Code Q&A: Ground Fault Protection of Equipment

June 16, 2016

NEC requirements for ground fault protection of equipment

Q. What is the Code rule for ground fault protection of equipment?

Find the Answer

A. Service disconnects and feeder circuits rated 1,000A or more, supplied from a 4-wire, 3-phase, 277/480V wye-connected system must be protected against ground faults in accordance with Sec. 230.95 [215.10 and 230.95]. The requirement for ground fault protection of equipment doesn’t apply to [240.13]:

1) Continuous industrial processes where a non-orderly shutdown will introduce additional or increased hazards.

2) Installations where ground fault protection of equipment is already provided.

3) Fire pumps [695.6(H)].

Article 100 defines “Ground Fault Protection of Equipment” as a system intended to provide protection of equipment from ground faults by opening the overcurrent device at current levels less than those required to protect conductors from damage. This type of protective system isn’t intended to protect people, only connected equipment. See Sec. 215.10 and Sec. 230.95 for similar requirements for feeders and services.

Ground fault protection of equipment isn’t required for emergency power systems [700.27] or legally required standby power systems [701.26].

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.