> Three phase systems actually are a carry over from the days of early induction motors Three phase is better than one for transmission: you can pass more powe

> Three phase systems actually are a carry over from the days of early induction motors Three phase is better than one for transmission: you can pass more power for a given distance with a given budget of copper/aluminium wire. In other words, you have three wires rather than 2, but they can be lighter overall, and require less materials and fewer and less expensive poles.