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Code Q&A: Metal Frame as Grounding Electrode

June 7, 2012

Your most pressing National Electrical Code (NEC) questions answered

Q. What does the Code require in order to use a metal frame of a building as a grounding electrode?

A. The metal frame of a building/structure can serve as a grounding electrode when it meets at least one of the following conditions [250.52(A)(2)]:

• At least one structural metal member is in direct contact with the earth for 10 ft or more, with or without concrete encasement [250.52(A)(2)(1)].

• The bolts securing the structural steel column are connected to a concrete-encased electrode [250.52(A)(3)] by welding, exothermic welding, steel tie wires, or other approved means [250.52(A)(2)(2)], as shown in the Figure.

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.