Existential Angst wrote:

It's funny, we started with copper, went to tinned copper, went back to
copper, slid further back to effing aluminum (goodgawd), learned from that
mistake and went back to copper again. Altho power companies use aluminum
in parts of their service -- and steel!

As several people have said, steel is not used as a conductor.

Aluminum is rather widely used inside buildings for larger sized wire.
It is very common to use aluminum wire for the service wires from the
utility connection to the meter to the service panel. The problems were
with 15 and 20A branch circuits. Aluminum can still be used for them
too, but not likely any time soon.

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bud--