Listed flexible metal conduit can be used as the equipment grounding conductor if the length in any ground return path does not exceed 6 ft and the circuit conductors contained in the conduit are protected by overcurrent devices rated at ______ or less.
a) 15A
b) 20A
c) 30A
d) 60A
See answer and applicable Code reference
The correct answer is: b) 20A
Part VI of Art. 250 covers equipment grounding and equipment grounding conductor requirements. The acceptable types of equipment grounding conductors that can be run with or enclosing the circuit conductors are outlined in Sec. 250.118. As noted in 250.118(5), listed flexible metal conduit must meet four conditions to serve as an equipment grounding conductor. One of those conditions, (5)(b), states: "The circuit conductors contained in the conduit are protected by overcurrent devices rated at 20A or less."
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.