Www Ecmweb Com Sites Ecmweb com Files Uploads 2015 01 Ecm Mini Ad 2014

Code Q&A: Sizing the GEC

Feb. 16, 2017

NEC guidelines for sizing grounding electrode conductors

Q. What are the Code requirements for sizing the grounding electrode conductor (GEC) at a service to a rod type electrode and concrete-encased electrodes?

Find the Answer

A. Metal underground water pipe electrodes and metal in-ground support structures must be sized in accordance with Table 250.66. Other electrodes such as ground rods, concrete-encased electrodes, and ground rings can be sized using Sec. 250.66(A) through (C).

(A) Rod-type grounding electrode. If the GEC or bonding jumper connects to one or more ground rods [250.52(A)(5)] and doesn’t connect to another type of electrode that requires a larger conductor the GEC isn’t required to be larger than 6 AWG copper.

(B) Concrete-encased grounding electrode. If the GEC or bonding jumper is connected to one or more concrete‑encased electrodes [250.52(A)(3)] and doesn’t connect to another type of electrode that requires a larger size conductor, the GEC isn’t required to be larger than 4 AWG copper.

These materials are provided to us by Mike Holt Enterprises in Leesburg, Fla. To view Code training materials offered by this company, visitwww.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.