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View Full Version : OT, Crazy "springy copper" electric cord wire



J Tiers
08-22-2017, 10:53 AM
So, the plug on the CAD computer (Dell laptop) power supply cord had the insulation crack right at the plug. The cord was one with the clover-leaf end on it, not the standard 15A rectangular IEC end that is common these days, so I did not have a spare handy.

I strip the wire and start to put a new plug on it.

Well, the wire is very small gauge, stranded. That in itself is not an issue. But I needed to twist the strands to form a tight bundle.

Surprise! They cannot be twisted! All the twisting I did, resulted in them simply springing a little farther apart. They WOULD NOT twist.

Next I tried doubling them back to form a thicker bundle. THE STRANDS WOULD NOT BEND! At least they would spring over, but straightened as soon as they were released. I finally completely doubled them over, and crimped the bend. At that point they would spring back to a 90 deg angle.

I've never seen anything as springy as these, I'd swear they were made of phosphor bronze, and not copper. (I checked with a magnet and no, they are not copper plated steel).

Anyone ever seen hat before? It was a first for me.

Doozer
08-22-2017, 11:23 AM
Titanium wire? (kidding)

-D

bob_s
08-22-2017, 11:29 AM
Yep.

Copper wire produced in the third world is drawn without being annealed.

My first experience with installing UPS units in Pakistan led to importing North American manufactured wire for subsequent installations.

J Tiers
08-22-2017, 12:28 PM
Yep.

Copper wire produced in the third world is drawn without being annealed.

....

This stuff is hard enough to bend that a person can understand making knives out of it. But I think it has to be an alloy, its harder than I have ever seen work-hardened copper, and much springier. Odd.

BobinOK
08-22-2017, 12:33 PM
May be litz wire, almost impossible to work with without special tools and connectors.
https://en.wikipedia.org/wiki/Litz_wire

Willy
08-22-2017, 12:35 PM
I remember helping a buddy a few years ago set up a ham radio station, he had something along the lines of what you have.

https://www.tetemtron.com.au/1-63mm-Hard-Drawn-Copper-Wire-p/te-hdcw1.63.htm

Can't figure out why it would be used in an application like a supply cord though???

bob_s
08-22-2017, 12:58 PM
In NA and EUR copper is smelted to 99% purity for the purpose of making wire.
If wire is being made from recycled materials there may be considerable fractions of zinc, iron, tin, aluminum, sulfur,... all of which lead to much less ductile alloys/mixtures.

Try annealing a sample. If it turns a bluish color at the cool end, you can bet your bottom buck that it contains either/or both iron and nickel.

Baz
08-22-2017, 01:00 PM
Have you tried the magnet test? Very low current they could easily expect to get away with copper plated steel. Didn't something similar come up last year?

chipmaker4130
08-22-2017, 01:03 PM
Yes, its not the wire but the application that seems odd. In the old days, all the cheapo 'earphones' (what we now call earbuds), used a similar wire. Those strands were flat, though, and were nearly impossible to twist and/or solder.

Some time ago, someone (Evan, maybe) posted about buying some heavy gauge speaker wire only to have it snag on a magnet on the way out. Sure enough it was copper plated steel wire advertised as 'copper'. From China of course.

Oops, I see Baz types a lot faster than I do!

J Tiers
08-22-2017, 01:10 PM
I had already checked with magnet.... not the issue.

Paul Alciatore
08-22-2017, 01:39 PM
Old style headphones and headsets had a very flexible cord with wires that were stiff, hard to work with, and hard to solder. I always thought they were steel plated copper but I have no evidence to that effect. Now I wonder what they really were.

kendall
08-22-2017, 03:06 PM
I've run into that issue a few times, always managed a work-around by heating the wire (Hemo's clipped above the working area while applying heat). Can't say anything for durability because I always said f it and replaced the next time they broke without checking out why.

The thing I run into most often lately is wire that looks like 12 gauge, but when I have to perform a repair and cut away the insulation I find that the actual wire itself is maybe 18 or 20 gauge.

J tiers post reminds me a lot of trying to work on the wiring on late 70s/early 80s GMs, not sure what the heck they used for wire, but was almost impossible to repair without entirely replacing the wire.

J Tiers
08-22-2017, 05:50 PM
I got irritated, dug into some old boxes, and found a cord with the "cloverleaf" IEC connector on it, so the immediate issue is gone.

That wire is REALLY springy... maybe it's hard-drawn, but.... it appears to be maybe 22 GA, or smaller, with a dozen or more strands, so the individual strands are very thin. The wire was so thin as a bundle, that the clamp type plug screws would not even hold it.

If I WANTED wire that springy, I bet I;d have a hard time finding it. Maybe I should keep the remains of the cord, so I have a supply (for what reason I might want it, I cannot explain).

darryl
08-22-2017, 06:29 PM
Makes me wonder if the strands are coated with something- perhaps nylon. I've had a few instances where the strands resist twisting together, and didn't solder worth a damn either.

PStechPaul
08-22-2017, 08:42 PM
It might be worthwhile to check the resistance of the wire. If you don't have a DLRO, put one or two amps through it and check the voltage drop. It's probably not phosphor bronze or beryllium copper, since they are expensive, but perhaps an alloy of various recycled metals that has such stiffness and spring.

Beryllium copper is probably most likely, however:
http://www.ngk.co.jp/english/products/electronics/berylliumcopper/wire/

strokersix
08-22-2017, 08:47 PM
While I don't have any personal experience, I've seen hose and cable braiding operations. I'll bet the hard drawn wire is easier to process through the braiding/extrusion process. Just a guess.

Arcane
08-22-2017, 08:49 PM
......Beryllium copper is probably most likely, however:
http://www.ngk.co.jp/english/products/electronics/berylliumcopper/wire/

X 2.

http://www.leespring.com/materials.asp

CCWKen
08-22-2017, 08:56 PM
One of my dash cams came with a USB/PC interconnect cable that is stiff as a coat hanger. I checked the pin out to make sure there wasn't something funny going on then threw it in the trash. I use a standard (and flexible) Mini to Type A USB cable. I don't know what they expected you to do with that piece of plastic coated rebar. :D

J Tiers
08-22-2017, 09:47 PM
It makes some sense that it would be BeCu, as a "high quality" option, with long life under repeated flexing. That's just what it would get. And, the wire itself was small, so the total quantity of BeCu would be small.

Would still be good, if the cable sheath had not pulled out of (or torn off of) both the IEC end and the NEMA end. That really increased the flexing, and concentrated it at a point. I'm surprised it lasted as long as it did. There was essentially no way to shrink or add any sort of reinforcement, the difference in diameter, and the shapes, pretty much precluded any such "fix".

I shall keep the wire just on principle. May be useful. Now I need to find my other specialty wire, so I can put this with it. Been looking for the coil of nichrome so long I have almost forgotten why I wanted it. (to make new heaters for a motor overload).

wombat2go
08-22-2017, 10:52 PM
I am not sure, but doubt that BeCu would have been used in consumer wire for computers etc,
The Be was listed as toxic in many countries since 1970's
https://en.wikipedia.org/wiki/Beryllium_copper

The end product is safe, but the production of BeCu shapes is a problem.
I was involved in 1980's with welders running ~ 10,000 to 40,000 Amp. ( I forget exactly)
For flex conductors, the BeCu shims were purchased , but for some applications the machine shop had to make.
Special procedures were followed and documented , as I remember.
search : rwma-copper-alloys
C17200 etc

johansen
08-23-2017, 10:06 PM
ITS NOT COPPER. and I won't be surprised if you can't solder it.

someone i know bought some used servers just a couple years ago, rather than ship a used iec power cord they bought new ones to ship with them.

one of them was open circuit iirc.. and the investigation discovered the other ones had a 10 ohm resistance. the wire was perhaps 7 strands of perhaps 28 gauge wire. the color looked similar to brass or some aluminum bronzes.

MattiJ
08-24-2017, 02:56 AM
Old style headphones and headsets had a very flexible cord with wires that were stiff, hard to work with, and hard to solder. I always thought they were steel plated copper but I have no evidence to that effect. Now I wonder what they really were.

I have seen some really funky wires on headphones. One variety was glassfiber core wrapped with flat, insulated copper ribbons. Another sort was with insanely thin, plain-looking enameled copper wires and total PITA to solder.

J Tiers: Is there any markings on the cable itself?

J Tiers
08-24-2017, 12:27 PM
Nothing special marked. No company name, unless "SL" is it. Does say it is PVC insulated.

Solders fine.

Don't know if it anneals, soldering did not seem to anneal it. Used a lighter flame, and because of either the thin gauge, or the material, the wire strands just burned up and fell off as soon as they got to annealing temp, which was nearly instantly. Left a gray looking coating almost like wood ash. I stayed out of the smoke as much as possible.

Don't know what it is, but it seems less useful than it might be, other than for fuse wire My experience with copper, even in reasonably thin strands, is that it oxidizes slowly. I have seen copper strands get bright glowing orange-red, and stay that way without burning, for much longer than this did.

MattiJ
08-24-2017, 12:48 PM
Nothing special marked. No company name, unless "SL" is it. Does say it is PVC insulated.

Solders fine.

Don't know if it anneals, soldering did not seem to anneal it. Used a lighter flame, and because of either the thin gauge, or the material, the wire strands just burned up and fell off as soon as they got to annealing temp, which was nearly instantly. Left a gray looking coating almost like wood ash. I stayed out of the smoke as much as possible.

Don't know what it is, but it seems less useful than it might be, other than for fuse wire My experience with copper, even in reasonably thin strands, is that it oxidizes slowly. I have seen copper strands get bright glowing orange-red, and stay that way without burning, for much longer than this did.

Copper clad aluminium?
I'd imagine also that to be quite malleable but easy melting would match.
(Seen some thick "HIFI" cables made of fine gauge copper clad aluminium)

J Tiers
08-24-2017, 01:16 PM
Copper clad aluminium?
I'd imagine also that to be quite malleable but easy melting would match.
(Seen some thick "HIFI" cables made of fine gauge copper clad aluminium)

Entirely possible. Must be hard aluminum if so, since it is very springy. I'll have to see what the resistance is.