This has to do with a fundamental doubt I have always had about power distribution. Say you hook up a room heater to your power supply. How exactly does the power distribution detect an increased 'load' and accordingly allot more power to your room. The way I understand it, the generating substation sends you electrical power at a fixed voltage (say 220V ). So 'loading' the power supply with the high resistance coil of a room heater should cause a reduced current to flow (according to V = IR ), and accordingly, a much smaller power output (according to P = i(squared)R ). So heaters should be the least power intensive of all household appliances, but obviously they are not, so what am I missing?