As I understand it, every residential house is on single phase power. We have two different power distribution networks, one for residential and one for industrial power. One is single phase and the other is three phase. Has any one wondered why some power pylons has a single pair of lines per arm, while others have four lines. Well this is the two different networks, residential power is not taken off the three phase network. The power to the sub-stations is also single phase. There is something called the "Ring Main" which usually resides under the roads or pathsways. Every house is connected to every other house on that particular Ring Main. There is a netted tree topology to the power distribution, if that makes any sence. There are several Ring Mains that come out of each sub-station, all stared at the sub-station.