My lighting circuit wiring is very old. In the bathroom I have three wires, sheathed in fabric that come from metal conduit. One wire is a switch live, another one permanent live and the third is neutral. In the bathroom light fitting (not loop-in) switch live is in one terminal and neutral and permanent live are joined together in the other. If you disconect permanent live, then the bathroom light will work, but some of the other lights in the flat stop working - so i\\\'m presuming that the permanent live is a circuit cable. I have an extractor fan with timer which I want to make sure will work before incorporating an isolating switch. I want it to come on with the light switch and over run and I also want the bathroom lights and other lights to work, obviously. The fan works perfectly if I connect the three wires appropriately, and I presume I could get the bathroom light to work, but because the permanent live and neutral are separated, half the lights in the flat stop working. What I\\\'m wondering is if there is a way to solve this problem, or should I buy a non-timer fan instead. Would this type of fan only have two terminals - a switch live and neutral? Could I therefore just extend a twin and earth cable from the light fitting and wire up the fan to work with the light switch, while keeping the permanent live and neutral together at the light fitting?