Ran into a problem yesterday with wire sizing. I've been called on this before and need some advice. Walked onto apartment job and saw guys pulling #4 SE aluminum to the furnaces. The furnaces were already made up in one building and pulled in the next(16 units total). The next day I walked with the inspector and he said the #4 is too small because we have to rate it off 75 degree charts for the lugs. Min ampacity is 58.5 MOPD is 60. Went into the code book and saw 6-2 copper is too small. Then i figured we would run 6-2 SE copper. Called the inspector and he said SE cable if it runs through the interior of a building has to be rated off 60 degree chart. I knew the aluminum was going to fail and I know the 6-2 nmb is too small. Do I have to run 4-2 or are their any exceptions or anything else I am missing? Thx