60 or 75 degree for MC

[DannyBoiii]

I have always heard that you use 75 degree table for MC but after looking into it further I cant find much that would back that up.
Under 330.80 the NEC redirects you to 310.14 or 311.6 which didn't give much of an answer either. I was mostly interested once I started looking into cost differences for running MC to RTU's in commercial settings.

Also
What is your code interpretation for how many #12 MC cables can be bundled together before you have to derate? I say 10 but would like to hear what others have to say

 

[wwhitney]

I checked the listing standard for MC cable (UL 1569), and it says the inner conductors can be any type listed in the NEC. So in theory you could have some MC cable made with, say, TW conductors, and then you'd be limited to the 60C ampacity. But in practice I expect all you'll find commercially available are MC cables with at least 75C rated insulation on the inner conductors. Regardless, the answer is to check the specs/labeling of your MC cable or the conductors therein.

As for the second question, see 2017 NEC 310.15(B)(3)(a)(4).

Cheers, Wayne

 

[roger]

AFC's MC TUFF uses THHN conductors and has a maximum rating of 90 deg, you can find this info on their website.

 

[infinity]

What is your code interpretation for how many #12 MC cables can be bundled together before you have to derate? I say 10 but would like to hear what others have to say

After 20 CCC's you need to derate to 60%.