Code Q&A

Q. We have a heat tape system installed on a metal roof. Someone told us to use a GFCI on the circuit, and someone else told us not to. Does the NEC offer any guidance here?

Mike Holt

Sept. 10, 2009

Q. We have a heat tape system installed on a metal roof. The heat tape has arced against the metal before, and we are concerned we will burn the place to the ground. Someone told us to use a GFCI on the circuit, and someone else told us not to. Does the NEC offer any guidance here?

A. Yes. Fixed outdoor electric deicing and snow-melting equipment must have ground-fault protection of equipment (GPE), unless the equipment uses mineral-insulated, metal-sheathed cable embedded in a noncombustible medium [426.28]. This GPE protection is different from a GFCI because it trips at a higher current value (30mA as opposed to 5mA).

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.