I eat lunch once per week with a senior manager of the local electric utility. He says they use a wire made of a steel core and aluminum outer as the primary conductor. Only the service entrance drop is insulated.but......i thought there must be larger losses in the wires, they are made of steel!
The neighborhood feed is usually 900-1000 volts. I find amazing that 20 or so homes can have 200A service from that one wire.