Branch Circuits & WiringQuestion 222 of 521
Which statement about Type MC cable ampacity is correct?
a.Like NM, MC ampacity is limited to the 60°C column
b.MC ampacity may be based on the 75°C or 90°C rating of its conductors, subject to terminations
c.MC is always limited to the 75°C column
d.MC is always taken at the 90°C column regardless of terminations
Explanation
Per 330.80, MC cable ampacity follows 310.15 based on the conductor temperature rating (commonly 90°C for derating), then limited by the termination temperature per 110.14(C). Unlike NM, it is not capped at 60°C, but it is also not simply taken at 90°C at the terminals.
Law Reference: 2023 NEC §330.80Practice all 521 questions free — no signup required.
Related questions on this topic
- Per 334.30, Type NM cable must be secured and supported at intervals not exceeding what distance along the run?
- Per 334.12, which of the following installations is NOT permitted for Type NM cable?
- Per 330.30, Type MC cable must be supported and secured at intervals not exceeding what distance?
- Under what condition may Type MC cable be installed in a wet location?
- Per 320.40, what must be installed at each termination of Type AC (armored) cable to protect the conductors from the cut edge of the metal armor?
- Per 320.30, Type AC cable must be secured and supported at intervals not exceeding what distance?
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