Tinned copper to aluminum connections? Cannot find info anywhere

I’ve searched all over the net for info regarding direct connections of aluminum and **tinned **copper wiring, but could not find anything.

I’ve been writing these up as I would any direct copper to aluminum connections, as I often see such wires combined without appropriate means for connecting copper to aluminum on sub-panel feeds (with sub-panels that are typically not properly grounded), but am wondering if such connections interact as badly as connections of bare copper to aluminum, as I’ve typically observed such connections, even obviously very old ones, to be free of noticeable corrosion.

It stands to reason the “tinning” would alter the electrical properties of the wiring, but I’ve been unable to find any info regarding this.

Any info would be appreciated.

Double tapped refers to two conductors on the same termination point of a circuit breaker. Some are rated for that and some are not.

Perhaps you mean something else.

I’m referring to interaction between tinned copper and aluminum, *not *properties of terminals or circuit breakers.


I know about that. But cannot find the information about the effect of “tinning” on such connections, which for all I know may or may not be significant. I’m really curious.

Tin and copper have almost the same galvanic reactivity.


Thanks. Graph provides excellent information. Of course, one needs to know what the metal used for “tinning” actually is.

It I am sure is tin and they Tinned all Knob and tube wires as all joints where soldered to make good contact .
To solder copper wires required cleaning before soldering .
Tinned wires took the solder and a ggod joint was easy to do .
Been there done that many years ago.
Solder is made up with a large amount of tin in it .

I believe that part of the issue is the thermal expansion and contract differential between copper and aluminum wires. Whether or not the copper is tinned or not is pretty much irrelevant. That is probably why there is little specific discussion regarding tinning and this issue. As was pointed out any galvanic action with aluminum would be similar between copper and tin as well.