8 thhn in E.N.T.

[dhsvcs]

What is the ampacity of 3 #8 thhn ( 2 H, 1 N + #10 grnd ) ccc in ambient temperature of 70 degrees F contained in E.N.T. ? Assume 75 C terminals. Is it 50 A ?
Where does the 60C rating for ent come into effect ?

 

[Krusscher]

110.14(C)(1) would determine the temp rating if it wasn't provided. I don't believe just the fact that its installed in E.N.T would ever change the rating on the conductors. Given the ambient temperature you can use Table 310.15(B)(1) to further your calculations.

 

[winnie]

See NEC 362.10

If you install conductors in 60C ENT, your conductor use temperature is limited to 60C. So you need to use the 60C ampacity column even though you have 90C conductors and 75C terminations.

You do get credit for the 70F ambient temperature, so the ampacity of the #8 conductors is 43A.

-Jon

 

[Krusscher]

See NEC 362.10

If you install conductors in 60C ENT, your conductor use temperature is limited to 60C. So you need to use the 60C ampacity column even though you have 90C conductors and 75C terminations.

You do get credit for the 70F ambient temperature, so the ampacity of the #8 conductors is 43A.

-Jon

Doh, guess I missed that bit. I wonder if this question was supposed to include the rating of the ENT or we just assume 60 since it wasn't provided.