Code Q&A: Sizing an Equipment Bonding Jumper

March 26, 2015

NEC rules for sizing an equipment bonding jumper sized for parallel feeder circuits in a cable

Q. What are the rules for sizing an equipment bonding jumper sized for parallel feeder circuits in a cable?

Find the Answer

A. Bonding jumpers on the load side of feeder and branch circuit overcurrent devices are sized in accordance with Sec. 250.122, based on the rating of the circuit overcurrent device [250.102(D)]. For example, let’s say you’re installing parallel cables that are protected by a 1,200A overcurrent device. A quick check of Table 250.122 reveals the minimum size bonding jumper needed is 3/0 AWG. Each parallel cable must contain a full size equipment grounding jumper based on Table 250.122 [250.122(F)].

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.