Q. When is ground fault protection of equipment required for feeder circuits?
A. Each feeder disconnecting means rated 1,000A or more supplied by a 4-wire, 3-phase, 277/480V wye-connected system must be provided with ground-fault protection of equipment in accordance with 230.95 and 240.13 [215.10]. See the definition of "Ground-Fault Protection of Equipment"in Art.100.
Exception 2. Equipment ground-fault protection isn't required if ground-fault protection of equipment is provided on the supply side of the feeder and on the load side of the transformer supplying the feeder.
Ground-fault protection of equipment isn't permitted for fire pumps [695.6(H)], and it's not required for emergency systems [700.26] or legally required standby systems [701.17].
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.