Now I am confused. I get several posts saying we use copper service wire and now one we don't. My house was built in 1961, so I can't go by its wiring. The wire from the pole transformer are aluminum. But if it were a new house ?......
Unless restricted by local codes aluminum is used nowadays for all wiring except the branch circuits in your house. The problem with aluminum wiring in houses lies in the wire nut connections and the connections to breakers, switches and receptacles. The small diameter aluminum wire oxidizes increasing resistance and it expands and contracts when current flows through it much more than its copper counterparts. The constant expansion and contraction causes loose connections and "loose wires cause fires".
Inside the house: copper. Overhead wires belonging to the utility: aluminum. Substation: some of each. Copper wires from xformer to house haven't been installed in these parts for decades.
"ALL new service whether overhead or underground is now aluminum. Most wires carrying the high voltage (distribution primary wires) on the poles on the street will be aluminum in new construction. SOME older distribution wires in non-urban areas is copper, but it is nearly all replaced with aluminum now.
Even substation transformers in a lot of cases are wound with aluminum instead of good ol' copper, simply because of the cost of copper vs. aluminum.
Aluminum is not as "conductive" as copper for sure, but it sure is cheaper, lighter, and isn't stolen.
I recall back in the 70's or so when aluminum prices spiked, and homes in the area had aluminum siding stolen at night by vandals who were headed to the scrap yard with it.