There's a subpanel mounted directly to a basement concrete wall which shows signs of arcing between the box and the wall. What are the possible causes?
Regardless of the cause, is it a bad idea to mount a metal box directly on a concrete wall because of the possibility of an unintentional earth connection?
Regardless of the cause, is it a bad idea to mount a metal box directly on a concrete wall because of the possibility of an unintentional earth connection?