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Replacing 2 Gang Switch .... but Strange Wiring

Discussion in 'Electrics UK' started by AndyM230, 13 Mar 2019.

  1. AndyM230

    AndyM230

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    Hi,

    Looking to replace a 2 gang switch with a new smart switch but the wiring has me a little confused.
    The existing switch controls a single ceiling light on gang 1 and a pair of wall lights on gang 2.
    The existing switch has what seems to be two independent permanent lives incoming, one to L1 (com) on each gang as opposed to the normal 1 that would be bridged across from gang 1 to gang 2.
    Existing switch then has what appears to be three switched lives ... one out to ceiling light on gang 1 (L2) and two out to the wall lights on gang 2 (both wires in L2).

    Now the smart switch is only expecting a single permanent live coming into the switch (as was I) so I’m confused as to what to do with the two seperate permanent lives.
    Can I just connect them both into the permanent live in on the smart switch?
    Also is it OK to have the two switched lives out to the wall lights connected into a single terminal or should that really be using a connector block?

    I’ve fitted a few of these things around the house with no issues where wiring had been as expected but this setup has me confused so would appreciate any advice.
     

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  3. EFLImpudence

    EFLImpudence

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    Ok.

    I wouldn't call either normal - but ok.

    Might be.

    You do realise that the switches are two triangles so L1 at the top relates to L2 at the bottom and vice versa; not L1 at the top and L2 at the top?



    There is the possibility that the two wires in the same terminal are loop in and loop out, and only one wire goes to the two wall lights, as there do not seem to be enough neutrals for the way you have described it.
    If one of the cables has twin brown wires and both go to the nearest switch in the picture this is likely to be the case so you will have to check and wire differently
     
  4. securespark

    securespark

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    What would happen if the feeds to both switches originated from different circuits?
     
  5. AndyM230

    AndyM230

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    Yep, aware of that.

    I’m making assumptions for what each wire does just based on how they are currently connected to the switch as they are unhelpfully not colour coded. If the two wires in L2 on gang 2 are loop in/loop out how should they be wired to the replacement switch?

    I’m still left with the problem of two permanent lives and only one terminal too.
     
  6. AndyM230

    AndyM230

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    Honestly no idea, I’ve only ever seen switches with a single permanent live before where it has been bridged across the gangs where required so this setup is new to me.
     
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  8. EFLImpudence

    EFLImpudence

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    Need to know -

    Does one of the cables have twin brown wires which both go to the nearest switch in the picture?
     
  9. winston1

    winston1

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    Well you would join 2 circuits together so so 2 separate circuits rated a 6 amps would become one circuit rated at 12 amps (not quite but you get the idea). Both MCBs would need to be switched off to isolate it.
     
  10. AndyM230

    AndyM230

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    Yes indeed, the two brown wires coming to gang one (nearest in picture) both emmanate from the same cable.
     
  11. EFLImpudence

    EFLImpudence

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    In that case, you need to determine which one of those goes to the light, i.e. is NOT the Live.
    Terminate that Live in a connector block and position out of the way.

    Then you need to determine which is the Live on the far switch.
    Is it one of the two wires that are together or the single wire?

    ONLY IF they are on the same circuit -

    put that Live (either the single wire or the two wires that are together) in the L of the new switch, and the remaining two wires in the two lighting terminals.

    Do you need a Neutral for the new switch to work? If so connect to the Blue wires.
     
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