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Stumped by the Code? Grounding Electrode Conductor Rules

March 20, 2017
Your most pressing National Electrical Code (NEC) questions answered

All questions and answers are based on the 2017 NEC.

Q. If more than one electrode is available, what does the Code allow for connecting one grounding electrode to another electrode?

A. Grounding electrode conductors (GECs). GECs and bonding jumpers are permitted to terminate and use the following to extend the connection to another electrode(s) [250.68(C)]:

Fig. 1. Be careful when using an interior metal water pipe as part of the grounding system. There are specific rules to follow with regard to connection points and continuity.

(1) Interior metal water piping that’s electrically continuous with a metal underground water pipe electrode and is located not more than 5 ft from the point of entrance to the building can be used to extend the connection to electrodes. Interior metal water piping located more than 5 ft from the point of entrance to the building isn’t permitted to be used as a conductor to interconnect electrodes of the grounding electrode system (Fig. 1).

(2) The metal structural frame of a building can be used as a conductor to interconnect electrodes that are part of the grounding electrode system, or as a grounding electrode conductor. Hold‑down bolts securing the structural steel column to a concrete‑encased electrode [250.52(A)(3)] can connect the metal structural frame of a building to the concrete‑encased grounding electrode. The hold‑down bolts must be connected to the concrete‑encased electrode by welding, exothermic welding, the usual steel tie wires, or other approved means (Fig 2).

Fig. 2. Metal structural steel columns are one of three approved methods for extending the grounding electrode conductor to an electrode.

(3) A rebar‑type concrete‑encased electrode [250.52(A)(3)] with an additional rebar section to an accessible location above the concrete, where not in contact with the earth or subject to corrosion, can be used for the connection of the grounding electrode conductors and bonding jumpers.

These materials are provided to us by Mike Holt Enterprises in Leesburg, Fla. To view Code training materials offered by this company, visit www.mikeholt.com/code

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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