Wires in all Canadian houses are two phases. Each hot wire to ground is 110 V. The voltage between two hot wires are 220 V. The wires in kitchen outlets have two phases. Anyone can wisely use them. In addition, many high power appliances need 220 V to reduce the power lose on the wire. For example, when I use my vacume machine on second floor, the voltage drop is up to 20 V. This is caused by the stupid low votage and high current with the high power equipment. If the voltage is doubled, the power lose on wire can be reduced to a quater.