Using a two gang light switch for two way and one way lighting

Discussion in 'Electrics UK' started by ron eccles, 29 Aug 2019.

  1. ron eccles

    ron eccles

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    I am thinking of fitting a two gang switch in place of the single switch that works the stairs light. I would like one switch to power the two way stairs light and the other switch to power a single light at the bottom of the stair.
    The wires in the two way are yellow, red, blue. The yellow being the live. I was wondering whether I could take feed from the yellow, to power the one way lamp I want to fit. Trouble is I do not think either of the other two wires are a neutral. Can anybody suggest what to do?
    The two gang switch I have has the contacts Common 1, and two more stated as 2 and 3, not L1 or L2. The second switch on the unit is listed the same, but the other way up. (see diagram)
    Switch 2 is the existing switch I want to replace with Switch 1 switch.jpg
     
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  3. VDubDan

    VDubDan

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    I'M NOT A SPARKY - DON'T BELIEVE ANYTHING I SAY!

    I don't think this is going to work the way you hope.

    You won't have a neutral in the switch unless they've "looped" into the switch, which you'd definitely see/notice. So, the loop is in the light fitting (which is pretty standard, especially if they're pendants) and then live runs down to the switch and switched live runs back up. The fact you've got a two way switch attached doesn't really matter here, that just extends the live and switched live.

    There's a diagram on this page - under "Example Wiring - 2 Way Switches", the top picture represents yours. (https://www.downlights.co.uk/faq-wire-light-switch.html)

    So that's your first issue - no matter what, you need to run a neutral from somewhere to your new lamp.

    Now, the next problem you've got is you want to mess with the second switch, which is the "remote" switch basically. When it comes to upstairs/downstairs this poses an issue because the loop is at the top of the stairs. I presume you have upstairs and downstairs lighting circuits/breakers - you can test this by flicking them both and working out which circuit the landing light is on. It's probably upstairs - so even if you borrow the "live" which is carried downstairs, you'll have no easy way to get it back to the upstairs neutral. Skipping this and using the downstairs neutral is called a "borrowed live" which are pretty frowned upon now as they're hard to isolate.

    The last thing is that on Switch 2, both Yellow and Blue are effectively a switched live, so you'd need to combine them both into a connector to get a permanent live - that sounds pretty nasty.

    Like I say, not a spark or even close to it so they may have some better ideas, but I don't think you can achieve what you want as simply as you hope.
     
  4. Tigercubrider

    Tigercubrider

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    Not a sparky but...
    You need a 2 way 2 gang switch. Not sure if they even make a switch that is 2 gang with one 2 way and one single way.
    Normally you use a 2 way switch and a four way cable back to another 2 way

    You haven't stated whether this is a replacement switch to old wiring or a new install
     
  5. ron eccles

    ron eccles

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    I thought that might be the problem, no neutral. I had the single light wired into the downstairs loo circuit, but as I have now got to bury the cable in the wall before I decorate and the fact the wall is breeze block, I thought I would try and run a shorter method by using the two way circuit. Oh well, back to cutting strips out of the breeze block. Thanks for confirming what I suspected.
     
  6. EFLImpudence

    EFLImpudence

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    Ok.

    Ok. Permanent live yellow.

    You will have to get a neutral from the same circuit to the light position and the live via the switch to the light.
    As you have to do that anyway, you may as well run a cable to the new light from a supply somewhere - existing light or consumer unit - and also a cable from new light to switch.

    It doesn't matter what they are called. the triangles will correspond.
     
  7. ron eccles

    ron eccles

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    Thank's. As I posted above, I have gone back to where the power was coming from in the first place. There I have the live neutral and earth, so all is safe. I just now have to bury the wire. Better than having to start adding new wires. Thanks for your input anyway.
     
  8. DIYnot Local

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