Surprises about electrical conductivity

Interesting... wonder what the conductivity of the "leadless" solders and "silver bearing solders" are. :)

A guy I know told me about how he thought his tooth enamel wasn't conductive until he stripped the insulation on a plugged-in extension cord with his teeth.

Make a joint that is well-wrapped mechanically. Measure it's resistance. Then solder it.

I bet you a case of cokes that it's lower resistance once it's soldered.

Then make the joint, without wrapping it first, only soldering. I bet another case of cokes the two soldered joints will have the same resistance.

Jim

I 'spect that the usually thin sections and its intimate contact with materials having high thermal conductivity makes the poorer electrical conductivity of lead/tin solders not such a beeg problem, 'eh?

P.S. I heard somewhere recently that someone calculated that there's more copper existing in wiring and plumbing in the USA than remains in the known national reserves. Can anyone confirm that?

Jeff (Who remembers visiting that big open pit copper mine in Coppertown, Utah circa 1955.)

Yipes! That certainly fits the subject.

Steve

Tom Gardner wrote:

How Darwinian of him.

Very interesting!

Which then suggests brazing electrical connections? :)

You omitted alum, nickel, gold.

Old wiring, at least in parts of NY, were soldered AND wire nutted!! I think soldering of splices in house wiring is a very good, safe idea. Just not all that convenient.

Now here's sumpn fer you electricians:

I have old cloth-covered #9-10 solid wire in my old cloth-covered house, and sed wire is, I believe, *silver plated*!!!! Well, plated w/ sumpn, brite and shiny. If it *is* silver, it is a marvelous idea, because sposedly the bulk of the current density in a conducting wire lies on the surface of the wire. If it's tin plated, the question is then *why*! Nickel??

Might make sense then, to silver, or even copper plate aluminum wire. Like our pennies. :)

Copper corrodes. It turns pretty green and blue. It eats up the wire. If it is plated with something - it won't.

If you remember the old telephone lines - those with lots stretched across crossbars....

Those are copper covered Steel. Thick - but it is known once the copper is breached - as the steel changes the resistance. Methods were developed to calculate the distance of the open, break or change in impedance.

We got some of this when the lines were falling down - abandoned lines. They were on Air force property and old telegraph/telephone lines.

We used it in a massive grape arbor - strong steel copper clad wire.

Learned to coil wire with two hands that day.

Martin

Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder

Proctologically Violated©® wrote:

**HE** told you? I would have expected to hear about THIS one from the CORONER! WOW! I got my tongue across a 9 V battery once, when I was 99.9% sure it was dead. It may have been weak, but definitely was not dead. I can't even imagine what 120 V in the mouth would be like. Better not talk about this too much or we'll hear about it being used at Abu Ghraib in next week's papers!

Jon

There are totally MASSIVE amounts of copper in power company transformers all over the place. I suspect that the total copper in the little distribution transformers on everybody's power poles are a bit more than the amount in the substation transformers serving them, but it all adds up. The copper in generating station alternators is also pretty huge.

Most power company transmission lines are aluminum with steel strength cables in the center.

Jon

No way is it Silver! It is most likely tin or solder. Unless, of course, it is aluminum wire. If it is aluminum, be VERY careful to only use the proper aluminum-rated connections on everything - breakers, switches, outlets, etc. And, torque all connections every 10 years or so. Or, replace the damn fire hazard stuff with copper at the earliest convenience.

For anti-corrosion properties. Tin and solder don't corrode quickly. Tin oxide is a pretty good conductor, too, as it is used to make the see-through wiring on the glass plates of LCD displays. Silver DOES corrode badly in the ever-present sulfur compounds in our dirty air. It turns deeply black, which is why if the stuff on your wires still looks "silver", it isn't Silver.

Wire wrap wire IS plated with pure Ag, and it definitely tarnishes on the outside of wire-wrap joints over time. That doesn't seem to keep them from still working, though.

Jon

Respectively beg to differ, Martin. The standard telephone wire was #9 copper. It was copper, not plated with anything. There is quite a lot of it still around. Generally the telegraph lines were heavier and sometimes they were made of iron. I'm not sure why - extra storm protection maybe.

The old wire chiefs had fault location down to a science. One of the first jobs I had was working on the AT&T Long Lines test board. There were several tests used. Wheatstone and Varley were a couple I recall. I had the privilege of working under a retirement aged test boardman. He taught me a lot. That was my first encounter with a Wheatstone bridge. The bridge was part of the test board, where the test guys could patch into the various circuits - and isolate them from traffic. Elaborate resistance records were kept on each circuit (pair of #9 line wires). Those records were continually updated. They made it possible for a wire chief on the test board to locate the distance out to a line fault. This was all done away with when the TDR (Time Domain Reflectometer) was perfected.

Crossbars, unless you are referring to the common crossbar switch in central offices, were out on the poles and known as *cross arms*.

Little known trivia: Coast - to - coast telephone circuits existed before electronic amplification. This were done using lumped inductance loaded, heavy wire pairs, generally the lower capacitive, "pole pair". Expensive enough it made most folks send telegrams.

Bob Swinney

Well, Jeff (Who remembers visiting that big open pit copper mine in

but if you were to return to the same mine, you wouldn't recognize it. For one, do you recall driving through a long tunnel, from Bingham Canyon to Copperfield, the town on the other side of the tunnel? That's where the observation point was when you go back far enough in time, for which '55 should qualify.

Not only is the tunnel no longer there, neither is the mountain. It has all been mined and is now a much larger hole in the ground. It was that way when I left Utah. I can't imagine what it must look like now.

Bingham Canyon was one of the places that was a complete throwback in time. Not much changed there, it just slowly died off and was destroyed by the mine. Narrow street, just barely wide enough for one car to pass another, I have fond memories of the place.

The town you mentioned, Copperton (not Coppertown), is actually a couple miles outside of the mining district, and was, for the most part, the company town. It still exists as far as I know. Everything else is long gone.

Harold

Toll lines, yes. The long distance lines were copper.

The drops used for houses were, indeed, copper covered steel wire. Black rubber-like insulation with a pair of wires within-----sort of an overgrown version of 300 ohm TV cable----that had no value when taken to the salvage yard. Any of us old scroungers know that.

Harold

Bill

to contact me, do not reply to this message, instead correct this address and use it

will iam_ b_ No ble at msn daught com

Seems to me simple coulombic forces (very large, btw) would drive the electrons radially outwards. Assuming the wire were actually momentarily charged, like a capacitor.... Which, then, mebbe it's not, so then my argument fails.... much too confusing....

I think I'll solve Maxwell's Equations tonite, during CSI or sumpn.....

-- Mr. P.V.'d formerly Droll Troll "William B Noble (don't reply to this address)" wrote in message news: snipped-for-privacy@4ax.com...

Yup. It was "P" wire. I still have some "P clamps around here someplace.

Pete Stanaitis

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Harold and Susan Vordos wrote:

Robert. You must have been working with the original transcontinental telephone lines. They were indeed 9 or 10 gage solid copper wire. However many later Open Wire lines were smaller gage and copper steel.

Many farmer lines used Iron as I think it was cheaper

Bill K7NOM

.

Or, perhaps, to make it easier to solder. Nothing easier to solder - and with a greater chance of getting perfect wetting - than pieces already tinned.

John Martin