I'm a little confused about how many conductors I can put in a conduit.
I have a bunch of 20A circutis and I'm wondering how many 12 THHN's I can put in (1) conduit.
I know that 110.14(C) says that:
Conductors with temperature ratings higher than specified for terminations shall be permitted to be used for ampacity adjustment, correction, or both.
I think that means that I can use the 90 degree table for derating. Using the 90 degree table I can get 9 current carrying conductors in one conduit.
30A x 70% = 21A
Now that's the way I figure it. I've been told though that I have to use 110.14(C)(1) which would limit me to the 60 degree table. Using that table I could only have 3 current conductors in one conduit.
Can I use the 90 degree table for derating at all ampacities?
I have a bunch of 20A circutis and I'm wondering how many 12 THHN's I can put in (1) conduit.
I know that 110.14(C) says that:
Conductors with temperature ratings higher than specified for terminations shall be permitted to be used for ampacity adjustment, correction, or both.
I think that means that I can use the 90 degree table for derating. Using the 90 degree table I can get 9 current carrying conductors in one conduit.
30A x 70% = 21A
Now that's the way I figure it. I've been told though that I have to use 110.14(C)(1) which would limit me to the 60 degree table. Using that table I could only have 3 current conductors in one conduit.
Can I use the 90 degree table for derating at all ampacities?