Q. When does the Code allow the building metal structure to serve as a grounding electrode?
Find the Answer
A. Only metal in-ground support structure(s) in direct contact with the earth vertically for 10 ft or more can serve as a grounding electrode [250.52(A)(2)]. Note: Metal in‑ground support structures include, but aren’t limited to, pilings, casings, and other structural metal.
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.