All the conductors were running through a 12" nipple, so derating was not a factor.315(b)(2)(a). This inspector got mad at my written response and sent back a note "refer to 90.4".(authority having jurisdiction bla bla blaaa).....that was pretty weak if you ask me.
He also wanted me to supply my ground rod with a 1/0 thhn. I had already brought a 1/0 to building steel. I quoted 250.53(E) (supplemental grounding electrodeshall not be required to be larger than #6 copper).
He didn't like that one much either.
All said and done there is a piece of 1/0 going to the ground rod and i added (1) more set of 3/0 thhn to make him happy about the whole cir mil idea. Had to change all my lugs to make that one work
. What can you do? Thanks again for all your help.