Type AC cable installed in thermal insulation shall have conductors that are rated at 90°C. The ampacity of the cable in this application shall not exceed that of a ______ rated conductor.
a) 60°C
b) 75°C
c) 90°C
d) none of the above
See answer and applicable Code reference
The correct answer is: a) 60°C
Article 320 covers the use, installation and construction specifications for armored cable. As noted in Sec. 320.80(A), "Armored cable installed in thermal insulation shall have conductors rated at 90°C. The ampacity of cable installed in these applications shall not exceed that of 60°C rated conductor. The 90°C rating shall be permitted to be used for ampacity adjustment and correction calculations; however, the ampacity shall not exceed that of a 60°C rated conductor.
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.