I tried to install a new light fitting, which is a 3 plate spotlight. but i have 4 black wires 4 red wires and 3 yellow/green wires from the mains
and the fitting has 3 brown wires and 3 blue wires
(three sets of the wires have a gray outer jacket and one has white)

on the old fitting all the red wires are clumped together but not attached to the fitting it's self, and the same with the yellow/green wires
the black wires had 3 going in to one conection and the fouth going into the other but i am not sure which is which any help with this would be great

thanks

dave, February 2010

oh so you dont know which one that is?
do none of the black cables have any red sleeving/tape on them?
that would be the switch wire.
do you have a continuity meter?

chris gray, February 2010

first things first.
if there are 4 red conductors, 4 black conductors, there must also be 4 green/yellow conductors (earth).
1st isolate and make safe the circuit you want to work on, and test that it is dead. (turn off the mcb/rcd/rcbo at your consumer unit)
the 4 red cables that were in a connector block by themselves need to stay in that connector block, otherwise you are going to have issues with your full curcuit.
put the 3 black cables with the 3 blue cables in a connector block.
put the remaining black cable (should have red indicator on it) into a connector block with the 3 brown cables.
if you new light is a class2 fitting it may not require an earth. the green and yellow cables need to be put into a connector block of their own as well.

chris gray, February 2010

i belive that one set of the wires is from the light switch

dave, February 2010