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Solid aluminum or tinned copper?


blazenut
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How old is the house?

If it's older than about 1962-63 it's probably tin-coated copper. All of the solid aluminum wiring that I've ever seen was NM in either black or white; no rag wrap and none of the new modern yellow and orange.

ONE TEAM - ONE FIGHT!!!

Mike

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Not always.

Look very carefully at the ends of the wire on the bus bars. If you see a brown spot in the middle it's tinned copper.

Look at the bare ground wires for any nicks that would show the brown copper beneath the tin.

Might pull an outlet cover to see if the end of the wire or nicks can be seen.

Look closely at the wire sheathing wherever it is exposed.

Like Bill said. Training & Experience.

The nice thing is that SOME Experience can be prepared for, not experienced, but prepared for on THIS messasge board.

Far better to hang your ass out here than on the job.

Perhaps it would help you learn better if you offered to pay the electrician's charges. It would certainly help with customer relations.

I learn more from my mistakes when they hurt, hopefully just a little!

-

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Here is a link you might look at:

http://www.inspect-ny.com/aluminum/recogniz.htm

A big clue as to the type of wire is the insulation style. As Mike said above, I have never seen Alumimun wire that is enclosed in rag wrapped insulation.

To my eye tinned copper has a pinker hue than Aluminum wire. Look for scrapes on the wires in the panel for copper beneath the tin. Also check out the end cuts and bare ground wires.

Also, I don't think (someone help me here) that there is any Aluminum wire in two wire (no bare ground wire) NM cables.

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A big clue as to the type of wire is the insulation style. As Mike said above, I have never seen Alumimun wire that is enclosed in rag wrapped insulation.

Also, I don't think (someone help me here) that there is any Aluminum wire in two wire (no bare ground wire) NM cables.

I'm going to interject here for clarity. What Mike is talking about (NM, yellow, orange...) is the cable sheathing, the outer covering that encloses the insulated individual wires. There's typically a lot of confusion and cross use between sheathing and insulation around here so for those who are still getting familiar with what's what... The insulation is the stuff that coats/encloses the individual wires, separates them or should I say, insulates them, from contact with each other. The outer jacket being the sheathing which basically holds the individual wires together creating a cable and protecting the insulation from damage.

That said, the original wiring, Knob & Tube and then eventually assembled cables such as old NM or BX had the wires insulated with a cloth loom, usually woven cotton and latter Rayon, that was saturated with rubber. (I grew up calling this Loomex, I think it was a trade name but not certain) Components in the rubber are corrosive to the Copper so it was tinned to create a barrier that protected the Copper.

The outer sheathing may have been cloth loom, BX, & later PVC, still with rubberized cloth loom insulation on the enclosed wires. Once we moved to more modern plastics & thermoplastics for the insulation there was no longer a need for tinning the wire.

So, if you see rubberized loom insulation it will be Tinned Copper. If you see any type of plastic it will almost certainly be Aluminum. The outer sheathing 98% of the time is also a cloth loom or BX, or unsheathed Knob & Tube when it is tinned Copper but there was an era when the outer sheathing was plastic and the insulation was still rubberized loom (I have seen this only once or twice in my career, I'm fairly certain it's not just my recent lack of sleep getting to me).

Aluminum will always have a plastic insulation and non woven sheathing. By the time Aluminum came around, grounded receptacles were required by the NEC.

Also if you've got an older cable that has a ground wire present but it is smaller then the main conductors, that will also certainly be Tinned Copper.

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Components in the rubber are corrosive to the Copper so it was tinned to create a barrier that protected the Copper.

This I did not know. Good info, Kyle.

I didn't know it, either. Thanks.

There's quite a bit of info on the web that says tinning was (also?) done to make soldering wires easier.

Tinning a wire for soldering is a bit different than tin coated copper for home wiring.

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Components in the rubber are corrosive to the Copper so it was tinned to create a barrier that protected the Copper.

This I did not know. Good info, Kyle.

I didn't know it, either. Thanks.

There's quite a bit of info on the web that says tinning was (also?) done to make soldering wires easier.

Tinning a wire for soldering is a bit different than tin coated copper for home wiring.

How so? I ask, because in the book Old Electrical Wiring written by David Shapiro (1998 McGraw-Hill), which is written entirely about old house wiring, on page 403 it says "Old splices, (those installed before, say, World War II) were done up differently-some better, a few worse. They were almost always bulkier, and they took longer to create. Splicing, or "making up joints", was done by first twisting the wires together (not necessarily clock-wise), then soldering them (underline is mine), then taping them with self-annealing rubber tape, and over that applying friction tape."

It goes on to say that after that, solderless connectors became quite popular, eliminating the need for soldering.

From page 406...

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tn_2009620231140_misc.jpg

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So again, what's the difference you speak of?

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Components in the rubber are corrosive to the Copper so it was tinned to create a barrier that protected the Copper.

This I did not know. Good info, Kyle.

I didn't know it, either. Thanks.

There's quite a bit of info on the web that says tinning was (also?) done to make soldering wires easier.

Tinning *might* make soldering the wires easier -- and, clearly, old wiring was routinely soldered -- but that isn't why the wire was tinned. It was tinned because it had to be, as Kyle pointed out, to prevent the copper from corroding while in contact with the old rubber insulation.

If the wire hadn't been tinned, it wouldn't matter how easy or hard it was to solder because it would have corroded away inside the insulation.

Besides, to make up a proper solder connection you had to first clean the wire with emery cloth, then make up a splice that was mechanically and electrically sound without solder, then apply flux, and then heat up the splice and apply the solder. Tinning wouldn't have sped up the process much.

Ironically, those old time-consuming skill-intensive splices really weren't much good. A cheap, modern wire nut makes a far superior electrical connection.

- Jim Katen, Oregon

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and some single strand stuff...

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tn_200962033413_tinnedcopper.jpg

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Richard: Why is the top of the left end of the middle wire brown if it's single strand aluminum?

Erby, it was meant as an example of single strand tinned copper, not aluminum. Hence the obvious copper at the cut ends. See the file name when you click on the photo. Sorry, by this time I'd forgotten about the thread title and thought we were just talking about tinned copper. I'll edit that post a bit to avoid further confusion.

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Components in the rubber are corrosive to the Copper so it was tinned to create a barrier that protected the Copper.

This I did not know. Good info, Kyle.

I didn't know it, either. Thanks.

There's quite a bit of info on the web that says tinning was (also?) done to make soldering wires easier.

Tinning a wire for soldering is a bit different than tin coated copper for home wiring.

How so? I ask, because in the book Old Electrical Wiring written by David Shapiro (1998 McGraw-Hill), which is written entirely about old house wiring, on page 403 it says "Old splices, (those installed before, say, World War II) were done up differently-some better, a few worse. They were almost always bulkier, and they took longer to create. Splicing, or "making up joints", was done by first twisting the wires together (not necessarily clock-wise), then soldering them (underline is mine), then taping them with self-annealing rubber tape, and over that applying friction tape."

It goes on to say that after that, solderless connectors became quite popular, eliminating the need for soldering.

From page 406...

Click to Enlarge
tn_2009620231140_misc.jpg

70.2 KB

So again, what's the difference you speak of?

The tinning was done for a different reason. Tinning a wire does make soldering it easier, but tin coated copper wire (as the thread originally was about) was to prevent corrosion.

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The tinning was done for a different reason. Tinning a wire does make soldering it easier, but tin coated copper wire was to prevent corrosion.

I hear ya. Really. I even read my old Wire in Electrical Construction, published in 1900, and put out by John A. Roebling's Sons Co. (anyone else recognize the name? Mitenbuler did, the old son-of-a-gun).

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Anyway, the book mentions household wire was first tinned before rubber cement, then rubber, was applied, but not why it was first tinned. And the reason I mention this book is 'cause I got lots and lots of old electrical books...dozens, all published before 1925. I went through most of them last night and found all sorts of references to wire tinning, but not "why" it was tinned.

I don't mean to beleaguer this point, but the only references on the web I can find about tinning wire say it was done to help soldering. I can't find a gol-darn thing about it being done to prevent wire corrosion. However, I ain't one to doubt Mr. Katen, and I'm not saying anyone else don't know what they're talking about, but I was just wondering if anyone has a written reference for such.

Also, what started me thinking this way years ago about soldering wiring was an old-timer electrician telling me why (he believed) wire was tinned. Heck, I believed him, too.

As always, thanks so much.

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. . . I don't mean to beleaguer this point, but the only references on the web I can find about tinning wire say it was done to help soldering. I can't find a gol-darn thing about it being done to prevent wire corrosion. However, I ain't one to doubt Mr. Katen, and I'm not saying anyone else don't know what they're talking about, but I was just wondering if anyone has a written reference for such. . .

Here's one from Southwire:

http://www.southwire.com/processGetArti ... 02a8c0____

It's talking about the need -- or lack of need -- for tinning of modern wires that are clad in certain types of insulation or that are exposed to corrosive environments. Since no one solders this kind of wire anymore, they're clearly no concerned with ease of soldering.

Here's a book that talks about copper coatings:

http://books.google.com/books?id=sxkPJz ... t&resnum=8

Here's a straightforward one from Websters:

http://www.websters-online-dictionary.o ... opper.html

Here's Wikipedia's page on electrical wiring:

http://en.wikipedia.org/wiki/Electrical_wiring

They have an interesting comment, "Rubber was hard to separate from bare copper, so copper was tinned, causing slightly more resistance."

For me, the idea that wire was tinned to make soldering easier just doesn't make sense. If you abrade the wire and use flux, bare copper wire solders beautifully.

What do the old books say about the soldering process? Do they instruct you to abrade the wire and use flux? Do they mention the advantages of tinned wire in the sections that deal with making up connections?

If pre-tinned copper is easier to solder, why didn't we have pre-tinned copper plumbing pipes?

- Jim Katen, Oregon

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Jim,

Thanks for the links. They are sure convincing. Nice to learn.

No, my books don't mention tinning in relation to soldering; they all stress getting the wires hot enough, not just the soldering iron, and like you say, to get the copper clean; also acid free flux, etc., but no tinning words. (They also mention neat-o gasoline fueled torches in lieu of electric soldering irons.)

Hate to say it, though, my 382 page copy of the 1947 National Electric Code plainly states on page 408 that this new-to-the-scene Katen chap should not be relied upon regarding tinning & soldering information.

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Perhaps you have a newer, revised edition?

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Jim,

Thanks for the links. They are sure convincing. Nice to learn.

No, my books don't mention tinning in relation to soldering; they all stress getting the wires hot enough, not just the soldering iron, and like you say, to get the copper clean; also acid free flux, etc., but no tinning words. (They also mention neat-o gasoline fueled torches in lieu of electric soldering irons.)

I had assumed that the torches were predominant method because I nearly always see charred patches of wood near the splices. I wonder how long it would take to heat up a #12 wire western union splice with an iron?

Hate to say it, though, my 382 page copy of the 1947 National Electric Code plainly states on page 408 that this new-to-the-scene Katen chap should not be relied upon regarding tinning & soldering information.

Perhaps you have a newer, revised edition?

Musta been talking about my father . . .

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