Q. Does the NEC specifically state that a generator must be grounded to the earth if its wiring is connected to the premises via a transfer switch that does not open the neutral?
A. According to the grounding requirements of the NEC, the answer is no, since it would serve no purpose to do so. But many generator manufacturers have boilerplate instructions specifying how they want the generator grounded. Because the instructions specifically require grounding, you have to waste your time and money to drive a ground rod [11.3(b)].
It’s unfortunate that many generator manufacturers don’t understand the principles of grounding and the NEC requirements for such equipment. I hope that one day the generator manufacturers would simply state that the generator must be grounded in “accordance with the NEC.”
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.