Double light switches

[richardttt]

Hi all, I'm new here so go easy if this is a silly question. I have a double light switch in my hall that I want to separate in to two singles. The first switch controls the dining room light (which is the one I want to move) and the second works with another switch upstairs to work the landing light. There is a total of four wires coming into the switch, two red and two black.

I thought it would be a matter of taking the apprpriate wires out of that and re-routing them into a new switch for the dining room, but it appears that if I do that, the landing light wont work as the wires cross over and one live has a link from one switch to the other. Any ideas? Rich

 

[ricicle]

This sounds like a possible contender for 'the borrowed Neutral'.
The link provides a Line into the common of the landing switch from the downstairs circuit (I assume you have 2 lighting circuits- up + down) Then a red and black are used as 'strappers' to the top switch and a wire goes out from the common of the top switch to the landing light.
The landing light then uses the Neutral from the upstairs circuit.
Can be very dangerous if you are not familiar with it and it's dangers..
You could pull the fuse for the upstairs circuit to do some work, and if the landing light was switched to the on position there is a possibility of a disconnected Neutral on the upstairs circuit becoming ' live' without you knowing until it was too late !!

 

[richardttt]

That may explain a near miss I had some time ago. I switched off the breaker that was labeled up "upstairs lights" and set about moving a light switch to the other side of the bedroom door. I did all the work and before switching power back on at the fuse box I flicked the new switch - the damn light came on! It had been live all the time I had been working on it.

So do I need to borrow a wire from another light to move my switch - nothing is easy in this house!

 

[wingcoax]

The other side of this scenario is that you can also have two "live" wires at the switch point, due to a feed from upstairs as well as downstairs.

 

[Taylortwocities]

Why are you splitting the switch?

How far will they be separated?

 

[ColJack]

The other side of this scenario is that you can also have two "live" wires at the switch point, due to a feed from upstairs as well as downstairs.

no he doesn't, he has one live feed from the dining room light that is linked over to the hall switch and then 2 strappers from that to upstairs..

what the OP needs to do is disconnect the switched live from the dining room light ( leaving the live connected and running to the hall switch ) and run a new T+E to the location of the new switch.. job done..

we can sort the shared neutral out later if there is one..

 

[wingcoax]

Coljack, I meant that this is a possibility on other circuits in other installations, as an illustration of what can happen when circuits crossover.

 

[richardttt]

Sounds bloody complicated haha. we are re arranging the downstairs and knocking a wall down so the two switches will be either side of the wall when I'm done. Maybe I'll wait until the builder starts so that all the mess is at the same time. thanks for the replys though - I'm sure I'll get my head round it.

 

[sparkwright]

All you are doing is copying what you already have, only providing a longer link wire. Use twin and earth cable, connect the earth wire to the other earths, assuming you have some. Terminate both ends of the spare core in a terminal block.

Use oval PVC conduit, so if any re-wiring is required later on you can simply draw new cables in.

 

[ColJack]

Coljack, I meant that this is a possibility on other circuits in other installations, as an illustration of what can happen when circuits crossover.

ah sorry, thought you were talking about the OP's specific set up, not hypothetical ones..