Thread: Black copper wiring

I did an inspection yesterday on a home that was built in 1997. The copper wiring in the service panel and the pool panel was completely black. There was no indication of overheating just that the wires had turned black. The inside panel was normal as was the copper on the air conditioner.

Has anyone encountered this and is it a problem? The first photo is the service panel and the second is the inside panel.

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Sounds like a chemical reaction similar to Chinese drywall.
Was it located inside or outside?
Near the pool, equipment, or chemical storage?

Originally Posted by Jim Luttrall

Sounds like a chemical reaction similar to Chinese drywall.
Was it located inside or outside?
Near the pool, equipment, or chemical storage?

My first reaction when seeing it was "OH crap, Chinese Drywall". Only the home was built in 1997 which was before any of the reports of Chinese Drywall that I have heard of. Also the problem is outside and the inside wiring has not problem. The home is in good condition and the roof is original so the chances of major renovations after the hurricanes is not likely.

The pool panel is about 20 to 25 feet away from the pool and around the corner. The main panel is about 30 feet farther away so I don't think it is related to the pool. No storage of any kind in the area.

Hmmm...
That is a puzzler. I'm still leaning toward some type of environmental concern.
How close are you to the ocean?
Maybe there was sulfur or other chemical used for insect control.
Just throwing out ideas here, since I have no idea!

I understand throwing out possibilities, I have been looking at various things but nothing I can be sure it the issue. I have inspected much older houses that the copper looked fine. As to the ocean, we are about 50 miles away. Not likely to be the problem.

Was it all the conductors or just certain ones? Did you ,by chance, take note of the circuits that had the discoloration. Then go to those cicuits and remove some device plates to observe the wiring at those devices? This approach would tell you if it's the entire run of NM Cable or just at the panel locations.

I know that many homes in FL have whole home pest management systems that run through the walls. Does this home have a system like that?

Originally Posted by Scott Patterson

I know that many homes in FL have whole home pest management systems that run through the walls. Does this home have a system like that?

Scott

I read all the posts and was about to reply about pest/termite control. sounds likely. I have come across that myself and no one could figure it out. The only possibility that we could come up with was a reaction to (maybe) particular chemicals for pest control or possibly termite treatment.

Originally Posted by Robert Sole

I did an inspection yesterday on a home that was built in 1997. The copper wiring in the service panel and the pool panel was completely black. There was no indication of overheating just that the wires had turned black. The inside panel was normal as was the copper on the air conditioner.

Has anyone encountered this and is it a problem? The first photo is the service panel and the second is the inside panel.

That effect is usually caused by a sulfur compound in the air. I've personally demonstrated it with the fumes from a charging lead-acid battery and with the fumes from a leaking container of dormant fruit tree spray (contains sulfur). You can also make it happen by exposing the copper to sewer gases. It only takes a few days of exposure for the effect to occur, so the culprit might be long gone.

Pool chemicals will also corrode copper but, in my experience, they tend to turn it green or green/white instead of black.

I've never seen the black stuff cause any problems, but I've always recommended having an electrician strip the wires back to clean copper and re-make the connections. It's what I'd do in my own house.

-Jim Katen, Oregon

The copper for all the circuits in the exterior panel were black. Not just some of them. The home also did not have the tubes in the wall pest system. I have one of these systems in my own home and no discoloration.

I have not seen this in any other homes that I inspected, even very old homes. Rather odd.

Thanks to all that replied. I sent the report with a recommendation to have the panel checked by an electrician to ensure that it did not cause any problems.

What is chinese drywall?

Originally Posted by Ryan Stouffer

What is chinese drywall?

It seems the latest lovely product to come out of China is drywall that's contaminated somehow with toxic sulfur compounds. Seems to be mainly in.
http://www.inspectionnews.net/home.....e-drywall.html
Labeled Home ...

Hi, All &

Am thinking "past" storage of corrosive materials...

All should read this....
CPSC Ties Drywall, Corrosion - WSJ.com

WASHINGTON -- Federal regulators said Monday there is a "strong association" between chemicals emitted by Chinese drywall and metals corrosion, a finding that could pave the way for the government to help homeowners facing billions of dollars in repair bills. But who will pay for the damages remains unclear.

Originally Posted by Robert Sole

The copper wiring in the service panel and the pool panel was completely black. Has anyone encountered this and is it a problem?

Rob, I think that is the corrosion by the chlorine in the moist air, which comes from the chlorine gas/tablets dosed in the swimming pool. Did you smell the chlorine from the pool?

I have an Intersting question? I ran accross a apartment/condo building that is being built hear in Kerrville texas. The contractor is using spray foam on the building units (soy based and the other one). all the copper stub outs, ground wires in boxes, and the HVAC copper lines have a black oiley sticky film on them. on the #12 wire in the boxes it is more black but the larger copper lines show the green/black almost like the copper was touching dissimmilar metal and causing Electrolisis. (<- cant spell LOL). EDIT: thought id mention that the copper stubs are on that new green plastic water pipe nad not touching other metal and the copper HVAC lines are not touching any metal eather in the attic space they are wraped where the cross metal.

I guess my question is is there a spray foam product near that pannel?

has anyone else seen this happining out there?

Originally Posted by Robert Sole

I did an inspection yesterday on a home that was built in 1997. The copper wiring in the service panel and the pool panel was completely black. There was no indication of overheating just that the wires had turned black. The inside panel was normal as was the copper on the air conditioner.

Has anyone encountered this and is it a problem? The first photo is the service panel and the second is the inside panel.

If i were a betting man i would be willing to wager that the oxidation is being caused by the concentrated pool chlorine. if you were to open the back of a light fixture near the pool and examine the wiring you will probably find the same condition

I vote for just saying "I do not know what has caused this to turn black". It will never get you into trouble and many times folks will appreciate your honesty.

That's what he said he did, Scott. See post #10.

But it makes interesting discussion and education here!

Expanding the horizons of knowledge, so to speak.

The only time I've ever found black wire the house had a sulphur spring under it controlled by a sump pump. BUT, the pump wasn't working.

-

I couldnt tell by the pics but the blackened copper wire may have anti oxident paste which usually is black in color....oxidation on copper wires usually turns the copper wire green.......

Originally Posted by Erby Crofutt

That's what he said he did, Scott. See post #10.

But it makes interesting discussion and education here!

Expanding the horizons of knowledge, so to speak.

The only time I've ever found black wire the house had a sulphur spring under it controlled by a sump pump. BUT, the pump wasn't working.

-

Well heck, I missed that one! Still good advice!

I agree with the sulphur and black wire. Green wire in my experience has been from chlorine or fertilizer.

I've run across this several times over the years and there seemed to be a rash of it in Florida around 7 to 10 years ago. At that time, there seemed to be a consensus among electrical engineers that the condition was the result of lack of grounding. This raised the ire of electrical installers (electricians) who would unearth the ground electrode which showed them to be properly installed. Engineer's maintained their position in spite of this saying that even though the ground was installed to code, the system was not grounded properly. One experts opinion to resolve the problem was to install what he called an "exponential ground system" (basically a trench with ground wires all the way around the permiter of the house). very expensive. Don't know how it all ended up. Whenever I ran across, as an HI, I referred it to a sparky.

Originally Posted by Tom McDonnell

I've run across this several times over the years and there seemed to be a rash of it in Florida around 7 to 10 years ago. At that time, there seemed to be a consensus among electrical engineers that the condition was the result of lack of grounding. This raised the ire of electrical installers (electricians) who would unearth the ground electrode which showed them to be properly installed.

That has been the consensus, and simply exposing a ground rod to show that there is a proper clamp on it and that it is properly installed DOES NOT mean the ground is any good.

Engineer's maintained their position in spite of this saying that even though the ground was installed to code, the system was not grounded properly.

Yep, as I just pointed out, having one, two, three, even ten ground rods with proper clamps DOES NOT mean it is grounded properly ... using "properly" not to mean "per code" but to mean "an effective ground".

One experts opinion to resolve the problem was to install what he called an "exponential ground system" (basically a trench with ground wires all the way around the permiter of the house). very expensive. Don't know how it all ended up. Whenever I ran across, as an HI, I referred it to a sparky.

It was my understanding that installing a ground which created a proper effective ground solved most of those problems.

However ...

What Robert described is different.

I did a final electrical today where the electrician had installed a single ground rod 2 weeks ago and I told him he needed to install a second ground rod or prove the resistance of the first was less than 25 ohms.

I went back today and the second ground rod has been installed, and the where the nice, shiny, copper wire is exposed is turning dark, not quite black yet, but it has been less than 2 weeks.

The pool pump is to the left and the pool heater is to the right, with the new service equipment in the middle of them with the required working space in front of the service equipment.

I am siding with, in Robert's case, that chemicals in the air from the pool are the cause. Where the copper wire between the ground rods was buried and it removed the soil to trace the wire to find the second ground rod, the copper was still nice and shiny copper, just not the copper which had been exposed.

Just read an article from Science Encyclopedia:
Copper corrodes only slowly in moist air—much more slowly than iron rusts. First it darkens in color because of a thin layer of black copper oxide, CuO. Then as the years goes by it forms a bluish green patina of basic copper carbonate, with a composition usually given as Cu2(OH)2CO3. (The carbon comes from carbon dioxide in the air.)

In the pictures it appears that wires connected to the neutral bar are double tapped. Couldn't that cause a problem and is it legal?

Appreciate any input thanks Rich

The attached photos demonstrate how copper will turn black when exposed to hydrogen sulfide from a charging battery.

I'd like to see someone repeat this test with pool chemicals to see if the corrosion is black or green. Does someone here have access to some pool chemicals?

Also, for those who believe that copper can be turned black by lack of proper grounding or by some other purely electrical phenomenon, please provide an explanation for the mechanism and the procedure by which I can demonstrate the process.

- Jim Katen, Oregon

Originally Posted by Richard Porter

In the pictures it appears that wires connected to the neutral bar are double tapped. Couldn't that cause a problem and is it legal?

Appreciate any input thanks Rich

It can cause problems, though it usually doesn't.

I don't know whether or not it's legal. That would depend on what laws have been adopted in your area.

Unless the terminals are listed for holding more than one grounded conductor, the NEC prohibits the practice in 110.14(A). It says, " . . . Terminals for more than one conductor and terminals used to connect aluminum shall be so identified." The prohibition goes back at least as far as the 1947 NEC. More recently, (since 2002) the NEC also prohibits the practice in 408.41, which simply says, "Each grounded conductor shall terminate within the panelboard in an individual terminal that is not also used for anot6her conductor."

- Jim Katen, Oregon

For those who recall the posts, back in 2004 or there abouts, I was doing new construction inspections and found blackened service conductors on the house which had never had power connected to it, and in fact the conductor had never yet been connected.

There must have been something in the environment which caused that.

I have found the black/bluish copper in panels for septic pumps. The break down of sewage is very corrosive and the fumes would flow through the conduit into the panel. Other times have been in utility. storage rooms, barns etc. which had pool chemicals or fertilizers.

I'd think that the owner might have stored or used dry acid (sodium bisulfate) for reducing alkalinity (rather than Muratic Acid) as suspect pool chemistry to copper.

I must be missing something (cheap default viewer perhaps?), I don't see any blackened copper in the picture would appreciate it being pointed out.

IIRC Copper Sulfide is also a pool chemical, outside panel + humidity/moisture.....

Originally Posted by H.G. Watson, Sr.

I'd think that the owner might have stored or used dry acid (sodium bisulfate) for reducing alkalinity (rather than Muratic Acid) as suspect pool chemistry to copper. I must be missing something (cheap default viewer perhaps?), I don't see any blackened copper in either picture would appreciate it being pointed out.

H.G.

I missed it the first time that I looked as well. In the left/first pic, look between the grouping of neutral wires at the upper half of the pic and the lower half of the pic. Between them are dark wires that are somewhat difficult to see. They turn down in the center of the pic.

Originally Posted by Gunnar Alquist

H.G.

I missed it the first time that I looked as well. In the left/first pic, look between the grouping of neutral wires at the upper half of the pic and the lower half of the pic. Between them are dark wires that are somewhat difficult to see. They turn down in the center of the pic.

Gunnar

Thanks! I see it now (said the blind man!) (may have also opened same pic twice ).

Instead of Chinese drywall, maybe it's Chinese copper? I wonder where some of our materials are coming from and the manufacturing process and maybe what the plastic insulation is made of. There might be some residual chemical on the wire that oxidizes when exposed to oxygen.