Thread: Copper or aluminium Wire

This was a condo built in 1981. Grounds and neutrals in the panel are copper, although the conductors appeared to be aluminium at the breaker terminal. This may be a dumb question but it would not be my first nor last, but is this simply discoloratoin or are these copper coated. The pics suck.

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I can't see anything worthwhile in the photos. However, 1981 was after AL wire was commonly installed. I have never seen a cable with both CU and AL mixed.

Did you check the cable sheath for any identifying marks?

That big open knock-out at the top needs to be filled.

To me the service wires appear to be stranded aluminum with an anti-oxidant compound on them. It's hard to tell though from the picture.

Although I can't see much in the picture, it's got to be copper.

Since they used NM-sheathed cable, the neutrals, grounds and hots all come from the same sheath. So if the first 2 are copper, so is the third.

Dom.

The larger stranded wires on the right and the big feeders are Al. We can't see the connections of the solid branch wires at the breakers, but as was said above, they are copper by default if the neutrals are copper.
Black and white pics at a lower resolution would be better.

Matt are you referring to the feeders?

Aluminum is common in that case .

No the branch wires at the breaker terminals. You can not see them in the photos, but when I shined my flashlight on them they looked like aluminium. Plus I scratched a few of the neutrals and I did not look like copper beneath the scratches. Maybe it was the crappy lighting.

The house is wired with Aluminum and Copper circuits.

On enhancement I can see where the first and third neutrals from the right side look like they may be Aluminum.

Try going to your original and reading the jackets.

Could be tin coated copper. If possible always look at the cut ends for confirmation.

Originally Posted by Ken Rowe

Could be tin coated copper. If possible always look at the cut ends for confirmation.

I haven't seen coated copper except in the very old rubber insulated cables, none of which were plastic sheated NM.

Originally Posted by mathew stouffer

but when I shined my flashlight on them they looked like aluminium. Plus I scratched a few of the neutrals and I did not look like copper beneath the scratches.

Mat,

Sounds like they might be copper clad aluminum, which is treated and rated like aluminum.

You did notice all those NM cable in those clamps or bushings (whichever they are), and the top open KO (which was mentioned by others), and the the whites used for hot conductors, and the multiple taps, and what look like cut off strands of the feeder conductor stranded grounding conductor, and the stranded grounding conductor of the feeder being split into more than one terminal, and ...

more than likley it is copper clad aluminum cable where the inner core is aluminum and outer coating is copper...installer may have stripped ungrounded conductor on wrong gauge and removed copper coating and exposed aluminum..

Thanks guys. So copper clad aluminium have a smiliar failure rate as solid strand aluminium?

Originally Posted by mathew stouffer

Thanks guys. So copper clad aluminium have a smiliar failure rate as solid strand aluminium?

First of all, I know nothing about Copper clad Al as used in branch circuit wiring. However, in electronics, the "skin effect" refers to the fact that the outer skin conducts more current. So it stands to reason that copper clad Al is a better conductor and would be less likely to have expansion problems from heat build-up. There is less likelyhood of tarnishing as well, except where the Cu is scraped off. One bad is the Al core is still going to be brittle, so breakage is one thing that would be a concern.

I got this much from inspectapedia:
K. HOMES WITH COPPER-CLAD ALUMINUM WIRE
Copper-clad aluminum wire has a thin copper outer skin and a core of aluminum.
Therefore it looks like copper, except on close examination of a cut end.
Markings on the cable jacket would include "Al" or "Aluminum". There is no known
history of connection overheating problems associated with copper-clad aluminum
wire. No corrective actions are required for copper-clad aluminum wire.
L. MISIDENTIFICATION - PLATED COPPER WIRE
Plated copper wire is relatively common in older homes, and it looks like
aluminum wire. It was commonly used with rubber-based insulation. Identification
can be made by careful inspection of a cut end of the wire. In general, plated
copper wire would not be present in nonmetallic sheathed cable ("Romex"), it is
most generally found in metallic sheathed cable ("BX"). Cable of the "BX" type
is not likely to contain aluminum wire.

http://www.inspectapedia.com/aluminum/alreduce.pdf