Has anyone seen this before?

[Daniel Rogers]

Today I opened a service panel and found that all the exposed copper wiring was black with tarnish. I've never seen all copper wiring so completely and evenly tarnished in a sevice panel.
The house was built 1993. Interior panel in a laundry room. No evidence of any chemicles or gas sources. No chinese drywall. No exposure to weather. No evidence of over heating, scortching, burning. No other copper wiring in the house or AC coil was tarnished.
I've talked to a couple very competent electricians and they've never seen anything quite like this. I don't think the wiring was tarnished before installation because it's tarnished at the cut ends and still shiney copper under the terminal screws where the air could not get to.
I told the buyer it's not a problem and won't affect electrical performance or safety.
Has anyone seen this before?

[Rick Cantrell]

Today I opened a service panel and found that all the exposed copper wiring was black with tarnish. I've never seen all copper wiring so completely and evenly tarnished in a sevice panel.
The house was built 1993. Interior panel in a laundry room. No evidence of any chemicles or gas sources. No chinese drywall. No exposure to weather. No evidence of over heating, scortching, burning. No other copper wiring in the house or AC coil was tarnished.
I've talked to a couple very competent electricians and they've never seen anything quite like this. I don't think the wiring was tarnished before installation because it's tarnished at the cut ends and still shiney copper under the terminal screws where the air could not get to.

There is evidence of chemicals, that is what is causing the problem.

I told the buyer it's not a problem and won't affect electrical performance or safety.

I would not have made that statement

Has anyone seen this before?

Yes, chlorine, contaminated (Chinese) drywall, other chemicals.

[Vern Heiler]

I have not seen that before but my thoughts would be toward the SEC conduit entering the panel. If the buried end of the conduit is in the gravel of a foundation drain then chemicals could leach into the gravel and gas off. The conduit would be a path for the gas to enter the panel.

[Speedy Petey]

There is evidence of chemicals, that is what is causing the problem.

Really? ONLY inside the electrical panel?
How do you explain that?

[Lon Henderson]

FWIW, curiosity would have taken hold of me and I would have gone beyond my normal inspection. I would have removed a few outlet and switch covers inside the house to have a peak at the wiring there. Similar discoloration would have been note worthy for concern.

[Jim Luttrall]

Interior panel in a laundry room. No evidence of any chemicles or gas sources. No chinese drywall.

No other copper wiring in the house or AC coil was tarnished.

I don't think the wiring was tarnished before installation because it's tarnished at the cut ends and still shiney copper under the terminal screws where the air could not get to.

I told the buyer it's not a problem and won't affect electrical performance or safety.

The evidence of chemical contamination IS the oxidation / corrosion of the copper inside the panel.
The fact that it is present in the laundry room only would lead to the presumption that the contamination was initiated in the laundry room (chlorine bleach?) or was sucked in from outdoors due to air pressure differential at the laundry room vs outdoors.

I would not have told the client "it is not a problem..."
If you don't know what caused it, how can you comment on the future performance or safety? Seems you just bought any future problems!

[Scott Patterson]

When I find copper with a green patina it has always been linked to chlorine. When I find it with a black or dark patina it has always been linked to chemicals with sulfur,such as some yard sprays or powders. I even found some black copper in a panel in a storage room that also had a battery charger charging a boat battery in it. If it is a drywall issue you will find the black copper in other parts of the home as well.

It really is not a big deal as far as the effect on the wire.

But if it makes you feel better and you want to deflect some liability then defer it to an electrician or even better simply say that you do not have a clue as to what caused it or if it is going to be a problem down the road.

[Vern Heiler]

Really? ONLY inside the electrical panel?
How do you explain that?

See #3. It is in a laundry room and I only see makeup air installed rarely. Running the dryer creates a low pressure in the room which would draw in gas through the conduit. Could have been sulfer chemicals used at the exteroir of the home as Scott suggested.

[Raymond Wand]

From the past on this issue.

Copper Wire Discoloration - InspectionNews.com

[Rick Cantrell]

Really? ONLY inside the electrical panel?
How do you explain that?

Copper used for electrical wire is not an alloy, it is pure copper.
Pure copper is very reactive to many chemicals such as chlorine and sulfur, but there are others.
For the most part, other metals are not as reactive as copper, they may not corrode as fast.
Also we do not know if it was "ONLY inside the electrical panel", it may have not been seen in other places.

[Ted Menelly]

Really? ONLY inside the electrical panel?
How do you explain that?

Airborne

[Speedy Petey]

Also we do not know if it was "ONLY inside the electrical panel", it may have not been seen in other places.

As per the OP, who was actually at the house.

No evidence of any chemicles or gas sources. No chinese drywall. No exposure to weather. No evidence of over heating, scortching, burning. No other copper wiring in the house or AC coil was tarnished.

[H.G. Watson, Sr.]

Missing strand material (tinning missing exposing copper), that's evidence of something amiss. Indicated (white insulated) groundED conductors multiply tapped in bus (sharing bare - thus indicated as groundING conductors) (green circules) suggestive of what is and was violation and indication of something WRONG in the panel, (groundinG conductors sharing terminal with groundED conductors - DISIMILAR conductors (in this case one insulated/coated, one bare) sharing terminal, requiring investigation, and since installed in violation of the listing & mfg.'s labeled instructions of the Square D panelboard/load center/cabinet, the Standard(s) of Safety it would have been investigated nd listed under, and the NEC (of whichEVER vintage this may be/have been manufactured & listed, and whichever vintage installed under, as per what can be seen.

The "tarnish", discoloration, coating, oxidation, or markings are not universal throughout nor consistant even within area of exposed conductor - see second circle red marked in photo. Both areas within circles suggestive of heat, damage, arc, transient, contact event, etc..



Brackish, tidal, and swamp areas subject to ocean/bay salt "air", sulfur (vegitative deterioration, etc.) additional possbilities. Untinned copper in marine (salt water, tidal areas) will oxidize (black) right quick.

Laundry room is suggestive of laundry detergents, soda, bleach, non-chlorine oxiding "bleach" such as "oxyclean", and ammonia. Laundry room also suggests moisture rich (at times) environment. Laundry room also suggests a clothes dryer sucking air in heating it and venting to outdoors. Laundry room suggests CHEMICAL exposure, oxidizing agents and moisture. General region of OP (south east virginia, Hmpton Roads) suggests marine or coastal, possibly tidal, brackish, geography. Vintage might also suggest possibility of backstabbed receptacles on the circuits.

The OP did not indicate the "AC Coil" or the HVAC was in the laundry room containing panel either.Yes I've seen. A Quart can of stripper, ever-leaking fumes, being burnt off by the electric or gas dryer and settling in the (naturally ventillated) indoor panel with some condensation can result in what is pictured. So would uncoated copper near bay, brackish swamp areas, or tidal streams, or near ocean/bay, salt water areas (effected by coastal fog counts). Wouldn't expect a 1993 vintage clothes dryer still in place - and doubt the OP removed the cover for the dryer receptacle (electric or gas) or checked terminal connections. I don't recall the OP having indicated the presence of exposed plumbing in said "laundry room" - nor the material thereof, nor if same was original, either.

[Jim Port]

Could someone please circle the missing strand?

[Jim Port]

Thanks Robert, since I only saw one stranded conductor and did not see a broken strand I was wondering what someone else was seeing.