Courtesy of www.MikeHolt.com. Based on the 2023 NEC.
Question: Class I, Division 1 locations are those areas in which ignitible concentrations of _____ can exist under normal operating conditions.
a) combustible dust
b) easily ignitable fibers or flyings
c) flammable gases or flammable liquid-produced vapors
d) pyrotechnics
See answer below.
Answer: c) flammable gases or flammable liquid-produced vapors
Section 500.5(B)(1)(1) states Class I, Division 1 locations are ones "in which ignitible concentrations of flammable gases, flammable liquid-produced vapors, or combustible liquid-produced vapors can exist under normal operating conditions."
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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.