwaiters, escalators, etc., 620.6 Fixed e lectric space-heating equipment, 424.44(E), 424.45(E), 424.99(B)(5) Fountains, 680.5 1 (A) Garages Commercial, 511.12 Dwelling units, 210.8(A) (2) Generators, 445 .20 Naturally and a rtificially made bodies of water, electrical equipment fo r, 682.15 Permitted uses, 210.8, 215.9 Personnel, protection for, 426.32 Receptacles, 2 10.8 Appliances, 21 0.8(0 ) Bathrooms in dwelling units, 210.8(A) (1) Bathrooms in other th an dwelling units, 210.8(B) ( 1)

Co nstruction sites, at, 590.6 Eq uipment requiring servici ng, 210.8(E) Fountains, 680.57(B), 680.58 Garages, in dwelling units, 210.8(A) (2) Health care facilities, 5 l 7.20(A) , 517.21 Kitchens in dwelling units, 210.8(A) (6)

Marinas, boatyards, floating buildings, and docking facilities, 555 .33 ( B) ( I), 555.35 Mobile homes, .5.50. I 3(B), 550.32(E) Outdoor, 2 I0.8(A) (3), 210.8(B)(4), 210.8( F) Park traile rs, 552.4l(C) Pools, 680.5, 680.6, 680.22 (A) ( 4), 680.22 (A) (5 ), 680.22(B) (4), 680.32, 680.62(E) Recreational

veh icles, 551.40 (C), 551.41 (C) Replacement, 406.4(0) Required, 210.8 Rooftops in othe r than dwelling units, 2 10.8(B) Sensitive electronic equipment, 647.7 (A) Spas and hot rubs, 680.43(A), 680.44 Recreational vehicles, 551.71 (F) Relocatable structu res, 545.28 Swimming pools, see Swimming pools, fountains, and similar installations

Solar photovoltaic systems, 690.4l (B) Temporary installations, 590 .6 Grounding , Arc. 250 AC systems, 250.20, 250.24 through 250.26 Agricultural buildings, 547.9 Air-conditioning units, 250.114 Anesthetizing locations, 5 17.62 Antenna, 8 10. l.5, 810.2 1, 810..58, 810.7l ( B) AppLiances, 250. 114 Audio signal processing, amplification, and reproduction equipment, 640.7 Bonding, see Bonding Bulk sto rage plants, 515.16 Busways, 368.60 Over 1000 volls, 368.260 Cablebus, 370.60 Capacitors, 460.10, 460.27 CATV systems, 820.93, 820- IV Circuits, 250--1 Less t han 50 volts, 250.20 (A) Clothes dryers, 250. 114, 2.50. 140 Clothes washers, 250.114 Con1mu nications

Ground-fault curre nt p ath

Definition, Art. 100 Ground-fault de tection e quipmen t, 712 .55 Ground-fault protection

Connections at services, 230.82 Cranes and hoists, 610.42 Critical operations power systems, 708.52 Deic ing and sn ow-n1elting

equipment, 426.28 Emergency systems, 700.3 1 Equipment, 210. 13, 2 15 . 10, 240.13 Defi nition, Art. 100 Fire pumps, 695.6(G) Floati ng buildings, 555.53 Heailh care facilities, 517.17 Interconnected elecu-ic power production sou rces, 705.l l(E) Legally required standby systems, 701.31 Marinas and

boatyards, 555.33(B) ( 1), 555.35, 555.53 Motors, 430- IV, 430--V, 430. 130 Personnel, see G rou nd-fault circuit interrupters Pipeline h eaters, 427.22, 427.27 Service disconnecting means, 230.95

systems, 800.49, 800.106(A), 800-lll Continuity, 250.96 Conu-ol, radio equipmen t, 810.7 l ( B) Control panels, 409.60 Cranes and h oists, 610--VII DC systems, 250.162, 250.164 De icing, sn ow-melting systems, 426.22(A), 426.27, 426.44 Direct current microgrid systems, 712.52 Dishwashers, 250.1 14 Electric vehicles, wireless power transfer equipmen t, 625.101 Electrode system, 250-lll Elevators, 250.1 12(E), 250.116, 250. 136, 620--IX Enclosures, 250.64(0 ), 250.64(E), 250- IV Equiprnem, cord-and-plugconnected, 250.114 Fire alarm systems, 250.112 (I ) Fixed equipment, 250.1 10, 250.112, 250.116, 250.134, 250.1 36 Electric space-heating equipment, 424.45(F), 424.99(B)(6) Patient care a reas, 517. l 3

NAT IO NAL ELECTRJCAL CODE

2020 Edition

INDEX

Fixed industrial process e lectrode-type boilers, 425.85 Fixmres, la mpholde rs, etc., 4 10. l.55( 8 ), 4 10-V Fountains, 680.54(A), 680. 55 Freezers, 250.1 14 Fuel cell systems, 692-V Garages, com mercial, 511.16 Generators, 2.50.34 Hazardo us (classified) locations, 501.30, 5 02.30, 503.30, 505.25, 506.25 Health care facilit ies, 5 17. l3, 517.19 High density polyeth yle ne condui1., 353.60 Induction and dielectric heating equipment, 66.5-II Information technology equipment, 645 .14, 645 .1.5 Instrument transforn1ers, 1~e1ays,

etc., 250- X Intrinsically safe systems, 504.50 Irrigation machines, 675.11 (C), 675.12, 675.1 3 Lightning surge a rresters, 242.12 Manufactu red buildings, .545.11 Mera! boxes, 314.4, 314.40(D) Metal e nclosures for conductors, 250.80, 250.86 Metal faceplates, 404.9(8), 406.6( 8 ) Metal siding, 250.116 IN Methods, 250- VII Mobile homes, 550.16 More than 1000 volts between conductors, 300.40 Motion picture studios, 530.20 Motor fi.ie l d ispensing fac ilities, 514.16 Motors and co ntrollers, 2.50-VI, 430.12(E), 430.96, 430- XIII Nam rally and anificially m ade bodies of water, electrical equipment for, 682-III Nonelectrical equipment, 250.1 16 Organs, 650.5 Over IO00 volts, 250-X, 300.40, 490.36, 490.37 Panelboards, 408.40, .517.19( E) Patient care spaces, .517.13 Patie nt care vicinity, 517.l 9( 0 ) Portable equipment, 2.50. 11 4 Radio and televisio n equipment, 8 10.7, 810.15, 810.20(C),

2020 Edition

810.21, 810.58, 810.71(8) Rang·es and similar appliances, 250.140 Receptacles, 2.50.146, 250.148, 406.4, 517.13, 517.l 9(H ) Recreational vehicles, 55 1.54, 55 1..55, .5.5 1.76 Refrigerators, 250.1 14 Re locatable structu res, feeders in, 545.22(D) Resisto rs a nd reactors over 1000 volts, 470.19 Sensitive electronic equipment, 647.6 Separate bui ldings, 250.32 Separately derived systems, 250.21 (A), 250.30 Signs and ouLline lighting, 600.7(A), 600.24(8), 600.33( 0 ) Sola r phot0voltaic signs, 600.34( 0 ) Spas and rnbs, 680.6, 680.8( 8 ), 680.43( F) Spray application, dipping, coating, and printing processes, 516. I0(A) (6), 5 16. 16 Substatio ns, 250.1 91, 250.194 Surge arresters, 242.1 2 Swimming pools, 680.6, 680.8(8), 680.23( 8 ) (3), 680.23(8) (4), 680.23( F) (2), 680.24( 0 ), 680.24( F) Switchboards, 250.l l 2(A), 408.22 Switches, 404.9(8 ), 404.1 2 Systems, 250-1, 250-II, 645.1 4 Theaters and simila r locations, 520.81 Tools, mo to r operated, 250.114 Transfo rmers, 450.5, 450.6(C), 450.10 Welders, electric, 630.15 Wind electric systems, 694- V X-ray equipment, 5 17.78, 660-IV Grounding conductors, 250-III, 250-Vl; see also Equipment g rounding conducto rs; Grounding electrode conductors EarL11 as, 250.4(A) (5), 250.54 Enclosures, 250-IV Flat conductors, no nmetallic extensions, 382.104(C) Identification, multiconductor cable, 250. 119 Installation, 250.64, 250. 120 Material, 250.62

NATIONAL ELECTRJCAL CODE

Objectionable curre nt over, 250.6 Restricted use, 250 .121 Sizes, 250.122 Grounding electrode conductors, see also

Electrodes, grounding Communications circuits, 800.49, 800.100 Connection to e lectrodes, 250-1, 250.24(0 ), 250-III Definiti o n, Art. 100 Installation, 250.64 lnte rsystem, connecting, 250.94 Material, 250.62 Optical fiber cables, 760.180, 770.100 Radio and television equipment, 810.21, 810.58 Separately derived systems, 250.30 Sizing, 250.30(A) (6) (a), 250.66, 250.166 Solar photovoltaic systems, 690.4 7 Surge-protective devices, 242.32, 242.56 Systems a nd circuits over I kV, 250.l 90( 8 ) Wind electric systems, 694.40(8) Grounding electrodes, see Electrodes, grounding Grounding point

Patien t equipment, 517.19( D) Definitio n, 517.2 Reference, 517.19, 517.82(8 ), 517.160(A)(2) Definition, 517 .2 Grounding-type attachment plugs, 406. I 0 Ground ring, 250.52(A)(4),

250.53(F), 250.66(C), 250.166(E) Grouped cables or conductors, 520 .54 (C),

620.21 (A), 620.44, 640.8, 6.50.6, 690.3 1(B) (2) Definition, 520.2 Grouping, switches, circuit breakers, 404.8. See also

Accessible Grouping of disconnects, 230. 72 Group installation, motors, see

Motors, grouped Guarded

Definiti on, Art. 100 Guarding, guards, see also

Enclosures Cables Coaxial, 820.l00(B)

Flat cond uct0r cable (Type FCC), 324.40 (C), 324.40(E), 324. l00(B) Definition , 324.2 Over IO00 volts, requirements for, 300.40 Portable, 400.32 Circuit breaker handles, 240.41( B) Conductors, contact, 610.21 (A) Connectors, solar photovoltaic systems, 690.33(8 ) Construction sites, 590.7 Elevators, dumbwaiters,

escalat0 rs, etc., 620.71 Generators, 445.15 Grounding, 250.l 90(C) (2) Induction and dielecu·ic heating equipment, 665- II Intrinsically safe appararns, cable shields for, 504.50(8 ) Lamps, theaters, dressing rooms, etc., 520.44(A), 520.47, .520.65, 520.72 Live parts, 110.27 Elevators, dumbwaiters,

escalato rs, etc., 620.5(8 ) Manholes, tunnels, and vaults, I I 0.78 In theaters, 520.7 Luminaires, agriculmral bu ildings, 547.8(8) Motion picture studios, 530.15 Mot0rs a nd motor controlle rs, 430- XII Over 600 volts, 400.32, 590.7 Over 1000 volts, l 10.33(A), 110.34 Service equipment, carnivals, circuses, and fa irs, 525.1 0(A) Transformers, 450.8 Ventilation openings, 11 0.78 X-ray installations, 5 17.78, 660-IV Guest rooms or s uites

Arc-fault circuit-interrupter protectio n, 210.12(C) Branch-circuit voltages, 210.6(A) Cooking equipment, b ra nch circuits for, 210. 17 Definiti on, Art. 100 Omlets, 210.60, 210.70(8), 220.l4(M) Overcurrent d evices, 240.24( E) Tamper-resistant receptacles in, 406.1 2(2) Gutters, auxiliary, see Auxiliary gmters

70-869

NATIONAL ELECTRICAL CODE

-H-

Habitable rooms, 2l0.70(A) ( I),

210.70 (8 ) De fini tion, Art. 100 Hallways, outlets, 210.52(H) Handhole enclosures, see

Enclosures, Handhole e nclosures Handlamps, portable, 410.82 Hangars, aircraft, see Aircraft hangars Hazard current

Definitio n, 517.2 Hazardous areas, see Hazardous (classified ) locatio ns Hazardous atmospheres, ArL 500 Class I locations, 500.5(8 ) Class II locations, 500.5(C) Class Ill locations, 500.5(0) Groups A throug h G, .500.6 Specific occupancies, An. 510 Hazardous (classified) locations, Classes I, II, and Ill, Divisions I and 2, Art.

500; see also Hazardous (classified) locations, Class I, Zone 0, 1, a nd 2 locatio ns Aircraft hangars, 513.3 Anesthe tizing locatio ns, 5 l 7.60(A), 517.61 Bulk storage plants, 5 1.5 .3 Class I, see Hazardo us (classified) locatio ns, Class I Class I, Zone 0, 1, and 2, see Hazardous (classified) locatio ns, Class I, Zone 0, 1, a nd 2 locatio ns Class 11, see Hazardous (classified) locations, Class II Class I II, see Hazardo us (classified) locations, Class Ill Combustible gas detection system, 500. 7 ( K) Dust-ig nition proof; 500.7( 8 ) DustS, explosive, Art. 502 Dus ttight, 500.7(C) Equipme n t, 500.8 Approval fo r class a nd properties, 500.8( 8 ) Marking, 500.8(C) Optical fiber cable, 500.8( F) Suitabili ty, 500.8(A) Temperature marking, 500.8(0 ) Threading, 500.8(E)

70-870

Explosio n proof equipment, 500.7(A) Fibe rs/fl yings, lin t, highly combustible material, Art. 503, Art. 506 Flammable liq uids, Art. 500, Art. .501 Garages, commercial, 511.3, 511.4 Gases, flammable, Art. 500, Art. 501 Gaso line service statio ns, see Motor fi.iel dispensing facilities General, 500.4 Group classifications, 500.6 Ho ists, 503.155 Inhalation anesthetizing locations, see

Anesthetizing locations Intrinsic safety, 500.7 (E) . See also Intrinsically safe system s Ligh ting systems, less than 30 volts, 411.8 Material groups, 500.6 Pro tection techniques, 500. 7 Specific occupancies, Art. 510 Vapors, flammable, Art. .500, Art. 501 Hazardous ( classified) locations,

Class I, 500.5( 8 ), 500.6(A), An. 501; see also Hazardous (classified) locations, Classes 1, 11, and III, Divisio ns I and 2; H azardous (classified) locatio ns, Class I, Zone 0, 1, and 2 locatio ns Bo nding, 501.30(A), 504.60 Circuit breakers, 50 I.I 15, 501. 135 (B) (3) Control transforme rs a nd resistors, 50 l .10.5(8 ) (3), 501.120 Cranes and hoistS, 610.3(A) (I) Drainage of equipment, 501.15( F) Exposed partS, 501.25 Flexible cords, 501.140 Fuses, .50 I.I 15, 501.13.5 (B) (3) Gro unding, 501.30 Hermetically sealed, 500.7(.l) Inductio n and dielectric heating equipment, 665.4 Luminaires, 501.130 Metal-clad cables, 330. 130 Meters, instruments, and relays, 501. 105 Motor controllers, 501. 11.5 Motors and gene rato rs, 501. 125

No nincendive circuit, 500.7( F) Nonincendive component, 500.7( H) No nince ndive equipment, .500.7 (G) Oil immersio n, 500.7(1) Process sealing, 50 1.17 Receptacles and attachme nt plugs, 501.145 Sealing, 501. 1.5, 50 1.17 Sig naling, alarm, re motecontrol, and con1munication s

systems, 50 I . I 50 Surge protection, 501.35 Switches, 501.ll 5, 501.1 30 (8 )(5), 501.1 35(8 )(3) Transforme rs and capacitors, 501.100 Uti lizatio n equipme nt, 501.135 Wiring methods, 501.10 Zone 0, I , and 2 locations, see Hazardous (classified) locations, Class I, Zone 0, I, and 2 locations Zone equipment, 501.5 Hazardous (classified) locations, Class I, Zone 0, I , and 2 locations, Art. 505

Bonding, 505 .25(A) Class I, Zo ne 0, I, a nd 2 group classificatio ns, 505.6(A) thro ugh (C) Classification of locatio ns, 505.5 Class I, Zo ne 0, 505.5(8 )( 1) Class I, Zone 1, 505.5(8 ) (2) Class I, Zo ne 2, 505.5(8 ) (3) Conductors and conductor insulato r, 505.1 8 Docume ntation, 50.5.4 Equipment constructio n, 505.9 Class I temperature, 505.9(0 ) Listing, .505 .9( 8 ) Ma rking, 505.9(C) Optical fi ber cable, 505 .9 (F) Suitability, 505.9(A) Threading, 505.9(E) Equipment for use in, 505.20 Exposed pans, 505.19 Flexible cords, 5 05. 17 Grounding, 505.25 Material gro ups, 505 .6 Process sealing, 505.26 Protection techniques, 505.8 Combustible gas detection system, 505.8 (I) Encapsulatio n "m", 505.8(G), .506.8(E) De finiti o n, Art. 100

Flameproof "cl", 505.8(A) Definiti o n,Art. 100 Increased safety "e", 505.8(F), 505.22 Definitio n,Art. 100 Intrinsic safety "i", 505.8(C), 506.8(C), 506.8(1) Definition,An. 100 Liquid immersion "o", 50.5.8(E) Definition, Art. 100 Powder fillin g "q", 505.8(H ) Definiti o n, Art. I 00 Purged and pressurized, 500.7(0), 50 l. l25(A), 505.8(8 ) Definiti o n, Art.100 Type of protection "n", 505.8(0 ) Definiti on,Art. 100 Reference standards, 505.4 Sealing Dra inage and, 505.16 Process, 505.26 Special precaution, 505.7 Wiring methods, 505.15 Zo ne equipment, 505.9(C) (2), Fig. 505.9(C) (2) Hazardous (classified) locations, Class II, 500.5 (C),

ArL 502; see also Hazardo us (classified) locations, Classes I, I I, and III, Divisio ns I and 2 Bonding, 5 02.30(A) Circuit b reake rs, 502.1 15 Cranes and hoists, 610.3(A) (2) Exposed partS, 502.25 Flexible cords, 5 02.140 Fuses, 5 02.115 Grounding, 502.30 Luminaires, 502.130 Moto r controlle rs, 502.11 5 Moto rs a nd gene rators, 502.125 Receptacles a nd attachment plugs, 502.145 Sealing, 502.15 Signaling, alarn1, rernote-

contro l, and communicatio ns systems,

meters, insrrumen rs, and relays, 502.150 Surge protection, 502.35 Switc hes, 502.115 Transforme rs and capacitors, 502.1 00 Utilizatio n equipment, 502.135 Ventilating piping, 502.1 28 Wi ring methods, .502.10

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

Zone 20, 21, and 22 locations for flammable dusrs, fibe rs/ flyings, An. 506 Zone equipment, 502 .6 Hazardous (classified) locations, Class III, 500.5 (D), Art. 503; see also Hazardous (classified) locations, Classes I, II, and III, Divisio ns l and 2 Bonding, 503.30(A) C ircuit breake rs, 503.115 Conu·ol transformers and resistors, 503.120 Cranes and hoisrs, 503.155 , 610.3(A) (3) Exposed parrs, 503.25 Flexible cords, 503.1 40 Fuses, 503. 11.5 Grounding, 503.30 Luminaires, 503. 130 Motor controlle rs, 503.1 1.5 Motors and generators, 503.125 Receptacles and attachme nt plugs, 503.145 Signaling, a larm, re motecontrol, a nd local loudspeaker intercommunications, 5 03.150 Storage battery cha rging equipment, 503 . 160 Switches, 503.115 Transformers and capacitors, 503.100 Utilization equipmen t, 503.135 Ventilation p ip ing, 503.128 Wiring methods, 503.1 0 Zo ne 20, 21, and 22 locations for flammable dusts, fibers/ flyings, Art. 506 Zo ne equipment, 503.6 Hazardous (classified) locations, specific, Art. 510 Hazardous (classified) locations, Zone 20, 21, and 22, Art. 506 Bonding, 506.25(A) Classification of locatio ns, 506.5 Documeniation, 506.4 Equipment installation, .506.20 Man ufacture r's

instructio ns, 506.20(E) Temperamre, 506.20(F) Equipment requirements, 506.9 Listing, 506.9 (8 ) Marking, 506.9(C) Su itability, 506.9(A) Temperamre, 506.9( D) Threading, 506.9(E) Flexible cords, 506.1 7

2020 Edition

Grounding, 506.25 Material g roups, 506.6 Protection techniques, 506.8 Dust-ig nitionproof, 506.8(A) Dusttight, 506.8( D) Encapsulation, 506.8(E) Enclosure, 506.8(G) Intrinsic safety, 506.8(C), 506.8(1) Nonincend ive equipment, 506.8(F) Pu rged and pressurized, 506.8(8 ), 506.8(H) Definition, Art. 100 Reference standards, 506.4 Sealing, 506.16 Special precautions, 506.7 Wiring methods, 506.15 Zone equipment, 506.9(C) (2) Headers Cellular concrete floo r raceways, 372.2, 372. 18(A) Cellular metal floor raceways, 374.2, 374.56 De finitio n, 372.2, 374.2 Health care facilities, Art. 5 17 Co mmunication s, signaling systems, data systems, less than 120 vol LS, no minal, 517-VI Other-than-patient care areas, 517.8 I Signal transmissio n between applia nces, 517.82 De finitions, 517.2 Essential electrical system s, 517-III Ambulatory h ealth care centers, 517.45 Clinics, medical and dental offices, and oth er health care facilities, 5 17.4.5 Connectio ns Alternate power source, 51 7.35 Equipment branch, 517 .44 Life safety b ranch, 517.43 Critical branch, 51 7.32 Definilio n, 517.2 Equipment branch, 5 17.44 Hospitals, 517.29(A) IN No. I Life safety b ranch, 517.32, 517.33 Nursing homes and lim ited care facilities, 5 17.40 Power sources, 517.35, 517.41 Requirem e nts, 5 17.3 1 Inhalation anesthetizing

NATIONAL ELECTRJCAL CODE

locatio ns, 517- IV

Classification, 517.60 Grounded power systems in anesthetizing locations, 517 .63 Grounding, 517.62 Line isolation monitor, 5 17. 160(8) Low-voltage equipment and instrumen ts, 517.64 Wiring and equipment, .5 17.61, 517.160 Isolated power systems, 517- VII Anesthetizing location s, 5 17.63(E), 517.63(F) Circuits, 517.64(C) Cri tical care areas, 51 7.l 9(F), 517.l 9(G) Definition, 517.2 Essential electrical systems, 5 17.3 l (C)(2) Grounding, 517.I 9(G) Installation, 517.160(A) Low-voltage equ ipment, 517.64(8), 5 l 7.64(C) Wet proced ure locations, 517 .20 (B) X-ray installation, 5 17 .76 Power sources, 517.3l(F) Wiring a nd protection, 517- 11 Anesthetizing locations, 517.61 Applicability, 517.10 Critical care areas, 5 17. I9 Essential electrical systems, 5 17.3 I (C) Fixed electrical equipment and gro unding of receptacles, 517.13 Gen eral care a reas, 517.18 Gen eral installation/ construcrion c riteria, 517.11 Ground-fau lt circ uitinterrupter p rotection, 517.20(A), 517.21 Gro und-fault protection, .517.17 Grounding, 517.13 Panelboard bonding, 517.1 4, 517.19(E) Receptacles, 5 17. I 3,5 17 .1 6, 517.19, 517.31 (E), 5 17.42(E) Wet locations, 5 17.20 Wiring methods, 5 17.12 X-ray installations, 5 17-V Connection to supply circuit, 517.71 Control circuit condu ctors, 517.74

Disconnecting means, 5 17.72 Equipment insiallations, 517.75 Guarding and grounding, 5 17.78 High tensio n x-ray cables, 517.77 Overcurrent protection, 5 17 .73 Rating of supply conductors, .51 7.73 Transformers and capacitors, 517.76 H eater cords, Table 400.4, 422.43(A) H eat generating equipment, see Induction and dielectric h eating equipment H eating, see also H eating systems; Inductio n and d ielectric h eating equipmen t Dielectric Definitio n, 665.2 Induction Definitio n, 665.2 H eating, ventilating and air conditioning (HVAC) systems, An. 708 H eating appliances, Art. 422; see also Infrared lamp industrial h eating appliances; Water h eaters H eating cables, Art. 424 H eating ele ments Marking, 422.61 Res istan ce, see Fixed electric h eating equipment for p ipeli nes a nd vessels; Fixed omdoo r electric deicing and snowmelting equipment H eating equipment Central, 422.12 Definitions, 665.2 Fixed, see Fixed electric h eating equipment for p ipelines and vessels; Fixed electric space-heati ng equipment; Fixed outdoor electric deicing and snow-me lting equipment Induction and dielectric, see Induction and d ielectric h eating equipment Outside, 5 .5 0.20(8) Receptacle outlets, 210.63(A) Swimming pools, see Swimming pools, fountains, and similar installatio ns H eating panels and h eating panel sets, radiant, see Fixed electric space-heati ng

70-871

NATIONAL ELECTRICAL CODE

equipment, Radiant heating panels and heating panel sets Heating systems Definition, 426.2 Impedance, see Fixed electric heating equipment for pipelines and vessels; Fixed outdoor electric deicing and snowmelting equipment Induction, see Induction heating systems Skin effect, see Fixed electric heating equipment for pipelines and vessels; Fixed outdoor electric deicing and snov,rmelting equipment Heavy-duty lampholders Branc h circuits, 210.21 (A), 210.23, Tab le 210.24 Unit loads, 220.14(E) Herme tically sealed, 500.7 (J ) Definition, An. 100 Herme tic refrigerant motorcompressors, see also Aircondition ing and refrigerating equipment Ampacity and rating, 440.6(A) Definitio n, Art. 100 Marking, 440.4 Rating and inte rrupting capacity, 440. I 2(A) High density polyethylene conduit (Type HDPE), Art. 353 Bends, 353.24, 3.53.26, Chap. 9, Table 2 Bushings, 353.46 Construction specifications, 353- 111 Definition, 353.2 Grounding, 353.60 Installatio n, 353-11 Joints, 353.48 Listing, 353.6 Marking, 353.120 Number of conductors, 353.22, Chap. 9, Table I Size, 353.20 Splices and taps, 353.56 Trimming ends, 3.53.28 U nderground installations, Table 300.50 Uses not permitted, 353.12 Uses permitted, 353.10 High-impedance grounded neutral systems , 200.2(A), 250.20(0 ), 250.30 (A)(3 ), 250.36, 2.50. 186(A)(4), 250.187 Hoists, Art. 6 10. See also Cranes

70-872

Bonding, 610-\111 Conductors, contact, 610- 111 Control, 610-\11 Electrolytic cells, 668.32 Flexible cords, 400.l0(A) (5) G rounding, 250.22(1), 250. l 12 (E), 250. 11 6( I), 610-\111 Hazardous (classified) locations, 503. 155 Ma rinas and boacyards, 555.8 Motors and controlle rs, disconnecting means, 430.1 12 Ex., 610-1\1 Nameplates, 610.14(G) Overcurrent protection, 610-V, 610.53 Wiring, 610-11 Hoistways Busways in, 368. 12 ( B) Cablebus in, 370.12(1) Definition, Art. I00 Flexible metal condu it, 348.20(A) Messenger-supported wiring, 396.12 Surface raceways, 386.12( 4), 388.12 ( 4) Wiring in, 620.21 (A) (1), 620.37, 725.136(H), 760.53(A) (3), 760. 130(8 ) (3), 760.136(F) Hoods, range, cord-and-plugconnected, 422.16(8) (4) Hoods for commercial cooking, lighting in, 410. l0(C) Horticultural lighting, 410-XVI G ro und-fault circuit interrupte r, 410.184 Grounding, 410.182 Installation, 410.174 Locations not permitted, 410.176 Hospitals, see also Heald1 care facilities Definitio n, 5 17.2 Essential electrical systems, 517.29 IN (A) No. I Patient care space, see Patient care space Psychiatric Definition, .517.2 Host signs, 600.35(A) Definitio n, 600.2 Hotels and motels Branch-circuit vo ltages, guest rooms and suites, 210 .6(A)

Lighting load, Table 220.12 Lighting outlets required, 210.70(8) Overcurrent devices, guest rooms and suites, 240.24(E) Receptacle ground-fau lt circui t interrupter protection, 210.8( 8 ) Receptacle outlets, guest rooms and suites, 210.60, 210.70(8), 220.14(M)

see Spas, hot tubs, and immersion pools Houseboats, see Marinas, boacyards, floating buildings, and docking facilities HVAC systems, Art. 708

H ot tubs,

Hybrid systems Definition, Art. 100 Hydromassage bathtubs, 680-\111 Definition, 680.2 -IIdentification, see also Color code; Markings Agricul tural building d istribmion poims, 547.9(0)

Boxes (outlet, device, pull, a nd junction), 3 14.44 Branch circuits, 210.5 Critical operation s power systems wiring, 708. l 0(A) Direct-buried cables, Table 300.50 Noted Disconnecting means, 110.22, 230.70(8), 620.51(0 ) Service disconnects, 230.2(E) Emergency circuits and systems, 700.l0(A) Feeders, 2 15. 12 Fixed electric space-h eating equipment, 424.45 (A), 424.58, 424.99(A) Fixed resistance and electrode industria l process h eating equipmem Duct heaters, 425.58 Resistance-cype boilers, 425.71 Flexible cords, identified conductors within, 200.6(C), 2.50. l 19(C), 400.22, 400.23 Grounded conductors, Art. 200, 400.22, 402.8 Grounding-pole, 406.10(8) High-leg, 110.15, 230.56, 408.3(E) (1), 408.3(F)

In tri n sically safe systems, 504.80 Sensitive e lectric equipment conductors, 647.4(C) Se,vice disconnecting means, 230.70(8) Switchboards and panelboards, 408.3(F), 408.4 Ungrounded conductors, 210.5(C), 215.12(C) Wiring device terminals, 250.126, 504.80 Identified Definition, An. 100 Illumination, see also Lighting; Lun1inaires

Battery system working spaces, 480.I0(G) Means of egress, 517.33(A), 5 17.43(A) Modular data centers, 646. 15 Task,5 17.34 Defin ition, 517.2 Working spaces, 518.6 Immersible appliances, 422.41 Immersion heaters, cord-and-plugconnected , 422.44 Immersion pools, see Swimming pools, fountains, and similar installations Impedance heating systems, see Fixed electric heating equipment for p ipe lines and vessels; Fixed outdoor e lectric deicing and snow-melting equipment IN, explanatory material, 90.5 (C) Incandescent lam ps, Art. 410. See also Hazardous (classified) locations Guards Aircraft hangars, 513.7(C) Garages, 511 .7(8) Theater dressing rooms, 520.72 Lamp wattage, marking on 1uminaire (fixture), 410. 120 Medium and mogul bases, 410.103 Signs with lampholders for, 600.4(C) Increased safety "e", 505.8( F) De finition , An. 100 Motors and generators, 505.22 Independent Circuits for emergen cy lighting, 700. 17

NAT IO NAL ELECTRJCAL CODE

2020 Edition

INDEX

Suppons, services, over buildings, 230.29 Wiring, emergency circuirs, 700.l0( B) X-ray control, 660.24 Individual branch circuits, see Branch circuits, individual Induced currents, metal enclosures, 300.20 Induction and dielectric h eating equipment, Art. 665 Ampacity of supply conductors, 665. IO De finitions, 665.2 Disconnecting means, 665.12 Guarding, grounding, and labeling, 665-II Access to interio r equipment, 665 .22 Capacitors, 665.24 Component interconnection, 665 .19 Control panels, 665 .21 Enclosures, 665.20 Grounding and bonding, 665.26 Marking, 665.27 Shielding, 665 .25 Warning labels o r signs, 665.23 Hazardous (classified) locations, 665.4 Output circuits, 665.5 Overcurrent protection, 665.11 Remote conu·o l, 665.7 Induction heating systems, see also Induction and dielectric heating equipment De finition , 427.2, 665.2 Fixed equipment for p ipelines and vessels, 427- V Inductive loads Signs, 600.6(8) Switches, cypes, ratings, 404.14 Indus trial control panels, Art. 409 Arc-flash hazard warning, 110.1 6 Conductors Bus bars, 409.l 02 Minimum size and ampacity, 409.20 Constrnction specifications, 409lll De finition, Art. 100 Disconnecting means, 409.30 Enclosures, 409.l 00 Grounding, 409.60 Installation, 409- II Marking, 409.1 IO Overcurrent protection, 409.21 Service equ ipme nt, 409.108

2020 Edition

Spacing, minimum, 409.106 Wiring space in, 409.104 Industrial equipment limitedpower circuits, 725. 12I(A) Industrial installation, supervised De finitio n, 240.2 Overcurrent protection, 240Vlll Industrial machinery, An. 670 De fini tion, 670.2 Disconnecting means, 670.4(8) Nameplates, 670.3 Supply co nductors and overcurrent

protection, 670.4 Industrial manufacturing system De fini tio n, 670.2 Industrial process heating equipment, fixed, see Fixed resistance and electrode industrial process heating equipment Informational notes, explanatory material, 90.5 (C) Information technology equipment, Art. 645 Class 2 and Class 3 circu its, power source for, 725.12 1(A) De finitions, An. 100, 645.2 Disconnecting means, 645.4(1), 645.10 Engineering supervision, 645.25 Grounding, 645.14, 645.15 Health care faci lities, 517-VI Marking, 645.1 6 Powe r distribution units, 645 .17 Selective coordination, 645 .27 Special requiremen rs for in fo rmatio n technology equipment rooms, 645.4 Supply circuits and interconnecting cables, 645 .5 Uninte rruptible power supplies (UPS), 64.5.11 Information technology equipment rooms De finition, An. 100

Special requiremen rs, 645.4 Zones, 645.l0 (A) (3) De finitio n, 645.2 Informative annexes, 90.5 ( D), Annexes A thro ugh] Infrared lamp industrial heating appliances, 422 .48, 425.14 Branch circuirs, 210.23(C), 422.11 (C), 424.4(A)

NATIONAL ELECTRJCAL CODE

Overcu rre n t protection, 422.l l (C) Inhalation anesthetizing locations, see Anesthetizing locations Inherently safe optical radiation "op is", 500.7(L), 505.8(K), 506.8( K) Definition, An. 100 Innerduct, 770.l I0 (A)(3), 770.l 13(E) Definition, An. 100 Inserts Cellular metal floor raceways, 374.18(C) Underfloor raceways, 390.75 In sight from Air-,;onditioning o r refrigerating equ ipment, 440.14 Definition, Art. 100 Duct heaters, 424.65 Electric-discharge lighting, 410. 141 (B) Fixe d electric space-heating equ ipment, 424.19(A) Irrigation machines, 675.8(8 ) Motor driven appliances, 422.31 (C) Motors, motor controlle rs, 430.l 02 Room a ir conditioners, 440.63 Sig ns, 600.6(A) Institutions, emergency lighting, Art. 700 Instructions, l 10.3(8) Instrumentation tray cable (Type ITC), Art. 727 Allowable ampacity, 727.8 Bends, 727.10 Construction, 727.6 Definition, 727.2 Marking, 727.7 Overcurre nt protection, 727.9 Uses not permitted, 727.5 Uses permitted, 727.4 Instruments, meters, relays Grounding, 250-IX Hazardous (classified) location, 501.105, 502.1 50 Low-voltage, 517.64 Instrument transformers, grounding, 230.82( 4), 250-IX Insulation Conductors, see Conductors, insulated Double, see Do uble insulated Equ ipment, I 10.3(A)(4) Faceplates, 406.6(C)

Fixmre wire, 402.3 IN, Table 402.3 Flexible cords, Table 400.4, 400.21(8 ) Heating cables, 424.36, 424.42 Luminaire and lampholder parrs, 410.52, 410.56 Thermal insulation Armored cable installed in, 320.8 0 (A) Luminaires, installed near, 410.I 16(8 ) Service-entrance cables installed in, 338.10 (8 )(4) Insulators Nonabsorbent, 230.27, 394.30(A) Open wiring,

see Open wiring

o n insulators Outdoor overhead conductors, 399.30(C) Integrated electrical syste ms, Art. 685 DC system grounding, 685.12 0 rde rly shutdown, 685- 11 Overcurrent protection, location of; 685.10 Ungrounded control circuirs, 685.14 Integrated gas spacer cable (Type IGS), An. 326 Construction, 326-III Conductors, 326. I04 Conduir, 326.11 6 Insulation, 326.112 Marking, 326.120 Definition , 326.2 Installation, 326-II Ampacity, 326.80 Bend ing radius, 326.24 Be nds, 326.26 Fittings, 326.40 Uses not permitted, 326.12 Uses permitted, 326. IO Inte ractive inverters, IN Fig. 690.1 (b), 705.70(3) IN Definition , An. I00 Energy storage systems, 706.16(C), 706.33(8 )(3) Multimode inverters, 705.70(3) IN Utility-interactive inverters Energy storage systems, 706.16(F) Fuel cell systems, 692.6.5 Inte ractive systems, see also Utilityinteractive inverters

Definiti on, Art. 100 Energy storage systems, 706.16

70-873

NATIONAL ELECTRICAL CODE

Fuel cell systems, 692- Vll So lar photovoltaic systems, 690.54 Wind electric systems, 694.50, 694.60 Intercommunications systems, see Communications circuits; Hazardous (classified) locations Interconnected electric power production sources, Art. 705 Definitions, 705.2 Directory, 705.10 Disconnecting means, 705.12(A), 705.20 Equipment approval, 705.6 Fuel cell system installation, 692.4( 8 ) (1) Generators, 705.6, 705.1 4, 705.30(8), 705.30(0) Ground-fault protection, 705.11 (E), 705.32 Interrupting and short-circuit current rating, 705.16 Loss of primary source, 705.40 Output characteristics, 705.14 Overcurrent protection, 705.11 (C), 705. 12(A), 705.1 3(C), 705.30 Power control systems, 705.12, 705.13 Power source omput circu its, 70.5. 11, 70.5.12 Definition, 705.2 System installation, 705.8 Unbalanced interconnection, 705.45 Utility-interactive inverters

Energy st0rage systems, 706.16(F) Fuel cell systems, 692.65 Wind electric systems, marking, 694.50(A) Wiring methods, 705.25 Intermediate metal conduit (Type lMC), Art. 342 Bends, 342.24, 342.26, Chap. 9, Table 2 Bushings, 342.46 Conductors outside of building, 230.6(5) Construction, 342-111 Couplings and connectors, 342.42 Definition, 342.2 Dimensions, Chap. 9, Table 4 Dissimilar me tals, 342.14 Expansio n fittings, 300.7(8 ) IN

70-874

Installation, 342- 11 Listing, 342.6 Marking, 342.120 Maximum number of conductors and fixture wires in, Tables C.4 and C.4A Number of conductors, 342.22, Chap. 9, Table l Reaming and threading, 342.28 Securing and supporting, 314.23( E), 314.23(F), 342.30 Size, 342.20 Splices and taps, 342.56 Underground installations, 300.50 (C), Table 300.50 Uses permitted, 342. IO Intermittent duty Definition, Art. l00 Motors, 430.22(E), 430.33 Interpretations, formal, 90.6 Interrupter &witch Definition, Art. 100 Interrupting rating, I 10.9, 240.60(C) (3), 240.83(C), 712. 72 Definition, An. 100 lntersystem bonding termination, .54.5.27, 770. 100(8) Definition, Art. l00 Intrinsically safe apparatus Bonding, 504.60(A) Cable shields for, 504.50( 8 ) De finitio n, Art. 100 Grounding, 504.50(A) Installation, 504.10, 504.20 Listed, 504.4, 505.20(A) Marking, 505.9(C) (2) Ex. 3, Table 505.9(C) (2) (4), Table .506.9(C) (2) (3) Permitted equipment, 500.8(8)(2) Sealing, .504.70 Ex. Intrinsically safe circuits, 504.30 Definition, Art. I00 Intrinsically safe systems, Art. 504 Bonding, 504.60 Conductors, separation of, 504.30 Definition, Art. 100 Enclosures, 504.30 (A) (2), 504.50(A) Equipment installation, 504.10, 506.8(C), 506.8( 1) Equipment listing, 504.4 Grounding, .504..50 Identification, 504.80

Sealing, 504.70 Separation of intrinsically safe conductors, 504.30 Wiring methods, 504.20 Intrinsic safety "i", 505.8(C), 506.8(C), 506.8( 1) Definition, Art. I00 Introduction, An. 90 Invasive procedure Definition, 517.2 Inverters, see also Interactive inverters Definition, Art. I00 Input circuit, 706.30 (A)(3 ) Defin ition, Art. 100 Multimode, IN Fig. 690 .1(b), 705.70(3) IN De finition, Art. 100 Output circuit, 706.30(A) (2) Definition, Art. 100 Solar photovoltaic systems, IN Fig. 690.l(b), 690.6, 690.8 (A) (I), 690.9 (A), 690. l 3(C), 690.15, 690.31 (B), 690.47(A) (2) IN Utilization output circuit, 706.30(A) ( 4) Definition, 706.2 Wind electric systems, 694.l 2(A) Irons, see Flatirons Irrigation machines, Art. 675 Bonding, 675.14 Center p ivot, 675-11 Defin ition, 675.2 Collect0r rings, 675.11 Conductors, 675.5, 675.9 Curre nt ratings, equivalent, 675.7 Definitions, 675 .2 Disconnecting means, 675 .8 Grounding, 675.11 (C), 675.12, 675.1 3 Irrigation cable, 675.4 Lightning protection, 67.5.1.5 Marking, 675 .6 Motors on branch circuit, 675.10 Supply source, more than one, 675.16 Island mode, 705.40, 705.50, 710. 1, 710.6 1N Definition, Art. 100 Isolated Arcing parts, 110.18 Circuits, low voltage, 517.64(C) Definition, An. 100 Electrolytic cells, portable equipment, 668.20( 8 ) Equipment grounding conductor, 250.146(0)

Heal th care facility power systems, 517- Vll Critical care areas, 517.l 9(F), 517.l 9(G) Definition, 517.2 Essential electrical systems, 5 I 7.3 1( C) (2) Grounding, .5l 7. I9(G) Installation, 517.160(A) Wet procedure locations, 517.20(8) Phas e installations, 300.5(1) Ex.2 Sensitive e lectronic equipment, ground receptacles, 647.7(8) Isolating means, over 1000 volts, 490.22 Isolating switches, see Switches, isolating Isolation by elevation Circuits over l000 volts, 110.34(E) Circuits under l000 volts, 110.27(A) Resistors and reactors over 1000 volts, 470.1 8(8 ) Isolation e quipment, systems (motors), 430.I 09(A)(7) Definition, 430.2 Isolation transformer, see Transformers, Isolation

:JJ oints, see also Splices and taps Electrical nonmetallic tubing, 362.48 Expansion, see Expansion joints Grounding electrode conductor, 250.64(C) High density polyeth ylene conduit, 353.48 Insulating, fixtures, 4 10.36( 0 ) Insulation of; 110.14(8) Reinfo rced thermosetting resin conduit, 355.48 Rigid polyvinyl chloride conduit, 352.48 Strain at, 400.1 4 Joists Air-handling, space, 300.22 (C) Ex . Armored cable, 320.15, 320.23(A) Concealed knob-and-tube wiring, 394.23 Electric space heating cables, 424.41(1), 424.41 U) Holes through or notches in, 300.4(A)

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

Nonmecallic sheath ed cable, 334.15 (C) Open wiring, crossing, 398.15 (C) Parallel to fra ming members, cables and raceways, 300.4(0 ) Jumpers, bonding, 2.50. 168 Cable trays, 392.60(C) Communications circuits, 800.lO0(D) Commun ity antenna television and radio distribmion systems, 820.100 Ex. De finitions, Art. l 00 Equipment, 250.98, 250.102, 310.10 (G) (6), 517. l 3(B) De finition, Art. 100 Gene rators, 2.50.35 (B) High-impedance ground ed neutral

system, 2.50.36( E), 250.36(G) Separately de ri ved systems, 250.30(A) (2) Expansion joints, telescoping sectio ns of raceways, 250.98 Grounding e lectrode system, 2.50.53(C), 250.64(F), 250.68 Grounding-type receptacles, 250.146 Hazardous (classified) locations, 250.1 00, 501.30 (A), 502.30 (A), .503.30(A), 505.25(.A) Health care facilities, 5l 7.l3(B), 517.19 (D), 5l 7 .19( E) Main, 250.24(B), 250.28 De finitio n, Art. 100 Wire o r busbar, as, 250.24(A) (4) Metal, structural, 250.l04(C ) Optical fiber cables, 770.JO0 (D) Panelboards, 408.3(C) Piping systems, 250. 104 Radio and televisio n equipment, 8 10.2 1 (J) Separately derived systems, 250.30(A), 250.30(B) (3) Service equipme nt, 250.28, 2.50.92 (B), 250.I02(C), 250.186 Solar photovolta ic systems, 690.43(B) Supply-side, 250.30(A) (2), 250.30 (B)(3) De finitio n, Art. JOO Switchboards, 408.3(C) Syste m, 250.28, 250.30 (A)

2020 Edition

Definition, Arr. JOO Junction boxes, see also Boxes; Pull boxes Accessibility, 314.29 Cellular concrete floor raceways, 372.l8(C) Cellular metal floo r raceways, 374.1 8(B) Covers, 3 l4.28(C), 3 l4.72(E) De icing and snow-me lting cables, 426.22 (F), 426.24(B) fountains, 680.52 Motor controlle rs and disconnects, 430. I0(A) Nonheating cable lead s, 424.43 O ver 1000 volts, 31 4-IV Sensitive electronic equipment, 647.4(B) Separation from moto rs, 430.245( B) Size Conducto rs 4 AWG and larger, 314. 16, 314.28(A) Conducto rs 6 AWG and smalle r, 3 l4. 16(C) ( I ) Construction specifi cations, 314- III Suppo rt, 314.23 Swimming pools, 680.23 (C) (2), 680.24 Switch enclosures, II 0.59, 404.3(B) Underfloor raceways, 390. 74 -KKitchen Arc-fau lt circuit-inte rrupte r protection, 2 IO. I2(A) De finitio n, Art. 100 Fixed e lectric space-h eating equipment cables, 424.44 (E) Recepiacles in, 2l0.8(A) (6), 210 .52 Kitchen equipment, commercial, 220.56, 422.11 (F) (2) Knife switches Butt co ncacrs, 404.6(C) Connection, 404.6(C)

Construction specifications, 404-1 1 Enclosures, 404.3(A) Ex. I Gene ral-use, 404. l 3(C) Interrupt curre nt, 404.l 3(B) Isolating, 404.l 3(A) Moror-d rcuit, 404.13(D) Positio n, enclosed and open types, 404.6 Ra tings, 404.14

NATIONAL ELECTRJCAL CODE

600-volt, 404.26 Knob-and-tube wiring, Art. 394 Accessible attics, 394.23 Clearances, 394.19 Conductors, 394.1 04 Construction, 394-III Definition, 394.2 Devices, 394.42 Installation, 394-1 I Securing and supporting, 394.30 Splices and taps, 394.56 Throug h or parallel to fram ing members, 394. 17 Uses not p ermiued, 394.12 Uses permitted, 394.10 Knockouts Bonding Over 2.50 volts, 250.97 Ex. Service equipment, 250.92(B) Openings to be closed, l 10.12 (A), 3l4.l 7 (A) -L-

Labeled Definition, Art. 100 Labels required, see Warning signs (labels), at equipme nt Lacquers and paints Application, Arr. 516 Atmospheres, 500.5 (B), 500.6 (A), Art. 50 I, Art. 505 Lampholders Branch circuits supplying, 2 10.23 Circuits less than 50 volts, 720.5 Combustible material, near, 410.97 Damp orwer locations, 410 .I 0(A), 410.96 Double-pole switched, 410.93 Heavy-duty, see Heavy-duty lamp holders Insiallation, 4 IO-VIII Mog ul base, 210.6(C) ( 4), 410.103 Ollldoor, 225.24 Outler boxes, 314.27(A)

Pe ndant Bathroo ms, 4 IO. I0(D) Clothes closers, 410.1 6( B) Not in theater dressing rooms, 5 20. 71 Screw-sh ell types fo r lamps o nly, 4 I0.90 Support, 3l4.23( F) Unswitched over combustib le material, 4 IO. 12

Lamps, Arr. 410. See also Luminaires; Hazardous (classified) locations Arc, po rtable, 520.61, 530.17 Auxiliary equipment, 4 10-IX Backstage (bare bulb), 520.47 Clothes closers, in, 410. 16 Electric discharge, 4 10.62(C), 410.104, 41 0-XII, 410XIII Fluo rescent, see Fluo rescent lun1inaires

Guards, see Guarding, guards Hand lamps, portable, 4 10.82 Incandescent, see Incandescent lamps Infrared, see Infrared lamp industrial heating appliances Motion picture projectors, 540.14, 540.20 Motion picture studios Film sLOrage vaults, 530.51 Stage, portable, 530.1 6, 530.17 Viewing, cutting rabies, 530.41 Ollldoor, location, 225.25 Pendant conductors, 4I0.54 Po rtable, see Ponable luminaires Stand, 520.68(A)(3), 530.1 8(G ) Definition , 520.2, 530.2 Theaters Border and p roscenium, 520.44 Dressing rooms, lamp guards, 520 .72 Festoons, 520.65 Footlights, 520 .43 Stage, arc la mp for, 520.61 Switchboards, pilot ligh ts, 5 20.53(A) Wattage marking, flush and recessed luminaires, 410 .120 Laundry Arc-fault circuit-interrupter protection, 210.12(A) C ircuit load, 220.52( B) Outlets Dwelling, 2 IO.I I (C) (2), 210.50(C), 210.52(F) Mobile ho mes, 550.13(D) (7) Receptacles, 210.8(A) (10) Laundry area, 21 0.8(A)(l0), 210.l 2(A), 2l0.52(F), 550.12(C), 550. 13( 0 ) (7), 550. 18 Definition , Art. 100 Leakage-current detectorinterrupte r, 440.65 Definiti o n, 440.2

70-875

NATIONAL ELECTRICAL CODE

LED ligh ting, Art. 41 0

Clothes closets, 410.16 Connection of luminaires, 410.24, 410.62(C) Feeder and branchcircu its, 410.68 Luminaire rating, 4I0.74(8) Mounting, 410.136, 410.137(8) Sign illumination systems Definition, 600.2 The rmal insulation installation, 410.l 16(8) Legally required standby systems, Art. 701 Capacity and rating, 701.4 Circuit wiring, 701- 11 Definitio n, 701.2 Ground-fault protection, 701.31 Grounding, 701.7(8) Overcurrem protection, 701- IV Signals, 701.6 Signs, 701.7 Sources or power, 701-111 Tests and maintenance, 701.3 Transfer equipment, 701.5 Wiring, 70 I.I 0 Lengths Branches from busways, 368.56( B) Conduit bodies, 314.71 Electrical metallic tubing, 358.120 Electrical nonmetallic tubing, 362.120 Enclosures, handhole, 314.71 Free conductors at outlets and s,vitches, 300.14, 424.43, 426.23(A) High density polyethylene condu it, marking, 353.120 Intermediate metal condu it, 342.120 Liquid tight flexible nonmetallic conduit, 356.120 Open wiring in nonmetallic flexible tubing, 398.15(A) P,,11 andjunction boxes, 314.28, 314.71 Re inforced thermosetting resin conduit, 355.120 Rigid metal conduit, 344.120 Rigid polyvinyl chlo ride conduit, marking, 352.120 Space-heating cable, nonheating leads, 424.34 Surface metal raceways, 386.120 Surface nonmetallic raceways, 388.120

70-876

Taps, 210.l 9(A) ( 4) Ex. 1, 240.21, 240.92(8) Motor branch circuit, 430.53(0) Motor feeders, 430.28 Life safety branch Definition, 517.2 Essential electrical systems, 517.25, 517.29 IN,5 17.31 to5 17.33, 517.35, 517.40 IN No. 2, 517.42 (A), 517.43, 517.44 Life support equipment, electrical, 517.45(8) De finition, 517.2 Lighting Battery-powered lighting units, 5 I7.63(A) Definition, 517.2 Branch circui ts, calculation of load, 220.12 Cove, 410.18 Decorative, 410- XV, 590.3(8 ), 590.4()) Ex., 590.5 Emergency, Art. 700; see also Exits, emergency lighring for Exits, see Exits, emergency lighting

Feeders, calcu lation of load, 220.42, 220-IV Festoon, see Festoon ligh ting Fixn1res, see Luminaires

Mobile h omes and manufactured homes, 550.12(A) Modular data centers, 646-111 Outlets, see Lighting outlets Outline, see Outline lighting Park trailers, 552 .46(8 ) ( I), 552.47 Sensitive electronic equipmem, 647.8 Swi mming pools, see S,vimming pools, fountains, and similar installations Systems, see Lighting systems, 30 volts or less Track, see Lighting track Lighting assembly, cord--and-plugconnected Definition, 680.2 Lighting hoist, stage, 520.40 Definition, 520.2 Lighting o utlets, 210.70, 314.27(A), 410.36(A), 410-111 Definition, Art. 100 Lighting systems, 30 volts or less, An. 411 Branch circuit, 4 11.7

Hazardous (classified) locations, 411.8 Listing required, 411.4 Location requirements, 411.5 Secondary circuits, 411.6 Lighting track, 410-XIV Construction requirements, 410.155 Definition, Art. I00 Fastening, 4 10.1.54 Heavy-duty, 410.153 Installation, 410. 151 Load calculations, 220.43 (B) Lightning (surge) arresters, see Surge arresters Lightning protection systems, see Surge (lightning) protection Lights, see also Lamps; Lighting; Luminaires

Border, 520.44 Cables for, theaters, 520.44(C) Definition, .520.2 From railway conducrors, 110.19 Scenery, theaters, halls, 520.63 Strip, 520.64 Defi nition, 520.2 Limited care facilities, see also Health care facilities Definition, 517.2 Essential electrical systems, 5 17.40, 517.42 Limited finishing workstations, 516.5 (0 )(5) Definition, Art. I00 Line isolation monitor, 517.160(8 ) Definition, 5 17.2 Lint, flyings, Art. 503, Art. 506 Liquid immersion "o", 505.S(E) Definition, An. 100 Liquid tight flexible metal conduit ('fype LFMC), Art. 3.50 Bends, 350.24, 350.26, Chap. 9, Table 2 Construction specifications, 350-III Couplings and connecrors, 350.42 Definition, 350.2 Dimensio ns, Chap. 9, Table 4 Grounding and bonding, 350.60 Installation, 350-11 Listi ng, 350.6 Marking, 350.120 Maximum number of conductors and fixture wires, Tables C.8 and C. SA Number of conductors, Chap. 9, Table 1

Number of conducrors and cables, 350.22 Securing and supporting, 350.30 Size, 350.20 Splices and taps, 350.56 Uses not permitted, 350.12 Uses permitted, 350. 10 Liquidtight flexible nonmetallic conduit (Type LFN C), Art. 356 Bends, 356.24, 356.26, Chap. 9, Table 2 Construction specifications, 356-111 Couplings and connectors, 356.42 Definition, 356.2 Dimensions, Chap. 9, Table 4 Grounding and bonding, 356.60 Installation, 356-11 Listing, 356.6 Marking, 356.120 Maxim um number of conductors and fixture wires, Tables C.5 through C.7A Number of conducrors o r cables, 356.22 Securing and supporting, 350.30, 356.30 Size, 356.20 Splices and taps, 356.56 Trimming, 3.56.28 Uses not permitted, 356.12 Uses permitted, 356.10 Listed Definition, Art. 100 Live parts , see also Enclosures; Energized parts; Guarding, guards Arc-flash hazard warning, 110.1 6 Capacitors, 460.3(8) Definition, An. 100 Elevators, dumbwaiters, escalators, etc., 620 .4 Exposed, 110.26 Generators, protection, 445.14 Guarding, see Guarding, guards Lampholders, 410.5, 410.1 42 Lamp terminals, 410. 142 Lighting systems, electric discharge, 410.130(8), 410.140(C) Luminaires and lamps, 410.5, 410.140(C) Metal ,vireways, 376.56(8 ) (4) Motion p icture and television stud ios, 530.15, 530.62 Over 1000 volts, 490.24, 490.35

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

Storage batteries, 480.l0(B) Thea ters, 520.7 Transformers, guarding, 450.8(C) In tunnels, 110.56 Loads

Appliances, ho usehold cooking, demand table, 220.55 Branc h circuits Calculatio ns, Art. 220 Maximum, 210.25, 220.18 Pe rmissible, 2 10.22 through 2 10.24, Table 2 10.24 Branc h circuits, calculations, Annex D Continuous, see Continuou s load De ma nd Clo thes dryers, 220.54 Ho useho ld coo king appliances, 210.21 (B) (4), 220.55 Eme rgency systems, 700.4 (C), 700.1.5 Energy management system s, managed by, 750.30 Farm, 220--V Feeders, calculatio ns for, 215.2(A), An. 220, Annex D Electrified truck parking space equipment, 626.11 Marinas, boatyards, floati.ng buildings, and clocking facilities, 555.6 Mobile ho me parks, 550.31 Mobile ho mes, 550.18 Ind uc tive Signs, 600.6(B) Switches, types, racings, 404. 14 Marinas, boatyards, floating b uild ings, and clocking fac ilities, 555.6 Mobile ho me parks, .550.3 l Mobile ho mes, 550.18 Motors, conductors, 430--11 Nonlinear De finitio n, Art. 100 Recreatio nal vehicles, 551.31 Service, calculatio ns for, Ar t. 220 Stage equip me nt, circuit loads, 520.4 1 Location boards, 530.1 5( 0 ), 530.18(D) De finitio n, 530.2 Locations

Air-conditio ning o r re frigerating equip ment, disconnecting means, 440. 14

2020 Edition

Audio signal processing, amplificatio n, a nd re p rod uctio n equipment, 640.3 Cap acitors, 460.3(A) Communications circuits Protective devices, 805.90( B) Raceways, 800. I 13( B) th rough (L)

Co mmunity antenna televisio n and radio distribution system s, 820--I I Crane a nd hoist disconneCLing means, 6 10-IV Damp o r wet, see Damp o r wet locatio ns De finition, Ar L 100 D,y, see Dry locatio n Electric d ischarge lig hting transformers, over 1000 volts, 410.144 Elevator motor disco nnecting means, 620.51 (C) Essential electrical system, health care faci lities, 517.30 (C), 517.41 (C) Foreig n pipes, a ccessories, transforme r vaults, 4.50.47 Ge ne rators, 445.10 Gro und ing connectio ns at electrodes, 250.68 Hazardo us, see Hazardo us (classified) locatio ns Intrinsically safe equipment, 504.l 0 (B) Lamps, ou tdoors, 22.5.25 Luminaires, 410-II Mobile hom es d isconnecting means a nd bra nchcircuit p rotective equipment, .550.11 Mo tion picture p roj ectio n equi p ment, 540.11 Motor d isconnecting means, 430.102 Motor feede r taps, 430.28 Ex. Motors, 430.14 Optical fibe r cables, 505.9 (F), 770. 113( B) t hroug h (J ) Outlet boxes and conduit boxes, 314.29 Overcurrent d evices, 240-II Overhead service, 230.54 Pa nelboards, clamp o r wet, 408.37 Recreatio nal vehicle disconnecting means a nd d istri butio n panelboard, 551.45( B) Resisto rs a nd reactors, 470.2

NATIONAL ELECTRJCAL CODE

Service disco nnecting means, 230.70(A), 230.72(A) Ex. Service o vercurre nt p rotectio n, 230.91 , 230.92 Shooting, 530.l 8(E), 530 .18( F) Definiti on, 530 .2 Sig ns, electric, 600.9, 600.1 0, 600.2 1, 600.33(A), Table 600.33(A)(a), 600.42(G), 600.42(H ) Sig n switches, 600.6(A) Splices a nd taps Auxilia ,y gu tters, 366.56 Wireways, 376.56, 378.56 Surge arresters, 242.22 Surge protective d evices, 242.46 Swimming pool j unctio n box a nd transforme r e nclosures, 680.24 Switch boards, 408.1 6, 408. 17, 408.20 Switches in d amp o r wet locations, 404.4 System grounding connections, 250-II Transforme rs and vaults, 450.1 3 Ve ntilatio n o penings for tra nsforme r vaults, 450.45(A) Wet, see Wet locatio ns; Damp or wet locations Locked rotor motor current

Cod e letters, 430.7 (B), Table 430.7 (B) Conversio n, Table 430.251 (A), Table 430.251 (B) He rmetic refrigerant motorcom pressors, 4 40.4(A) Locknuts, double, required

Hazardous (classified ) locatio ns, 501.30(A), 502.30 (A), 503.30 (A), 505.25 (A), 506.25 (A) Mobile homes, 550.1 5( F) Over 250 volts to ground, 250.9 7 Ex. Recreatio nal vehicles, 551 .47 (B) Loudspeakers

Definiti o n, 640.2 In fire-resistant

constructio n, 640.2.5 Permanent

installa tio ns, 640.2 1(B), 640.25 Protectio n of, 640.4 Te mpo rary installa tions, 640.42 (B) Low-voltage circuits, see also

Remote-control,

signaling, and powerlimited circuits Definiti on, 551.2 Less than 50 volts, Art. 720 Modula r data cente rs, 646.20(A) Park trailers, 552.l 0 Low-voltage fixed electric spaceheating equipment,

424-X Low-voltage lighting systems, see

Ligh ting systems, 30 volts o r less Low-voltage suspended ceiling power distribution syste ms, Art. 393

Conductor sizes and types, 393.1 04 Connectors, 393.40 (A) Constructio n specificatio ns, 393-II l Definiti ons, 393.2 Disconnecting mea ns, 393.2 I Enclosures, 393.40 ( B) Grounding, 393.60 Installatio n, 393-II Listing, 393.6 Overcurrent p rotectio n, 393.45(A) Securing and supporting, 393.30 Splices, 393.56 Uses no t permitted, 393 . 12 Uses pe rmitted, 393.10 Lugs

Connectio n to termina ls, 110. I 4(A) Listed type at electrodes, 250.70 Luminaires, Ar t. 410. See also Hazardo us (classified) locatio ns Adjustable, 4I0.62( B) Agricultural build ings, 547 .8 Autotransformers Ballasts supplying fluo rescent luminaires, 410.138 Supply circuits, 210.9, 215.11, 220.1 8 Auxiliary equip men t, 410.1 37 Bathtubs, near, 410.l0( D), 550.1 4(0 ), 551.53(B) Boxes, canopies, pans, 4 10--III Bra nch circuits, 368. I 7(C), 410.24(A), 410.68 Computatio n o t: 210.l 9(A) ( 4), 220.12, 220. l4(O) Sizes, 220.1 8 Vo ltages, 2I0.6, 41 0.130 Clo thes closets, 410.16 Definitio n, 410.2 Combustible material, near, 410.11, 410.12,

70-877

NATIONAL ELECTRICAL CODE

410.23, 410.70, 410.l l 6(A) (2), 410.136 Connection, fluorescent, 410.24, 410.62(C) Consr.ruction, 4 10.155, 410-VII, 410- XJ Cords, flexible, see Cords, Flexible Damp, ,vet, or corrosive

locations, 410.1 0(A), 410.l0(B), 410.10(0) (2), 410.30(8) (1) Decorative lighting, 410-XY Definition, Art. 100 Dry-niche, 680.23 (C) Definition, 680.2 Ducts or hoods, in, 410.10 (C) Emergency, directly conr.rollecl, 700.24 DefiniLion, 700.2 Emergency systems, 700. 12 (1) (2), 700.24 Flat cable assemblies, luminaire hangers installed ,vitl,, 322.40(8) Fluorescent, see Fluorescent Jumina ires Flush, 410- X, 410-XI Fountains, 680.51 Grounding, 410-V Horticultural lighting, 410-XVI Indoor sporLs, mixed-use, and all-purpose facilit ies, use in, 410.I0(E) Inspection, 410.8 Listing, 4 10.6 Live parts, 410.5 Location, 410-11 Marking, 410.74(A) Motion picrure and television studios, Art. 530 Mounling, 410.136, 410.137 No-niche, 680.23(0 ), 680.24, 680.26(8 )(4) Definition, 680.2 Omlet boxes, 3 14.27(A) Outlets required, see Lighting outlets Overcurrent protection, wires and cords, 240.5 Park trailers, 552.l 0 (G), 552 .20(0 ), 552.54, 552.59 Polarization, 410.50 Po rtable, see Portable luminaires Raceways, 410.30(8), 410.36(E), 410.64 Rating, 410.74 Recessed, see Recessed lurninaires

70-878

Recreational vehicles, 551.20 (D), 551.53 Sensitive electronic equipment, 647.8(8 ) Showers, near, 410.10( 0 ), 550.14(0 ), 551.53(8) Show windows, 4 10. 14 Spray application, clipping, coating, and printing processes, 516.6(C), 516.6( 0 ), 516.37 Strip lightS, 520.64 Definition, 520.2 Support, 314.23( F), 355.12(8), 358.12, 362.12(2), 410IV, 50 l.l 30(A) ( 4) Swimming pools, spas, and similar installations, 680.6, 680.22( 8 ), 680.23, 680.26(8) (4), 680.33, 680.43( 8 ), 680.51, 680.62(F), 680.72 Theate rs, Art. 520 Wet-niche, 680.23(8) Definition, 680.2 WeL or clamp locations, in, 410. I0(A), 410.10(0) (2), 4 I0.30( 8 ) ( l)

Wiring, 410-VI Luminaire stud construction, 410.36(C) -M-

Machine rooms Branch circuits, lighting and receptacles, 620.23 Definition, 620.2 Guarding equipment, 620.71 Wiring, 620.21 (A) (3), 620.37 Machinery space Branch circui ts, lighting and receptacles, 620 .23 Definition, 620.2 Wiring, 620.21 (A) (3), 620.37 Machine tools, see lndus r.rial machinery Mandatory rules, permissive rules, and explanatory material, 90..5 Manholes, I IO- \/ Access, 110. 75 Covers, I 10.75( 0 ) Dimen sions, 110.75(A) Locatio n, I I 0.75 (C) Marking, 110.7.5(E) Obstructions, 110.75 (8) Conductors Bending space for, 110.74

Class 1, installation, 725.48( 8 ) (3), 725.1 36(F) Class 2, 3 installation, 725.133, 725. l 36(F) Over 1000 volts, 300.3(C) (2) (cl) Control circuits installed in, 522.24(8) (3) Fixed ladders, 110.79 Ventilation, 110.77, 110.78 Work space, 110.72, 110.73 Manufactured buildings and relocatable structures, Art. 545 Bonding and grounding, 545.11 Boxes, 545.9 Component interconnections, 545. 13 Definitions, 545 .2 Grounding electrode conductor, .545. 12 Protection of conductors and equipment, 545.8 Receptacle or switch witl1 integral enclosure, 545. l 0 Serv ice-entrance

conductors, 545.5, 545.6 Service equipment, 545.7 Supply conductors, 545.5 Wiring methods, 545.4 Manufactured homes, see also Mobile homes; Recreational vehicles Definition, 550.2 Manufactured phase Definition, 455.2 Marking, 455 .6(8) Manufactured wiring systems, An. 604 Construction, 604.100 Definition, 604.2 Installation, 604.7 Listing requirements, 604.6 Markings, 604. I00(B) Uses not permitted, 604.12 Uses permi ued, 604. 10 Marinas, boatyards, floating buildings, and docking facilities, Art. 555 Bonding, 555.6 Circuit breakers, 555.32 Connections, .555.30, 55.5.36 Cranes, 555.8 Definitions, 555.2 Disconnecting means, 555 .36 Distribution system, 5.55.5 Elecr.rical datum plane distances, 555.3

Enclosures, 555.31 Equipment grounding conductors, 555.37 Flammable liquids at, Fig. 515.3 Floating bu ildings, 555-111 Ground-fault circuit interrupters, 555.33( B) (I), 555.35 Ground-fau lt protection, 55.5.33(8)( I), 555.35, 555.53 Hoists, 555 .8, 555.9 Load calw lations, 555.6 Marina power omlets, 555.32 Definition, 555.2 Marinas, boatyards, and docking facilities, 555-11 Maximum voltage, pier power distribution systems, 555.5 Motor fuel dispensing stations, 514.3, Fig. 515.3, 555.11 Panelboards, 555.32 Railways, 555.8 Receptacles, 555 .6, 555.33, 555.35(A)(l) Repair fac ilities, 555.12 Service conductors, 555.50, 555.52

Service equipment, location, .555.4 S,vitches, 555.32 Transformers, 5.55.7 Wiring methods and installation, 555.34, 682.15(8) Markings, 110.21, 311.16; see also Identification; Marking under enl1ies for specific wiring and equijimenl Fielcl-applied hazard, 11 0.21 (B) Manufacmrer, 110.21 (A) Means of egress Battery rooms, 480.l0(E) Healtl1 care facilities, 517.33, 517.43(A), 517.43(8) Illumination, 517.33(A), 51 7.43(A) Mechanical execution of work, I 10. 12, 640.6, 720.l J, 725.24, 760.24, 770.24, 800.24, 830.24, 840.24 Medical office (dental office) Definition, 517.2 Me dium voltage cable (Type MV), Art. 31 I Ampacity, 311- IV Construction specifications, 311- 11 De finition , 311.2

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

Installation, 311-111 Marking, 311.16 Support, 311.40 Meeting rooms

Outlets, 210.65 Me mbrane enclosures

Definition, An. 100 Spray application operations in ,5 16-1\1 Messenge r-supporte d wiring, Art. 396

De finition , 396.2 Grounding, 396.60 Installation, 39~11 Messenger support, 396.30 Splices and taps, 396.56 Uses not pe rmicted, 396.12 Uses permitted, 396. 10 Messenger wire, 310.20, Table 310.20 Definition, Art. 100 Metal-clad cable (Type MC), Art. 330

Accessible attics, 330.23 Ampacity, 330.80 Be nds, 330.24 Conductors, 330.104 Construction specificatio ns, 330-111 Definition, 330.2 Equipment grounding conductor, 330. 108 Hazardous (classified) locations, 330.130 Installation, 330-11 Insulation, 330.112 Marking, 3 11.16 Sheath, 330.1 16 Single co nductors, 330. IO(A) (12), 330.3 1, 330.80 (8 ) Support, 330.30 Th rough or parallel to framing me mbers, 300.4(A), 330.17 Uses not permiued, 330. 12 Uses pe rmitted, 330.10 Me tal-enclosed switchgear, see Switchgear, metale nclosed Metal frame of building

Bonding, 250. 104, 2.50.194 Gro unding e lectrode, 250.30(A) (8), 250.52(A) (2), 250.68(C) Metal g utters, see Auxiliary g uuers Metal outlet boxes, see Boxes, metal

2020 Edition

Metals

Corrosion, protection against, see Protection, Corrosion Dissimila,; 110.14, 250.70, 342. 14, 344.14 Fe rrous, 300.6 (A), 300.20 Me tal s iding, grounding of, 250.l 16 IN Me tal wireways, see Wireways,

metal Me tal working machine tools and plastic machinery, see

Industrial machinery Meters

Connection and location at services, 230.82, 230.94 Ex. 5 Grounding of cases, 250.174, 250.176 Grounding to gro unded circuit conducto r, 250.142(8 ) Ex. 2 Hazardous (classified) locations, 501.105, 502.150 Recreational vehicle site, 551.78( 8 ) Me ter socket enclos ures , see

Cabinets, cutout boxes, and meter socket enclosures Me tric e quivalents

Raceways, trade sizes, 300.1 (C) Me tric tutits of measure ment, 90.9 Microgrid interconnect devices , 705.70

De finition, 705.2 Microgrid &yste ms, 705- 11; see also

Direct current microgrid systems Definition, 705.2 Eme rge ncy systems, 700.12 (H ) Legally required stand by system s, 701.12(1) Mineral-insulated me tal-sheathed cable (Type MI), An. 332

Ampacity, 332.80 Be nds, 332.24 Boxes and fittings, 332 .40 Co nductors, 332.104 Construction specifications, 332- 111 Defin ition, 332.2 Equipment-grounding conducto rs, 332. 108 Installation, 332-11 Insulatio n, 332.II2 Sheatl1, 332 .II 6 Single conductors, 332.3 1, 332.80 (8 ) Support, 332.30

NATIONAL ELECTRJCAL CODE

Te rminal seals, 332.40(8 ) Thro ugh or parallel to framin g members, 300.4, 332 .I 7 Uses not permiued, 332.12 Uses permitted, 332.10 Mobile equipment

Definition, Art. 100 Mobile home lot

Definition, 550.2 Mobile home parks , Art. 5.50

Definitions, 550.2 Distribution system , 550.30 Electrical wiring system Definition, 550 .2 Feeder and service demand factors, .550.1 8, 550-111, Table 550.31 Minimum allowable demand factor, 550 .31 Mobile home service e quipment, 550.32 Service e quipment, 550.I , 550.1 6, .5.50.32 Definition, 550.2 Mobile homes, Art. 550. See also Park trailers; Recreational vehicles Accessory buildings or structures Definitions, 550.2 Applia nces, 550.12 (8 ), 550.1 2(D), 550.14, 550.1 5 (J), 550.1 8 Arc-fault circuit-interrupter protectio n, 550.25 Branch-circ uit protective e quipme nt, 550.1 I Branch ci rcuits, 550.II , 550.12 Calculations of loads, 550. 18 Communications circuits, 800.106 Definitions, 550.2 Disconnecting means, 550.II Expandable and dual units, wiring, 550.I 9 Feeder, 550.33 General requirements, 550.4 Ground-fault circuit interrupter, 550.13(8) Grounding, 550.16 Insulated neutral required, 550.I6 (A)(I) Luminaires, 550.1 4, 550.20 Multiple section, wiring, 550 .19 Nameplates, 550.11 (D) O ptical fiber cables, 770.106 Outdoor outlets, luminaires, air--

cooling e quipment, 550.20 Powe r supply, .550.10 Receptacle o mlets, 550. 13

Se,v ice equipme nt, 550.32 Definition , 550.2 Testing, 550.17 Wiring methods and mate rials, 550.15 Mobile X-ray equipment, 660.4 ( B), 660.2 1 Definition, 660.2 Modular data centers, An. 646 Definition, 646.2 Enclosures, cords and cables for connecting, 646.9 Equipment, 646- 11 Field-wiring compartments, 646.8 Lighting, 646-111 Nameplates, 646.5 O vercurrent protection, 646.6(8) Short-circuit current rating, 646.7 Supply conducwrs, 646.6 Workspace, 646- 1\1 Modules, s olar photovoltaic syste ms , IN Fig. 690.l (a),

690.7 (A), 690.8(D), 690.32, 690.43(A), 690.47(8), 690.51; see also AC modules and systems, solar photovoltaic systems; Solar photovoltaic systems Definition, 690.2 Mog ul base lampholders, 210.6(C) (4), 4 10.103 Monitor

Definition, 750.2 Monopo le circuits, 690 .7(C),

690.3 l (E) Definition, 690.2 Monorails, 555 .8, An. 610 Definition , 555.2 Moorings

Definition , 555.2 Motion picture and television s tudios , An. 530

Definitions, .530.2 Dressing rooms, 530-111 Feeder conductors, sizing, 530. 19 Film storage vault, 530- V Grounding, 530.20 Lamps, portable a rc, 530.17 Live parts, 530.15 Luminaires, portable, 530.1 6 Overcurrent protection, .530.18, 530.63 Portable equipme nt, 530.6 Definitio n, 530.2 Stage or set, 530- 11

70-879

NATIONAL ELECTRICAL CODE

Substations, 530---VI Viewing, cutting, and patching tab Ies, 530---IV Wiring Pe rmane nt, 530. l I Portable, 530.12 Motion picture projection rooms, see Projection rooms, motion picture Motion picture theaters, see Theaters Motor-circuit switches, 404.7, 404.13(0 ), 430.109(A) (1), 430.l l0(A) Ex., 430.11 0 (C) (2) Ex. Definition, Art. l00 Motor control centers, 430-\11 II Arc-flash hazard warning, I l 0. l 6 De finition, Art. 100 Gua rding live parts, l l 0.27 Illuminatio n at, l l0.26(O) Working spaces about, 110.26 Motor controUers, 430---\111 Defini tio n, 430.2, 620.2 Disconnecting means, 430.75, 430-IX, 430.227 Electrically operated pool covers, 680.27(B)( I ) Hazardo us (classified) locations, 50 1.1 l5, 502 .l I.5, 503 .l l 5 Marking, 430.8 Power conversion equipment, 430.131 Tunnels, 110.55 Motor fuel dispensing facilities, Art. 514. See also Hazardous (classified) locatio ns Circuit disconnects, 5 14. 11 Classification of locations, .5 l4.3 Equipme n t, 514.4, 514.7 Grounding and bonding, 5 14. 16 Mainte nance and servicing, 514.1 3 Marinas, boatyards, and docking facilities, 555.1 1 Sealing, 5 14.9 Unde rground wiring, 514.8 Wiring, .5 14.4, 514.7, 5 l4.8 Motor-generator arc welders, see We lde rs, electric Motor homes, see also Mobile homes; Recreatio nal vehicles De fini tio n, 551.2 Motors, An. 430 Adjustable speed drive and drive systems, 430 .88, 430---X Definitio ns, Arc. 100 Air-conditio ning units, Art. 440

70-880

Appliances, motor-driven, see Appliances Branch circui ts, 430---11 Adjustable speed drive systems, 430. 130, 430. l3 l Combination loads, 430.54, 430.63, 430. I 3 I O verload protection, 430---III Sh on-cirCLtit a nd gro und-fault protection, 430---1\1, 430. 130 Taps, 430.28, 430.53(0) Torq ue motors, 430.52( 0 ) Bushing, 430.13 Capacito rs, 430.27, 460.9 Circuit conductors, 430---11 Code leccers, Table 430.7(B) Conductors, 430---11 Adjustable speed drive system s, 430.122 Ampacicies, 430.6 Comb inatio n loads, 430.25 Continuous duty, 430.22 Direct-current moto r-rectifie r supplied, 430.22(A) Eq uipme nt grounding conductors, 250.122 (D), 430.245(C) Feeder demand factor, 430.26 Intermitte nt duty, 430.22(E) Moto r and other loads, 430.24 Several moto rs, 430.24 Single motor, 430.22 Small motors, 430.22(G) Wound rotor secondary, 430.23 Wye-start, delta-run, 430.22(C) Continuous duty, 430.32 Controller rating, 430.83(0 ) O verload protection, 430.32(A), 430.32(C) Wound-rotor secondary, 430.23 Control circuits, 430---VI Cord-and-plugconnected, 430.109(F) Curre n t, foll load, see Full-load current m otors

Curtain, theater, 520.48 De finitio ns, 430.2 Disconnecting means, 430.75, 430.95, 430---IX, 430. I28, 430.227 Electronically protected, 430.7 (A) (16), 430.32(A) (2), 430.32 (B) (2)

Definitio n, 430.2 Feeders Calculation of load, 220..50, 220---IV

Dema nd faetor, 430.26 Full-load curre n t, see Full-load current m otors Fuseholder, size of; 430.57 General, 430---1 Ground-faull protection, 430---IV, 430---V, 430. I30 Grounding, 250---VI, 430.12(E), 430.96, 430- XIII Grouped, 430.24, 430.42, 430.53, 430.87, 430.112 Ex. Guards for attendants, 430.233 Hazardous (classified) locations, 501 .1 25, 502.1 25, 503.1 25, 505.1 6( E) (2), 505.22 Hig hest rated or smallest raced, 430.17 Industrial machinery, Arc. 670 lnte rmittentdmy, 430.22( E), 430.33 Liq uids, protectio n from , 430.1 1 Live parts, protection of, 430---XII Location, 430.14 Mainte nan ce, 430. l 4 (A) Marking, 430.7 Motor control centers, 430.98 Terminals, 430.9(A) Motor control cente rs, 430---VIII Multispeed, see Multispeed motors Overcurrent protection Branch circuits, 430-IV Combined overcurre nt protection, 430.5.5 Control circuits, 430.72 Equipment gro unding con d u ctors, 250.122(0 ) Motor control centers, 430.94 Motor feeders, 430- V Over l 000 voles, 430.225 Overheating, dust accumulations, 430.16 O verload protectio n, 430-III, 430..55, 430. 124, 430.225(B), 460.9 Ove rte m pe ra tu re protection, 430.126 Over 1000 volls, 430- Xl Pan winding, see Pan-winding motors Power conversio n equipment, 430.1 31 Rating o r settin g ofbranchcircuit short-circuit and ground-fault protective devices, Table 430.52 Restarting, automatic, 430.43 Short-circuit protection, 430---IV, 430---V, 430.130

Speed limitations, 430.89 Starting, shunting, 430.35 Swimming pools, fountains, and similar

installations, 680.21, 680.27(B)(l) System isolation equipmen t, 430. 109(A) (7) Definition , 430.2 Tables, 430-XIV Taps, 430.28, 430.53(0 ) Terminal h o usings, 430.1 2, 430.245(A) Terminals, 430.9 Three overload units, Table 430.37 Torq u e motors Branch circuits, 430.52( 0 ) Controller rating, 430 .83(0 ) Disconnecting means, 430. 109(G), 430.l l0 (B) Ultimate trip current, 430.32(A)(2) Ventilation, 430. 14(A), 430.16 Wiring diagram, Fig. 430. 1 Wiring space in enclosures, 430.10 Mounting of equipment, 110 .13, 314.23, 404.9(A), 404.10, 410---IV Moving walks, see Elevators, dumbwaiters, escalato rs, moving walks, p latform lifts, and stairway ch airlifts Multimode inverters, IN Fig. 690.l (b), 705.70(3) IN Multioutlet assembly, Art. 380 Calcula tio n of load, 220.14 (H) De finition , Art. 100 De flected insulated conductors, 380.23(A) Installation, 380---11 Insulated conductors, 380.23 Metal, through d ry partitions, 380.76 Pull boxes, use as, 380.23(B) Uses not permitted, 380.12 Uses permitted, 380.1 0 Multiple branch circuits, 2 l 0.7 Multiple circuit connections, grounding, 250.1 44 Multiple conductors (conductors in parallel), see Co nductors, multiple Multiple fuses (fuses in parallel), 240.8, 404.27 De finition , Arc. 100 Multispeed motors Bra n ch circuits, 430.22(B)

NATIONAL ELECTRJCAL CODE

202 0 Edition

INDEX

Locked-rotor code letters, 430.7 (B) (I) Marking, 430.7 (B) ( ! ) Overload protection, 430.52 (C) (4) Multiwire branch circuit, 210.4 De finition , An. 100 -N-

Nacelle, 694.40(A) De finition, 694.2 Nameplates, seeunder entries for specific wiring and

equifimenl Natural and artificially made bodies of water, electrical wiring and equipment for, An. 682

De finitions, 682.2 Grounding and bonding, 682-1 II Installation, 682-II Neat and workmanlike installation, 110.12, 720.11 , 725.24, 760.24, 770.24, 800.24 Neon tubing, 600.5(C) ( I), 600.32, 600.41 De finition , 600.2 Network interface unit De finition , 830.2 Network-powered broadband co1n1nunications

systems, An. 830 Buildings, 830-II, 830.93(A), 830- V Cables omside or entering, see Cables o mside and entering b uildings Installation me thods within, 830-V Underground circuits entering,

see

Underground circuil:S entering buildings Cables o m side a nd e nte ring buildi ngs, 830-II, 830.93 Aerial cables, 830.44 Between buildings, 830 .44 (E) On buildings, 830.44(F) Clearance from ground, 830.44( B) Final spans, 830.44(0 ) Over pools, 830.44(C) On poles, 830.44(A) Entrance cables, 830.40 Low-power circuil:S, 830.40 (B) Medium-power circuil:S, 830.40 (A) Cable types, 830. 179 De finitions, 830.2

2020 Edition

Grounding method s, 830-IV Listing, 830-VI Low-power cables, 830.133(A) ( ! ), 830. I79(C) Marking, 830.179 Mec hanical execution of work, 830.24 Med ium-power wiring, 830. l 33(A) (I), 830. 179( B) Power limitations, 830.15 Protectio n, 830-I II Grounding of metallic membe rs, 830.93 Physical damage, protection against, 830.44(F) (3), 830.47(C) Primary electrical protection, 830.90 Unde rground circuits entering buildings, 830.47 Direct-buried cables and raceways, 830.47 (B) Pools, unde r, 830.47(D) Underground system s, 830.47(A) Network terminal, 840.101 , 840.170 (A) Definition, 840.2 Neutral, see also Grounded conductors Bare, 230.22 Ex., 230.30 (A) Ex., 230.41 Ex. Busways, over 1000 voll:S, 368.258 Cartridge fuses a nd fuseholders, 240.60 (A) (2) Common Feeders, 2 I 5.4 Oul:Side wiring, 225.7(B) Conductor, 3 I0. 15(E), Annex B, Tables B.2 ( I ) through B. 2(1 0) De finit io n, Art. 100 Continuity o f; 300.13( B) Direct current generators, 445 .12 (D), 445.13 Electrode-type boilers, over l000 volts, 490.72(D), 490.72(E) Energy storage system s, 706.30(C) Feede r and service lo ad, 220.61, 220.82(A), 220.84(A), Annex D Floating buildings, conductors in, 555.55 Grounding of AC systems, 250.4, 250.24, 250.26, 250.36 DC systems, 250.4, 250.162( B)

NATIONAL ELECTRJCAL CODE

Hig h-voltage systems, 250.182 dirough 250.187 IdenLificaLion, An. 200 Installation, 200.4 Inte rconnected electric power production sources, 705.28(C) Messenger supported wiring, 396.30 (B) Multiple circuil:S, 200.4(B) Multiwire branch circuits, 210.4(C), 240.15(B) (1) Overcurrent relays and curre nt u·ansformers, 240.l00(A)(l) Point, 240.15 (B) (3), 240.50(A) (2) Definition, Art. 100 Direct curre nt generators, 445. 12 (D) Ranges and dryers, grounding, 210.19(A) (3) Ex. 2,250.140 Recreatio nal vehicle distribmion system, 551.54(C), 55 l.72( D) Switchboard, stage, 520.27, 520.27(A) (2), 520.53(B), 520.54(J ) Ungrounded conductors Overcurrent protection, 240.15( B) Tapped from g rounded systems, 210.1 0, 215 .7 Uninsulated, where permiued, 230.22 Ex., 230.30 (A) Ex., 230.41 Ex., 250.140 Ex., 338. I 0(B) (2) N eutral systems High-impedance grounded, see High-impedance grounded nemral systems Over l 000 volts, 200 .2(A), 2.50.182, 250. I84, 250. I 86 (A)( 4), 250. I 87 Nightclubs, Art. 518 Nipples, conduit, Chap. 9, Note 4 Noise, see Electrical noise Nonautomatic Definition, ArL 100 Nonconductive optical fiber cables, see Optical fiber cables Nonelectrical equipment, grounding, 250. 1 I6 Nongrounding-type receptacles, replacemenl:S, 2.50.1 30 (C), 406.4(D)(2) Nonincendive circuits, 500.7( F) Definiti on, Art. 100

N onincendive component, 500.7( H)

Definiti on, An. 100 N onincendive equipment, 500.7(G), 506.8(F) Definition , Art. I00 N onincendive field wiring, 501.10 (B)(3), 50 1.I 00( B)(6), 502.10(B)(3), 502.150( B), .503.10(A) (4), 504.30(A) ( l) Definition, An. 100 N onincendive field wiring apparatus, .500.8(C) (6) Definiti on, An. 100 Nonlinear load, 210.4(A) IN, 220.6 l (C), 310.15( E), 400.5 (A), 450.3 IN 2, 450.9 Definition, Art. 100 Nonmetallic boxes, see Boxes, no nmetallic Nonmetallic conduit, see Liquid tight flexible nonmetallic conduie Nonmetallic ' underground conduit with conductors Nonmetallic extensions, Art. 382 Bends, 382.26 Boxes and fittin gs, 382.40 Concealable, 382.15(B) Be nds, 382.26(B) Definition, 382.2 Flat conductors, 382. l 04 Listing, 382.6 Securing and supporting, 382.30(B) Uses permitted, 382.10 Construction specifications, 382-II I Definition , 382.2 Devices, 382.42 Exposed, 382.I0(B), 382.1 5 Flat conductors, 382.l 04 Installation, 382- 11 Insulation, 382.112 Listing requiremenl:S, 382.6 Marking, 382. 120 Securing and supporting, 382.30 Splices and taps, 382 .56 Uses not permitted, 382 .12 Uses permitted, 382 .10 Nonmetallic-sheathed cable (Types NM, NMC, and NMS), Art. 334 Accessible attics, 334.23 Ampacity, 334.80

70-881

NATIONAL ELECTRICAL CODE

Be nds, 334.24 Boxes and fittings, 334.40 Conductors, 334.104 Construction, 334-lll DefiniLion, 334.2 Devices of insu lating material, 334.40( 8 ) Devices wiLh integral e nclosures, 334.40 (C) Exposed work, 334. 15 Installation, 334-11 Insulation, 334.11 2 Listed, 334.6 Nonmetallic outlet boxes, 334.40(A) Sheath, 334.11 6 Support, 334.30 Through or parallel to framing members, 300.4, 334.17 Unfinished basemen LS, 334.15 (C) Uses not permitted, 334.12 Uses permitted, 334. IO Nonmetallic underground conduit with conductors (Type NUCC), ArL 354

Bends, 354.24, 354.26, Chap. 9, Table 2 Bushings, 354.46 Conductor terminations, 354.50 ConstrucLio n speci fi cations, 354-lll Defi nition, 354.2 Grounding, 354.60 Installation, 354-11 JoinLS, 354.48 Listing, 354.6 Marking, 3.54.1 20 Number of conductors, 354.22, Chap. 9, Table I Size, 354.20 Splices and taps, 344.56 Trimming, 354.28 Uses not permitted, 354.12 Uses permitted, 354.10 Nonmetallic wireways, see

Wireways, nonmetallic N onpower-limited control circuits

Amusement attractio ns, .522. I0 (B) Nonpower-limited fire alarm circuits (NPLFA), see

Fire alarm systems, Non power-limited circuiLS N ontamperable

Circuit breake rs, 240.82 Type S fuses, 240.54( 0 ) Number of services, 230.2

70-882

Disconnecting means, 230.71, 250.64( 0 ) Service-entrance conducLOr sets, 230.40 Nurses ' stations, 5 17.34(A) Definition, 517.2 Nursing homes, see also Health care faci lities De finition, 517.2 Essential electrical systems, 517.40, 517.42 -0 Occupancy, lighting loads, 220. 12,

Table 220.12 Office furnishings, Art. 60.5

De finitio n, 605.2 Lighting accessories, 605.6 Partitions, 605.3 Fixed-type, 605.7 Freestanding type, 605 .8, 605.9 Interconnections, 605.5 Wireways, 605.4 Official interpretations, 90.6 Oil (filled) cutouts, 490.2 1(D) Definition, An. 100 Oil-filled equipment, 490.3(A); see also Transformers, o ilinsulated Oil immersion, .500.7(1) Definitio n, Art. 100 Oil-insulated transformers, see

Transformers On-site power production facility, 695.3(A)

Definitio n, 695.2 On-site standby generators, 695.3(8)(2),

695.3( 0 ), 695.4(8), 695.6(C) Ex. 2 Definitio n, 695.2 Openings in equipment to be closed, 110.12(A),

312.5(A), 314.17(A) Open wiring on insulators, An. 398

Accessible attics, 398.23 Clearances, 398.19 Conductors, types permitted, 398. l04 Construction specificatio ns, 398-lll Definition, 398.2 Devices, 398.42 Exposed work, 398.15 Flexible nonmetallic mbing, 398.15(A) Installation, 398- 11 Securing and supporting, 398.30

Through or parallel to framing members, 398.17 Uses not perm itted, 398.12 Uses permitted, 398.10

Optical system with interlock "op sh", 500.7(N), 505.8(M),

506.8(M) Definition, Art. 100 Optional standby systems, Art. 702

Operable, externally

Definition, An. 100 Operating device

Definition, 620.2 Operating rooms, hospital, 5 17- 1\1

Emergency lighting system, Art. 700 Receptacles, 517. I 9(C) Optical fiber cables, Art. 770 Abandoned cable, 770.25 Defi nition, 770.2 Access to electrical equipment, 770.21 Applications of listed cables and raceways, 770.154 Within buildings, 770- 111, 770.1 00, 770-V Composite cable, 770.3(C) Definition, Art. 100 Conductive cable, 770.48(A) De finition , Art. JOO Definitions, Art. 100, 770.2 Fire alarm systems, 760.3(F) Grounding, 770.93, 770- 1\1, 770.114, 770.180, 840.93(A) Information technology equipment, 645.5 (E) (3) Installation, 770-V Listing, 770.113(A), 770-\11, 840. 170(8 ) Location, 505.9(F), 770. 113(8 ) through (J) Marking, Table 770.1 79 Mechanical execution of work, 770.24 Nonconductive cable, 770.48, 770.110(8 ) (2) Defi nitio n, Art. 100 Outsid e and entering bu ildings, 770-11 Premises-powered broadband communication

systems, Art. 840 Protection, 770-lll Raceway system, 770.26, 770.110, 770.l 13(E), 770.1 33, Table 770. l 54(a) Substitution cables, 770.154 Unde rground, 770.47 Optical network terminal (ONT), 840.93(C) Optical radiation, 500.8(G)

Definition, Art. 100 Equipment, .50.5.9(G), .506.9(G)

Capacity and raLing, 702.4 Circuit wiring, 702- 11 Definition, 702.2 Grounding, 702.7(8) , 702.11 Portable generaLOr grounding, 702.11 Signals, 702 .6 Signs, 702. 7 Transfer equipment, 702.4(8), 702.5 Organs

Electronic, Art. 640 Definiti o n, 650.2 Pipe, Art. 650 Conductors, 650.6 Defi nitions, 650.2 Grounding, 250.112(8), 650.5 Installation of conducLors, 650.7 Overcurrent protection, 650.8 Source of ene rgy, 650.4 Outdoor overhead conductors over I 000 volts, Art. 399

Definition, 399.2 Support, 399.30 Uses permitted, 399.10 Outdoor receptacles, 210.8(A) (3), 210.8(F), 210.52(E), 210(8)(4), 406.9, 680.22(A), 680.32 Outdoor spray area, 516.1 8(2) IN 1, Table 516.18 Definition, Art. 100 Outlet boxes, see Boxes Outlets

Appliance, 210.50(C) Commun ications ci rcuiLS, 805.156 Definition, Art. 100 Discontinued Cellular concrete floor raceways, 372.58 Cellular metal floor raceways, 374.58 Underfloo r raceways, 390.57 H eating, air-conditioning, and

refrigeration equipmenc, 210.63(A), 550.12(0) Laundry, see Laundry Lighting, see Lighting outleLS Load s, 220.14 Marina, 555.32, 55.5 .33(A) (I ) Meeting rooms, 210.65

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

Multioutlet assembly, see Multioutlet assembly Outdoor, 550.20, 551.53(C), 552.41 (E), 552.53(C), .5.52.59 Power De finitio n, Art. 100 Receptacle, 210.50 De fini tio n, Art. 100 Dwellings, where required, 210.52 Guest roo ms, g uest suites, and do rmitories, 210.60 Meeting rooms, 2 10.65 Required, 210-111 Vacuum assembly, central, 422.15 Outlet spacing, dwelling baseboard heaters, 210.52 Outline lighting, Art. 600. See also

Signs Bonding, 600.7( 8 ), 600.33( D) Branch circuits, 220. I 4(F), 600..5 De finitions, Art. l 00, 600.2 Grounding, conductor size, 600.7 (A), 600.24(8), 600.33(D ) Output circuits

Amplifiers, 640.9(C) Defin ition, 690.2, 692.2, 694.2 Fue l cell systems, 692.61 Heat gene rating equipment, 665 ..5 Interconnected e lectric power production sources, 705.11, 705.12 De finitio n, 705.2 Solar photovoltaic systems, 690.1, 690.6(8 ), 690.7 th rough 690. 9, 690.3 1 Wind turbines, 694.I 0 (A), 694.1 2(A), 694.30 (C) Output power, maximum, wind turbine, 694.12(A) (I )

De finitio n, 694.2

Size, 225 .5, 225.6, 225.50 Disconnection, 225.31, 225.51, 225.52 Ligh ting equipment installed outdoors, 225.7 Marinas, boatyards, floating bu ild ings, and docking facilities, .5.55.34(8 )(2) More tlian o ne building or structure, 225-II Access to occupants, 225.35 Access to overcurrent protective d evices, 225.40 Disconnect Construction, 225 .38 Disconnecting means, 225.31 Grouping of, 225.34 Location of; 225.32 Maximum numbe r, 225.33 Rating of, 225.39 Suitable for service equipment, 225.36 Identificatio n, 225.37, 230.2(E) Number of supplies, 225.30 Outdoor lampholders, 225.24, 225.25 Outdoor lamps, location o f, 225.25 Over 1000 volts, 225-III Physical damage, protectio n against, 225.20 Po int of attachment, 225. I 6(A) Spacing, open conducto rs, 225.14 Support Masts, 225.17 Open conductors, 225.12 Over buildings, 225.15 Vegetation, 225 .26 Wiri ng o n b uildings, 225.10 Outside of buildings

Separately derived system s, 250.30(C) Services considered, 230.6 Ovens, wall-mounted, see also

Cooking unit, counter-

Outside branch circuits and feeders, Art. 225

Calculation of load Branch circuits, 220-1, 220-II Feeders, 220-II I C ircuit entering, exiting, o r

attached to buildings, 225.11 Conductors Clearance Fro m b uildings, 225 .19, 225.61 From ground, 225.18, 225.60 Covering, 225.4

2020 Edition

n1ounted; Ranges

Branch circuits, 21 0.l 9(A) (3), 210.23(C), 220.55, Table 220.55 Connections, 422. 16(8 ) (3) Demand factors a nd loads, Table 220.55 Feeders, calculation of load, 220.82( 8 ) (3) Grounding, 2.50.140 O vercurrent

De finition, Art. 100

Branch ci rcu it, 240.24(8) (2) Definiti o n, Art. 100 Enclosed, 230.208(8 ), 312.8 Standard, 240.6 Overcurrent protection, Art. 240 Agriculmral build ings, 547.9 Air-conditioning a nd refrig·eraling

equ ipment, 440-II I Amusemen t attractions, 522.23 Appliances, 422 .11 Auxiliary gutters, 366.56 (D) Branch circuits, 2 10.20, 240.4, 250.32(8 ) (2), 250.32(C)(2), 520.52, 545.24(8) Busways, 368.17 Capacitors, 460.8(8), 460.25 Circuit b reake rs, 240-VI I Circuirs, r en1ote control,

signaling, and powe, limited Class I systems, 725.43 Class 2 and Class 3 systems, Chap. 9, Tables I l (A) and 11( 8 ) Communications systems, see 0

Communicatio ns

circuits, protection Conductors, see Con cl uctors Cords, flexible and tinsel, 240 .5, 400.1 6 Corel sets, extensio n, 240.5 Cranes and ho ists, 610- V Critical operations power systems, 708-IV Current-limiting Definition, 240 .2 Direct current microgricl systems, 712.70 Disconnecting and guarding, 240- IV Electric pipeline, vessel heating e quipment, 427.57 Electric space-heating equipment, 424.22 Electric vehicle cha rging systems, 625.4 1, 625.60(C) Electroplating systems, 669.9 Elevators, dumbwa iters,

escalators, etc., 620- VII Emergency systems, 700.10(8 ), IN Fig. 700.I0(B)(a), IN Fig. 700. 10( 8 ) (b), 700-VI Enclosu res, 230.208(8) , 240-111, 3 12.8 Energy storage systems, 706.31 Exciters, 445.l 2(A)

Feeders, 215.3, 250.32(8 ) (2), 250.32(C) (2) Feeder taps, 240.21(8), 240.92(8), 430.28 Fire alarm systems, 760.43, 760.45, Chap. 9, Tables 12(A) and 12(8) Fire pumps, 230.90(A) Ex. 4, 430.31, 695.3(C)(3), 695.3(H ), 695.4(8), 695.5(8), 695.5 (C) Fixed resistance and e lectrode incl ustrial process heating equipment Electrode-type boilers, 425.82 Resistance-type boilers, 425. 72 Supply conductors, 425. 19(A), 425.22(C) Fixture wires, 240.5, 402. 12 Flexible cords, see Cords, flexible Fuel cell systems, 692.9 Fuses and foseholclers, 240.8, 240-V, 240- Vl , 404.27 Generators, 445. I 2 Health care fac ilities, 517.17(8), 517.3 l (G) Induction and dielectric heating equ ipment, 665.11 Industrial control panels, 409.21 Industrial installation s,

supervised, 240-VIII Industrial machinery, 670.3(8 ), 670.4 (C) Instrumentation tray cable (Type ITC), 727.9 In tegrated electrical systems, 685.1 0 Inte rconnected electric power production sources, 705 .11 ( C), 705. I 2(A), 705.1 3(C), 705.30 Legally required standby systems, 70 1- IV Lighting track, 410.153 Location, 230.9 1, 230.92, 240.92, 240-II Low-voltage suspended ceiling power distributio n systems, 393.45(A) Mobile home, 550.1 1 Modula r data centers, 646.6(8) Motion p icture and televisio n studios, 530.1 8, 530 .63 Motors, see Motors Multiple fuses a nd circuit b reake rs (in paralle l) , 240.8, 404.27 Occupant access to, 240.24(8) Organs, 6.50.8

Overcurrent devices, see also

NATIONAL ELECTRJCAL CODE

O vercu rrent protection

70-883

NATIONAL ELECTRICAL CODE

Over 1000 volts, 110.52, 240- lX, 460.25, 490.52 Panelboards, 408.2, 408.36, 408.52, 408.54, 408.55 Ex. I Paralleled fuses and circuit breakers, 240.8, 404.27 Park trailers, .552. I0(E) Phase converters, 455.7 Portable distribution or termination boxes, rides, tents, and

concessions, 525.22(C) Recreational vehicle parks, 551.74 Recreational vehicles, 551.43, 55l.45(C) Remote-control circuits, Table 240.4(G), 72.5.41(A)(2), 725.43, 725.45 Sensitive electronic equipment, 647.4(A) Services Equipment, 110.16(8 ), 230-VI I Over 1000 volts, 230.208 Temporary installations, 590.8(8) So lar photovoltaic systems, 690.9 Storage battery prime movers, 480.6 Supervised industrial installations, 240-Vlll Supplementary, 240.10 Definition, Art. 100 Switchboards, 408.2 Television studios, see Motion picmre and television studios Te mpo rary installations, 590.8 Theaters Portables, conductors fo,; 520.68( C) Stage switchboards, 520.21(3), 520.25 (A), 520.50(C), 520.52, 520.62( 8 ) Transformers, 450.3, 450.4(A), 450.5(A) (2), 450.5(8) (2), 450.6(8) Vertical position, e nclosures, 240.33 Welders, e lectric, 630.12, 630.32 Wind electric systems, 694.12(8), 694. 15 X-ray equipment, 517.73, 660.6 O verhead gantry, 626.23 Definitio n, 626.2 Overhead service conductors, 230-II,

800.44 Clearances, 230.24, 230.26, 551.79

70-884

Definition, Art. 100 Insulation or covering, 230.22 Location, 230.54 Means of attachment, 230.27 Minimum size, 230.23 Po int of attachment, 230.26, 230.28 Supports over buildings, 230.29 Overhead spans, 225.6(A) Overload

De finition, Art. 100 Pro tection, see a.lso Overcurrent protection Cranes and ho ists, 610.43 Fire pumps, 695.6(C) Motors, motor circu its, and conu·ollers, 430-lll, 430.55, 430.225(8) , 460.9, 610.43, 620.61(8) O ver 600 volts

Circuit breakers, see Circuit breakers Conductor applications and insulations rated 600 volts, Table 310.4(A) Grounding, Art. 250 Portable cables, 400.30, 400.36 Switches, knife, 404.26 Temporary, Art. 590 Over 1000 volts, Art. 490 Ampacity, 310.15, 392 .80(8) Bending, 300.34 Bonding, 490.74 Boxes, pull and junction, 314-IV Busways, 368-IV Capacito rs, 460-1I Circu it conductors, 110.36 Circu it inte rrupting devices, 490.21 Conductors, 110-111, 300.39 Condu it bodies, 314-IV De finitions, Art. 100, 490.2 Direct current microgrid systems, 712- VII Distribution ClllOUts, 490.21 (C) Elecu·ic discharge lig hting, 4 10.140 Electrode-type boilers, 490-V Bonding, 490.74 Branch circuit requirements, 490.72 Electrical supply system, 490.71 Pressure and temperature limit control, 490.73 Elevation of unguarded live parts, I I0.34(E) Enclosed power switchgear and industrial contro l assemblies, 490-lll

Accessibility of energized parts, 490.35 Arrangemem of devices in assemblies, 490.31 Circuit breaker locking, 490.46 Circuit breakers interlocks, 490.45 Clearance for cable conductors entering enclosure, 490.34 Door stops and cover plates, 490.38 Enclosed equipmen1., 490-III Fused inte rrupter switches, 490.44 Gas discharge from imerrupting devices, 490.39 Grounding, 490.36, 490.37 Guarding, 490.32, 490.33 Inspection windows, 490 .40 Interlocks - interrupter switches, 490.42, 490.45 Location of industrial control equipment, 490.41 Service equipment, 490.47 Stored energy for opening, 490.43 Enclosure for e lectrical installations, I 10.31, 490-1 11 Enclosures, handho le, 3 14-IV Equipment, Art. 490 Fuses and fuseholders, 490.21(8) Grounding, Art. 250, 490.36, 490.37 Headroom above working spaces, l l0.32 Jllumination of working spaces, 1 I0.34(0) Indoor installatio ns, 110.31 Insulation shie lding, 300.40 Isolating means, 490.22 Load interrupters, 490.21 (E) Metal clad cable, 330. 112 (8 ) Mobile and portable equipment, 490-IV Collector rings, 490.54 Enclosures, 490.53 High-voltage cables for main power supply, 490.56 Overcurrem protection, 490.52 Power cable connections to mobile machines, 490.55 Moisture, mechanical protection, metalsheathed cables, 300.42 Oil-filled equipment and cutouts, 490.3(A), 490.21( 0 ) Outdoor installations, I 10.31

Omdoor overhead conductors, Art. 399 Outside branch circuits and feeders, 225- lll Overcurrent protection, 110.52, 240-IX, 460.25, 490.52 Protection of equipment, I I 0.34(F) Res istors and reactors, 470-II Separatio n, 490.24, Table 490.24 Se,vices, 230-Vlll Subs rations, see Substations Temporary, Art. 590 Tray installations, Art. 392 Tunnel installation, I 10-IV Voltage regulators, 490.23 Wiring methods, 230.43, 300- II, Table 300.50 -PPanelboards, An. 408

Arc-flash hazard warning, 110.1 6 Bonding, 408.40, 517.14, 517.! 9(E) Circuit directory, 408.4 Componem parts, 408.53 Damp or wet locations, 408.37 Definition, Art. 100 Distribution, 550.10(8), 550.11, 55 1.45, 55 1.54(8 ), 552.45, .552.55(8 ) Enclosure, 408.38, 545 .22(C), 545.26 General, 408.30 Grounded co nductor terminations, 408.41 Grounding, 408.40, 5 17.19(E) Installation, l 10.26(E) Marking, 408.58 Overcurrent protection, 408.36, 408.52, 408.54, 408.55 Ex.I Ratings, 408.6 Reconditioning, 408.8 Rela tive arrangement of switc hes and fuses, 408.39 Relocatable strucwres, 545-II Sensitive e lectro nic equipment, 647.4(A) Service equipmen t, 408.3(C), 408.36 Ex. 1,408.36 Ex.3 Spacing, minimum, 408.56 Support for busbars and conductors, 408.3 Wire-bending space, 408 .55 Working spaces about, 1 I0.26 Paralle led

Alternate sources, Art. 705

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

Circuit breake rs and fuses, 240.8, 404.27 Conductors, see Conducto rs, pa ralleled

Patient bed location, 517.18( 8 ),

Elevators, du1nbwaiters, escalators,

5l7.34(A), .5 17.80; see also Health care facilities De finitio n, 5 17.2 Patient care vicinity, 517.16(A) De fini tion, 517.2 Pediatric locations, 517.18(C)

etc., 620.12(A) (I ) Power production sources, An. 705 Park trailers, Art. .552. See also Mobile homes; Recreational vehicles Appliance accessibility and faste ning, 552 .58 Bonding, 552.57 Branc h circuits, 552.42, 552.46 Calculatio ns, 552.47 Combinatio n e lecu·ical systems, 552 .20 Conductors and boxes, 552.48, 552.49 Connection of terminals and splices, 552.51 Cord, 552.43(8), 552.44 De finition, 552.2 Distributio n panelboard, 552.45, 552.55(8) Grounded conductors, 552.50 Ground-fault circuit inte rrupters, 552.41 (C) Grounding, 552.55, 5.52.56 Low-voltage systems, .552.10, 552.60(8 ) Luminaires, 552. I0 (G), 552.20(D), 552.54, 552.59 Nominal 120- o r 120/ 240--volt systems, 552.60(A), .552-lV Omdoor o mlets, fixtures, equipment, 552.41 (E), .552 ..53(C), 552.59 Power supply, 552.43 Receptacle outlets required, 552.53 Receptacles, 551.20 (F), 5.52.20(F), 552.41, 552.48(K), 552.48( L) Switches, 552.52 Tests, factory, .552.60 Wiring methods, 552.48 Parts, see specific ty pe suc h as Live parts Part-winding motors, 430.4 Code letter markings, 430.7( 8 )(5) Conductors, 430.22(D) De finition, 430.2 Patching tables, motion picture, .530--lV Path, ground-fault current, 250.4(A) (.5)

2020 Edition

517.19 De finition, 517.2 Patient care space, 517.13,

Pendant conductors, lamps, 410.54 Pendants

Aircraft ha ngars, 513.7(8 ), 513.16(8 ) (] ) Anesthetizing locations, 517.61 (B) (3) Ex. 2, 5 17.6l (C)( l ) Ex. Bathrooms, 410. I 0(D) Clothes closets, 410. 16( B) Connectors, cord, 2 10.50(A) Dressing rooms, theater, 520.71 Flex ible cord, 3 l4.25(C), Table 400.4, 400.10 (A) ( I )

Rotary Definiti o n, 455.2 Stan-u p, 455 .21 Static Definition, 455 .2 Te rminal housings, 455.10 Photovoltaic systems, see Solar photovoltaic systems Physical damage, see Protection, physical damage Piers, see also Marinas, boatyards, floating b uildings, and docking facilities Definition, Art. 100 Fixe d, 514.3(C) (2) Definition, Art. 100 Floating, 514.3 Definition, An. 100 Pipe, gas As grounding

e lectrode, 250.52(8 ) (l) Pipe electrodes, 250.30 (A)( 4 ),

250.30 (A) (8), 250.52(A) ( ! ), 250.52(A) (5), 250.53, 250.66(A), 250.68(C), 250.70

Garages, commercial,

511.7(A) (2), 511.16(8) (I )

Hazardous (classified) locations, 501.130(A) (3), 501. 130(8 ) (3), 502. l30(A)(3), 502. 130 (8)(4), 503.130(C), 511.7(A) (2) Mobile hom es, 550.l4(C) Performance area

De finition, 520.2 Periodic duty

De finition, Art. 100 Permanent plaque or directory, 225.37,

225.52( F), 230.2(E), 705. 10, 706.21 (A) Permission, special

De finition, Art. 100 Permissive rules, 90 .5 ( B) Person, qualified

De finition, Art. 100 Phase converters, Art. 4.5.5

Capacitors, 455.23 Conductors, 455.6 Co nnection of single-phase loads, 455.9 Defi nition, 455.2 Different types ot; 455-11 Disconnecting means, 455.8, 455.20 Equipment gro unding connection, 455 .5 Marking, 455.4 Overcurrent protection, 455.7 Power interruption, 455 .22

NATIONAL ELECTRJCAL CODE

Pipe heating

Cable outlet Mobile home, 550.1 3(E) Park trailer, .552.41 ( D) Cord-and-plug connected assembly, 422.50 Pipeline , see also Fixed electric heating equipment for p ipelines and vessels Definition, 427.2 Pipe organs, see Organs, pipe Piping systems, bonding, 250. 104 Plants

Bulk storage, Art. 515 Cleaning a nd d yeing, 500.5(8 ) ( I ), Art. 50 I, Art. .505 Clo tl1ing manufacturing, 500.5( D), Art. 503, Art. 506 Plate electrodes, 250.52(A) (7), 250.53, 250.66(A) Platform lifts, see Elevators, dumbwaite rs, escalators, moving walks, platform lifts, and stairway cha irlifts Plenwns, 300.22 Definitio n, Art. 100 Wiring in, 300.22 CATV coaxial cable, Table 820.1 79 Communications

ci rcuits, Tables 800.154 (a) mro ug h (c),

800.l 79(A), 800.182(A), 805.I 70(C) Fire alarm systems, 760.3(8 ), 760.53(8 )(2), 760. l 35(C) Non-power-limited fire alarm circuits, 760.53( 8 ) (2) Optical fiber cables, Table 770.1 54(a) Re mote control, signaling, and power-li mited circuits, 725.1 35(C), Table 725. 154 Pliable raceways, 362.2 Plugging boxes, motion picture studios, 5 30.14,

.530. l 5(D), 530.l 8(E), 530.18(G) Defi nition, 530.2 Plugs, attachment, see Attachment plugs Point of entrance

Definition, 770.2, 800.2 Polarization

Appliances, 422.40 Connections, 200.11 Luminaires, 410.50 Plugs, receptacles, a nd connectors, 200. I0(B) Po rtable handlamps, 410.82 Receptacle adapters, 406. I0( B) (3)

Screw-;;he ll-type lampholders, 410..50 Poles Communications

wiring, 800.44(A) Coaxial cables, 820.44(A) Network-powered broadband communicatio ns cables, 830.44(A) Conductors Climbing space provided, 225.1 4( D) Protection against physical damage, 225 .20 Optical fiber cables, 770.44(A) Signs o n, 600.5(D) (3) Supporting luminaires, 410.30 (B), 410.64 Wind turbines supported by, 694.7( F) Pool covers, see Covers Pools, see also Swimming pools, fountains, and similar installatio ns Definitions, 680.2 Porches, receptacles for, 2 l0.52(E)(3) Portable appliances, 550.1 8(A) (2)

Definiti on, 550.2

70-885

NATIONAL ELECTRICAL CODE

Portable equipment

Audio signal processing, amplification, and reproduction equipment, 640- 111 DefiniLio n, 640.2 Definition, Art. 100, 520.2, 530.2 Disconnecting means, 5 17.17(C) Double insu lation, 250.1 14 Ex. Electric vehicle supply equipment (EVSE), 625.17(C)( l ), 625.44(A) Definit ion, 625.2 Electrolytic cells, 668.20, 668.21, 668.30 Fire alarm sysLems, 760.135(.l) Generators, 250.34, 708.20( F) Grounding, 250.114, 250.138 Conductor size, 250.122, Table 250. 122 High-voltage

equipment, 250.188, 250.190 Signs, 600.3, 600.4( F) Ex., 600.7(A)(l) Ex., 600.9(B), 600.10 Stage and slLidio, 520.5( B), 520- V, .530.6 DefiniLion, 530.2 X-ray, 660.4( B), 660.2 1 Definition, 660.2 Portable handlamps, 410.82 Portable luminaires, 4 10.82, 513.l 0(E) (1), 515.7 (C) Arc lamps, 520.61, 530.1 7 Flexible cords for, Table 400.4, 400.10 Handlamps, 410.82 Hazardous (classified) locations, 50 1.1 30(B)(4), 502. 130( B)(I), 503.130( 0 ), 51 l.4(B) (2), 516.6( 0 ) Live parts, 410.5 Motion p icture slLidios, in, 530.16 Show windows, showcases, 400. 15 Ex. 2 Spray application, dipping, coating, and p rinting processes, .; 16.6(0 ) Stage eq uipment, 520.68(A) (4), 530.16, 530.17 Portable power distribution unit, 520.62, 525.22

Defi nition, 520.2 Portable structures, 525.6, 52.5.11

Clearance to, 525.5 (B) De fi nition, 525.2 Disconnecting means, 525.21 (A)

7 0-886

Equipment bond ing, 525 .30 Portable wiring, 525 .21 (B) Portable switchboards, theater stages, 520-1\/ Portable wiring

Motion picwre studios, 530.12 Tents and concessions, 525.21 ( B) Positive-pressure ventilation, .500.5( B) (2),

500.7( 0 ). 501.125(A), 505.8( B), 506.8(B) Powder filling "q", 505.S(H ) Definition, Art. l00 Power, emergency systems, see

Emergency systems Power and control tray cable (Type TC), Art. 336

Ampacity, 336.80 Bends, 336.24 Conductors, 336. 104 Construction specifications, 336-111 Definition, 336.2 Installation, 336- II J ackel, 336.ll 6 Marking, 336.120 Support, 336.10(7) Uses not perm iued, 336.12 Uses permiued, 336. IO Power distribution blocks, 376.56(B) Power-limited circuits, see Remote-

control, signaling, and power-limited circu its Power-limited control circuits

Amusement atLraCLions, 522. I0(A) Power-limited fire alarm circuit (PLFA), see Fire alarm

systems, Power-limited ci rcu its

Power-limited tray cable (Type PLTC), 725.135, 725.154

Class I, Division 2 locations, 501.I0( B) ( I) Definition, Art. 100 Marking, 725.l 79(E) Power outlets, see Outlets Power production equipment, see

also Fuel cell systems; Generators; Solar phoLOvolcaic sysLems; Wind e lectric systems Definition, Art. l00 Power production sources, see

lmerconneCLed eleCLric power production sources

Power source

Premis es wiring (system)

Alternate, 424.101 (B), 51 7.31 (F), 517.35, 551.33, 700.3(F), 750.20; see also Critical operations power systems; Generators Defin ition, .5 17.2 Emergency systems, 700.3(F), 700---111 Photovoltaic, identification of, 690.56 Power supply

Information technology equipment, 645.5 Low-voltage suspended ceiling power distribution sysLems Defin ition, 393.2 Mobile homes, 550.10 Relocatable structu res, 545.22 Supervisory control and data acquisition

Definition, Art. 100 Pressure (solderless) connectors, 250.8 (3),

250.70 Definition, Art. J OO Pressure controls

Electrode-type boilers, over 1000 volts, 490.73 Fixed industrial process electrode-type boilers, 425.84 Fixed industrial process resistance-type boilers, 425.74 Pressu rized

Definition, Art. J OO Prevention of fire spread, see Fire

spread Primary pad, 625.101, 625.102

Definition, 625.2 Prime movers Batteries, overcur rent

(SCADA), An nex G Defin ition, 708.2 Power

Electrified Lruck parking spaces, 626.25 Recreational vehicles, 5.51 .44, 551.46, 55l.54(A) Defi nition, 551.2 Preassembled cable in nonmetallic conduit, see Nonmetallic

underground condu it wiLh conduCLors Premises

Definition, 800.2 Premises communications circuits, 840. I70(E)

Definition, 840.2 Premises community antenna television circuits, 840.l 70(F)

Definition, 840.2 Premises-powered broadband co1n1nunication systems, Art. 840

Cables outside a nd entering bu ild ings, 840---11 Definitions, 840.2 Grounding, 840.93, 840- IV Installation within bu ild ings, 840---V Listi ng, 840- Vl I Premises powering of

protection, 480.6 Definition,Arr. 100 Generators, emergency shmdown, 445.18 Printing processes, Art. .516 Process seal

Definition, Art. 100 Product safety standards, Annex A Projection rooms, motion picture, Art. 540

Audio signal equipment, 540---IV Definitions, 540.2 Projectors, nonprofess ional, 540---III Defin ition, 540.2 Listing, 540.32 Projection rooms, .540.3 1 Projectors, professional type, 540- II Conductor size, .540. 13 Conductors on hot equipmenL, 540. 14 Defin ition, 540.2 Flexible cords, 540.15 Listing, 540.20 Location of equipmenL, 540.l l Marking, 540.21 Projector room, 540. IO Work space, 540.1 2 Prosce nium

Definition, 520.2

communications

equipment over con1munications

cables, 840---VI Protection, 840-111 Underground circuits entering bu ild ings, 840.47

Protected optical radiation "op pr", 500.7(M), 505.8( L),

506.8(L) Definition, Art. 100

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

Protection Combustible material, appliances, 422.17 Communications systems, see Communications circuits Community antenna television and radio distribution systems, 820.93, 820.100(8 ) Corrosion Aluminum metal equipment, 300.6(8 ) Boxes, metal, 3 12.l0(A), 3 14.40(A), 3 14.72(A)

Cable trays, 392. l0(D ), 392.l00(C) Conductors, 3 10.l0 (F) De icing, snow-melting equipment, 426.26, 426.43 Electrical metallic tubing, 3.58. I 0 (8 ) Flat conductor cable, 324.101 General equipment, 300. 6 Intermediate metal conduit, 342 .10(8 ) and

MoLOr overload, 430-III, 430.55, 430.225(8)

Inte rmediate metal conduit, 342.l0( E)

Service-entrance cable, 338.12(A)( I )

Motor ovenem perature, 430.126

Irrigatio n machines, 668.30 (E) Lamps, electric discharge lighting, 4I0.145 Lighting track, 410.151 (C) (1) Liquicltight flexible metal conduit, 350. I 2 Liq uicltight flexible nonmetallic conduit, 356.12(1) Live parts, l 10.27( 8 )

Service-entrance conclucLOrs, 230.50 Service-lateral conclucLOrs, 230.32 Space-heating systems, 424. I 2(A) Surface raceways, 386.12(1), 388.12(2)

O vercurren t, see O vercurren t

protection O verload, see Overload Park traile rs, wiring, 552.1 0 (C) (I), 552.48 Physical damage Agricultural buildings Luminaires, 547.8(8 ) Wiring, 547.5(E) Armored cable, 320.12, 320.1.5 Audio signal processing, amplification, and re production equipment, 640.45 Busways, 368.l 2(A) Cabinets, cmom boxes, and meter socket enclosures, 3 12 .5 Conducto rs, 250.64( 8 ), 300.4, 300.50 (C) Communications systems, 800. I00 (A) (6) Network-powered broadband communications cable, 830.44(F) (3), 830.47(C) Optical fibe r cables, 770. I00(A) (6), 840.47(A) (3) Radio and television

(D )

Metal-clad cable, 330.12(2), 330.11 6 l\'ietal equipment, 300.6(A), 300.6(8), 312. I 0(A) Mineral-insulated metalsh eathed cable, 332 .12(2) Mobile home power supply cords, 550.l0( H ) Power and control tray cable, 336.10(8) Rigid metal conduit, 344. 10 (8) and (D) Storage batte ries, 480.4(A) Strut-type channel raceways, 384.l00( B) Underfloor raceways, 390.12 Ground fau lt, see Ground-fault p rotection Ground-fau lt circuit inte rru pter, see Groundfau lt circuit interrupters Hazardous (classified) locations, 500.7, 505.8, 506.8 Liquids, motors, 430. I l Live parts, 445. 14, 450.8(C) Luminaires and lamps,

conductors a nd insulation for, 410.56 Marinas, boatyards, and clocking facilities, wiring, 555.34(B) ( 4) Mobile home powe r supply cords, 550.I0(G), 550.I0(H)

2020 Edition

receiving

statio n, 8 10.21 (D ) Cords, flex ible, 400.1 2(7), 400.17, 640.45 Cri tical operations power systems, 708. I0(C) ( I ) Electrical metallic tubing, 358. 10(E) Elecu·ical nonmetallic wbing, 362.1 2(8) Electric signs, 600.33(C), 600.4l (D) Emergency system, 517.31 (C) (3) Fire alarm

systems, 760. 130( 8 ) ( I ) Fixed resistance and electrode industria l p rocess h ealing equipment, 425. 12(A) Flat cable assemblies, 322.10 (3) Flexib le metal conduit, 348.12(7) Flexib le metallic rnbing, 360.12(5) Informatio n technology equipment cables, 645 .5( 0 )

NATIONAL ELECTRJCAL CODE

Low-voltage suspended ceiling power distribution systems, 393.12(3) Ltm1 inaires, 410.1 0( E), 501.130(A)(2), 501.1 30 (B) (2), 502. I 30 (A)(2), 502.1 30 (8 )(3) Messen ger-supported wiring, 396. I 2 Metal;;lacl cable, 300.42, 330.12 Mineral-insulated m etalsh eathed cable, 332.10( 10), 332.1 2(1) Multioutlet assembly, 380.12(2) Nonmetallic-sh eath ed cable, 334.15( 8 ) Open con cl uctors and cables, 230.50(B) (2) Open wi ring, 398.15 (A), 398.1 5(C) Organs, 650.9 Overcurrent devices, 240.24(C), 240.30 (A) Park trailer wiring, 552.I0(C) (I ), 552.480) Power and control tray cable, 336.1 0(7), 336.1 2(1) Raceways, 300.5(0 )(4), 300.50 (C) Recreatio nal vehicle park unde rg round branch circuits and feede rs, 551.80(B) Rec reational vehicle wiring, 5.5 1.47 Reinforcing thermosetting resin conduit, 355.l 2(C) Remote-control circuits, 725 .3 1( B) Resistors and reactors, 470. I 8(A) Rigid metal conduit, 344.1 0( E) Rigid polyvi nyl chloride conduit, 352. I 2(C)

Swimming pools,junction boxes, 680.24(C) Transformers, 450.S(A) Tunnels, I 10.51 (C) Type P cable, 337.12 (1), 337 .30 UF cable, 340.12 (10) U nderground installations, 230.32, 230.50(A), 300..5(0) and (J) Wireways, 376. 12( I ), 378. I 2( I ) Thermal protection, see The rmally protected ( th ermal protection) Type of protection "n", 505.8( D) Definition, Art. 100 Protective devices, see Arc-fault circuit in terrupters;

Circuit breakers; Fuses; Ground-fault circuit inte rrupte rs;

Overcurrent protection Protective equipment, see Guarding, guards Protectors, commwtications systems, see Communications circ uits Public address systems, Art. 640 Public assembly places, see Assembly occupancies Pull boxes, see also Boxes; J unctio n boxes Accessibility, 314.29 Construction specifications, 314.72, 314-III Gutters, auxiliary, used as, 366.58( 8 ) Multio utlet assem blies used as, 380.23( B) Nonmetallic wireways used as, 378.23( B) O ver 1000volts,314--1\/ Sizes 4 AWG and larger conducLOrs, 314.28(A) 6 AWG and smaller conducLOrs, 3l 4. l 6(C) (l )

O ver l000 volts, 3 14.71 Pwnps, see also Fire pumps

70-887

NATIONAL ELECTRICAL CODE

Energy storage systems, fl ow banery, 706.44 Grounding, water

pumps, 250.1 12 (L), 250.I I2(M) Pool Double insulated, 680.21 (B), 680.3 1 Motor replacements, 680.2 1 (D) Storable pools, 680.31 Purged and pressurized, 500.7 (0 ) , 501.125(A), 505.S(B) Definition, An. 100

-QQualified person Definition, An. 100 -R-

Raceways Adjusunent factors for more than three current-

carrying conductors in, Table B.2(1 1) Ampacities of conducLOrs in, 310.16, Table 310.1 6, 310.18, Table 310.18 Bonding, 250--V, 501.30 (A), 502.30(A}, 503.30(A), 505 .25(A) Busways, see Busways Cables trays, supported by, 392.18(G) CATV coaxial cable, 820.133 Cellular concrete floor, see Cellular concrete floor raceways Cellular metal floor, see Cellular metal floor raceways Class I circuits, 725.48(8) ( 1), 725.51 Communications,

see

Communicatio ns circuits Conductors in service, 230. 7 Continuity, 300. IO, 300. 12 Cords, flexib le, installed in, 400.1 7 Definition, An. 100 Drainage, 225.22, 230.53 Electrical metallic tubing (Type EMT), see Electrical metallic lllbing (Type EMT) Electrical nonmetallic mbing (Type ENT), see Electrical nonmetallic lllbing (Type ENT) Eme rge ncy circuits, independent, 700.10 (0 )

70-888

Equipment grounding conductor installation, 250.120(A) Expansion joints, 250.98, 300.7(8 ), 352.44 Exposed LO d ifferent temperan,res, 300.7 Fire alarm systems, 760.3, 760.48, 760. 130(B)(l), 760. 13.5(E), 760.136 (C) Fire resistive system, 728.5 (C) Fixed outdoor electric deicing and snow-melting equipment, 426.22 Flexib le metal conduit (Type FMC), see Flexible metal condu it (Type FMC) Flexible metallic mbing (Type FMT), see Flexible metallic tubing (Type FMT) G rounding, 250.1 32, 250-IV Shon sections, 250.86 Ex. 2, 250. 132 Induced currents, 300.20 Installed in grooves, 300.4 (F) Insulating bush ings, 300.4(G), 300.16(8) Inte rmediate metal conduit (Type IM C), see Intermediate metal condu it (Type IMC) Intrinsically safe systems, 504.50(A) Liquid tight flexible metal condu it (Type LFMC), see Liquid tight fl exible metal conduit (Type LFMC) Liquid tight flexible nonmetallic conduit (Type LFNC), see Liquidtigln fl exible nonmetallic condu it (Type LFNC) Luminaires (fixmres) Po les used as raceway, 410.30( B), 410.64 Supponed by raceway fittings, 410.36(E) Manufacmred wiring systems, 604.l00(A) (5) Network-powered broadband con1munications

systems, 830. 133(A) (I) Number of conductors, 300. 17; see also Conducto r fill Optical fiber cable, 770.26, 770.110, 770.113( E), 770. 133, Table 770.154 (a) Pliable, 362.2

Remote-conu·ol, signaling, and power-limited circuit cables, installation, 725.135(E), 725. 136(C), 725.139 Rigid met.al conduit (Type RMC), see Rig id metal conduit (Type RMC) Rigid polyvi nyl conduit (Type PVC) , see Rigid polyvinyl chloride conduit (Type PVC) Seal, 225.27, 230.8, 300.7(A), 300.S0( F) Secured, 300.11 (A) Service, see Service raceways Signaling Class I circu its, 725.48 Smn-type channel, see Strm-type channel raceway

Suppon for nonelectrical equipment, 300.l l(C) Supporting conducLOrs, venical, 300.19 Support ot; 392.18(G) Surface metal, see Surface metal raceways Surface nonmetallic, see Surface nonmetaJlic raceways

Underfloor, see Underfl oor raceways Underground, 300.5, 300.50 V\lireways, see VVireways, metal; Wireways, nonmetallic Wiring, exterio r surfaces of bu ildings, 225.22 Radiant heating panels and radiant heating sets, see Fixed electric space-heating equipment Radio and television equipment, ArL 810. See also Community antenna television and radio d istribmion (CATV) systems Amateur transmitting and receiving stations, 810--III Antenna lead-in protecLOrs, 810 .6 Community television antenna, 810.4 Interior installation u-ansmitting stations, 810--IV Noise suppressors, 810.5 Receiving equipment - antenna systems, 810--11 Radiographic equipment, see X-ray equipment Rail, 393 .30( B) Definition, 393.2

Railway conductors, power and light, 110.19 Rainproof De finition , An. 100 Rain tight Definition, An. 100 Ranges, 422.16 (8 )(3), 422.33( 8 ); see also Cooking unit, counlermounted; Ovens, wallmounted Branch circuits, 210.19(A) (3), 210.23(C) Calculation of load, 220.55, Table 220.55 Conductors, 210.19(A) (3)

Maximum load, 220.18(C) Feeders, calculation of load, 220.82( 8 ) (3) Grounding, 250.140 Hoods, co rd-and-p lug connected, 422.16(8)(4) Load s, demand factors and, 210.21 (8 )(4), Table 220.55 Mobile homes, 550.15( E), 550.16(A), 550.16(8) (3) Receptacles, 250.140 Ex. Rate d load current, 440.4(A) Definition, 440.2 Rate d power Definirion, 694.2 R e actors, see Resistors and reactors

Readily accessible , see also Accessible Definition, An. 100 Reaming, ends of metal conduits, 342.28, 344.28, 358.28 Re-bar electrodes, 250.50 Ex., 250.52(A) (3), 250.68(C) (3) Receptacles, cord connectors, and attachment plugs (caps), An. 406 Agricultural buildings, 547.5(G), 547.6 Ai1°conditioning or refrigerating equipment, 440.55, 440.63

Anesthetizing locations, 5 17.64(F) Branch circuits, 210.2l (B), 210.52 Configurations, 550.I0 (C), 551.46(C), 552.44(C) Critical branch, 517.34(A) Critical operatio ns power systems, 708. I 0(A) (2) Definirio n, An. 100

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

Disconnecting means, 422.33, 440.63 Electric vehicle charging systems, 511.10(8 ), 62.5.56, 625.60 Electrified truck parking space supply equipment, 626.24(8 ), 626.25 (B) (4), 626.31 (C), 626.32 ElevaLOrs, dumbwaite rs, escalators,

etc., 620 .22 (A), 620.23 Faceplates, 406.5, 406.6, 406.9( E) Flexible cords connecting inlets LO receptacles, 400.I0(A)( ll ) Ground ing type, 250.130 (C), 250.146, 406.4(A), 406.10, 406.11, 517.13, 517.19(H ) Hazardous (classified) locations, 501.145, .502 .145, .503.14.5 Health care facilities, 517.1 3, 5 17.18,517.19, .5 17.31 (E), 5 17.34(A), 517.42(E), 517.61 Insulated grounded terminals, 250.146( 0 ) Irrigation machines, 675.17 Isolated ground, 5 17.16 Less tha n 50 volts, 720.6, 720.7 Manufactured wiring systems, 604. IO0(C) Marinas, boatyards, floating buildings, and dockyards, 555.6, 555.33, 555.35 (A)( l ) Maximum cord-and-plugconnected load LO, 2 l0.21 (8 )(2), Table 2 10.21 (B) (2), 2 10.23 Minimum ratings, 406.3(8 ) Mobile homes, 5.50.I0 (C), 550.12, 550.13 Modular d ata cente r equi p me nt e nclosures, 646.12 Motors, 430. l 09 (F) Mounting, 406.5, 406.9(E) Nongrounding-ty pe, replacement, 250.130(C), 406.4(D )(2) Nonime rc hangeable, 406.4(F), 406.8 Nonmetallic extensions, 382.42 Office furnish ings, 605.9 Omdoor, see Outdoor receptacles Outlers, 210.50 De finition, Art. 100

2020 Edition

Dwellings, where required, 210.52 Guest roo ms, guest suites, and d o rmito ries, 210.60 Loads, 220. l 4 Meeting rooms, 210.65 Park traile rs, 552.20(F), 552.41, .552.44(C), .5.52.48, 552.53 Patient bed location, 5 17.1 8( 8 ), 517. 19(8 ) Po rtable distributio n o r termination boxes, rides, ten t.s, and

concessions, 525.22 (C) Ratings for various size circuits, 2 I0.21 (B) (3), Table 210.21 (B) (3) Recreational vehicles, 55 l.20( F), 55 1.4l, .551.46, 551.47(P)(l), 551.52, 551.55( F), 551.72(C) Re placement, 406.4( D) Selected, healtl1 care facilities, 517.34(A) De finitio n, 517.2 Sensitive electronic equipmem , 647.4(0 )(2), 647.7 Showcases, wall cases, 4 l0.59(8 ) Show windows, in, 210.62 Stages and sers, 520.62(8 ), 530.21 Submersible o r fl oating equipmem , for bodies of water, 682.14 Swimming pools, 680.2 l (A)(3), 680.22(A), 680.22( 8 ) (5), 680.31, 680.32, 680.34, 680.35(A), 680.43(A), 680.62(E), 680.84 Ta mper-resistan t, 406.12 Child care facilities, 406.12 (3) Dwelling uni rs, 406.12(1) Guest rooms and suites, 406.12 (2) Replacements, 406.4(0 )(5) Tempo rary installations, 590.4( 0 ), 590.6(A) Terminals, identificatio n, 200. 10(8) Theaters, 520.45 Vo ltages between adjacent devices, 406.5() ) Weather-resistan t, 406.4(0 ) (6), 406.9(A) Wind electric systems, small, 694.7(E) Recessed luminaires, 410- X, 4 10-X I Clearances, installation, 4IO. l l6 Co nstructio n, 410- XI

NATIONAL ELECTRJCAL CODE

As raceways, 410.64 Te mpe ratures, 410.115 Wiring, 410.117 Reconditioned equipment Definition, Art. 100 Equ ipme nt prohibited from reconditioning, 2 l0. l5, 240.62, 240.88, 240.102, 410.7 Panelboards, 408 .8 Switchboards, 408.8 Recording systems, Art. 640 Recreational vehicle parks, .55 l- VI Calculated load, 551.73 Demand factors, Table 55 l.73(A) Definitions, 551.2 Disconnecting means, 551.77(8) Distribution system , 551.72 Grounding, 55 1.76 Omdoor equipme m , protectio n of, 551.78 Overcurrent protection, .55 l .74 Overhead conducLOrs, clearance for, 55 l.79 Receptacles, 551.7 l, 55 l.8 l Underground wiring, 551.80 Recreational vehicles (camping trailers, motor homes, park trailers, travel trailers, truck campers), Art. 551 Alternate power source restrictions, 55 1.33 Appliances, 551.20(D), 55 l.4l(C) Ex. l , 551.42, 551.55(F), 551.57 Attachment plugs, 551.20(F), 551.46(C) Bonding, 551.55(A), 551.55( 8 ), 5.5 1.56 Branch circ uits, 551 .42, 551.43 Calculatio n for loads, 55 l.42( D) Combination e lectrical systems, 551-11 Conductors, 55 l .48 Connections Gro unding, 551.54, 55l.55 Power supply, 551.46 Splices and terminals, 551.50 Definitions, 551.2 Distribution panelboard, 55 l .45 Expandable unirs, connection, 551.47( P) Generator installatio ns, 551.30 Ground-fault circuitimerrupter, 551.40(C), 551.4l (C), 551.7l (F) Grou nd ing, 55 l .54, 55 l .55 Grou nding conducLOr splices, 551.50

Id entification of gro unded conductor, 551.49 Luminaires, 551.20(D), 551.53 Motors, 551. 51 (A) (2) Multiple supply source, 55 1.31 Otl1er power sources, 551- III Outlet boxes, 5.51.48 Overcurrem protectio n Branch circuit, 55 l .43 Distribution panelboard, 551.45(C) Power sources, other, 55 l .3 l Power-supply assembly, .55 l .44, .551.46, 551.54(A) Definition , 551.2 Receptacles, 55 l.20(F), 55 l.4l , 551.52, 551.72(C) Supply source 120-volt o r 120/ 240-volL system, 551- IV Switches, 55L5l System voltages, 551-IV Tags, labels, and marking, 551.46 (D) Tesrs, factory, 551- V Wiring methods, 551.47 Recreational vehicle site Definition , 55 1.2 Supply equipment, 551.71, 551.77 Definitio n, 551.2 Grounding, 551.76 Marking, 551.77(F) Recreational vehicle stand Definition, 551.2 Refrigeration compressor motors and controls, Art. 440 Refrigeration equipment, see Air 0

conditioning and

refrigerati ng equipm ent Refrigerators, grounding, 250.114 Regulator bypass ~·witch, over 1000 volts, 490.23 Definition , Art. l 00 Reinforced thermosetting resin conduit (Type RTRC) , Table 300.50, An. 355 Bends, 355.24, 355.26, Chap. 9, Table 2 Bushings, 355.46 Construction specifications, 355- III Definiti on, 355.2 Expansion fittings, 300.7(8 ) IN Grounding, 355.60 Installation, 355- 11 J oinrs and expansion fittin gs, 35.5.44, 35.5.48 Listing, 355.6

70-889

NATIONAL ELECTRICAL CODE

Marking, 355.1 20 Number of conductors, 355.22, Chap. 9, Table I Securing and supporting, 3 14.23(E), 355.30, Table 355.30 Size, 355.20 Splices and taps, 3.55.56 Trimming, 355.28 Uses not permitted, 355.12 Uses permitted, 355.10 Relays

Automatic load control, 700.26 Definition, 700.2 Emerge ncy systems, 700.23, 700.26 Hazardous (classified) locations, 501.105, 502.150 Overload, motor overcurrent protection, 430.40 Reverse-current, transformers, 450.6 (8 ) Relocatable structures, see Manufactured buildings and relocatable structures Remote control

Circuits, Sl!f! Remote-control, signaling, and powerlimited circuits Disconnect control Energy storage systems, 706.15 (8) Information technology equipment, 645.l0(A) Definition, 645.2 Of induction and dielecu-ic heating equipment, 665.7 Switches, 517.63(0 ) Remote, 250.112( 1), Art. 725 Abandoned cables, 725.25 Definition, 725.2 Access t0 e lecu-ical equipment, 725 .21 Class l circuits, 725-11 Circuits extending beyond one building, 725.52 Conductors, 725.49 Different circuits, 725.48 Extending beyond one building, 725.52 Insulation, 725.49(8 ) Number in raceways and cable trays, 725.51 Overcu rren t protection, 72.5.41 (A) (2), 725.43 Size and use, 725.49(A) Definitio n, Art. 100

70-890

Locations, 725.45 Overcurren t protection, 725.41 (A) (2), 725.43, 725.45 Ph ysical protection, 725.3l(B) Power limi tations, 725.41 Wiring methods, 725.46 Class 2 and Class 3 circu its, 725- 111 Applications of PLTC cables, 725.154 Circuits extending beyond one building, 725.141 Conductors, 725. 133, 725.143 Definition, Art. 100 Installation, 725. 133 through 725. 141 Interconnection of power supplies, 725.121 (B) Listing, 725-IV Marking, 72.5. 12 l (C), 725.1 24, 725.170, 725.179 Overcurrent protection, Chap. 9, Tables 11 (A) and l l (B) Power and data

transm ission, 725.144, Table 725.144, 725.170 Power sources, 725 .12 I (A), Chap. 9, Tables 11 (A) and (B) Separation, 725. 136 Wiring med1ods Load side, 725. 130 Supply side, 725.127 Definitions, Art. 100, 725.2 Identification, 725.30 Mechanical execution of work, 725.24 Motors, 430---VI Overcurrent protection, Table 240.4(G), 725.41 (A) (2), 72.5.43, 725.45, Chap. 9, Tables 11(A) and I I (B) Safety-control equipme nt, 725.31 Requirements for electrical installations, An. 110 Residential occupancies, see

Dwellings Resistance AC resistance and reactance,

cables, Chap. 9, Table 9 Conductor properties, Chap. 9, Table 8 Heating equipment, see Fixed electric heating equipment for pipelines and vessels; Fixed resistance and elecu-ode industrial process heating equipment Welders, 630-111

Resistors and reactors, An. 4 70

Combustible material, on, near, 470.3, 470.18(C) Conductor insulation, 470.4 Hazardous (classified) Class II locations, 502.120 Location, 470.2 1000 volts and unde1; 470-1 Over 1000 volts, 470- 11 Grounding, 470.19 Oil-filled reactors, 470.20 Space separation, 470.3 Restaurants, service or feeder load, 220.88 Retrofit kits, 600.4(8)

Definition, Art. I 00 General use, 600.35 De finition, 600.2 Sign specific, 600.35 De finition , 600.2 Reverse polarity protection (backfeed protection)

Definition, 393.2 Low-voltage suspe nded ceiling power distribution systems, 393.45 (C) Rheostats

Construction specificatio ns, 430.81 (C) Stages and studios, 530.15(C), 540.20 Ride device

Definition, 522.2 Rigid metal conduit (Type RMC), Art. 344 Bends, 344.24, 344.26, Chap. 9, Table 2 Bushings, 344.46 Cinder fill , 344.l0(C) Conductors outside of bu ilding, 230.6(5) Construction specifications, 344-111 Couplings and connectors, 344.42 Definition, 344.2 Dimensions, Chap. 9, Table 4 Dissimilar metals, 344.14 Expansio n fittings, 300.7 (8 ) IN Fe rrous, 300.6(A) Grounding, 344.60 Installation, 344-1 I Listing, 344.6 Marking, 344. 120 Maximum number of conductors and fixture wires in, Tables C.9 and C.9(A) Number of cond uctors, 344.22, Chap. 9, Table l

Reaming and d1reading, 344.28 Securing and supporting, 314.23(E), 314.23( F), 344.30 Size, 344.20 Splices and taps, 344.56 Underground installations, 300 ..50(C), Table 300.50 Uses permitted, 344. 10 Wet locations, 344.10(0 ) Rigid polyvinyl chloride conduit (Type PVC), Art. 352

Bends, 352.24, 3.52.26, Chap. 9, Table 2 Bushings, 352.46 Construction specifications, 352- 111 Definition, 352.2 Dimensions, Chap. 9, Table 4 Expansion fittings, 300.7(B)IN, 352.44, Table 352.44 Exposed, 352.l0(F) Grounding, 3.52.60 Installation, 352-11 J oints, 352.48 Listing, 352.6 Marking, 352.120 Maxim um number of conductors and fixture wires in, Tables C.10 dirough C.12 (A) Number of conduct0rs, 352.22, Chap. 9, Table I Schedule 80, 300.5 (0 ) (4), Table 300.50 Securing and supporting, 314.23(E), 352.30, Table 352.30 Size, 352.20 Splices and taps, 3.52 ..56 Trimm ing ends, 352.28 Uses not permitted, 352.1 2 Uses permitted, 352.10 Road show connection panel, 520.50 Rod e lectrodes, 250.52(A)(5),

250.53, 250.66(A), 250.70 Roof decking

Cables and raceways installed under, 300.4(E) Luminaires installed in or under, 410.l0(F) Roofs, conduits exposed to swtlight on, 310. 15(8)(2) Room air conditioners, Sl!f! Air conditioners, room

Rooms, motion picture projection, see

NAT IONAL ELECTRJCAL CODE

2020 Edition

INDEX

Projection rooms, motion picn,re Rotary phase converter

De finition, 455.2 Rules, permissive, 90.5(8 ) Running threads, 342.42(8) ,

344.42(8) -SSafety, examination of equipment for, 90.7 Screws, tightening torque tables, Annex I Screw she lls

Electric-discharge luminaires and LED luminaires, 410.62(C) (2) Ide ntification Polarity, 200.1 0, 4 10.50 Te rminals, 200.10 Lamp holde rs, 410. 122 Sensitive elecu-onic equipment lu minaires, 647.8(C)

Separately derived systems, 250.21 (A),

250.28( D), 250.30, 250.35 (A) De finitio n, Art. 100 Feede rs or branch circu its, buildings/ su-ucn,res supplied by Grounded systems, 250.32( 8 ) (2)

Ungrounded system s, 250.32(C) (2) Grounding elecu·ode conductors, 250. 169 Metal piping and frames, bonding of; 250.104( 0 ) Po rtable generators, 702.1 1(A) Surge protective devices, connection of, 242. 14(C) Service cables, see also Serviceentrance cable (Types SE and USE) De finition, Art. 100 Se rvice conductors,

De finition, Art. 100 Sealing, see also Hazardous (classified) locations Busways, vapor seals for, 368.234(A) Conduit system s, 501.15, 502.15, 505.16, 506.1 6 Intrinsically safe systems, 504.70 Raceway seal, underground service, 230.8 Temperature changes, 300.7 (A) He rme tically, .500.7(J) Raceways, 225.27, 230.8, 300.7(A), 300.50(F) Seating areas, receptacles in, 406.5( H ) Secondary ties, transformers, 450.6 Security &ystems , Art. 708 Selective coordination,

see Coordinatio n, e lectrical systems Sensitive electronic equipment, Art. 647

Grounding, 647.6 Lighting equipme nt, 647.8 Receptacles, 647.7 Single-phase supply system, 647.3 T hree-phase supply system, 647.5 Wiring methods, 647.4 Separable power supply cable assembly, 626.25, 626.32

Defi nition, 626.2

2020 Edition

see

Conductors, service

Sealable equipment

Service drops

Co nnections, service head, 230.54 De finition, Art. 100 Service-entrance cable (Types SE and USE), Art. 338

Be nds, 338.24 Branch circuhs or

feeders, 338.1 0 (B ) Consu-uction, 338- III De finition, 338.2 Grounding frames of ranges and clothes d ryers, 250.140 Ex. Installation, 338-11 Installation methods, for branch circuits and feeders, 338.10(8 )(4) Marking, 338.1 20 Service-enu-ance conducto rs, 230-IV, 338. I0 (A) Support, 338.10(8 ) (4 ), 338. 12(A) (3) Uses not permitted, 338.1 2 Uses permitted, 338.10 Service-entrance conductor assembly, 338.100

Defin itio n, 338.2 Se rvice-entrance conductors, 230-IV

Cables used as, 338.l 0(A) Conductor sets, number of, 230.40 Considered outside of building, 230.6 De finition s, Art. 100

NATIONAL ELECTRJCAL CODE

Disconnecting means, 230- VI Drip loops, 230.52 Insulation, 230.41 Mounting s upports, 230.51 Overcurrent protectio n, 230.90 through 230.92, 230.208 Overhead system , 230.28(A), 230.40, 230.54 Definiti o n, Art. I 00 Over 1000 volts, 230- VIII Physical damage, 230.50 Service head, 230.54 Size, 230.42 Splices, 230.46 Underground, 300.5(0 ) (3), 338.1 2( 8 ) Definition, Art. 100 Wiring methods, 230.43 Service-entrance equipment, see

Service equipme nt Service equipment, 230-V

Arc-flash hazard warning, 110. 16(8) Definition, Art. 100 Disconnecting means, 230- VI Connectio ns, supply side, 230.82 Connections to terminals, 230.81 Elecu-ically operated, 230.94 Ex. 6 Grounded conductor, disconnection of, 230.7.5 Ground-fault, protection at, 230.95, 705.32 Grounding electrode conductor installation, 250.64( 0 ) Indicating, 230 .77 Location, 230 .70 (A) Marking, 230.70(8) Maximum number of disconnects, six s,vitch rule, 230.71 Multiple occupancy buildings, 230. 72(C) Over 1000 volts, 230.205, 230.206 Rating, 230.79, 230.80 Simultaneous openings, 230.74 Six switch rule, 230.7 I ( B) Suitable fo r use, 230.70(C) Ground-fault circuit cond ucror brought to, 250.186 Guarding, 230.62 Indusu-ial conu-ol panels as, 409.108 Marinas, boatyards, fl oating buildings, a nd docking faci lities, 5.5.5.4 Marking, 230.66

Mobile homes/ manufactured homes, 550.32 Modular data centers, 646.6 ( B) (I), 646.7(A), 646.8 Motor comrol ceme rs as, 430.95 Overcurrent protection, 230- VI I Accessibility, 240.24(A) Arc-flash hazard warning label, 1 10. 16(8 ) Location, 230.91, 230.92 O ver l000 volts, 230.208 Relative location, 230.94 Specific circuits, 230.93 Ungrounded conductors, 230.90(A) Over 1000 volts O vercurrent protection, 230.208 Switchgeat; 490.47 Panelboards, 408--111 Receptacles in area of; 210.63 Service lateral

Definition , An. 100 Physical damage, protection against, 230.32 Se,v ice-e nt rance conductor set supplied by, 230.40 System grounding connections, 250.24(A) ( I), 250.24(E), 250.64(0 )( 1) Service loads, calculations, An. 220,

Annex D Service point, 250.1 86

Definition, Art. 100 Service raceways

Conductors, others permitted in, 230.7 Drainage, 230.53 Se,vice head, 230.54 Underground, 230- 111 Services, An. 230 Definition , Art. I00 Farm, 220-V Ground-fau lt protection, 230.95 Insulation, 230.22 Masts, se,v ice, 230.28 Number, 230.2 Disconnecting means, 230.71, 2.50.64(0 ) Service-entrance conductor sets, 230.40 Overhead su pply, 230-II O ver 1000 volts, 230-VIII Separate ser vice Eme rgency systems, 700.12( F) Legally required standby systems, 701.12(F)

70-891

NATIONAL ELECTRICAL CODE

Supply to one building not through another, 230.3 Two or more buildings, 250.32 Unde rg ro und, 230-111 Service stations, gasoline , see Moto r fuel dispe nsing facilities Setting (of circuit breaker) De fini tio n, Art. 100 Shielding, see Guarding, guards Shore power, 555 .6, 555.33(A), 555.35(A)( l ), 555.36 Defini tio n, 555.2 Short-circuit current rating, 110.10 Defini tio n, Art. 100 Direct curre nt microgrid systems, 712.72 Industrial machinery, 670.5 Interconnected electric power production sources, 705. 16 Modular data cente rs, 646.7 Surge protective devices, 242.1 0 Short-time duty, 430.22(E), 430.24(4) Ex. 1, 430.33 Defini tio n, An. 100 Showcases, wall cases, 410.59 Shower spaces, see Ba th cubs Show windows De finition, Arc. 100 Flexible cords, 400.1 5 Luminaires, 41 0.14 Branch circuits, 220.14(G) Feeders, 220.43(A) Receptacles, 2 10.62, 3 14.27(8 ) Ex. Sidelights, borders, and proscenium, 520.44 Signal equipment, see also Audio signal processing, amplification, and reprod uction equipmen t; Sig naling circuics Defini tion, 620.2 Signaling circuits, see also Fi re alarm systems; Re motecontrol, sig naling, a nd power-limited circuits Critical operations powe r systems, 708.14 De finitio n, Arc. 100 Health care facilities, 517- VI Installatio n requirements, Art. 725, Art. 760 Signaling systems, Arc. 708 Signals for heated appliances, 422.42 Sign body De finitio n, 600.2

70-892

Signs Discharge, lighting, electric, 410-XII, 410--X III Electric, Art 600 Ballasts, transformers, and e lectronic power supplies, 600.2 1 through 600.24 Bonding, 600.7(8), 600.33(0) Branch circuits, 220.14(F), 600.5 Definitions, An. 100, 600.2 Disconnects, 600.6

Enclosures, 600.8 Field-installed secondary wiring, 600.12 Field-i nstalled skeleton tubing, 600--11 Applicability, neon secondary circuit

conductors, 600.30 Grounding, 250.11 2(G), 600.7 (A), 600. 24( B), 600.33( 0 ) Listing, 600.3 Locatio n, 600.9, 600.10, 600.21, 600.33(A), Table 600.33(A) (a), 600.42(G), 600.42( H ) Ma rkings, 600.4, 600.5( 8 ), 600.35(A) (4) Portable o r mobile, 600.10 Sectio n signs, 600.3, 600.7( B)( l ) Ex. Definition, 600.2 Solar photovoltaic powered sig n, 600.34 Definition, 600.2 Exit, health care faci lities, 517.33( 8 ), 5 I7.43( 8 ) Ma ndated standby, 701.7(A) Outline ligh ting, Art. 600 Standby, 702. 7 Warning, see Warning signs (labels), at equi pment Simple apparatus, 504.4 Ex. Definitio n, Art. JOO Installation, 501.l0(B) (3), 502. IO(B) (3), 503. I0(A) (4), .504.10, .505. 15(C) ( 1)(7), .506.15(C)(8) Ma rking, 500.8(C) (6), 505.9(C) (2) Ex. 2 Site-isolating devices, .547.9(A) De finitio n, 547.2 Skeleton tubing, 600.4(F), 600.6, 600. 7 (A) ( l), 600--I I De finitio n, 600.2 Slips De finitio n, 555.2

Smoke ventilator control, stage, 520.49 Snap switches AC gene ral use, 404.14

Accessibility, grouping, 404.8(8 ) Electric-discharge lighting, 4 10.1 39 Enclosures, 404.3(A) Ex . l Genera l-use, 225.36, 404.7, 404.8(C), 404.9, 404.IO, 404.1 3(C), 404.14, 430.83(C), 430.109 De finition , Art. 100 Grounding, 404.9( 8 ) Motors, 430.83(C), 430.109(C), 430.1 09(G) Mounting, 404.10 Multipole, 404.8(C) Ratings, 404.14 Snow melting, see Fixed outdoor electric d eicing and snow-melting equipment Solar cell, IN Fig. 690.1 (a) Definition, 690.2 Solar photovoltaic powered signs, 600.34 AC modules and systems, see AC modules and systems, solar photovoltaic systems Definition, 600.2 Electronic power conveners, see Electro nic power con veners Solar photovoltaic systems Cables, 690.31 (C) Circuit sizing a nd current, 690.8 Connectio n to supply side of ser vice disconnect, 230.82(6) DC combine r, 600.34(A), 690.4(8 ) De finiti o n, 690.2 DC-to-DC conveners, see DC-toDC conveners Definitions, Art. 100, 690.2, 691.2 Disconnecting mea ns, 690-111, 690.53, 690.54, 690.56, 691.9 Ground-fault procenion, 690.4 1( B) Large-scale, Art. 69 1 Marking, 690.13(8 ), 690.3 1( B) ( I ), 690.3 1( D ) (2)

Overcurrent p rotectio n, 690.9 Rapid shutdown of systems o n buildings, 690.12 Stand-alone systems, 690.1 0, 690.56(A) Voltage, 690.7

Solderless (pressure) connectors, 250.8 (3), 250.70 De finitio n, Art. 100 Solidly grounded, 430.83(E), 490.71 , 712.30 De finition , Art. JOO Photovoltaic systems, 690.3 1( B) (1), 690.3l ( E), 690.41, 690.42, 690.45(0 ), 690.47 Solidly, 110.54(A)

Swimming pools, fountains, and similar installations, Table 680.9(A) Sound recording equipment, An. 640 Audio sig nal processing, amplification, and reproduction equipmen t, 540.50 T hea ters, 520.4 Space Cabinets and cmom boxes, 312.7, 3 12.9, 312. 11 Climbing space, line conductors o n poles, 225.14( D) Lig htning rods, conductor enclosures, equip men t, 250.60, 250.106 IN No. 2 Outside branch circuits a nd feeders, 225 .14 Over l 000 volts, separation, 110.32 through 110.34 Working, see Working space Space heating, fixed, see Fixed electric space-heati ng equipment Spacing between bare metal parts, 408.56, Table 408.56 Spas, hot tubs, and immersion pools, 680--IV De fin itio ns, 680.2 Indoor installations, 680.43 Omdoor installations, 680.42 Pac kaged equip ment assembly Definiti o n, 680.2 Flexible connectio ns, 680.42(A) Protection, 680.44 Wiring, 680.42(C), 680.43 Ex. l Protection, 680.43 Storable, 680--111 Special permission Definitio n, Arc. 100

NAT IO NAL ELECTRJCAL CODE

2020 Edition

INDEX

Spider (cable splicing block), 530.1 5(D)

Definition, 530.2 Splash pads, 680.50 Definition, 680.2 Splices and taps Antennas, 810.14 Auxiliary guuers, 366.56 Cabinets and cutout boxes, 3 12.8 Cable trays, in, 392.56 Cell ula r concrete floor raceways, 372.56 Cellular metal floor raceways, 374.56 Concealed knol:>-andtube, 394.56 Conduit bodies, 300.15, 314.16 (C) (2) ConstrucLio n sites, 590.4(G) De icing and snowmelting, 426.22(B), 426.24(B) Electrical metallic tubing, 358.56 Electrical no nmetallic tubing, 362.56 Equipme nt grounding conductors, 250.122(G) Fire resistive system , 728.5 ( H) Flat cable assemblies, 322.56 Fla t conductor cable, 324.56 Flexible cords and cables, 400.13, 400.36, .530.1 2(A), 530.1 2( B), .590.4(G) Flexible metal conduit, 348 .56 Flexible metallic tu bing, 360.56 Ge neral provisions, 110.14 Hazardous (classified) Class I locations, 501.15(C) (4) High densicy polyeth ylene conduit, 353.56 Inte rmediate metal conduit, 342 .56 Liquidtight flexible m etal conduit, 350.56 Liquidtight flexible nonmetallic conduit, 356.56 Low-voltage suspe nded ceiling power d istribmio n systems, 393.56 Luminaires, 4l0.56(C), 410.56(D) Messenger-supponed wiring, 396.56 Nonmetallic extensions, 382.56 Nonmetallic underground conduit with conductors, 3.54.56 Reinforced thermosetting resin conduit, 355 .56 Rigid metal condui t, 344.56

2020 Edition

Rigid polyvinyl c hloride conduit, 352.56 Service-entrance conductors, 230.46 Space-heating cables, 424.40, 424.41 (D) Strut-type channel raceways, 384 .56 Surface raceways, 386.56, 388.56 Underfloor raceways, 390.56 Underground, 300.5(E), 300.50(D) Wireways, 376.56, 378.56 Spray application, clipping, coating, and printing processes, Art. 516 Classificatio n of locations, 516.5, 516.18, 516.29 Definitions, Art. 100 Equipment, 516.5(A) (3), 516.6, 5 16.7, 5 16. IO, 516.38(B) Grounding, 5 16.16 Me mbrane enclosures, 516--IV Open containers, 5 16-II Printing, dipping, and coating processes, 516--V Processes, 516--III Wiring, 516.6, 516.7, 516.38(A) Spread of lire or products of combustion, see Fire spread Stage effect (special effect), 530. 12(B) Definition, 530.2 Stage equipment, theaters De finitio n, 520.2 Fixed, 520-III Lig hting hoist, 520.40 De finition , 520.2 Po rtable, 520.5(B), 520- V Definition, 520.2 Stage property Defin ition, 530.2 Stages, motion picture and television, 530- II De finition, 530.2 Stage set De finition, 530.2 Lighting, 530.12(A), 530.13, 530.16, 530.18, 530. 19(A), 530.23 Stairway chairlifts, see Elevators, dumbwaiters, escalators, moving walks, p latform lifts, and stairway cha irlifts Stand-alone systems, A rt. 7 I0 Defin itio n, Art. 100 Energy storage systems, 706.16(F), 706.21 (B)

NATIONAL ELECTRJCAL CODE

Fuel cell system installation, 692.4( B)(3) Solar photovoltaic systems, I N Fig. 690.1 (b), 690.10, 690.56(A) Wind electric systems, 694.12(A) (3), 694.54(C) Standby systems, see Emergency systems; Legally required standby systems; Optional standby system s Static phase converter, 455 .20 Definition, 455.2 Steel, structural, boncling, 250.104 Steel siding , 250.116 IN Storage, dry stack Definition, 555.2 Storage batteries, Art. 480 Accessibilicy, 480.4 (0 ) Airc raft hangars, 5 13.I0( B) Charging equipme nt, 503. 160 Container, 480.8, 480.I0(C) Definiti o n, 480 .2 Critical operations power systems, 708.20(E), 708.20(F) (4) Definitions, 480.2 Disconnecting means, 480 .7 Emergency systems, 700. 12 (C), 700.1 2(0 )(3), 700.12(1)(2) Energy storage systems, 706.8 Fire pumps, 695. 12(C) Garages, 511.10 Insulation, 480.8 Legally required standby systems, 701.12 (C), 701.12(D) (4 ) Locations, 480.10 Overcu rre nt protection for prime movers, 480.6 Sound recording e quipment, 640.9(B) Support, 480.9 Te rminations, 480.4 Vents, 480.11 Wiring and equipme nt supplied from, 480.4 Strike termination devices, see also Surge arresters As a g round, 250.60 Structural metal, see Metal frame of building Structures Definition, Art. 100 Portable, see Portable structures Relocatable, Art. 545 Strut-type channel raceway, Art. 384 Construction specifi cations, 384--III

Definition , 384.2 Grounding, 384.60 Installation, 384--II Listing requirements, 384.6 Marking, 384.120 Number of conductors, 384.22 Securing and supporting, 384.30 Size of conductors, 384.21 Splices and taps, 384.56 Uses not perm itted, 384.12 Uses permitted, 384. IO Subassembly Definition, 600.2 Submersible equipment, 680.51 Substations, 490.48 Definition , An. 100 Grounding system at, 250.191, 2.50. 194 Motion pictllre and television studios, 530--Vl Supervision, engineering, 310.1 4(B), 645.25 Supervisory control and data acquisition (SCADA), Annex G Definiti o n, 708.2 Support fittings fill, boxes, 314.16(B) (3) Supports, see Securing and supporting and Suppon under entries for specific wiring a nd equipment Support space, 517.29(A) Definition, 5 17.2 Suppressors, raclio noise, 810.5 Surface metal raceways, Art. 386 Combination raceways, 386.70 ConstrucLio n specifications, 386--II I Definition, 386.2 Grounding, 386.60 Installation, 386--II Listing requirements, 386.6 Marking, 386. 120 Number of conductors or cables, 386.22 Securing and supporting, 386.30 Size of conductors, 386.2 l Splices and taps, 386.56 Uses not perm itted, 386.12 Uses permitted, 386.10 Surface nonmetallic raceways, Art. 388 Combination raceways, 388.70 Construction specificatio ns, 388--III Definition, 388.2 Grounding, 388.60

70-893

NATIONAL ELECTRICAL CODE

Installation, 388---11 Listing require ments, 388.6 Marking, 388.120 Number of conductors or cables in, 388.22 Securing and suppo rting, 388.30 Size of conductors, 388.21 Splices and taps, 388.56 Uses not permitted, 388. 12 Uses permitted, 388.10 Surfaces, exposed conductive, .517 .11

Definition, 5 17.2 Surge arresters, Art. 242, 250.106

Antenna discharge units, 8 10.20 Conductor routing, 242.48 Connections at services, 230.82( 4) De fini tio n, Art. 100 Fire pumps, 695.15 Gro unding, 242.12, 242.42, 242.52, 242.56, 250.60 Information technology equipme nt, 645.18 Interconnections, 242.54 Location, 242.46 Number required, 242.46 Radio and television equipment Receiving statio ns (ante nna discharge units), 8 10.20 Transmitting stations, a nte nna discharge units, 810.57 Selection, 242.42 Services over 1000 volts, 230.209, 242-11 1 Uses not permitted, 242.40 Surge (lightning) protection, Art. 242; see

also Surge-protective devices Communication circuit conductors, 800.53 Connections at services, 230.82( 4) Critical operations powe r systems, 708 .20 (0 ) Eme rgency systems, 700.8 Grounding, 250.106 Hazardous (classified) locatio ns, 501.35, 502.35 Ho istways and machine

rooms, 620.37( 8 ) Industrial machinery, 670.6 Irrigatio n machines, 675.15 Service equi pment, 230.67 Surge-protective devices, 242-1I, 501.35, 502.35, 694.7 (0 ) Conductor routing, 242 .24, 242.48 Connection, 242.26

70-894

De finitio n, Art. 100 Installation, 242.12(A), 242.14, 242. 16 Listing, 242.8 Location, 242.22, 242.46 Number required, 242.20 Over l000 volts, 242- 111 Shon circuit current rating, 242 . IO Uses not permitted, 242.6, 242.40 Suspended ceiling grid, 300.1 I (B), 393.30, 410.36( 8 ); see also Low-voltage suspended ceiling power distribution systems De finitio n, 393.2 Swimming pools, fountains, and similar installations, An. 680

Approval of equipme nt, 680.3 Bo nding, 680.6, 680.7, 680.23(8) (5), 680.26, 680.42( 8 ), 680.43( 0 ), 680.54(8), 680.57(E), 680.62(8), 680.62(C), 680.74, 680.83 Ceiling fans, 680.22(8 ), 680.43( 8 ) Cord-and-plug-connected equipment, 680.8, 680.2 I (A) (3), 680.22 (8 ) (5), 680.31, 680.35(A), 680.42(A) (2), 680.56 Deck area heating, 680.27(C) De finitio ns, 680.2 Fixed equipment, 680.8, 680.56, 680.57(C) (1), 680.62( 0 ) (1) Definition, 680.2 Fountains, 600.7(8)(8), 680--V Ground-fault circuit inte rrupte rs, 680.5, 680.6 Fountains, 680.51 (A) Hydro massage bathmbs, 680.71 J unctio n boxes for, 680.24 Luminaires, 680.22(8 ), 680.23(A) (3), 680.23 (F) (3), 680.24( 8 ), 680.24( 0 ) Motors, 680.2 1(C) Pool covers, 680.27(8) (2) Receptacles, 680.5, 680.6, 680.22(A) (4), 680.32, 680.43( 8 ) (1), 680.44, 680.57( 8 ), 680.58, 680.62( E) Signs, 680.57 (8 ) Spas, ho t tubs, 680.43( 8 ) (1), 680.44

Storable pool equipment, for, 680.31, 680.32, 680.33( 8 ), 680.35(A) Therapeutic pools, 680.62(A), 680.62( E) Wiring to, 680.24(8) Grounding, 680.6, 680.8( 8 ), 680.23( 8 ) (3), 680.23(8) (4), 680.23(F)(2), 680.24( 0 ), 680.24(F), 680.43(F), 680.54(A), 680.55, 680.57( E), 680.62( 0 ) Heaters and heating equipment Deck area heating, 680.27(C) Pool water heaters, 680.l 0 Hydromassage bathtubs, 680- \/II J unction boxes and enclosures, 680.23(C) (2), 680.24, 680..52 Lifts, electrically powered, 680- \/111 De finitio n, 680.2 Lighting, 411.5( 8 ), 680.6, 680.22( 8 ), 680.23, 680.26( 8 ) (4), 680.33, 680.43( 8 ), 680.51, 680.62( F), 680.72 Through-wall, 680.23(E), 680.23( F) (2) De finition, 680.2 Low voltage contacts, 680.22(E), 680.23(A) (8), 680.43 (F) Ex . De finitio n, 680.2 Heater, 680.28 Luminaires, 680.22(8) (6 ), 680.22( 8 ) (7), 680.23(A) (3), 680.24(A)(2), 680.33, 680.35(E) Motors, 680.21 (C) Ex . Pool covers, 680.27(8)(1) Ex., 680.27( 8 ) (2) Ex. Overhead conductor cleara nces, 680.9 Perma ne ntly installed, 680-11 Portable equipme nt De finition, 680.2 Fountains, 680.50 Heaters, 680.3.5 (C), 680.45(C) (2) Imme rsio n pools, 680.35 Pumps, 680.35( 8 ), 680.45( 8 ) Sig ns, e lectric, 680.57(C) (2) Therapeutic pools and tubs, 680.60, 680.62( 0 ) (2) Receptacles, locatio n and protection, 680.21 (A) (3), 680.22 (A), 680.22( 8 ) (5), 680.32, 680.34, 680.43(A), 680.62( E), 680.84

Spas, hot tubs, and imme rsio n pools, 680--I II, 680--1\/ Splash pads, 680.50 Definition , 680.2 Storable, 680--III Definition, 680.2 Switches and switching devices, 680.22(C), 680.41, 680.84 Therapeutic pools and tubs, 680- \/1 Transformers, 680.23(A) (2), 680.24(8) Underwater lumina ires, 680.6, 680.23, 680.26(8 )(4), 680.33, 680.43(8 ) (2) Switchboards, An. 408 Arc-flash hazard warning, 11 0.16 Clearances, 110.26, 408.5, 408. 18 Combustible material, locatio n relative to, 408 .17 Conductor insulation, 408.19 Construction specifications, 408---1\/ Damp or wet locations, 408.16 De finition , Art. 100 Dry location, 408.20 Easily ignitable materials, near, 408.17 Grounding frames and structures, 250. l 12(A) Grounding instrum en ts, 408.22 Illuminatio n, 11 0.26(0 ) Installation, indoor and outdoor, 110.26 Instrumen ts, meters, a nd relays on, 250.174 Location, 408.1 6, 408.1 7, 408.20 Motion picture and televisio n studios, 530.64 Portable, theater stages, 520--1\/ Stage, 520- 11, 520-IV Definition , 520.2 Support, busbars, conductors, 408.3 Working spaces about, l l0.26 Switch es, Art. 404. See also Haza rdous (classified ) locations; specifi c types of switches Accessibility and grouping, 404.8 Agricultural buildings, 547.6 Ai r-co nditioning and refrigerating equipmen t, 440--11 Appliances, 422.34, 422.35 Bypass isolatio n, 700 ..5(8 ), 70 1.5(8), 708 .24 Definition , Art. I 00 Capacitors, 460.24

NAT IONAL ELECTRJCAL CODE

202 0 Edition

INDEX

C ircuit breake rs used as, 240.83( D)

Oil, over 1000 volts, 430.111 (8 )

Construclion specifications, 404-II Definitions, An. I 00 Devices, 240.83( D), 249.67( 8 ), 368.239 Devices, over I 000 volts, 240.67, 240.83(0 ), 368.239 De finitio n, Art. 100 Dimmer, se.e Dimme rs Disconnecting means

De finitio n, An. JOO Pa nelboards, 408.36(A), 408.39 Park traile rs, 552.JO(F) Regulator bypass, over l000 volts, 490.23 De finitio n, Art. JOO Remote-contro l, 5l7.63(0 ) Service, 230-VI

(3)

Appliances, 422-1 1I De finition, Art. 100 Identification, 110.22 Motors and controlle rs, 430-IX Services, 230- VI Electronic lighting control switch , 404.22 Eme rgen cy systems, 700-V X-ray equipment, 517.72, 660-II Enclosures, installatio n in, 404.3, 404. 12,404.28, 450.8(C) Fixed e lectric h eating equipment for p ipelines and vessels, 427.55 (A) Fixed omdoor electric deic ing and snow-melting equipment, 426.51 (D) Fixed resistance and electrode industrial process h eating equipme n t, supply conductors, 425.19 (C), 425.21 General-use, An. 404 De finition, Art. 100 Ind icating, 404.7, 422.35, 424.2 1, 425.21 Inte rrupte r, over l000 volts De finitio n, Art. JOO Isolating, 501.11 5( 8 ) (2) Capacitors, over 600 volts, 460.24( 8 ) De finitio n, Art. 100 Motors over 100 HP, 430.109(E) Outside branch circuits and feeders, 225.51 Services, over I 000 volts, 225.51, 230.204 Definition, An. JOO So lar photovoltaic systems, 690.15(8 ), 69 1.9 Knife, see Knife switches Manually operable, Art. 404 Motor-circuit, see Motor circuit switch es Motor controlle rs, 430-Vll 0

2020 Edition

Signs, o utline lighting, 600.6 Snap, see Snap switch es Solar photovoltaic systems, 690.15(8), 690.56(C) Stage lighting and effects conu·ol, 530.13, 530.1 5 Swimming pools, founta ins, and similar installations, 680.22 (C), 680.43(C) Theater dressing rooms, 520.73, 520.74 Transfer, see Transfer switch es Tunnels, 110.55 Unit Appliances, 422.34, 422.35 Fixed resistance and electrode industrial process h eatin g equipment, supply conductors, 425. 19(C) X-ray equipmen t, 517 .72, 660-11 Switchgear, metalenclosed, l 10.33(A), l 10.34( F), 230.211, 250. 112 (A), 490-III De finition, ArL 100 -T-

Tables, Chap. 9, Annex C AC resistance and reactance cables, Chap. 9, Table 9 Ampacities, Table 310. 15(8 )( I ) Amusement atu·action conducto rs, Table .522.22 Cable insulated, over 2000 volts Single insulated aluminum directly buried, Table 311.60 (C)(82) Single insulated copper directly buried, Table 3 I l.60(C) (8 I) Three-conductor aluminum in isolated conduit in air, Table 31 l.60(C) (76) Three-conductor aluminum isolated in a ir, Table 3 l0.60(C) (72) Three-conductor copper cable in isolated co nduit

NATIONAL ELECTRJCAL CODE

in air, Table 31 l.60(C)(75) Three-