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Wiring A Double dimmer switch

Discussion in 'Electrics UK' started by morrisphotos, 6 May 2009.

  1. morrisphotos

    morrisphotos

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    I wondered if anyone could help me as i am looking at replacing a 2 way switch with a dimmer switch. what i want to do is put it in my front room ware i have 4 WALL lights and 2 sealing lights but the problem is on the dimmer switch i have 3 conecters names L1 C L2 what wires go ware. 1 other thing in that room i have a mains loop so i have quite a few cables to wire in someware. H
    ere is a photo of the dimmer i have

    hope someone can help

    Thanks David
     
  2. ban-all-sheds

    ban-all-sheds

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    You are aware of how this will work, I hope? i.e. when you switch the lights on at the normal switch you aren't replacing they'll come on at whatever setting the dimmer was before, and you'll have to walk over to it if that's not the level you want?


    1. Are the lights the right sort to be dimmed?
    2. If they're ELV (http://www.diynot.com/wiki/electrics:voltage-bands) is the dimmer the right type?
    3. Can the dimmer cope with the total load of the lights?

    Aren't the terminals in the existing switches labelled COM, L1 & L2?

    If they're L1, L2 & L3 then the correspondence is:

    OLD. . . . . NEW
    . L1. . . . . COM
    . L2. . . . . L1
    . L3. . . . . L2


    They just stay as they are.
     
  3. ericmark

    ericmark

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    You have a very good diagram on the back of the switch. If you can't follow it you should not be doing the job. For each two way system you have one normal two way switch and one dimming two way switch. These are connected together using three core and earth cable and connected simply like for like so L1 on one switch connects to L1 on other switch. One of the two will also have the two switch wires from the light it controls these will double up with strapper wires in the L1 and L2 holes and does not really matter if they are wrong way around.
    I would normally direct to my web page but it only shows same as already shown on back of the switch.
     
  4. morrisphotos

    morrisphotos

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    what does the L1 L2 AND COM MEAN AND I AHVE A MAINS LOOP
     
  5. sparkyspike

    sparkyspike

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    L1, L2, and COM are all live terminals. Only live cables go there (not neutrals or earths). It doesn't really matter what they are called, which is why they are sometimes referred to as L1, L2 and L3.

    Basically the COM (common) terminal is at one end of the switch and L1 & L2 are at the other. The position of the switch dictates which of these 2 are then connected to COM by means of the switch.

    They are so many different ways to connect two way switches, that the term COMMON is not really relevant. This terminal can be used as a live feed (at one end) and switched live (at the other) or as a link between two 2 way switches (which is when it is known as the common wire. The other two wires are known as strappers).

    Are you referring to a hearing aid set-up when you mention mains loop? If it's working now ok and you repeat the same method on wiring up the new dimmers, then the loop won't be affected.
     
  6. morrisphotos

    morrisphotos

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    No I don't mean a hearing aid loop as the double dimmer switch is for lights only. The loop I mean is mains power loop to and from my main fuse box in the garage so thats why I have more cables to wire in to the dimmer switch then normally should
     
  7. sparkyspike

    sparkyspike

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    In which case, refer to ban-all-shed's instructions and you will be fine.
     
  8. ban-all-sheds

    ban-all-sheds

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    [​IMG]

    Alternative labelling:

    [​IMG]


    That's not currently connected to any terminals in your existing switch, so don't connect it to any terminals in your new one.
     
  9. morrisphotos

    morrisphotos

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    All I want to know is what colour cables go in to l1 l2 and C on the back of my double dimmer
     
  10. rebuke

    rebuke

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    Ideally you'd just reconnect them to what they were in on the previous switch, although I get the impression you didn't make a note of that before disconnecting it?

    What cables do you have in the backbox - a photo would probably be useful. Ultimately there is no defined standard, there are conventions, but nothing to force people to use them...
     
  11. ban-all-sheds

    ban-all-sheds

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    THE SAME AS THE ONES IN L1, L2 AND C(OM) ON YOUR EXISTING SWITCH!!


    :rolleyes:
     
  12. sparkyspike

    sparkyspike

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    We don't know which colours went where in the existing switch, so we won't be able to tell you which colours go where in the new switch. Only you know how the existing switch is wired up.
     
  13. ColJack

    ColJack

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    not being funny, but it's got the fraking wiring diagram on the back of the dimmer...

    L1 to L1
    C to C
    L2 to L2..

    :rolleyes:

    if you want more specific answers then we will need photo's of the wiring to the switches already installed..
     
  14. securespark

    securespark

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    That may not be true, Ban. The live loop in & out may well be attached to the commons.
     
  15. sparkyspike

    sparkyspike

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    If that were the case, it would already be connected to the old switch. Any cables not connected to the old switch, such as neutrals etc should stay where they are.
     
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