The development and application of the requirements of the Grounding Rules, General Rules and Parts 1, 2, 3, and 4 of ANSI C2-2002, the National Electrical Safety Code (NESC) are discussed and illustrated. Where the requirements of the 2007 Edition of the NESC differ from those of the 3rd, 4th, 5th, 6th, 1973, 1977, 1981, 1984, 1987, 1990, 1993, 1997, or 2002 Editions, the changes are clearly indicated. Sections of the text are identified by the NESC rule to which they refer; rule numbers that differ from those in an earlier edition are cross-indexed. Requirements of earlier editions for which no similar requirement exists in the 1973 or later editions, such as requirements for radio installations, either are not discussed or are discussed in less detail. In many cases, the evolution of rules from inception to the present is provided. The discussions and illustrations in this document are developed from the texts of all prior editions of the NESC, the published official Discussions of the 5th and prior editions, the unpublished Discussion of the 6th Edition, all official Interpretations of the Code, the Rationales issued with public drafts, Change Proposals and Subcommittee Recommendations (including Comments and final Subcommittee decisions thereon), and the editor's and reviewers' knowledge of items considered during revision of the 1973 and later editions. This document is intended specifically to aid users in understanding and correctly applying the requirements of the Grounding Rules, General Rules, and Parts 1, 2, 3, and 4 of the 2007 Edition of the NESC. It also is intended to aid those users in jurisdictions where earlier editions of the Code have been adopted or otherwise used by the administrative authority, or when considering facilities constructed under earlier editions of the NESC. It is especially useful to users of new or nonstandard designs, or construction, operation, and maintenance methods, for which specific requirements have not been detailed in the Code, as an aid in assuring that such installations and activities are consistent with the intent of the Code.