Hi, I've got a bit of a problem with my upstairs lights. Me and my housemate changed 3 light fittings from ones with fans to standard lights. Unfortunately, whilst the 2 I did are connected up ok (kept the wiring as before and the 3 red ones separate from the connections to the new light), my housemate decided that there must be a red cable going to the light so took it upon himself to create something a bit different!
Thus far it seems things can be rectified, however, the switched live is not marked so I do not know which it is. I am left with 3 triple core cables coming in, obviously the earth and permanent lives are fine but how would I be able to work out which is the switched live out of the 3 black wires? I have connected it up having guessed which might be the switched live but whilst that light works fine the others are now very dim and do not work at all when the offending light is on. Any help would be greatly appreciated. Thanks.