I am changing a ceiling light.

I have three red wires and three black wires with one red and one black at the switch. Which wires go where?

Cheers

Louise, July 2008

Forgot to say - check out DIYnot.com for pics of wiring etc....excellent stuff if you like wearing a flat cap! Cheers John

John, July 2008

You would use a test meter to look for continuity between the two switch wires - obviously with the switch 'on' the power would go down the red, and return via the black. With the switch off, the power would go down the red to the switch and stop there. If you have a mains testing screwdriver, with the neon bulb inside, it will glow on touching the reds, but not on the blacks...apart from the one that comes back from the switch, when it is turned on. Sorry if I'm making things worse....dead easy to be smart and patronising on the end of a PC!

John, July 2008

OK - that makes sense. So do I put the tester against the longer red light to see what happens?

Louise, July 2008

I was afraid you'd say that...! You have bypassed the switch - hence the light on all of the time. It sounds like the 2 red wires are the loop - if you split these, then the light in the next room wouldn't come on. Perhaps the other red wire is to the switch, and returning as one of the black ones.....often sparkies put a piece of coloured tape on the switch return to indicate which is which. If you have a test meter, you could use it to check out the switch wires - without one, its trial and error. Please be careful!!

John, July 2008

Confused Completely! I can wire and get the light to come on but it wont switch of.
I have two reds which seem to be together and one red which appears longer and three black wires.

Louise, July 2008

Are you ready for this? 3 red (live) wires = one from the fusebox, one continuing to the next room, one going to the wall switch. 3 black (neutral) wires = one from the fusebox, one continuing to the next room, one returning from the wall switch. So, if you look at the ceiling rose after unscrewing the lid, you'll see 3 terminals called 'loop' where the lives go to, 2 terminals for the neutrals, and connections that go to the existing light bulb. One of these connections will be a neutral, and the other will be a live return from the wall switch (these connections are the two outer ones). So, not just a simple job I'm afraid. Don't forget, even with the room light off, the terminals within the ceiling rose are very much alive - so get professional help if you're not sure.

John, July 2008