Is this Aluminum wire?

**Robert Foster** · 03-09-2012, 06:44 AM

Is the upper conductor in this pic aluminum ? The house was built in 1954.

Thank you.

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**Jim Port** · 03-09-2012, 06:57 AM

Based on the fabric covered insulation I would say it is tinned copper.

**John Arnold** · 03-09-2012, 07:01 AM

If you have pics from a different angle you may be able to see copper on the cut end.
Looks like tin coated copper to me, too.

**Robert Foster** · 03-09-2012, 09:42 AM

Thank you for the quick replies....unfortunately, the end of the conductor was inserted so far into the fuse holder that I couldn't see the end and take that picture...

**Jack Feldmann** · 03-09-2012, 03:49 PM

I'm going with tinned copper. You can sometimes get a better look at the neutrals.

Robert Meier · 03-09-2012, 03:50 PM

It's not aluminum.

**John Arnold** · 03-09-2012, 03:53 PM

Originally Posted by Jack Feldmann

...You can sometimes get a better look at the neutrals.

Excellent point.

Stephen G · 03-09-2012, 04:03 PM

They appear to be the same size, aluminum would be a larger wire for same service...

but why tin only one wire...did some older wires come pre-tinned

**Jerry Peck** · 03-09-2012, 04:53 PM

Originally Posted by Stephen G

They appear to be the same size, aluminum would be a larger wire for same service...

but why tin only one wire...did some older wires come pre-tinned

Copper reacts with the compounds in the rubber, so the entire length of the conductors in the rubber insulation are tinned.

The conductor which is not tinned is likely a newer conductor with thermoplastic insulation, no tinning required.

When you see tinned copper (and thus rubber insulation) it is time to re-wire because the rubber dries out and becomes brittle and cracks, effectively cracking micro-cracks along the wire, and each of those cracks is a leakage point for the voltage and current on that wire to try to find any other path back to the source.