Understanding the NEC


What does Section 210-8(b)(1) mean? The first number indicates the chapter (Chapter 2). The numbers before the hyphen indicate the article (Article 210). The numbers after the hyphen indicate the Code section (Section 8), and the letter and numbers in parentheses after the section indicate the subsection. In this case, Section 210-8(b)(1) is the rule that requires all receptacles in commercial and industrial bathrooms to be GFCI protected.

CAUTION: The Parts of a Code article are not included in the section numbers. Because of this, we have a tendency to forget what Part the Code rule is relating to. For example, Table 110-34 gives the dimensions of working space clearances in front of electrical equipment. If we are not careful, we might think that this table applies to all electrical installations. But, Section 110-34 is located in Part B Over-600-volt Systems of Article 110! The working clearance rule for under-600-volt systems is located in Part A of Article 110, Table 110-16.


Everybody wants to be able to use the NEC quickly, but unfortunately it doesn't work that way. How you use the NEC depends on your experience. An experienced Code user rarely uses the index. He or she knows which Code articles contain which rules and uses the Table of Contents instead of the index.

Let me give you an example of how handy the Table of Contents can be. What Code rule indicates the maximum number of disconnects permitted for a service? Answer: You need to know that there is an Article for Services - 230, and this article has a Part for Disconnection Means. Use the Table of Contents to find that the answer is around page 90. I'm sorry that I can't tell you the exact page number, because this book was written about six months before the actual Code Book was printed.

Once you are familiar with the NEC (completed this book) you should use the index to find your way around the Code. The index lists subjects in alphabetical order, and is usually the best place to start for specific information. Unlike most books, the NEC index does not list page numbers, it lists sections, tables, articles, parts, or appendices by numbers.

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