Posted by gfretwell:
I say GFCI protection for personnel (5ma) per 210.8(B)(4) outdoors or 210.8(B)(8) garage, depending on where these heaters are. (using 2011) If you are still on the 08 code, commercial garages have not been picked up yet.
Posted by Texas_Ranger:
There are a few interesting effects. One is that the copper conductor is discoloured (oxydised) even in relatively new wire. The process is known to the manufacturers and considered harmless if the conductors are cleaned before they are terminated. I have seen affected wires from ca. 1960 (...)