Does copper migrate through silver?

Lighten up boys. There is some solid state diffusion that can occur in the copper/silver system but at room temperature I do not think you have enough time to wait for it to cause you a problem. If you continue to be worried, contact your University's metallurgy department for a phase diagram of the system and an explanation. What you report is surely an oxidation layer that can be easily removed.

Sean-d, I noticed it first on the plate that holds the screws! I know it was silver when it was installed. Perhaps it is oxidation--I also noticed it on the insides.

As to wear, the plugs were just used once--about ten days each. They were left alone. It's a new receptacle.

I'll show you the ACME, Lak. You'll see...

My understanding is yes it will. That is why siver plated copper is often first plated with nickel of some other metal. The issue becomes the nickel, how does it effect the signal?

What you have is the silver corroding the copper underneath. This causes pock marks on the silver plating which cooks from the voltage applied to it, hence the coloration. Could very well be there's no nickel under the silver (typical of cheap-o plating with brighteners added to the silver to cut it.)

Pierre Spray, Mapleshade guru, says that using refrigirators as cable burners condition the molecules with unmusical properties and you need a zillion hours of music playing to recondition them ! (IF, they are able to be
reconditioned again!) Theo