Surprises about electrical conductivity

Harold and Susan Vordos says...

Black
overgrown
salvage
Cool! I always wondered how they made that damned telephone wire. New why---it was obvious---for strength.
Harold
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Robert Swinney 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

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Robert Swinney wrote:

Robert, One thing I'm absolutely certain of is when they finally ran the phone line up the two mile road to the little comunity of Marrysville in PA, where we lived at the time, in the 1940s (late, after the war) they used steel wire plated with copper. I collected some of the scraps hoping to use it. :-( ...lew...
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Lew sez:

True. But I was describing long haul transmission lines on cross arms of wood poles. The only ones I was familiar with from AT&T and RR experience were #9 hard drawn copper. I think that was used most all over the U.S. for open wire.
I think you are referring to what was generally called "parallel". Parallel consisted of 2 copper plated steel conductors of 17 - 18 AWG, laying side-by-side (not twisted) thus the name parallel; covered with a heavy rubber insulation. Parallel was flat and typically held in reuseable "P" clamps, although it could be "served up", or wrapped with soft copper to form a hook for hanging as well. P clamps were easy and fast to hang on poles in "J" hooks as I remember. Parallel was typically used only for short haul stuff such as house drops. Being flat, it lacked the cross-talk rejection characteristics of transposed open wire, or twisted pair.
Bob Swinney

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On Sun, 29 Jan 2006 12:11:03 -0600, "Robert Swinney"

You just described "C Rural" wire - they still make and use it today for long runs of one phone line. The big advantage being it will go 300 to 600 foot spans between poles depending on the ice and wind loading factors, just like the power line on the top of the pole.
http://www.superioressex.com/products/osp/spec-sheet/c-rural-wire.pdf
If they try using regular residential drop wire (1 or 2 pair) it can't handle that long of a span without inter-setting additional poles, and for one house it doesn't pay to hang a steel strand and lash a normal 25-pair Alpeth cable to it.
--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
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says...

That stuff makes great ham radio antennas. Err, so I've *heard*.

That's copperweld wire, not plated. It's drawn down from billet with the same steel/copper cross section to start.
Jim
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Robert Swinney wrote:

No this was a two mile run of open wire with one on each side of the pole. To about 4 or 5 people party line. Some other rememberances: A budy and I had a short pair of climbers (only up to the ankles OUCH) and a pair of earphones which we taped into the line ocaisonally. :-) ...lew...
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Bob - read my note- I said old failing abandoned - telegraph/telephone. This was in the High desert and mountains north.
I well know the TDR and Smith stuff - Long Lines used to send me stuff when I was a kid. I was in El Paso and my dad was ATT/WESTERN - Long Lines adopted my class and myself on the side I guess.
The lines ran from El Paso to New Mexico. High winds required concrete weights to hand on the wires to keep them from sailing in the wind - pulling out the poles. Some lines had 2 large fruit can size weights. So strength was needed. It was cut by scoring and snapping. The wire required about a 3' minimum diameter. I suspect they were 100 years old at the time - maybe 75. Likely used between forts and during the war. The one with Black Jack in charge vs. Mexico bandits.....
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
Robert Swinney wrote:

-
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Proctologically Violated wrote:

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
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Jon Elson wrote:

.
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
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Jon Elson wrote:

That is because the actual joint is "gas tight" and hence wont corrode. ...lew... (who has made a lot of wirewrap connections)
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allow me to point out to you that the surface effect is negligible at power line frequencies - at RF frequencies it becomes significant. the coating is for corosion resistance. To study further, look up surface effect - you can derive it yourself if you care to solve maxwell's equations as a function of freq.
On Sat, 28 Jan 2006 20:40:09 -0500, "Proctologically Violated"

Bill
www.wbnoble.com
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
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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
in message wrote:

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Proctologically Violated wrote:

Skin effect (current flowing on the surface of a conductor) only begins to become measurable at Megahertz frequencies. At 60 hz it would be essentially ZERO. ...lew...
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Blame it on Edison. I bet it was for DC.
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
Lew Hartswick wrote:

-
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On Sat, 28 Jan 2006 20:40:09 -0500, "Proctologically Violated©®"

Skin effect is almost totally irrelevent at 60 htz, and most of that old knob and tube wiring was bright tin plated. Copper plated aluminum would be a corrosion nightmare.
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spaco wrote:

It's all relative, though, Pete. Iron (or steel) at room temperature is about 12. Yet you don't think of that as being a poor conductor. Or the mercury used in a mercury switch, which is under 2. They are actually pretty decent conductors, with silver being an incredible one. Unless you compare it, of course, to a superconductor down around absolute zero....
John Martin
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Ah, but the resistance across anything is:
length/(area*conductivity)
The cross sectional area of a solder joint between two copper wires laid side by side is huge compared to the cross section of any given point in the wire and the length is very short. Even with lead, the joint would conduct better than the rest of the wire...
That's also why the lead car battery terminals someone else mentioned are not a problem (large cross-section). If your battery terminals are getting hot, it's because the contact surface between the post and the terminal is corroded or loose.
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