mc ampacty

[wyboy]

I thought mc was rated for ampacty from the 75 degree column (310.15 THWN/THHN). Now I see it is rated from the 60 degree column (310.15 THWN/THHN) from the factory if under if the circuit is rated 100 amp or less. Am I missing something or was I missing something before?

 

[augie47]

Most MC has type THHN conductors, but it's not a guarantee (see 330.112).
The ampacity is determined by 310.15 (see 330.80) and, as with any wiring method, the provisions of 110.14 apply
Look closely at 110.14 and I think you will find that MCV is normally terminated at it's 75? rating/

 

[wyboy]

I agree. But the South Wire specs say to use the 60 degree column for ampacty of circuits rated 100 amps or less even though if one read the NEC, it would seem to be the 75 degree column would apply so long as the terminal is rated at 75?.

 

[jumper]

Change the "if" to "unless" at the bottom of the chart.

If the equipment is marked for use at higher temperatures, the conductor ampacity shall be limited to the following per NEC 110.14(C).

http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet66