Totally enclosed motors shall have no external surface with an operating temperature that exceeds _____ when operating in Class I, Division 1 locations.
a) absolute zero
b) 80% of ignition temperature of the gas or liquid involved
c) 100°C
d) 40°C
See answer and applicable Code reference
The correct answer is: b) 80% of ignition temperature of the gas or liquid involved
Code requirements for equipment placed in Class I locations can be found in Part III of Art. 501. As noted in Sec. 501.125(A), in Class I, Division 1 locations, motors, generators, and other rotating electrical machinery shall conform to one of the four options shown. "Totally enclosed motors of the types specified in 501.125(A)(2) or (A)(3) shall have no external surface with an operating temperature in degrees Celsius in excess of 80% of the ignition temperature of the gas or vapor involved."
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.
