Recently a home inspector noted the exposed copper grounds and the stripped ends on copper conductors were black or tarnished inside the panel ? First thought I had was chinese drywall issue but no other issues in the home . I we looked deeper the home is about 10-12 y.old and the only thing that was strange was if the soil outside may be leaching some sort of corrosive gas thru the underground feeder power riser to the meterbase ? The panel is back to back with it and the ground wire to the grounding rod was clean as it entered the bay below the meterbase but blackened once it was in the panel ? Has anyone ever experienced anything like this ? Thank you in advance for responses.
Once the smell goes away and the sulfur dissipates it is very possible that they cleaned up all of the evidence and they may have actually replaced some or most of the drywall, so it is possible that you are looking at a drywall house and they just did not do anything about cleaning up the panel. I would call it no big deal but as a buyer I still might want a break on the price unless they told me a really good story. I do know a guy who was rehabilitating these houses but he went back to the FEPAC removing every bit of the drywall, sealing the block and started over. (new carpet, new cabinets, new plumbing fixtures, all devices were replaced etc) That was probably more than was necessary but he wanted a clear conscience when he sold the house.
If you have enough free conductor, cut off the exposed part, strip and re terminate.Other than esthetics, it is really not a problem. It does invoke thoughts of chinese drywall tho. On the bare grounds, steel wool will work, the finer grade the better.
Haven't seen it at the panel but I ran into it out in the field at receptacles and switches in one area of a hospital ward. If you pulled a receptacle out at the west or east end of the ward the copper was fine. But in between those two areas I found several where the copper was blackened. Assumed it was a reaction to cleaning chemicals used on equipment in that area.
A malfunction at the junction -------------------------------------- Dwayne
Are you sure this isn't moisture ingress? Copper turns green (verdigris) then black with moisture exposure and can be a mode of conductor failure over time. I use bootlace ferrules on all of my terminations these days, so that there is no real exposed copper.