Do you consider the size of conduit when calculating ampacity? i.e. # 12 THHN in a 2-1/2" conduit with 4 existing current carring conductors.
jt,
There are different rules for 'nipples' or conduits 24" or less in length, just guessing
maybe that is what the 2 1/2" is for ?
I think the question being asked here is does the cross-sectional area of the conduit affect the ampacity of the conductors? The answer being no.
Do you consider the size of conduit when calculating ampacity?
No, the NEC does not take pipe size into account.