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.
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.