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Aluminum - Silver Colored Wiring Basic Questions


dtontarski
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Would single strand AL wiring always be plastic sheathed and insulated, or was this manufactured prior to the Romex era and will I run across AL single strand that is fabric wrapped and rubber insulated?

I observed silver colored single strands in fabric today. What are the names/components of the other types of wire (non-AL) that have a silver finish?

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I think it is some type of coated copper and not AL. I'm looking for more information on coated copper...coated with what...what is the precise name for it...is it a copper alloy? I'm guessing that AL is probably plastic coated as Romex came into use in the mid-60's when the copper shortage came about.

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Originally posted by dtontarski

I think it is some type of coated copper and not AL. I'm looking for more information on coated copper...coated with what...what is the precise name for it...is it a copper alloy?

As Mike said, it's called tin-coated copper. Before thermoplastic insulation, electrical wires were insulated with rubber. The manufacturers added sulfur to the rubber to help it cure. Since sulfur is corrosive to copper, they had to protect the copper by coating it in tin. With the advent of thermoplastic insulation, there was no longer any need to coat the copper.

I'm guessing that AL is probably plastic coated as Romex came into use in the mid-60's when the copper shortage came about.

All of the aluminum wire I've ever seen is insulated with plastic. Some may have existed much earlier, but I doubt that it was used in houses. Perhaps aircraft?

BTW, Romex isn't synonymous with thermoplastic. The General Cable Company invented it in Rome, NY in the early '20s. It was made with cotton cloth & varnish.

- Jim Katen, Oregon

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When I was in high school electronics class during the late 60's, we were taught to "tine" the ends of copper wires before making connections. We would apply a soldering gun to the end of each wire and apply some flux and solder. It turned copper wires silver in color.

This may be what you are seeing in certain situations, and it can certainly lead one to wonder why the copper is silver-colored. I've been doing home inspections for 20 years now and although here in Phoenix we don't see much of this, I'll bet it's more common elsewhere in the country.

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Here in NJ where there is no shortage of houses well over 60 years old we see a lot of this. Tinned copper is actually very common here although almost never shiny even if it has not turned dark it is almost always dull in luster. You can just look at the snipped end of the neutral and see the copper core, or (IF your experienced with electrical work) it's very easy to scrape the tin and expose a little copper underneath. The other thing you might see, although extremely rare is Nickel coated copper that is common in commercial work. Only the hot lead is Nickel the others are plain copper. Due to the additional expense of the nickel you are likely to go your entire career and never see this stuff, but it is out there.

So far as the aluminum loomex (cloth insulated) I can't say it is not out there, but I have never seen it.

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  • 6 years later...
Originally posted by Jim Katen

Quote:Originally posted by dtontarski

I think it is some type of coated copper and not AL. I'm looking for more information on coated copper...coated with what...what is the precise name for it...is it a copper alloy?

id="quoteN">

As Mike said, it's called tin-coated copper. Before thermoplastic insulation, electrical wires were insulated with rubber. The manufacturers added sulfur to the rubber to help it cure. Since sulfur is corrosive to copper, they had to protect the copper by coating it in tin. With the advent of thermoplastic insulation, there was no longer any need to coat the copper.

Quote:I'm guessing that AL is probably plastic coated as Romex came into use in the mid-60's when the copper shortage came about.

id="quoteN">

All of the aluminum wire I've ever seen is insulated with plastic. Some may have existed much earlier, but I doubt that it was used in houses. Perhaps aircraft?

BTW, Romex isn't synonymous with thermoplastic. The General Cable Company invented it in Rome, NY in the early '20s. It was made with cotton cloth & varnish.

- Jim Katen, Oregon

I would love some help identifying this wiring, older home built in 1935, obviously some upgraded. Saw these wires started thinking aluminum, but some is obviously stranded, some I think is stranded but the ends are just compressed, cloth jacket, used on 120 Volt circuit supplying outlets and lights.

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All of the aluminum wire I've ever seen is insulated with plastic.

- Jim Katen, Oregon

I find Al here that has a plastic insulation but a cloth jacket, the early version.

I would love some help identifying this wiring, older home built in 1935, obviously some upgraded. Saw these wires started thinking aluminum, but some is obviously stranded, some I think is stranded but the ends are just compressed, cloth jacket, used on 120 Volt circuit supplying outlets and lights.

That is Tinned Copper. If you cut an end, you will see a copper core.

Pic 2, you have a neutral with two ground conductors all sharing the same screw. Bare ground wires can be doubled or tripled, but the neutral conductors should not be doubled with another wire, for safety.

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