copper buss bars plated with what?

[Dave C]

Many years ago I was a draftsman with a company that built distribution and substation transformers. As such, I spent quite a bit of time in the assembly shop where I witnessed the contact patches of bus bars being hot dipped in molten silver.

[Frank K]

Many years ago we upgraded the switchgear at the facility I managed. Our contract with the installer stipulated that he got to keep all of the removed switchgear and buss bars. No problem with that, it lowered his bid price. I did manage to liberate a couple of pieces of buss bar though. Six inches wide by 3/8" thick and 3 feet long. Silver flash-plated copper. As for uses, I've made a number of copper vise jaws from some of it.

[mickeyf]

From my experience (electrician) the plating is aluminium not silver.

I was under the impression that aluminium also formed relatively non-conductive oxides when exposed, and that was why per some codes it is only to be installed by trained electricians, not under home owner permits, and also why insurance companies cared whether your house wiring had it or not. ??

[garyhlucas]

The plating would definitely not be aluminum. Aluminum is a conductor, but aluminum oxide is such a good insulator they use it to make the insulators on high voltage switch gear! Silver could be used but tinplating is what I see in the specifications for motor control centers that we buy. Back in the 70s aluminum got a bad rap because they used it to make romex for house wiring and the switches and receptacles were not designed to handle the much greater expansion with temperatue than copper. So high currents would cause expansion and extrusion of the aluminum from the joint which caused a loose connection and more heating until a fire started.

As an industrial electrician I did a lot of large aluminum conductor jobs with no failures. However we had the right equipment and used the right techniques. That wasn't the case with house wiring where they were trying to save just a few dollars.