steel versus copper wire?

[astroboy]

How much more(if any) is voltage likely to drop if I used steel wire instead of copper? I don't know for a fact that it's steel, only that it's silver in color. I think what I'm really asking is the difference in resistance between the two metals. Resistance charts are easy enough to find here on the Ezone, but I assume they're for copper only. Is there a chart for steel wire as well?

Thanks,
Jeff

[steve lewin]

It's very unlikely to be steel. If it looks like ordinary plastic insulated connecting wire but the wire inside is a silvery colour the most likely thing for it to be is simply tinned copper (i.e. copper pre-coated with "solder" which stops it corroding). It could also possibly be silver plated OFC wire which is used for some hi-fi and car audio connections (if so it's good stuff and VERY expensive).

Either of those will be very similar to "plain" copper in terms of resistivity. If it really is steel it will be a lot higher resistance.

Steve

[Gordon]

Also it'll be much stiffer than the same thickness of copper if it's steel. I think that telephone wire (ie that strung between telegraph poles) is steel, and will also be plastic covered. The stuff used for field telephones by the military is also probably steel.

Gordon

[steve lewin]

It's also possible to find aluminium wire though it's quite rare. This is lighter than copper but not such good conductivity.

You need to find out what it is you actually have. Steel is fairly easy to spot because a magnet will pick it up, unless it's stainless steel (unlikely).

Steve

[vintage1]

Actually there is quite a lot of iron and steel wire about, often plastic coated, sold for garden and general packaging uses.

A quick google search reveals that specific resistivity for copper is 1.6 x 10 ^-8 ohm meters and iron is around 9.6 x 10^-8...

That is, iron has six times the resistance of copper, almost exactly.

Steel is somewhat between, at 4.5 x 10^-8 approximately. So its about 3 times copper resistance.

Nichrome is 1.5x 10^-6, or about 100 times more resistive than copper...which is interesting, on account of foam cutters etc.

Note also that resistance goes up as teh inverse square of diametr,. so a 10 thou wire is 1/4 the resistance of a 5 thou wire of the same length...

Dunno why you are asking, but I hope that helps.

PS you should never use anything but copper wire if low volt drop is what you want, although weight for weight, Aluminium is better, but it doesn't solder worth a damn:)

[escapee]

If it's finely stranded, it's most likely Cu - ductility & all that.
The cables running between phone poles often carry a steel strand(s) for reinforcement. The conductors have been Cu from the beginning.

[astroboy]

Thanks, all, for the info. I checked it out last night; it's definitely not aluminum, and a magnet didn't attract it. Scraping half a strand away, and looking at the cut end, didn't reveal a copper color(at least, not to my eyes). It wasn't expensive. It's not finely stranded, either. So I don't know what it is. FWIW, I did a crude test, though. I hooked up a foot of it between a pack and my homemade discharger. After several minutes of 5.2 amps, it was still cool to the touch. Unless heating varies logrithmically with current, it seems I might be okay with 10 amps.

Jeff

[5O'clockCharlie]

It is also possible that it is zinc coated copper. My dad gave me some and it has worked great. Thick insulated and thin strong wire. it strips very nice and is great if you have solder in a tight spot.