MC cable installation

C

cppoly

Senior Member
Location
New York
Can you run MC cable in a convector enclosure? If yes, then all that would need to be considered is ambient temperature correction? What about securing and supporting?
 
Yes you can run in a convector we.would do it all of the time in commercial buildings. The general support rules would apply so as long as they're followed it is permitted. How hot do the surrounding air get?
 
180 degrees. #12's are good for 30A x .29 temp correction = 8.7 amps.

Does this mean a 15 amp breaker is required and the load cannot exceed 8.7 amps?
 
cppoly said:
180 degrees. #12's are good for 30A x .29 temp correction = 8.7 amps.
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I get a .36 correction factor for 90C rated conductors: 180F = 82.2C. So allowable temperature rise is 7.77C. Versus the 60C temperature rise in the ampacity tables (90C rating - 30C ambient), which is 13%. Sqrt of that (heating power is I2*R) is 36% = 0.36. This is equation 310.15(B)(1) in the 2020 NEC.

So that gives you an ampacity of 10.8A for 1-3 CCCs. OK to protect at 15A, calculated load must not exceed 10.8.A.

Cheers, Wayne
 
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