The National Electrical Safety Code® (NESC®)
The one-stop resource for the National Electrical Safety Code.

NESC INTERPRETATIONS

The NESC Committee maintains an Interpretations Subcommittee to provide consensus responses regarding the intended application of the NESC. NESC Interpretations serve as the official explanation of the intention of code requirements until such time as the rules are modified. NESC subcommittees review all recent Interpretations as part of each code revision cycle to see if modifications of code language are needed.

NESC Interpretations are available for download at no charge. Interpretation Requests may be submitted to the NESC Interpretations Subcommittee when the wording of a specific rule or set of rules is ambiguous or incomplete, using the NESC Interpretation Request Form. (DOC) 

The Interpretations Subcommittee is limited to providing interpretation of the text of the Code in order to clarify the application or exact nature of a requirement of the Code. IEEE cannot process a request for consulting advice, including general application of the Code, design information and/or design approval.

 

NESC IR 585 (PDF) Rule 233B, 233C, 2 October 2018 
National Electrical Safety Code® Interpretations

NESC IR 584 (PDF) Rule 235C2a, 8 June 2018 
National Electrical Safety Code® Interpretations

NESC IR 583 (PDF) Rule 323B, 11 September 2017 
National Electrical Safety Code® Interpretations

NESC IR 582 (PDF)  Rule 124, 4 May 2017 
National Electrical Safety Code® Interpretations

NESC IR 581 (PDF)  Rule 96D and Rule 99A, 6 Dec 2016 
National Electrical Safety Code® Interpretations

NESC IR 579 (PDF)  Rule 110A, 24 May 2016 
National Electrical Safety Code® Interpretations

NESC IR 578 (PDF)  Rule 097B2, 29 June 2015 
National Electrical Safety Code® Interpretations

NESC IR 577a (PDF)  Rule 232.A, 9 December 2014 
National Electrical Safety Code® Interpretations

NESC IR 577 (PDF) Rule 232.A, 9 December 2014 
National Electrical Safety Code® Interpretations

NESC IR 576 (PDF) Rule 235C1b, 9 September 2014 
National Electrical Safety Code® Interpretations

NESC IR 575 (PDF) Rules 224A, 238D, 5 September 2014  
National Electrical Safety Code® Interpretations

NESC IR 574 (PDF)  Rule 184A4, 3 October 2013 
National Electrical Safety Code® Interpretations

NESC IR 573 (PDF) Rule 354D, 9 December 2013 
National Electrical Safety Code® Interpretations

NESC IR 572 (PDF) Rules 011 and 012, 28 May 2013 
National Electrical Safety Code® Interpretations

NESC IR 571 (PDF)  Rule 235C2b., 17 December 2012 
National Electrical Safety Code® Interpretations

NESC IR 570 (PDF)  Rule 094B., 17 December 2012 
National Electrical Safety Code® Interpretations

NESC IR 569 (PDF)  Rule 215C4b., 2 October 2012 
National Electrical Safety Code® Interpretations

NESC IR 568 (PDF)  Rule 410.A.3.b., 3 May 2012 
National Electrical Safety Code® Interpretations

NESC IR 567 (PDF) Rule 250C & 261A1c, 13 March 2012 
National Electrical Safety Code® Interpretations

NESC IR 566 (PDF) Rule 235C2b(1)(c)i, 26 March 2012 
National Electrical Safety Code® Interpretations

NESC IR565 (PDF) Section 2: Definitions - Sag, 10 April 2012 
National Electrical Safety Code® Interpretations

NESC IR564 (PDF) Rule 215C1, 15 November 2011 
National Electrical Safety Code® Interpretations

NESC IR563 (PDF) Rule 236G, 15 November 2011 
National Electrical Safety Code® Interpretations

NESCIR561 (PDF) Rule 261A2a, 11 May 2010 
National Electrical Safety Code® Interpretations

NESC IR560 (PDF) Rule 235C1a, 235E1, 15 Nov 2011 
National Electrical Safety Code® Interpretations

NESCIR559 (PDF) Rule 096C, 6 October 2009 
National Electrical Safety Code® Interpretations

NESCIR558 (PDF) Rule 410A3, 14 January 2009 
National Electrical Safety Code® Interpretations

NESCIR557 (PDF) Rule 410A3, 14 January 2009 
National Electrical Safety Code® Interpretations

NESCIR556 (PDF) Rule 261C, 29 October 2008 
National Electrical Safety Code® Interpretations

NESCIR555 (PDF) Rule 341B1c, 29 October 2008 
National Electrical Safety Code® Interpretations

NESCIR554 (PDF) Rule 444D, 29 October 2008 
National Electrical Safety Code® Interpretations

NESCIR553 (PDF) Rule 384C, 29 October 2008 
National Electrical Safety Code® Interpretations

NESCIR552 (PDF) Rule 215C1, 11 July 2008 
National Electrical Safety Code® Interpretations

NESCIR551 (PDF) Rule 215C5b, 20 January 2009 
National Electrical Safety Code® Interpretations

NESCIR550 (PDF) Rule 215C1, 20 March 2008 
National Electrical Safety Code® Interpretations

NESCIR549 (PDF) Rule 260B, 261A1b; Table 261-1A, 19 Mar 2008 
National Electrical Safety Code® Interpretations

NESCIR548 (PDF)  Rule 013B3, 26 March 2009 
National Electrical Safety Code® Interpretations

NESCIR547 (PDF) Rule 092B1, 14 January 2008 
National Electrical Safety Code® Interpretations

NESCIR546 (PDF)  Rule 110B2, 30 March 2007 
National Electrical Safety Code® Interpretations

NESCIR545 (PDF) Rule 232 & Table 232-1, 31 Jan 2007 
National Electrical Safety Code® Interpretations

NESCIR544 (PDF) Rule 410A3, 24 January 2007 
National Electrical Safety Code® Interpretations

NESCIR543 (PDF) Rule 234 & Table 234-1, 5 July 2006 
National Electrical Safety Code® Interpretations

NESCIR542 (PDF) Rule 111A & Table 111-1, 16 Dec 2005 
National Electrical Safety Code® Interpretations

NESCIR541 (PDF) Rule 234C3d, 16 Dec 2005 
National Electrical Safety Code® Interpretations

NESCIR540 (PDF) Rule 441 & Table 441-1, 16 Dec 2005 
National Electrical Safety Code® Interpretations

NESCIR539 (PDF) Rule 092E, 16 Dec 2005 
National Electrical Safety Code® Interpretations

NESCIR538 (PDF) Rule 252A and 251A3, 16 Dec 2005 
National Electrical Safety Code® Interpretations

NESCIR537 (PDF) Rule 234 & Table 234-1, 16 Dec 2005 
National Electrical Safety Code® Interpretations

NESCIR536 (PDF) Rule 017B & 094B2, 23 May 2005 
National Electrical Safety Code® Interpretations

NESCIR535 (PDF) Rule 233 Table 233-1, 23 May 2005 
National Electrical Safety Code® Interpretations

NESCIR534 (PDF) Rule 381G2, 23 May 2005 
National Electrical Safety Code® Interpretations

NESCIR533 (PDF) Rule 230C1, 6 February 2004 
National Electrical Safety Code® Interpretations

NESCIR532 (PDF) Rule 096C, 25 August 2003 
National Electrical Safety Code® Interpretations

NESCIR531 (PDF) Rule 279A2a, 25 August 2003 
National Electrical Safety Code® Interpretations

NESCIR530 (PDF) Rule 261D2a(2), 3 September 2002 
National Electrical Safety Code® Interpretations

NESCIR529 (PDF) Rule 230I, 24 July 2002 
National Electrical Safety Code® Interpretations

NESCIR528 (PDF) Rule 092E, 12 March 2002 
National Electrical Safety Code® Interpretations

NESCIR527 (PDF) Rule 234C, 28 May 2002 
National Electrical Safety Code® Interpretations

NESCIR526 (PDF) Rule 110A1, 21 February 2002 
National Electrical Safety Code® Interpretations

NESCIR525 (PDF) Rule 350F, 7 January 2002 
National Electrical Safety Code® Interpretations

NESCIR524 (PDF) Rule 351C1, 3 October 2001 
National Electrical Safety Code® Interpretations

NESCIR523 (PDF) Rule 235G, 31 July 2001 
National Electrical Safety Code® Interpretations

NESCIR522 (PDF) Rule 442G, 28 February 2001 
National Electrical Safety Code® Interpretations

NESCIR521 (PDF) Table 234-3, 11 July 2000 
National Electrical Safety Code® Interpretations

NESCIR520 (PDF) Rule 261 D4a, 7 July 2000 
National Electrical Safety Code® Interpretations

NESCIR519 (PDF) Rule 235F, 7 July 1999 
National Electrical Safety Code® Interpretations

NESCIR518 (PDF)  Rule 234D2, 9 September 1999
National Electrical Safety Code® Interpretations

NESCIR509-517 (PDF) 
National Electrical Safety Code® Interpretations 1997-1999, Eighth Interim Collection:
NESC IR 509, Rule 217B 
NESC IR 510, Rule 235 and Table 235-6 
NESC IR 511, Rule 239D 
NESC IR 512, Table 235-5 
NESC IR 513, Rule 97 
NESC IR 514, Rule 220D and 220E 
NESC IR 515, Rule 235C1, Table 235-5, Rule 235E1, Table 235-6 
NESC IR 516, Rule 232A and 261H 
NESC IR 517, Rule 314A, Rule 96C, Rule 354D

NESCIR500-508 (PDF) 
National Electrical Safety Code® Interpretations 1994-1997, Seventh Interim Collection: 
NESC IR 500, Rule 234C3b 
NESC IR 501, Rule 235-5, Footnote 6 
NESC IR 502, Rule 93D1 and 93D2 
NESC IR 503, Rule Definition: effectively grounded 
NESC IR 504, Table 235-5 
NESC IR 505, Rule 125B 
NESC IR 506, Rule 235C1, Exception 1 
NESC IR 507, Rule 110B2 
NESC IR 508, Table 124-1

NESCIR490-499 (PDF) 
National Electrical Safety Code® Interpretations 1994-1996, Sixth Interim Collection: 
NESC IR 490, Rule 350F 
NESC IR 491, Rule 234F2a, Exception (3) 
NESC IR 492, Rule 220B2e/Table 235-5 
NESC IR 493, Rule 150 
NESC IR 494, Rule 161A 
NESC IR 495, Rule 234C4 
NESC IR 496, Rule 261C2 
NESC IR 497, Rule 230F16 
NESC IR 498, Definition service drop & service point 
NESC IR 499, Rule 350G

NESCIR471-489 (PDF) 
National Electrical Safety Code® Interpretations 1993-1995, Fifth Interim Collection: 
NESC IR 471, Rule 350G 
NESC IR 472, Rule 280A 1b 
NESC IR 473, Rule 441 
NESC IR 474, Rule 235C 2b 
NESC IR 475, Rule 354 D1f 
NESC IR 476, Rule 96C 
NESC IR 477, Rule 441A 2b (1) 
NESC IR 478, Rule 125A 3 
NESC IR 479, Rule 261A 2b (1) (a) 
NESC IR 480, Rule 344 A1 
NESC IR 481, Rule 442E 
NESC IR 482, Rule 171 and Rule 173A 
NESC IR 483, Rule 99C 
NESC IR 484, Rule 239G 
NESC IR 485, Definition: communication line 
NESC IR 486, Rule 441 A2 
NESC IR 487, Rule 235 
NESC IR 488, Table 232-1 
NESC IR 489, Rule 92D2

NESCIR463-470 (PDF) 
National Electrical Safety Code® Interpretations 1991-1993, Fourth Interim Collection: 
NESC IR 463, Rule 442E 
NESC IR 464, Rule 442E 
NESC IR 465, Rule 239G 
NESC IR 466, Rule 97D 
NESC IR 467, Rule 127L, Table 127-5 
NESC IR 468, Rule 440 
NESC IR 469, Rule 381G 
NESC IR 470, Rule 232D4, Table 232-1 Footnote 8

NESCIR448-454 (PDF) 
National Electrical Safety Code® Interpretations 1991-1993

NESCIR444-466 (PDF) 
National Electrical Safety Code® Interpretations 1991-1993

NESCIR442-451 (PDF) 
National Electrical Safety Code® Interpretations 1991-1997

NESCIR11-443 (PDF) 
National Electrical Safety Code® Interpretations 1988-1990

NESCIR11-415 (PDF) 
National Electrical Safety Code® Interpretations 1984-1987

NESCIR11-212 (PDF) 
National Electrical Safety Code® Interpretations 1981-1984

NESCIR11-283 (PDF) 
National Electrical Safety Code® Interpretations 1978-1980

NESCIR92-212 (PDF) 
National Electrical Safety Code® Interpretations 1961-1977

NESCIR92-293 (PDF) 
National Electrical Safety Code® Interpretations 1943-1958

NESCIR530 (PDF) Rule 261D2a(2), 3 September 2002 
National Electrical Safety Code® Interpretations

NESCIR529 (PDF) Rule 230I, 24 July 2002 
National Electrical Safety Code® Interpretations

NESCIR528 (PDF) Rule 092E, 12 March 2002 
National Electrical Safety Code® Interpretations

NESCIR527 (PDF) Rule 234C, 28 May 2002 
National Electrical Safety Code® Interpretations

NESCIR526 (PDF) Rule 110A1, 21 February 2002 
National Electrical Safety Code® Interpretations

NESCIR525 (PDF) Rule 350F, 7 January 2002 
National Electrical Safety Code® Interpretations

NESCIR524 (PDF) Rule 351C1, 3 October 2001 
National Electrical Safety Code® Interpretations

NESCIR523 (PDF) Rule 235G, 31 July 2001 
National Electrical Safety Code® Interpretations

NESCIR522 (PDF) Rule 442G, 28 February 2001 
National Electrical Safety Code® Interpretations

NESCIR521 (PDF) Table 234-3, 11 July 2000 
National Electrical Safety Code® Interpretations

NESCIR520 (PDF) Rule 261 D4a, 7 July 2000 
National Electrical Safety Code® Interpretations

NESCIR519 (PDF) Rule 235F, 7 July 1999 
National Electrical Safety Code® Interpretations

NESCIR518 (PDF) Rule 234D2, 9 September 1999 
National Electrical Safety Code® Interpretations

NESCIR509-517 (PDF) 
National Electrical Safety Code® Interpretations 1997-1999, Eighth Interim Collection: 
NESC IR 509, Rule 217B 
NESC IR 510, Rule 235 and Table 235-6 
NESC IR 511, Rule 239D 
NESC IR 512, Table 235-5 
NESC IR 513, Rule 97 
NESC IR 514, Rule 220D and 220E 
NESC IR 515, Rule 235C1, Table 235-5, Rule 235E1, Table 235-6 
NESC IR 516, Rule 232A and 261H 
NESC IR 517, Rule 314A, Rule 96C, Rule 354D

NESCIR500-508 (PDF) 
National Electrical Safety Code® Interpretations 1994-1997, Seventh Interim Collection: 
NESC IR 500, Rule 234C3b 
NESC IR 501, Rule 235-5, Footnote 6 
NESC IR 502, Rule 93D1 and 93D2 
NESC IR 503, Rule Definition: effectively grounded 
NESC IR 504, Table 235-5 
NESC IR 505, Rule 125B 
NESC IR 506, Rule 235C1, Exception 1 
NESC IR 507, Rule 110B2 
NESC IR 508, Table 124-1

NESCIR490-499 (PDF) 
National Electrical Safety Code® Interpretations 1994-1996, Sixth Interim Collection: 
NESC IR 490, Rule 350F 
NESC IR 491, Rule 234F2a, Exception (3) 
NESC IR 492, Rule 220B2e/Table 235-5 
NESC IR 493, Rule 150 
NESC IR 494, Rule 161A 
NESC IR 495, Rule 234C4 
NESC IR 496, Rule 261C2 
NESC IR 497, Rule 230F16 
NESC IR 498, Definition service drop & service point 
NESC IR 499, Rule 350G

NESCIR471-489 (PDF) 
National Electrical Safety Code® Interpretations 1993-1995, Fifth Interim Collection: 
NESC IR 471, Rule 350G 
NESC IR 472, Rule 280A 1b 
NESC IR 473, Rule 441 
NESC IR 474, Rule 235C 2b 
NESC IR 475, Rule 354 D1f 
NESC IR 476, Rule 96C 
NESC IR 477, Rule 441A 2b (1) 
NESC IR 478, Rule 125A 3 
NESC IR 479, Rule 261A 2b (1) (a) 
NESC IR 480, Rule 344 A1 
NESC IR 481, Rule 442E 
NESC IR 482, Rule 171 and Rule 173A 
NESC IR 483, Rule 99C 
NESC IR 484, Rule 239G 
NESC IR 485, Definition: communication line 
NESC IR 486, Rule 441 A2 
NESC IR 487, Rule 235 
NESC IR 488, Table 232-1 
NESC IR 489, Rule 92D2

NESCIR463-470 (PDF) 
National Electrical Safety Code® Interpretations 1991-1993, Fourth Interim Collection: 
NESC IR 463, Rule 442E 
NESC IR 464, Rule 442E 
NESC IR 465, Rule 239G 
NESC IR 466, Rule 97D 
NESC IR 467, Rule 127L, Table 127-5 
NESC IR 468, Rule 440 
NESC IR 469, Rule 381G 
NESC IR 470, Rule 232D4, Table 232-1 Footnote 8

NESCIR448-454 (PDF) 
National Electrical Safety Code® Interpretations 1991-1993

NESCIR444-466 (PDF) 
National Electrical Safety Code® Interpretations 1991-1993

NESCIR442-451 (PDF) 
National Electrical Safety Code® Interpretations 1991-1997

NESCIR11-443 (PDF) 
National Electrical Safety Code® Interpretations 1988-1990

NESCIR11-415 (PDF) 
National Electrical Safety Code® Interpretations 1984-1987

NESCIR11-212 (PDF) 
National Electrical Safety Code® Interpretations 1981-1984

NESCIR11-283 (PDF) 
National Electrical Safety Code® Interpretations 1978-1980

NESCIR92-212 (PDF) 
National Electrical Safety Code® Interpretations 1961-1977

NESCIR92-293 (PDF) 
National Electrical Safety Code® Interpretations 1943-1958