I have a stupid question for everyone. Is the copper in wiring made from pure copper (not accounting for negligible impurities), or is it an alloy of some sort?
-Josh

Not only is it essentially pure copper, it is what is known as "oxygen free" copper.

"oxygen free" copper
They are required to use it on sattelites and on the space station.

Ya mean,... those guys selling the "oxygen-free" interconnects at $100 a foot are charging for a feature the $5 RCA cables from Radio Shack already have??? I'm shocked, I tell you! Shocked!!!

Ok, you got me....what benefits are their to oxygen free copper?

With oxygen free copper, the electrons sweat less.

http://www.audioholics.com/techtips/audioprinciples/interconnects/cableconstruction.php

this says there is no bennifit to oxygen free copper.

Yes, wire is made from pure copper. Even small amounts of impurities can greatly reduce conductivity.

Peter

Just imagine if the only good conductor of electricity was mercury. Instead of copper wire, you'd be using rubber hoses filled with mercury. Slices would be fun.... Talk about leakage.

SOme audiofools might be convinced that mercury filled garden hoses for speaker cable gave the music a "fluid" sound....

Heard, that back in WW2, some buildings built for the Manhattan project (A bomb development) were wired with silver wire, as copper was in short supply.

Not buildings, AFAIK, but the electromagnet windings and busbars for the calutrons at Oak Ridge, TN, used for uranium isotope separation:
http://www.childrenofthemanhattanproject.org/HISTORY/H-06b2-1.htm

They borrowed 15,000 TONS of it from the US treasury...

Normal THHN style wire is pure copper. If you get into higher temp wire specs, you'll find nickel plated types or copper-nickel alloys. I believe that they claim that pure copper has severe oxidation problems above 200 degrees C.
Joe

Ya know gents, I really dont think that your average THHN or romex is made from "Pure 100% Copper".

One reason I say this other than the obvious results of recycling, where most of our wire is coming from now. And that I had to once order a "100% PURE COPPER" Ground bar for Telco ground once, and it was 4X's the cost of a regular "copper" ground bar. It was also subtly different....

I have also recently seen some conductors that seem to have a little too much brass in the mix... i.e. kinda yellow.

Also, what is the difference in Hard, and Soft drawn copper? Do they whip air into it like wonder bread?

Anyway, I think the word "pure" may be subjective to a margin like >80%.

I'd expect copper to be pure within reason of standard manufacturing processes. If my memory is holding up brass is a mix of copper & steel. If steel were added it would probably make the wire more brittle & useless (maybe usefull in a ground rod, but not 14 ga.). I'm not sure what hard & soft drawn are, but it may just be a difference in the cooling process (as in quick or slow cooling).

Dave

google copper and do some reading. the copper used in wire is as pure as it can reasonably get. different processes determine the other properties.

Brass is an alloy of copper and zinc, not steel. (Bronze, by the way, is an alloy of copper and tin, sometimes with zinc, silicon and other metals added.)

All copper wire is formed by drawing it through successively smaller dies. The "hard-drawn" wire produced by this process has high tensile strength, but it's brittle and hard to bend.

For general-use electrical wire, the hard-drawn wire is annealed by heating then gradually cooling it to relieve crystalline stresses, producing so-called "soft-drawn" wire.

The irregular crystalline structure of hard-drawn or "work-hardened" copper wire has somewhat higher resistance than annealed wire.

Oxygen-free high-conductivity (OFHC) copper wire is at least 99.95% copper.

I can't seem to find my Machinery's handbook -it's been quite some time since I actually did any machining- but, IF I recall correctly...

"Oxygen free" copper is copper that has been processed in such a way as to eliminate microscopic voids....little pockets of air that greatly increase the electrical resistance of the copper.

I do know that "oxygen free" copper is one heck of a lot harder to machine than you would expect!

What does wire have to do with being shocked?

Reno, that's about right. In conventional cast copper (electrolytic tough pitch, or ETP), a tiny amount of oxygen is trapped between the crystal grain boundaries. Normally, it don't mean nothin'. The difference is conductivity is on the order of 1%.

In the presence of very high temperatures, though, atmospheric hydrogen can diffuse through the copper and react with the oxygen to form steam, which produces the microscopic voids you mentioned. These voids make the copper brittle, which is where the term "hydrogen embrittlement" comes from.

The embrittlement was a problem in motors and generators, due to the combination of high temperatures and mechanical vibration, and that's why OFHC was invented. It's mainly a matter of casting the copper ingots in an oxygen-free atmosphere.

Nowadays, almost all copper wire is oxygen-free anyway.

Oxygen Free Copper.

The real truth is it is a buzz word used by high-end audio cable manufactures to charge you 3 times what the product is worth.

All it really means is the copper is annealed in an oxygen free enviroment which most is made this way today.

Annealed means the copper is heated then cooled down slowly to prevent the crystalian structure from forming otherwise known as "Soft Drawn" copper. By keeping oxygen out of the process keeps it from bonding to the copper which limits corosion or petina.