Tou need a voit stick or voltage detector pen. Something like this http://www.screwfix.com/p/fluke-1ac-ii-voltage-detector-pen/85949
Turn on circuits one at a time and use the pen to see which are live, and them label them with a marker pen. Note for lighting circuits, turn all the lights on when testing as some lighting cables will appear dead when the lights are turned off.
This, imho is the only use for these devices, they should never be used to prove a circuit is dead before working on it.