The Meaning of a Word: Important definitions are found in Article 100

By Michael Johnston | Apr 15, 2021




Article 100 is the keeper of national electrical code definitions. The NEC Style Manual indicates that if a word or term is used in more than two articles, then it should have a definition in Article 100.

Article 100 of the 2020 NEC has three parts, “Part I, General;” “Part II, Over 1,000 volts, nominal;” and “Part III, Hazardous (Classified) Locations.” In this and previous editions of the NEC , there are also definitions in the .2 position of some articles. A definition located here usually means the word or term is defined for use in that article. In the 2020 NEC , there was a revision to clarify which .2 definitions applied only within the article and which definition(s) applied not only in that article, but applied to the term if it is used in other Code articles.

Enter the 2023 proposed revisions—not yet final—to Article 100 and the .2 definitions.

The NEC Style Manual provides an extensive number of rules that the Code -making panels must follow when developing the NEC rules. The 2020 NEC Style Manual was significantly revised by an assigned Usability Task Group, leading to big changes regarding the location of all definitions. The Style Manual now requires all defined words and terms to be located in Article 100 in alphabetical order. No longer will definitions appear in the .2 position of any article, and Article 100 will no longer have three parts.

The Usability Task Group’s consensus was that, by locating all of the definitions in Article 100, there would be only one place to look for a definition, and they would be listed alphabetically, just like a normal dictionary. There would also be a closer alignment with how definitions are managed in the other NFPA codes and standards. They are typically located in Chapter 3. From a usability standpoint, when a word or term in a rule is in question as to the meaning and context, the user simply refers to Article 100. It’s no different than using a dictionary, which most everyone should know how to do.

Defined words and terms in the Code provide clarity in the requirements in which they appear. For example, “outlet” is defined as “a point on an electrical system at which current is taken to supply utilization equipment.” This definition clearly differentiates an outlet from a receptacle (a contact device), which has its own definition. The receptacle is a device that is often installed in an outlet located at the end of a branch circuit, which is another term defined in the Code .

A branch circuit is defined as “the circuit conductors between the final overcurrent protective device protecting the circuit and the outlet(s).” Branch circuits are clearly differentiated from what the Code defines and refers to as “feeders,” and it goes on. The important point is that the use and understanding of words and terms as they are defined in the NEC is crucial in assisting users’ understanding of the requirements so they can properly and accurately apply them.

Slang words and terms mean different things to different people. In the electrical field, using slang words and terms can result in the wrong requirement being applied to an installation. As an example, if one were to ask, where is the “ground” for this transformer located, a degree of confusion is already introduced. The term “ground” is defined in the NEC as “the earth” and a transformer is often a separately derived system, which is another defined term. If the question is seeking where the “grounding electrode” or “grounding electrode conductor” for the transformer is located, then by definition, the communication is enhanced exponentially. In this case, the appropriate requirements can be applied to the exact situation being dealt with, assisting in understanding all related installation requirements, sizing rules and so forth.

Many slang terms and words fly off the tongues of people in the electrical industry, which are sometimes understood and sometimes not. The point of this writing is that it is vital to use a common language when applying the requirements of the Code . Use the NEC words and terms, many of which are defined. It will ultimately enhance knowledge and understanding of the Code , while supporting accurate application of these important rules.

About The Author

A man, Mike Johnston, in front of a gray background.

Michael Johnston

NECA Executive Director of Codes and Standards

JOHNSTON is NECA’s executive director of codes and standards. He is a member of the NEC Correlating Committee, NFPA Standards Council, IBEW, UL Electrical Council and NFPA’s Electrical Section. Reach him at [email protected]


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