90C wire 75C Breaker

wireday

Senior Member
If my #12 thhn is 90C, and the Breaker Im going to be using is 75C do I start my derating at 30 or 25amps? do they make 90c Breakers? thanks
 

Mulrooney

Member
I don't think anyone makes a termination rated for 90c. Always thought 110.14(C) should be with the 310. tables. Be less confusing. Just Saying.
 

Smart $

Esteemed Member
Location
Ohio
I don't think anyone makes a termination rated for 90c. Always thought 110.14(C) should be with the 310. tables. Be less confusing. Just Saying.
There are plenty of 90?C-rated terminations... just none in manufactured assemblies containing distribution or control equipment.
 

DBoone

Senior Member
Location
Mississippi
You would derate from 30A, get your ampacity, then compare to the 75C column and use the smaller of the two as our final ampacity correct?
 

DBoone

Senior Member
Location
Mississippi
What I meant was even if 75C (25A) was the ampacity one still could be limited to a 20A OCPD. Of course you and most others on here know that but I was mainly just throwing that out there to make sure I was correct.
 
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