Switch live should have a red sleeve on it.
Failing that TURN OFF THE ELECTRICITY! and try this...On a ceiling rose wired into a lighting ring main, there should be 2 black wires (neutral from the ring main) going in to a connection block of 3 the 3rd connection feeding the neutral to the light.
Next to that there will be another block of three with 2 redwires (Live feed from the ring main) the 3rd wire from this will be the switch wire going to your light switch (the live side of the switch) this then comes back (from the live switched side the on side if you like)to a block of 2 the 2nd connection supplying a switched live to the light.
Be Careful!!
Rivermersey, October 2006
