Enclosure Requirements in Class III Locations

Article 503 covers the requirements for electrical and electronic equipment wiring for all voltages in Class III, Division 1 and 2 locations.

Mike Holt

Sept. 3, 2014

In Class III locations, switches, circuit breakers, motor controllers, and fuses, including pushbuttons, relays, and similar devices, shall be provided with _____.

a) Class I enclosures
b) general duty enclosures
c) dusttight enclosures
d) seals at each enclosure

See answer and applicable Code reference

The correct answer is: c) dusttight enclosures

Article 503 covers the requirements for electrical and electronic equipment wiring for all voltages in Class III, Division 1 and 2 locations. As per 503.115, "Switches, circuit breakers, motor controllers and fuses, including pushbuttons, relays and similar devices, shall be provided with dusttight enclosures."

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.