The main question that will also need to be asked is what is it on mains your turning off and on , what type of load, what current, is it a motor, heater, light, 3amps, 5 amps, 13 amps ? etc. I also take it you mean AC mains when you ask 220, UK = 240, USA 110-120 , different frequency mains too, all this makes the type of circuit you use important. There can even be questions like is it soft start i.e. the voltage / current is slowly raised so as not to shock the circuits etc. sorry not to fill in all the gaps but my knowledge is more towards Software but I have an understanding of the electronics involved too.