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Double light switch to Double light dimmer - NEED HELP !

Discussion in 'Electrics UK' started by MoonMan2, 31 Aug 2013.

  1. MoonMan2

    MoonMan2

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    I am trying to convert a double light switch to a double dimmer switch. The switch is downstairs. One of the switches operates the dining room. The other switch operates the upstairs hall light. A switch upstairs also operates the upstairs hall light. I think this means that one of the lights is "2 way".

    The back of the double light switch currently installed looks like this:



    There are 6 connections, 3 on the top and 3 on the bottom, from the top they read:

    COMMON
    3 (TOP)
    2
    3
    2
    1(COMMON)

    The dimmer I want to install looks like:


    It has 6 connections, 2 sets of 3 which read:

    C
    L2
    L1

    Can someone tell how to connect to the new one please?
     
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  3. jj4091

    jj4091

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    L1 & L2 are the same as 2 & 3. C = Common. Before you fit it though is there an earth wire connected inside the back box
     
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  4. PrenticeBoyofDerry

    PrenticeBoyofDerry

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    is this what you have?
    Why would you want to dim a light on a hall/ landing?
     
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  5. ban-all-sheds

    ban-all-sheds

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    Particularly with the dimmer downstairs.

    MoonMan - are you aware that if the landing light is off, and you turn it on from the switch upstairs, it will come on at the brightness level set by the dimmer, so not necessarily full, and it will stay at that level until you have found your way down dimly lit stairs and turned the knob.

    If you must dim that light, and as PBoD asks, why would you want to, at least install a master-slave dimmer pair, if you can, so that you can control the brightness from each location.
     
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  6. riveralt

    riveralt

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    Firstly and this is the most important point - as JJ4091 implied - your new switch is metal and REQUIRES an earth wire between the new switch earth terminal and the earth lug on the back box which should currently hold you incoming earth wires.
    If there are no earth wires in the back box then you cannot fit this new dimmer...

    If the earthing is correct then on the new 2 gang dimmer decide which one will control the downstairs light and which one will control the upstairs light.

    Looking at the old switch you need to identify the two Common terminals - these are/should be the two terminals with the link wire between them - mark both terminals in someway and move them to the two C's on the new dimmer switch.
    Then connect the link wire between the two C terminals on the new switch.

    Again looking at the remaining cables in the old switch in the photograph - and in particular the right hand switch which should be your downstairs light - remove the remaining red cable (top right) and put it into L1 on the new switch - this is now you new downstairs dimmer switch.

    Then looking at the old switch left hand switch (the link (2 way) to the upstairs light) you have remaining a black and red conductor in the bottom right and left terminals - remove these and place them in the L1 and L2 terminals of the new dimmer (upstairs 2 way switch) in exactly the same way as the old switch - So if the old switch arrangement was 2 & 3 then on the new dimmer they go to L1 & L2.

    As others have said - having a dimmer control the landing lights from one location is not a good idea - either go back to two switches or consider the master slave approach as suggested by BAS.
     
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  7. MoonMan2

    MoonMan2

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    The casing is polished plastic with metal dimmer knobs.

    Does this still require an earth wire?
     
  8. riveralt

    riveralt

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    Yes!!
    It will explain in the instructions that came with the dimmer but I think the clue is in the fact that they provide an earth terminal in the switch - top left in the picture.
     
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  9. DIYnot Local

    DIYnot Local

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