2 way 2 gang dimmer switch problems!

Discussion in 'Electrics UK' started by ajstant, 12 Nov 2003.

  1. ajstant

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    Hi

    I have a problem with my two way s gang dimmer switches for the hall and landing lights. I used to have normal on/off switches downstairs and up, this seemed to work fine.
    When I replaced them with two two-way dimmers things started to go wrong.

    Downstairs I have 3 wires: red, yellow (with red band) and blue. For the same light but on the upstairs switch I have 5 wires: red (x2), black (with red band), yellow and blue. I have identified what I think is the constant live at both ends.

    The best I can get is a low glow on the upstairs light, no dimming and no control whatsoever from the downstairs switch!

    Can anybody please help me with this?

    Thanks very much,

    Andy
     
  2. il78

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    I take it that the hallway light is working fine on the dimmer……

    At the hallway switch:
    3 Core cable RED/YELLOW/BLUE
    YELLOW to C
    RED to L1
    BLUE to L2

    At landing switch:
    3 Core cable and 2 Core cable RED/YELLOW/BLUE & RED/BLACK
    YELLOW to C
    RED & RED to L1
    BLUE & BLACK to L2

    All earths to brass terminals

    I have been informed that 2 dimmers in circuit will not operate, so you must have a normal switch installed somewhere (ie, upstairs)
     
  3. ban-all-sheds

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    I take it you have bought proper multi-way dimmers, with a master/slave relationship, or some sort of intelligent control link between them?

    Not just dimmers that have 2-way switching capability so that you can have ONE dimmer in place of ONE 2-way switch?

    If not, you're *****d, as you can't have 2 conventional dimmers in series.
     
  4. ajstant

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    Both dimmers (upstairs and downstairs) are 2 gang 2 way switches. To be honest I didn't know they wouldn't be 'professional'.

    This means I can't do what I want then I presume? :( What will happen, nothing or something? :?:

    Why won't two dimmers work in series then?
     
  5. ban-all-sheds

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    It's nothing to do with them being professional - they could be the finest product in the world, but they still wouldn't be able to do what they weren't designed to do. Did they come with a wiring diagram which led you to believe that you could have two in the same circuit?

    What will happen is what's happening now.

    Because even if they were simple potentiometers their resistance values would add up, making the final voltage output very low. As they aren't but are semiconductor switching circuits then what will almost certainly happen is that the output from the first dimmer will not be enough to trigger any functionality in the second.

    But even if they were simple pots, nobody with even a modicum of knowledge of how two way lighting circuits work (i.e. which wires carry current and when, depending on relative switch positions), or of what voltage, current and resistance are would ever expect to be able to put 2 dimmers in series.

    Are you sure you are up to this?
     
  6. breezer

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    i think itt is a case of he didn't know you cant have two ordainairy dimmers controling the same circuit. after all it doesnt say on the box, that no one reads that you can't
     
  7. ban-all-sheds

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    Ah - maybe it's just me, but even if you don't know how they work, (and I don't, precisely), surely it must be obvious that what you have is a little box where you put 240V in at one end and get less than that out at the other end, which is why your light is less bright. And that if you then take that "less than", and feed it INTO another one of the magic boxes, you'll get so little out that the light won't work at all?

    But apparently not.

    I've never fancied a dimmer at one end of a two-way switch circuit, as I just know that I'd always be at the wrong end when I wanted to adjust the wick, so I've never looked at "2-way" dimmers - do they really not have a diagram showing 1 dimmer and 1 switch?
     
  8. Scoby_Beasley

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    Totally agree
     

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