Revision Standard – Active. The 2023 NESC(R) covers practical safeguarding of persons during the installation, operation, or maintenance of (1) electric supply stations, (2) overhead supply and communications lines, and (3) underground or buried supply and communication cables. It also includes work rules for the operation of electric supply and communications lines and equipment. This Code consists of the introduction, definitions, grounding rules, lists of referenced and bibliographic documents, and Parts 1, 2, 3, and 4 of the 2023 Edition of the National Electrical Safety Code.

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PDF Pages	PDF Title
1	2023 National Electrical Safety Code® (NESC®) Front cover
2	Title page
4	Important Notices and Disclaimers Concerning the NESC®
7	Foreword
13	Committee Membership
24	Procedure for revising the NESC
26	Time schedule for the next revision of the NESC
29	Contents
35	Figures
37	Tables
40	Section 1. Introduction to the National Electrical Safety Code® 010. Purpose 011. Scope
42	012. General rules
43	013. Application
44	014. Waiver for emergency and temporary installations 015. Intent
45	016. Effective date 017. Units of measure 018. Method of calculation
46	Section 2. Definitions of special terms
59	Section 3. References
62	Section 9. Grounding methods for electric supply and communications facilities 090. Purpose 091. Scope 092. Point of connection of grounding conductor
65	093. Grounding conductor and means of connection
68	094. Grounding electrodes
71	095. Method of connection to electrode
72	096. Ground resistance requirements
73	097. Separation of grounding conductors
74	098. Number 098 not used in this edition. 099. Additional requirements for grounding and bonding of communication apparatus
76	Part 1. Safety Rules for the Installation and Maintenance of Electric Supply Stations and Equipment Section 10. Purpose and scope of rules 100. Purpose 101. Scope 102. Application of rules 103. Referenced sections
77	Section 11. Protective arrangements in electric supply stations 110. General requirements
80	111. Illumination
82	112. Floors, floor openings, passageways, and stairs 113. Exits
84	Section 12. Installation and maintenance of equipment 120. General requirements 121. Inspections 122. Guarding shaft ends, pulleys, belts, and suddenly moving parts 123. Protective grounding
85	124. Guarding live parts
92	125. Working space about electric equipment
93	126. Equipment for work on energized parts 127. Classified locations
96	128. Identification 129. Mobile hydrogen equipment
97	Section 13. Rotating equipment 130. Speed control and stopping devices 131. Motor control
98	132. Number 132 not used in this edition. 133. Short-circuit protection
99	Section 14. Storage batteries 140. General
100	141. Switchgear and plant batteries 142. Grid storage batteries
101	Section 15. Transformers and regulators 150. Current-transformer secondary circuits protection when exceeding 600 V 151. Grounding secondary circuits of instrument transformers 152. Location and arrangement of power transformers and regulators
102	153. Short-circuit protection of power transformers
103	Section 16. Conductors 160. Application 161. Electrical protection 162. Mechanical protection and support 163. Isolation 164. Conductor terminations
105	Section 17. Circuit breakers, reclosers, switches, fuses, and other equipment 170. General 171. Arrangement 172. Application 173. Circuit breakers, reclosers, and switches containing oil 174. Switches and disconnecting devices
106	175. Disconnection of fuses 176. Open gaps and breaks 177. Arresters
107	Section 18. Switchgear and metal-enclosed bus 180. Switchgear assemblies
108	181. Metal-enclosed bus
110	Section 19. Photovoltaic generating stations 190. General 191. Location 192. Grounding configurations 193. Vegetation management 194. DC overcurrent protection 195. DC conductors
111	Part 2. Safety Rules for the Installation and Maintenance of Overhead Electric Supply and Communication Lines Section 20. Purpose, scope, and application of rules 200. Purpose 201. Scope 202. Application of rules
112	Section 21. General requirements 210. Referenced sections 211. Number 211 not used in this edition. 212. Induced voltages 213. Accessibility 214. Inspection and tests of lines and equipment
113	215. Grounding and bonding
115	216. Arrangement of switches
116	217. General
118	218. Vegetation management
119	Section 22. Relations between various classes of lines and equipment 220. Relative levels
120	221. Avoidance of conflict
121	222. Joint use of structures 223. Communications protective requirements 224. Communication circuits located within the supply space and supply circuits located within the communication space
123	225. Electric railway construction
125	Section 23. Clearances 230. General
132	231. Clearances of supporting structures from other objects
133	232. Vertical clearances of wires, conductors, cables, and equipment aboveground, roadway, rail, or water surfaces
144	233. Clearances between wires, conductors, and cables carried on different supporting structures
153	234. Clearance of wires, conductors, cables, and equipment from buildings, bridges, rail cars, swimming pools, supporting structures, and other installations
177	235. Clearance for wires, conductors, or cables carried on the same supporting structure
196	236. Climbing space
200	237. Working space
201	238. Clearances at the support between specified communications and supply facilities located on the same structure
206	239. Clearance of vertical and lateral facilities from other facilities and surfaces on the same supporting structure
212	Section 24. Grades of construction 240. General 241. Application of grades of construction to different situations
213	242. Grades of construction for conductors
215	243. Grades of construction for line supports
217	Section 25. Structural loadings for Grades B and C 250. General loading requirements and maps
234	251. Conductor loading
235	252. Loads on line supports
237	253. Load factors for structures, crossarms, support hardware, guys, foundations, and anchors
239	Section 26. Strength requirements 260. General (see also Section 20)
240	261. Grades B and C construction
249	262. Number 262 not used in this edition. 263. Grade N construction
251	264. Guying and bracing
253	Section 27. Line insulation 270. Application of rule 271. Material and marking 272. Ratio of flashover to puncture voltage 273. Insulation level
254	274. Factory tests 275. Special insulator applications
255	276. Number 276 not used in this edition. 277. Mechanical strength of insulators
256	278. Aerial cable systems
257	279. Guy and span insulators
258	28. Section number 28 not used in this edition. 29. Section number 29 not used in this edition.
259	Part 3. Safety Rules for the Installation and Maintenance of Underground Electric Supply and Communication Lines Section 30. Purpose, scope, and application of rules 300. Purpose 301. Scope 302. Application of rules
260	Section 31. General requirements applying to underground lines 310. Referenced sections 311. Installation and maintenance 312. Accessibility 313. Inspection and tests of lines and equipment
261	314. Grounding of circuits and equipment 315. Communications protective requirements
262	316. Induced voltage
263	Section 32. Underground conduit systems 320. Location
264	321. Excavation and backfill
265	322. Conduit, ducts, and joints
266	323. Manholes, handholes, and vaults
270	Section 33. Supply cable 330. General 331. Sheaths and jackets 332. Shielding 333. Cable accessories and joints
272	Section 34. Cable in underground structures 340. General 341. Installation
273	342. Grounding and bonding
274	343. Number not used in this edition. 344. Communication cables containing special supply circuits
275	Section 35. Direct-buried cable and cable in duct not part of a conduit system 350. General
276	351. Location and routing
277	352. Installation
279	353. Deliberate separations—Equal to or greater than 12 in (300 mm) from underground structures or other cables 354. Random separation—Separation less than 12 in (300 mm) from underground structures or other cables
282	355. Additional rules for duct not part of a conduit system
283	Section 36. Risers 360. General 361. Installation 362. Pole risers—Additional requirements 363. Pad-mounted installations
284	Section 37. Supply cable terminations 370. General 371. Support at terminations 372. Identification 373. Clearances in enclosures or vaults 374. Grounding
285	Section 38. Equipment 380. General 381. Design
286	382. Location in underground structures 383. Installation 384. Grounding and bonding 385. Identificaiton
287	Section 39. Installation in tunnels 390. General 391. Environment
288	Part 4. Work Rules for the Operation of Electric Supply and Communications Lines and Equipment Section 40. Purpose and scope 400. Purpose 401. Scope 402. Referenced sections
289	Section 41. Supply and communications systems—Rules for employers 410. General requirements
296	411. Protective methods and devices
298	Section 42. General rules for employees 420. General
302	421. General operating routines
303	422. Overhead line operating procedures 423. Underground line operating procedures
306	Section 43. Additional rules for communications employees 430. General 431. Approach to energized conductors or parts
308	432. Joint-use structures 433. Attendant on surface at joint-use manhole 434. Sheath continuity
309	Section 44. Additional rules for supply employees 440. General 441. Energized conductors or parts
319	442. Switching control procedures
320	443. Work on energized lines and equipment
322	444. De-energizing equipment or lines to protect employees
324	445. Protective grounds
325	446. Live work
326	447. Protection against arcing and other damage while installing and maintaining insulators and conductors
327	Appendix A—Uniform system of clearances adopted in the 1990 Edition
332	Appendix B—Uniform clearance calculations for conductors under ice and wind conditions adopted in the 2007 Edition
335	Appendix C—Example applications for Rule 250C, Table 250-2, Table 250-3(a), and Table 250-3(b)
350	Appendix D—Practical Approaches to Reducing Transient Overvoltages Factors for Live Work
355	Appendix E—Bibliography
360	Annex 1—Metric tables and figures
396	Annex 2—Letter symbols for units
398	Index A-C C-D
399	D-F
401	F-G
402	H-I
403	I-L L-O
405	O
407	O-R R-S
409	S-T
410	T-U U-W
412	Back cover

Published By	Publication Date	Number of Pages
IEEE	2023	412


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Standard Title	2023 National Electrical Safety Code(R) (NESC(R)) (Published)
Published Code	IEEE
Publication Date	2023
Pages Count	412

IEEE C2-2023

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