Aluminum?

(Chad Norlen, CPI) #1

Aluminum or tinned copper?

I looked and the silver color immediately told me aluminum, but the insulation looks older than the 60’s or 70’s. This house was built in 1903, originally wired with K&T, 60 amp service (so probably in the 20’s or 30’s). It had an addition put on in the late 50’s.

It is also the only suspect wire in the entire panel - everything else is obviously copper.

I scratched it and it stayed the silver color.

I’m thinking this may be a leftover KT wire based on the insulation. Your thoughts please?

(For those that just say “Report what you see & move on” or something about reaching into a panel, this is in my house & I opened the main…I’m trying to learn something.)

Thanks

(Cameron Anderson) #2

Tinned Copper, looks too old to be aluminum. Just loosen it to get a look at the cut end or find the corresponding ungrounded conductor(hot). It will be aluminum too if this one is.

(Chuck Evans, CMI TREC 7657) #3

Tinned copper to facilitate soldered connections for K&T. Don't need to mess with it. You know what it is.

(Robert Meier) #4

I agree tinned copper. Copper had a coating of tin to keep it from reacting with the old rubber insulation.

(Jim Port) #5

Aluminum will have a plastic insulation over the conductor, not fabric and rubber.

(Jeffrey R. Jonas) #6

Exactly as others above have already stated.

(Chad Norlen, CPI) #7

Thank you all - great information

(Chuck Evans, CMI TREC 7657) #8

[quote="Robert_Meier, post:4, topic:77169"]

I agree tinned copper. Copper had a coating of tin to keep it from reacting with the old rubber insulation.
[/QUOTE]

I like how you gently corrected my soldering comment.

From Wikipedia

[QUOTE]
Rubber insulation was hard to strip from bare copper, so copper was tinned, causing slightly more electrical resistance. Rubber insulation is no longer used for permanent wiring installations, but may still be used for replaceable temporary cables where flexibility is important, such as electrical extension cords
[/QUOTE]

On reflection, tinning would be unnecessary to facilitate soldering connections with copper.

Thanks Robert

(Billy Boerner) #9

Chad...

Tin (cloth/rubber)

AL (Plastic)

(Chad Norlen, CPI) #10

TY Billy

BTW Chuck - Roy is in your camp. 7 YO thread

This board needs some stickies or FAQ's or something. There's a lot of valuable information, but it's difficult to find.

(Chuck Evans, CMI TREC 7657) #11

[quote="cnorlen, post:10, topic:77169"]

TY Billy

BTW Chuck - Roy is in your camp. 7 YO thread

This board needs some stickies or FAQ's or something. There's a lot of valuable information, but it's difficult to find.
[/QUOTE]

Thanks but I am no longer in that camp. Roberts' gentle correction got me thinking: I've soldered a lot of copper in my days, it needs flux, but doesn't need to be pre-tinned to solder well. When I get to thinking, I research. When I research, I learn.

I am now the wiser for Roberts' comment above.