Replacing double switch to single in hall way.

[SWILSY]

I'm replacing switch from double to single as one light has been taken away and therefore double has been taken away. I think that I have mixed wires up so is there a way of finding out which are the common to wires and should I line at common on switch. I belled wires out going to ceiling rose so I know what these are but I am now left with three wires.

 

[jj4091]

Please try to explain more clearly. How many cables, what colour wires etc.

 

[pcboffinuk]

Hi,

To offer full advice we need to know whether either the removed or existing switches (or both) are two way - i.e. the light could be switched from two places, as is common in a hallway. and as jj mentions a breakdown of the cables and colours would also help.

If you have removed/isolated the wires from the removed lighting point, and have 3 wires left (and an earth? - essential if it is a metal plate you are installing) then it sounds like you have a 1 gang, two way setup.

In which case you either need to have noted which holes they came out of, or you need a multimeter to be sure.

In a 2 Way situation, you may be able to take off the other switch and note which colour goes where - then replicate the same at the new switch.

However, more information is needed before we can give you a reliable answer.

Gavin

 

[SWILSY]

The two wires going to ceiling rose are red and black, the rest of the cables are black. The problem is that the priginal switch was smashed during renovations to bathroom so I was unable to copy it. What voltages should I be looking for to find out what the other cables are?

 

[pcboffinuk]

The two wires going to ceiling rose are red and black, the rest of the cables are black.

That sounds like you have more than 3 wires then? a breakdown of what cables you have would be useful, otherwise its hard to give exact advice.

From what you have said, would I be right in thinking that you have:

1 cable with red and black cores that you know comes from the ceiling rose

3 cores that area all black that maybe go to another switch?

If so then you have a standard 2 way setup.

What voltages should I be looking for to find out what the other cables are?

The only voltages you should get are 230(ish)V or 0V unless you wire it incorrectly! (allowing for small inducted voltages etc)

If I'm correct about your setup, then one of the wires from the ceiling rose (perhaps Red but not necessarily) will be the live feed, and always at 230V

The other (black) core to the ceiling rose will then be the return switched live.

In a 1 way setup, these wires will go on either side of the switch (Com and L1) and you should be working.

If you do have a two way then it gets more tricky - but effectively these two wires will go between L1 and L2

The other 3 cores are the interlinks between the two switches, and will go into the same connection at each end, so wired com to com, L1 to L1 or however they are named.

A good picture is here on the Wiki

http://wiki.diynot.com/electrics:lighting:two_way_lighting

Sorry I can't be more exact, but if you give us an exact breakdown of cables/colours then we can offer further advice.

Gavin