Common GEC Requirements with Multiple Separately-Derived Systems

April 30, 2015
Article 250 covers the general requirements for grounding and bonding.

Each tap conductor to a common grounding electrode conductor for multiple separately derived systems shall be sized in accordance with ______, based on the derived ungrounded conductors of the separately derived system it serves.

a) 250.66
b) 250.118
c) 250.122
d) 310.15

See answer and applicable Code reference

The correct answer is: a) 250.66

Article 250 covers the general requirements for grounding and bonding. System grounding requirements are specifically outlined in Part II of this Article. As we drill further down into this Article, we find the requirements for grounding separately derived alternating-current systems in Sec. 250.30. As per 250.30(A)(6)(b), "Each tap conductor shall be sized in accordance with 250.66 based on the derived ungrounded conductors of the separately derived system it serves."

About the Author

Mike Holt

Mike Holt is the owner of Mike Holt Enterprises (www.MikeHolt.com), one of the largest electrical publishers in the United States. He earned a master's degree in the Business Administration Program (MBA) from the University of Miami. He earned his reputation as a National Electrical Code (NEC) expert by working his way up through the electrical trade. Formally a construction editor for two different trade publications, Mike started his career as an apprentice electrician and eventually became a master electrician, an electrical inspector, a contractor, and an educator. Mike has taught more than 1,000 classes on 30 different electrical-related subjects — ranging from alarm installations to exam preparation and voltage drop calculations. He continues to produce seminars, videos, books, and online training for the trade as well as contribute monthly Code content to EC&M magazine.

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