Weird color copper

[makemenuconfig]

I wanted to dig up an old thread. This question got posed a few years ago, regarding off-color copper in southwire's romex.

There were several theories including it being oxidized, an alloy, counterfeit, plated, manufacturing issue, annealing issue, etc.

Yesterday I started using a new spool where the current-carrying conductors exhibit this issue. Kind of a gold/brass color. I'm kind of skeptical of it. All of the roll I've checked so far is like this. It seems like whatever caused this happened prior to its assembly into a cable in the factory.

Not sure if anybody from the original thread is around. Was curious if the poster ever heard back from the manufacturer (or got a callback from the customer I guess).

 

[synchro]

What does it look like if you scrape off some of the top layer with a knife or grind some off?
And what does the cross section look like at the end of the wire?

 

[makemenuconfig]

Just tried brushing with a wire brush. Looks like normal copper once brushed, so does the end.

So that would remove alloy issues and I assume annealing issues as causes.

 

[Electromatic]

Maybe Southwire took SIMpull technology to the next step: Coating the copper to slide it into the insulation!

 

[busman]

It looks like you need a new wire stripper.

 

[Jraef]

It’s likely tinned and annealed which forms a surface alloy closer to bronze, which is done with UL-1426 marine wiring as a corrosion resistance, for which they charge extra. My guess would be that Southwire had a bunch of that more expensive annealed tinned bare wire laying around that wasn’t selling, along with a high demand for standard Romex, so they used that more expensive tinned wire to make the Romex. Solid wire for a marine application would be rare, but this may have been originally made as strands for larger stranded conductors. Just clutching at straws here though.

 

[4-20mA]

That doesn't look like tinned wire to me... probably an effect from the insulation process if I had to guess. But that's nothing like the tinned copper I've ever seen.

 

[Jraef]

That doesn't look like tinned wire to me... probably an effect from the insulation process if I had to guess. But that's nothing like the tinned copper I've ever seen.

I agree that it’s not typical for tinned wire, but if it is annealed (heated and cooled rapidly) after being tinned, it will essentially create bronze on the surface. Bronze is an alloy of copper and tin. That coloring looks like bronze and I have seen that color on large cables used in the marine industry.

 

[Dennis Alwon]

Whatever it is it is good to use for 20 amps. haha