Wire Composition

The wire was tinned. Tinned copper wire lasts up to 10 times longer than non-tinned wire. Used a lot in marine environments. Helps protect the copper from the elements. It also resists water corrosion and provides enhanced conductivity.

To add to what Ozzyb posted, and to further answer your questions, I would say that if it is indeed tinned copper, than your #2 would be more correct; since the tinned wire will not corrode as quickly, and thus will have lower resistance connections. And as far as #1 goes, it will certainly not be lower cost if it is tinned copper. Aluminum wire has been used as a substitute for copper for reduced cost and weight, with higher resistance and dis-similar metal issues as the downside. Are you sure the wire you were removing is tinned copper, and not aluminum? And if it is copper, be sure to send it for recycling, copper scrap is worth a bit these days.

Tom

Thanks for the info. The wire was through conduit that runs under the concrete floor. Yes, it has a copper core.

You didn't say whether this was data or power wiring.

I have seen a number of installations that used silver-plated copper wire. These were all places where quality was more important than price. Also, virtually all the silver-plated wire I've seen had Teflon insulation. Expensive, but it lasts forever! I have some that has been exposed to the sun and snow for 40 years, and it is just as flexible now as it was 40 years ago! You can tell: any silver that has been exposed to the atmosphere will oxidize to black, while tin will oxidize to white. In case you weren't aware, silver is the best room-temperature conductor (to my knowledge, no one has yet made a room-temperature superconductor).

Its a power wire, 6awg.

Then highly unlikely to be silver. Again, the oxide will tell.

I told him that I think the coating was silver or zinc. I was told two theories about the coating, 1) It is there to reduce costs and 2) was that it has to do with the conductivity of the wire.

It's a lead-tin alloy - also used in soldering copper wires and components with copper leads, etc. Percentage ratio of Pb:Sn depends on the properties of the solder best suited for the application.

First theory may be correct if you look at it from a 'protecting the bare copper and making it last' point of view, but Pb and Sn don't come cheap too.

I've never really noticed any difference in the current carrying capacity of tinned copper wire as compared to bare copper wire.

Please read the previous posts #1 & #2..........as explained tinned electrical conductors are used to inhibit corrosion.........all electrical wiring in marine applications should always be tinned.

Toomany; if you have ever noticed rubber covered tin plated wire, to keep the rubber from corrosion. perry

There can be two reasons depending on the coated metal.

1. It can be silver and in this case because of the "skin effect" (electrons prefer the surface of a conductor, in short) the overall performance of the wire would be better, less ohmage, less heat... (silver is the best conductor among other metals)

2. It can be any rust resistant metal just to protect the copper inner wire from corrosion.

Re Item # 2 your post we were not talking of rust (atmospheric corrosion), but marine corrosion or other areas of extreme corrosion which is something entirely different.

Some ships may have over 100km of wiring..........silver coated.........I think not. Tin is "cheap" and very effective against marine corrosion, e.g. naval brass or Admiralty bronze for example