Black Ground wires

[mnahrgang]

Got a new one for me today... 60 year old home with a newer Square D 200 Amp panel/service. NM Romex, and cloth covered copper wiring. No signs of fire or scorching, but all of the grounding (and grounded) conductors had a black coating on them. When I first looked at it, I thought it was aluminum, then tin coated, then I noticed they all had it. Is this a concern? What would you say if anything?

[Michael Larson]

Originally Posted by mnahrgang

Got a new one for me today... 60 year old home with a newer Square D 200 Amp panel/service. NM Romex, and cloth covered copper wiring. No signs of fire or scorching, but all of the grounding (and grounded) conductors had a black coating on them. When I first looked at it, I thought it was aluminum, then tin coated, then I noticed they all had it. Is this a concern? What would you say if anything?

Its oxidation and can be a sign of exposure to sulfur compounds including those in Chinese Drywall.

It can also occur in high moisture environment.

[mnahrgang]

Originally Posted by mlarson

Its oxidation and can be a sign of exposure to sulfur compounds including those in Chinese Drywall.

It can also occur in high moisture environment.

Ok... there you go. Wet basement.

[Blaine Wiley]

I saw it today. In this case it was Chinese Drywall.