Revisions included in the 2012 edition
- Scope, application and definition rules were extensively revised to provide clarification improvements , particularly with respect to whether the NESC or the National Electrical Code® (NEC®) (NFPA® 70) applies in certain situations.
- Grounding rules added specificity to the methods to be used to achieve effective grounding connections.
- The electrical supply stations rules added options for protecting energized parts from interference by activities outside the stations and for guarding inside the stations · The overhead general rules revised requirements for inspections and for facilities to be grounded or insulated.
- The overhead clearances rules added a new clearance zone for specification of conductor conditions to be used on warm islands within 25º north or south latitude.
- The overhead loading and strength rules deleted the older calculation methodology, added loading requirements for warm islands within 25º north or south latitude, revised wind loading requirements to allow easier determination of loads on portions of structures at specific heights above grade, revised aeolian vibration limitations, and clarified the conditions under which the constant is used to determine loading (in tension).
- The underground rules revised the inspection rules and clarified requirements for direct-buried cables and conduits not part of a conduit system.
- The work rules added options for determining appropriate arc ratings for apparel to be worn while working on energized lines, added maximum clearing times allowed for specified apparel arc ratings, revised the minimum approach distances (MADs) to meet the requirements of IEEE Std 516™-2009, and revised specification for the location of employee protective grounds.
- Appendixes were revised to add examples of calculating extreme wind loadings on a variety of structure types and to add an explanation of how to determine the maximum anticipated per-unit overvoltage factor T at a work site.