Code Quiz: EGC Sizing Requirements

June 27, 2019

Do you know the Code requirements for equipment grounding conductor sizing?

Question: What size equipment grounding conductor (EGC) is required for a feeder tap supplying a 60A breaker consisting of 8 ft of No. 6 THWN copper conductors tapped from a feeder supplied by a 400A circuit breaker?

See the answer below.

Answer: No. 6

Explanation: Section 250.122(G) requires the equipment grounding conductor (EGC) run with tap conductors to be sized in accordance with Table 250.122 based on the rating of the overcurrent device ahead of the feeder but not larger than the tap conductors. The 400A circuit breaker would normally require a No. 3 but a No. 6 is the largest EGC required to be run with the No. 6 tap conductors.

Lupacchino is a senior design engineer with Gaylor Electric, Inc. in Noblesville, Ind. and serves as an alternate on NEC Code-Making Panel No. 3. He is currently licensed in more than 80 jurisdictions. He can be reached at [email protected].

About the Author

John Lupacchino | Senior Design Engineer

John began his career in electrical construction as an apprentice and worked his way through the trade. He is currently licensed in more than 80 jurisdictions. With more than 35 years of experience, he now plays a vital role in Gaylor Electric’s Engineering Department, where he serves as a senior design engineer. With a focus on design engineering, quality assurance, and code compliance, he has earned the highest level of respect from industry professionals alike. John currently serves as an alternate on NFPA 70 Code Making Panel No. 3. In addition, he enjoys sharing his electrical knowledge through education. As an Associated Builders and Contractors instructor, he continues to help grow a new generation of high-performing construction leaders.