wiring light advice needed

wilkyduch · Jan 30, 2011

Thanks for taking the time to read this.
In my house all the upstairs and downstairs lights are on one circuit.The living room downstairs has one light which can be operated by two switches. Comimg into the ceiling rose are 4 identical twin and earth cables. I presume 1=supply 2=supply to next light 3= switcht 4=?
My questions are what is the 4th cable for - where does it come from go to etc. The other switch? How are the two switches connected? Also, how do you identify what cable is for what when they are all identical?
The reason for all this is I have a replacem.

I have identified the switch cable from how it was wired to the bulb holder previously , but could somebody explain what the fourth cable is and how the four cables should be wired into the terminal block.

Many thanks

SMB · Jan 30, 2011

I would suggest that the 4th cable is the switch-wire.

The 3 other cables are purely Live and Neutrals. The 4th cable is probably the switch wire. So, it has a permanent live and the other core will only become live once the switch is turned to the 'on' position.

The way the light works in a '2-way' manner is via the 'strappers'. These are a pair of wires (plus live feed or switch wire) which run between the two switches. It doesnt sound like you need to worry yourself about those.

Be careful.

Amp David · Jan 30, 2011

How many cable are at the switches?

Do you have wall lights or have there been wall lights in the past. Could be a feed for them

SMB · Jan 30, 2011

Good point Amp David.

Im rubbish at reading. Just re-read the OP's question.

There is a feed going elsewhere. Wall lights? I doubt it though. Permanant Live at wall lights? Perhaps if they had an independent pull switch I spose. Dodgy though.

Dis-connect the 4th mains feed wire and see what doesn't work.

Lets hope its not your shower.

SMB · Jan 30, 2011

Its difficult though without being there.

One of those twins is feeding something else.

Disconnecting the wrong one will not help.

Call a sparky in your area.

wilkyduch · Jan 30, 2011

Thanks for your help
Not sure as I'm away from home for a while but the house has had a refurb and there was a porch there in the past,, Could I ask in your opinion for just one light albeit with two switches would you normally expect to only see a max of 3 cable coming in? Also, If it was as you suggest how would this effect the wiring of the terminal block in the new light. Again with identical cables im not sure which might be the old porch feed which presumably i can disregard and which needs to be connected. thanks again

Amp David · Jan 30, 2011

SMB said:
There is a feed going elsewhere. Wall lights? I doubt it though. Permanant Live at wall lights? Perhaps if they had an independent pull switch I spose. Dodgy though

Seen it before, wall lights scrapped, cables plastered into the walls and at the switch the cable cut back and pushed out of the back box.

Could also be feeding a JB in the ceiling that fed the wall lights that had their own switch or pull cord incorporated.

SMB · Jan 30, 2011

I reckon that extra wire is a mains-feed, supplying something else. Maybe it was a feed supplying the porch?. What you need to do is identify the spare mains feed and disconnect it.

Thanks for your input Amp Dave.