Ceiling light wiring problem

[jasonhyland]

Hi, I'd be grateful if someone could help out with a wiring problem for a ceiling light. I'm afraid I know next to nothing about wiring !

I am replacing an existing light in the cloakroom. Stupidly I didn't make a note of the wioring before removing the exisiting light!

So, I have 4 cables coming out of the ceiling (see picture)

Untitled

• jasonhyland
• 11 Jun 2011
• 1

The cloakroom has a pull light switch for the clieling light and a extractor fan with another switch on the wall. The extractor comes on when the light is turned off and I guess is on a timer because it goes off after a short while.

The 4 cables are;

3 x red/black/earth
1 x yellow/blue/red

As you can see all the lives are connected already in a block. My light has a connector for live, neutral and earth, so I need to understand what to connect to what

I assume the 3 neutrals should connect to the neutral block - that leaves the yellow and blue. I'm guessing one of these acts as a "switched live?"

Any help would be very appreciated - we've no lights in the kitchen now

Wifey not v happy!

 

[bernardgreen]

Two of the black wires are neutral, the third one is a switched live from the switch. You first task is to identify which black wire is the switched live.

Best ( as in safest ) way is to use a multi-meter that will measure AC volts to 230 volts and continuity or ohms ( resistance ). So beg borrow or buy a multimeter ( about £ 10 in a local DIY retailer )

Other methods require a test lamp with clips and can present a safety hazard to in-experienced people.

 

[sparkwright]

Once you have identified which black goes to the switch, this black and the yellow go the live of the light fitting.

The remaining blacks and the blue go to the the neutral of the light fitting.

All earths go to the earth terminal.

The reds remain connected together.

 

[jasonhyland]

Thanks a bunch guys, nailed it with your help.

I identified the switched live by looking for the cleanest black (I reasoned the red sleeve had fallen off this one).

I'd like to understand the why as well as the how - anyone explain in laymans terms - or point me to a resource that might help?

I assume the 3 "feeds" are one in and 2 out - one of those out is to the next light in circuit and the other is to the fan?

Thanks again for help - appreciated greatly!

 

[sparkwright]

Thanks a bunch guys, nailed it with your help.

I identified the switched live by looking for the cleanest black (I reasoned the red sleeve had fallen off this one).

I'd like to understand the why as well as the how - anyone explain in laymans terms - or point me to a resource that might help?

I assume the 3 "feeds" are one in and 2 out - one of those out is to the next light in circuit and the other is to the fan?

Thanks again for help - appreciated greatly!

You don't identify switch wires like that!

There are usually two feeds, live and neutral. One feed is feed in. The other feed is to the light in the next room.

The switch wire gets it's feed from the two live feeds. This goes to the switch, where it will switch with that black wire with the red sleeve. This goes to the L terminal of the cloakroom light. So the switch controls this black live wire.

The fan comes on with the light, so the yellow is connected here.
Blue is the neutral.
The red on the fan provides the overun facility once the light has been switched off.

 

[Taylortwocities]

I'd like to understand the why as well as the how - anyone explain in laymans terms - or point me to a resource that might help?

At the top of the Electrics UK list there is a WIKI
It is titled in bold
PLEASE SEE IF YOUR QUERY IS ALREADY COVERED BY THE WIKI

Look in the lighting section./

You should have done that first

 

[bernardgreen]

I identified the switched live by looking for the cleanest black (I reasoned the red sleeve had fallen off this one).

Good thinking and worth a try in desperation

You did replace the sleeve for next time.

 

[jasonhyland]

Good thinking and worth a try in desperation
You did replace the sleeve for next time.

Yes, I do appreciate I probably made people who know what they are doing wince, but it was more than a guess ... and on the basis that my first attempt before seeking help here tripped the circuit at the fusebox I figured that was worst case.

... and yes, sleeve on and lesson learn for next time. Hence wanting to understand a bit more. Looking through wiki now....

Oh, and thanks again!

Jason.