320.80 Ampacity.

In MA, the 90°C rating of a type AC cable is not permitted to be used for ampacity adjustment and correction calculations.
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In MA, the 90°C rating of a type AC cable is not permitted to be used for ampacity adjustment and correction calculations.

MA amendments.

320.80(A). Delete the last sentence of the first paragraph, which reads: “The 90°C (194°F) rating shall be permitted to be used for ampacity adjustment and correction calculations; however, the ampacity shall not exceed that for a 60°C (140°F) rated conductor.

320.80(A) Thermal Insulation. Armored cable installed in thermal insulation shall have conductors rated at 90°C (194°F). The ampacity of cable installed in these applications shall not exceed that of a 60°C (140°F) rated conductor. The 90°C (194°F) rating shall be permitted to be used for ampacity adjustment and correction calculations; however, the ampacity shall not exceed that of a 60°C (140°F) rated conductor.

Where more than two Type AC cables containing two or more current-carrying conductors in each cable are installed in contact with thermal insulation, caulk, or sealing foam without maintaining spacing between cables, the ampacity of each conductor shall be adjusted in accordance with Table 310.15(C)(1).

Click here to see the Massachusetts amendments to the 2023 NEC®.

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320.80 Ampacity.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Which of the following is true regarding Type AC cable as amended in Massachusetts?

A: The 90°C (194°F) rating shall be permitted to be used for ampacity adjustment and correction calculations; however, the ampacity shall not exceed that of a 60°C (140°F) rated conductor.
B: Armored cable installed in thermal insulation shall have conductors rated at 75°C.
C: Armored cable installed in thermal insulation shall have conductors rated at 60°C.
D: Armored cable installed in thermal insulation shall have conductors rated at 90°C (194°F).
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