Wires in NM not pure copper?

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Old 04-07-17, 09:43 AM
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Wires in NM not pure copper?

I picked up some Cerrowire 14/2 from a big box store and noticed that the copper wires have a distinct yellow/gold tint. It is a big difference comparing it to the browner copper color that I normally see. Does anyone know what's going on?
 
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Old 04-07-17, 09:46 AM
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This product .pdf from their website calls it copper.

My manufacturing business has a lot of things plated. I'm always amazed and the wide variety of colors that can come from the same plating process. Sometimes it's a normal yellow zinc color I expect but sometimes when seen from certain angles it can be an iridescent pink while the next batch is almost a rainbow from light yellow to almost purple. All from the same yellow zinc process.
 
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Old 04-07-17, 01:25 PM
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Hmm. That pdf says uncoated copper but the plastic wrap just says copper wire. Doesn't look like plating as the ends are also off color.

I'm thinking they changed the specs to mix copper with something else that is less expensive.
 
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Old 04-07-17, 02:33 PM
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It would absolutely not be plated. Flex it a few times, fracture the plating, and presto - instant high resistance spot just waiting to start a fire. Imagine that recall...

It's entirely possible they're using an alloy of some kind, but whatever they're using must still conform to the ASTM standard for resistance, flexibility, tensile strength, etc.
 
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Old 04-07-17, 06:02 PM
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Copper wire is always an alloy and not pure copper. I have also seen the insulation coating skew the color of the copper wire. It is nothing to worry about.
 
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Old 04-07-17, 06:04 PM
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I don't think we could afford pure copper, anyway.
 
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Old 04-07-17, 08:33 PM
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I don't think you will ever find pure copper wire for regular electrical wiring.

Purest wire you can readily purchase is probably for audio cables. Although using one doesn't really have measurable improvements over regular copper wires, some audio enthusiasts insist they do and drop hundred and thousands of dollars on pure copper, gold, and silver wires. (By the way, gold is less conductive than copper).


Copper electrical wiring is not a pure copper, but it is pretty close to pure compared to most other copper products.

I don't know if it is true for sure, but I remember hearing copper wire can only be made from copper ore and not from recycled copper (at least not in cost effective way).
 
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Old 04-07-17, 08:41 PM
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Virtually all "copper" wire for electrical use is MORE than 99% Cu. Most has some intentional oxygen added, but you are talking now about 500ppm or so. Some copper conductors inside transformers is alloyed with silver to help high temperature performance. I tend to agree with the thought of the insulation leaching some pigment onto the surface of the conductor. If you are very interested, send me a sample of the wire; I have access to an XRF that will measure the elemental content, with % report of each.
 
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Old 04-08-17, 05:30 AM
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Ooh, I would love to have access to an XRF gun. They are way out of reach for me as a personal tool/toy. I am very jealous.
 
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Old 04-08-17, 05:58 AM
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Dane; the price of a handheld XRF has come down to a bit below $30k. Lots of scrap metal folks now have them to instantly tell just what they are buying. No, it's not my personal one!
 
 

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