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