Thanks for the quick reply, George. My mistake, I guess, was in using the 60 degree column. But now I see from the examples in NEC2008 Handbook for derating per article 310.15 that they actually use the 90 degree column (though this is for number of conductors in conduit). I can't find which column to use for temperature correction. Can you help me out with a code reference for using the 75 degree column? Much obliged.
