Discoloration

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pierre

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Westchester County, New York
"Green copper oxide around pipes, grounding connections, and conductor connections mean electricity is returning to the source along an undesirable path."

This quote is from an industry leader. I never heard this before and I am wondering if anyone can agree or disagree with this statement.

I have seen this event occur, but I always thought this was due to the environmental conditions...water, humidity, etc...
 
Re: Discoloration

I think you can safely say that copper oxide is green.

I also think that copper can oxidize in the absensce of electrical current.

I'd say as a global statement, hogwash.
 
Re: Discoloration

Yea Green copper pipe...Couple a years ago got a call from a concerned GC. The copper water pipe was turning green at all the joints! The water bond was also turning green! Must be an electrical problem. Two engineers went and looked but ended up scratching their heads. Couldn't figure out what it was. I go out and look. Everything the GC said was true! After a little showmanship and an Oscar performance I placed the blame squarely on the plumber!!! He didn't wipe up his flux after soldering the joints. The tiny bit of acid flux oxidized the copper and turned it green.
Also some got up on my water bonding conductor.

Never knew if the GC called the plumber, but haven't seen him on too many jobs.
 
Re: Discoloration

I think it is due to lazy plumbers who do not wipe the excess flux from their sweat joints.
 
Re: Discoloration

Has anyone ever seen all the conductors in a back to back service panel turn black ?Not the wires landed on the breakers still shiney CU but the bare grounds and the neutrals were all black.Rub your finger on them and it wiped off to a degree.One ahj said he had heard that it was from gases that had entered the service from underground and discolored the wires.But it was only the ungrounded conductors ;)
 
Re: Discoloration

"Green copper oxide around pipes, grounding connections, and conductor connections mean electricity is returning to the source along an undesirable path."
Click to expand...
If this is true it's a good thing that electricity knows the difference between desirable and undesirable paths.
 
Re: Discoloration

All metalic materials will oxidize in the presence of moisture/salt atmosphere. Dissimilar metals exerbate the problem by producing a voltage between them (like a thermocouple), called galvanic corrosion. Metals need to be passivated to prevent corrosion, other than stainless, you will never find bare metal on a boat (except for the next sentence). Often a sacrificial metal is used to protect components in a hostile environment, you boaters would know this as the zinc block you attach to the outboard motor. The previous posts where correct, a little acid, moisture, and voila! Generally, if all the copper is of the same alloy, corrosion should not be produced due to electical flow.

Is it possible this basement is damp as well?

here is an interesting site for corrosion and galvanic corrosion

http://www.corrosion-doctors.org/Aircraft/galvseri-compat.htm
 
Re: Discoloration

I guess I was referring to handrails, fishing rigs and general hardware. An aerospace term for Stainless is Corrosion REsistant Steel (CRES). Stainless will out do most other metals except for the low index metals like gold and platinum. Even brass will develop a patina (read that as corrosion)in air or salt water.

I'm sure some rich guy out there has his boat rails in gold.
 
Re: Discoloration

I was as surprised as the next guy to find that stainless wasn't all that bullet proof in a salt water environment. :(

Edit: You're right, stainless does pretty well if it doesn't get submerged much.

[ February 22, 2005, 05:58 PM: Message edited by: physis ]
 
Re: Discoloration

There are different grades of SS fastners. Most common is 304, better is 316 which has more nickel. I have seen 304 turn black in a chlorine enviroment.
 
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