Have 2 steamer units at a restaurant where the insulation on the conductors entering the units has melted off. it is melted about 4 inches where the connection (wire nuts) is to where in comes in from the FMC. I saw this at another restaurant about a year ago on a broiler. Ran new conductors and and assumed it was a bad connection that was the cause. Now that I've seen it a few times, I wonder if it is caused by something different. Anyone run across this before?