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Change a 2 gang light switch to a 3 gang.

Discussion in 'Electrics UK' started by Swell1, 15 May 2021.

  1. Swell1

    Swell1

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    Hello, our hall has a 2 gang switch, one for the hall light, the other for an outside light. I also have a separate switch for a light in a cupboard, if I put all of these on a 3 gang switch, how would this be wired? The cable to the 2 gang has 4 core and the cable to the single gang is 3 core.
    I can see on a 3 gang switch it has common and L1, L2 etc.
    Any advice appreciated.
     
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  3. terryplumb

    terryplumb

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    Two of the 3 gangs will just replicate what you have at the two gang switch. The third gang will need the wires that are currently present at your "seperate switch" ,transferred over to it, like for like .
     
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  4. Swell1

    Swell1

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    Hello, I've taken the 2 gang switch off and I took a picture of the wiring but I can't believe it but the picture has vanished and I'm a little stumped. Could some one please advise on the wiring for the 3 gang one way light switch?

    I have 2 cables to connect to it, one 3 core from a single light - red black earth.
    The second cable is 4 core for the hall light and outside light - red yellow blue earth.

    These lights are not controlled by any other switches, just these.

    Any help appreciated.
     
  5. terryplumb

    terryplumb

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    Show us a picture of the cables at the switch position ,and a pic of the back of the new 3 gang switch ( clearly showing the terminal identifications).
    Do you have a twin probe voltage tester or a multimeter ?
     
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  6. Swell1

    Swell1

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    Thank you, yes I have a twin probe meter.
     

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  7. terryplumb

    terryplumb

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    On your original 2 gang switch ,was there a short piece of wire joining across the two gangs ?
    Can you safely work on live circuit with your meter to establish voltages present at the red ,blue ,yellow conductors of the 3 core and earth ? One of them should be permanent live.
     
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  9. Swell1

    Swell1

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    Hello, yes there was a joining piece of wire, and the red seems to be the perm live on the 4 core cable.
     
  10. terryplumb

    terryplumb

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    Referencing your pic of switch from left to right..
    Put red into common on far left gang ,and a short bridge wire with it ,connect the other end of bridge to common terminal on middle gang.
    Put yellow into L1 of left gang and blue into L1 of middle gang.
    The far right gang will be for your twin and earth cable ( cupboard light ??). Put red into common and black into L1 on far right gang.
    All earth conductors to be sheathed yellow/ green sleeving ,and connected together into the switch plates earth terminal .
    Before doing any of the above isolate the supply and prove all conductors dead .
     
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  11. Swell1

    Swell1

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    Thank you so much this really is appreciated, I will do this is the morning and let you know! Thank you again.
     
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  12. terryplumb

    terryplumb

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    Your welcome.
     
  13. Swell1

    Swell1

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    Thank you it worked! however the middle switch for the hall has the light on when the switch is in the off position, do you know if this can be changed to match the rest? Thanks again!
     
  14. terryplumb

    terryplumb

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    Change the conductor that's in L1 into L2.
     
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