MC cable ampacity

[blueheels2]

So reading around the general consensus is that the conductors in MC cable are THHN and are rated at 90 degrees. Terminations are usually rated 75 degrees so it limits Max cable to that ampacity. NEC 330.80 refers you to 310.60or 310.15 for ampacity. I don’t see anything in either of those that spells out that MC is good for 75. NM clearly states to use the 60!degree column. MC isn’t in any column. Is that because we are just using the internal conductors to figure allowable ampacity. What am I missing?

 

[infinity]

You would protect the conductors according to their ampacity in T310.16 but within the limits of 240.4. So for example even though #12 AWG is rated for 25 for amps at 75°C your still limited to the ampacity of 20 amps in 240.4 unless it meets 240.4(G).

 

[roger]

Unlike NM the conductors in MC are identified as THHN/THWN so you use the tables in 310.

Notice the conductor information in the specification section below.

AFC Cable Systems, Inc. was founded in New Bedford, Mass in 1926 .

AFC Cable Systems, Inc., a part of Atkore International, is a leading designer, manufacturer and supplier of electrical distribution products.

www.afcweb.com

 

[blueheels2]

But table 310.16 doesn’t list MC cable so I assume we are basing it off of the THHN conductors in the MC?

 

[blueheels2]

Unlike NM the conductors in MC are identified as THHN/THWN so you use the tables in 310.

Notice the conductor information in the specification section below.

AFC Cable Systems, Inc. was founded in New Bedford, Mass in 1926 .

AFC Cable Systems, Inc., a part of Atkore International, is a leading designer, manufacturer and supplier of electrical distribution products.

www.afcweb.com

Thanks Roger that’s what I was looking for.

 

[infinity]

But table 310.16 doesn’t list MC cable so I assume we are basing it off of the THHN conductors in the MC?

Yes.