DornElectric111
Member
I have a 3phase, 120-208volt sub-panel with separate neutral and ground terminal bars. The neutral bar has clearly overheated where the main neutral conductor is landed and has burnt about 4 branch circuit neutrals as well. Also in that same area of the neutral bar was a bonding wire from the feeder bonding bushing, which should have been landed on the ground bar instead. This panel has been in operation for years and supposedly the only work done recently to this business (an automotive lube center), was an upgrade to their neon signage (which is fed out of this sub-panel). Could the sign installer have somehow caused this overheating (possibly sending neon voltage back or ???) in combination with the incorrectly landed bonding wire or could the bonding wire alone have caused the heat? Also, the sign circuit may be part of a multi-wire branch circuit and I can not be positive the branch circuits are on different phases. I was inside this panel months ago and the neutral was definitely in good shape then. Can anybody help me determine this heat issue so that I can replace this panel and know with confidence the issue will not reappear?