Blackened Grounds

I know this has been discussed here, but I’m not sure we’ve ever come to a concensus as to the issue that causes it.

The house has been vacant/unoccupied for nearly one year, built in 2005.

All grounding conductors are black. Some show signs that they may have been heated with a blueish tint.

Most of the ungrounded conductors (neutrals) were also black.

None of the ungrounded conductors were black.

Interior receptacles show no abnormal voltage-drop, and there was no discoloration at the conductors inside the home. The panel wiring showed no abnormal heat ranges with thermal imaging.

What say you?








Ever see a copper roof?

It’s you left-coast-outdoor-panel guys. :mrgreen:

WOW! Is the market that bad out there?

If it were really that simple, shouldn’t we expect that the ungrounded conductors be blackened as well?

How is that bad? Foreclosures are “hot.” Bank will try and hold out for a good price, but eventually they get realistic and reduce them to maket rates.

This one is in the desert, 3200 sq ft for $289k.

Well water? Sulfer? Maybe an aeriator
I know that turns copper black.

Aren’t these ungrounded & darkened as well?


Read the replies:


The copper and the black has nothing to do with the fact that one is hot and one is at ground level

Look at it this way if the breaker is closed both are at the same level

Copper changes color based on what is in the air and on what is on the wire

Why some of the “HOT” wires were not black I can not answer

Something is not known

I do not see a reportable issue without additional information

I do not think that a good electician could help without additional information


Joe your post did not help


Yep. Didn’t notice those at the time. . .

Could the presence of excessive harmonics within the system attract airborne particles?

Read through the replies they do discuss the issue and show that there is a problem, leaving the job and inspection that a HI was hired to do without mention on a report, is likely to come back to the frost and heat the argument, **again READ the replies!! :mrgreen: **


We have no information to suggest there is a problem other than cosmetic.

I would still “observe and report” what is present and also report the fact that no factual information has been located that explains the darkened copper.

Hey all, my first post - I am new to the board and really appreciate the serious stuff, the code specific items and the funnies too!

Boaters here]( seem to think the black copper is due to salt.


I see that in basement panels all the time when the house has sewer problems. Whatever the weird gas is that comes out of a sewer line will turn the exposed copper black/blue like that. Does the same thing to the copper pipes in the basement.

ok. so do we have a consensus yet? i’ve read salt, sewage issues, meth lab.

I vote yes.

The chemical is probably sulfur, where it is coming from is still up in the air.
It could be sewer gas (hydrogen sulfide), sulfer from water treatment (well water) or some customer generated chemical activity (meth lab)


I vote for sulfur/copper reaction. Unoccupied could mean dry plumbing traps that would allow sewage gas back into the property. Vacant property means the gas was concentrated during periods of no one entering. hydrogen sulfide in sewage gas oxidized the copper. How did the water lines look? I was in a house about a year ago where everything(plumbing and electrical) in the basement was blackened like this.