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Discussion Starter · #1 ·
What would cause this copper to have this discolored appearance? (Top wire is the discolored one). The wire is preexisting, and what you see is the copper in the wire -- I stripped off a foot of insulation to see if it was exposure of some sort.

For reference I put a piece of #12 THHN next to it.
 

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heat - that color ? not so sure about that.

that looks to me like more of a manufacturing glitch.

then again, what the hell do I know.
 

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Discussion Starter · #9 ·
Thanks for the answers so far. It was just something interesting I noticed today. That discolored copper wire was connected to a piece of #12 stranded THHN/AWM that was connected to a 20a OCPD. If I had to rate the quality of the connection I would say it was between starting a fire and causing some sort of nuisance.
 

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animal lover /rat bastard
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Thanks for the answers so far. It was just something interesting I noticed today. That discolored copper wire was connected to a piece of #12 stranded THHN/AWM that was connected to a 20a OCPD. If I had to rate the quality of the connection I would say it was between starting a fire and causing some sort of nuisance.
hmm, I guess I was totally wrong. :thumbsup:
 

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What would cause this copper to have this discolored appearance? (Top wire is the discolored one). The wire is preexisting, and what you see is the copper in the wire -- I stripped off a foot of insulation to see if it was exposure of some sort.

For reference I put a piece of #12 THHN next to it.
I've seen it too. It is also harder to form. I think that it is recycled and other metals get in the mix. The metallurgists at the plant make sure that it is "good enough" to be used in building wire.
 

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RIVETER said:
I've seen it too. It is also harder to form. I think that it is recycled and other metals get in the mix. The metallurgists at the plant make sure that it is "good enough" to be used in building wire.
Recycled copper added to the the mix. Has to be.
I was just using some 18/4 and one of the conductors was slightly brassy. Stood out against the other 3.
My guess is cheap a$$ cable.
 

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If you do a side by side comparision of the discolored wire and what we normally get you'll find the discolored wire is harder to bend. That's because it's what we call hard drawn copper wire. The annealing causes this. It doesn't hurt the copper or cause it to be any less conductive. It's just harder and a different color. Were they to recycle it the hardness would be removed when smelted and the color would return to that nice shiny copper color. The only downside is that the copper crystalline lattice is less random leading to faster metal fatigue if one were to bend it excessively.
 
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