#12 in conduit and still use a 20a CB

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According to what I was told there is a step that I missed, that would require me to change the CB to a 15 amp with too many current carrying conductors in a conduit.
 
Kal-EL said:
According to what I was told there is a step that I missed, that would require me to change the CB to a 15 amp with too many current carrying conductors in a conduit.

Like I said it is a trick question (not enough information) 1. if the conduit is less then 24'' you would not need to derate period. 2. what if each conductor terminated on a single 15amp receptacle, then it would need to be on a 15amp cb. 3. If the run was a mile long you would have to derate the wire for VD (not an NEC section though) 4. Are they not allowing you to start derating in the 90 degree column like the NEC allows ? if not why ?
The normal answer in an average situation would be 9 CCC's #12 thhn at 20a. in a raceway.
 
Kal-EL said:
According to what I was told there is a step that I missed, that would require me to change the CB to a 15 amp with too many current carrying conductors in a conduit.
(Nothing personal, Superman. Say hi to Kara for me.)

It's interesting to me the way people see this; that they need to install a smaller breaker. I look at it backwards: if you need a 20a circuit, what size wire will allow the use of the 20a breaker, and what size conduit do the wires require?

Now, I know that almost everyone knows that actual installations have to be sized as I posted, and I know this particular question is about a given wire size. It just seems that discussions forget that the load comes first.
 
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