splicing aluminum to copper elec wire

Horsedoc wrote:
I have a transformer by my house with copper cable attached to the aluminum cable coming into the house. The two are joined together with a squeeze-on connector or aluminum. Open to the air and rain in all weather. Only damage is where the squirrels have gnawed the squeeze-on.
Comment on that?

Electric Company linesman used the PROPER termination which is a TIN plated copper or TIN plated aluminum crimp. The TIN layer is less reactive to either copper or aluminum. The TIN layer allows for interfacing to dissimilar reactive materials like copper or aluminum.

If you notice, they did not "butt" or directly connect the dissimilar wires together, they are not touching, only the termination (crimp connector) touches both materials.

With the proper crimper with proper pressure, both wires and crimp portion of the terminations are crimped tight enough to reduce moisture infiltration under most circumstances.

Additionally, those crimp joints are outside and not anywhere close to flammable objects if the termination were to fail and over heat..

CU/AL Termination failure INSIDE your home in breaker panel, junction box or outlet/switch area can be catastrophic and lead to burning your house down.. That is the reason why Aluminum wire is no longer allowed to be installed in new buildings for BRANCH CIRCUITS since the late 1970s. That is why I was a bit shocked when the OP of this thread thought they had AL wire on their new built in oven (which it was not, it was actually tin plated copper which looks a little like aluminum).

See HERE for some explanation.

AL is still allowed for service entrance from the mast, to the electric meter socket to your main breaker. But, you must make sure when installing it you use NoAlox or OxGard on the service entrance wire and the termination is torqued properly.

EXISTING AL branch circuits in old buildings are "grandfathered" so you do not need to rip out and rewire it, but you do need to take special care with the devices interfaced to it to ensure connection isn't going to deteriorate from incompatible materials.

On edit..

Took a pix of the electric company connection at my house..



That is the neutral wire, the Hots, they covered with electrical tape so a pix of those wouldn't illustrate what I am talking about.

If you look very closely, you will see that the termination actually has TWO separate openings, one wire goes in one of the openings and the other goes into the other opening.. Neither wire can touch together.. Once both wires have been inserted they use a big crimper made for the connector to crimp both sides at the same time.