Light fitting


Postby chrisH » Sat Jun 09, 2007 11:17 am

Hi, I've just come to change a ceiling light fitting in my house. While removing the previous fitting (which was essentially just a hanging bulb) I found that it had four different two-core-and earth cables connected to it.

After some rummaging around in my loft it seems that these four cables all go to different parts of the house (and I assume different circuit boxes).

I'm assuming that the light only needs one of these to be connected to it - am I right in this assumption? Or because the light runs off of two different switches (one in hall, one on landing) - will it need all 4?

Next question, is it best to proceed through a process of elimination, to work out which cable is connected to the switch for the light?

And if any wires are left over, is it ok just to wrap them in insulation tape and leave them loose?
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Postby sparx » Sat Jun 09, 2007 2:40 pm

Hi, when I first read this I thought you it was tongue-in-cheek, but in case it's for real then I am very worried!!!
Do you realy believe electricians just run cables around for the fun of it?,
If there are 4 cables at a fitting it's because they need to be there, & all connected!
You say you have traced them, then you should be able to tell which one goes to your switch, find it at the light & mark it with tape, this is essential b4 doing anything else.
Presuming all 2core/E cables are Red/Blk's, the Blk from the sw. cable is really a switched live from the sw. to the light & must be marked with Red tape, this goes to the 'live-in' term of your new light. (maybe Brown flex)
The remaining Blks connect together with the 'Neutral-in' of your fitting.
(may be blue of flex)
The Reds, all 4 go together in a spare term block which has no connection to your fitting. All earths go together & to fitting earth.
if this does not make sense please get someone in who knows ,
regards SPARX
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Postby chrisH » Sat Jun 09, 2007 7:25 pm

Hi, thanks for your help. Sorry for ignorance, it was a serious request (in my defence I'm not sure if an electrician did wire my flat).

I've done what you said to do but this seems to result in a random light setting.

The light I am fitting is run off of two switches (one downstairs, one upstairs). The same two switches also operate two spotlights by the front door.

Basically, I have tried doing what you said, trying every black wire as the live switch one at a time, and each time I get a different combination of lights working.

I'm assuming that this is because I have two switches running the light - is there something extra I should be doing?
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Postby Petriburg » Sat Jun 09, 2007 8:31 pm

Hi Sparx,

I posted a reply on another topic in this forum, but I believe that the response above answers my question - apart from one problem... There's no red tape around the black sw cable.

What's the safest way to identify this one? I take it that there would be safety issues in doing a "trial and error" with the two sw cables?
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