Problem converting from 12v halogen to GU10 LED

Discussion in 'Electricians' Talk' started by Gangerman, Sep 25, 2017.

  1. Gangerman

    Gangerman New Member

    Hi, i'm hoping someone can shed some light on my situation.

    I've decided to convert all my bulbs to LED's, at first it was going really well, already had GU10 fittings upstairs and it was a matter of just replacing the bulbs. Then i go downstairs and realise I have MR16 bulbs, tried MR16 LED's but they didn't work so decided to buy 11 GU10 light fittings rather than go to the expense of buying all new transformers or MR16 Drivers.

    After removing all the old transformers and fitting the new GU10 fittings I turned the lights on but only one bulb lit up, the rest, completely dead, even when I try and put a GU10 halogen in...nothing. except only the first light in the series, that works whether I put an LED or halogen in, and that's the one connected from the junction box.

    My switch is a Varilight pro IR dimmer, I have two in the same room so they are 2 gang.

    I can't work out what the problem is, since everything worked just fine with my old MR16 set up and all i've done is replace the fittings. I have fire rated hats, but i don't think that makes a difference.

    I was told I do not need to bother with connecting the earth since the face plates on the switches are plastic, yet the fire hats are metal, so could that be part of the problem?

    I've pulled all the lights down again and now they are hanging from my ceiling whilst i scratch my head trying to work out what to do next before I call out an electrician.

    Another thing to mention is they are set up as a daisy chain.
     
  2. unphased

    unphased Screwfix Select

    Its probably just installer error. Double check your connection at the only fitting that works. You will probably find a wire has been poorly connected.
     
  3. DIYDave.

    DIYDave. Screwfix Select

    So you’ve not changed the dimmers then, same dimmers as were running the mr16s

    Shouldn’t be a problem there as the Varilight Pro are clever things that can run halogen or LED. Have you got them wired for 2-way switching though (didn’t know they could handle that) or are they switching 2 banks of lights independently, and the total wattage is within the dimmers parameters

    If all you’ve done is removed transformers and connected new cans, and wired them in parallel, ie. each fitting has a switched live and a nuetral going to it, which is fed from the previous light, and only the 1st light is working, the problem must lie at that first light, surely

    Earthing or not,as you mentioned won’t stop the lights from working.

    Many items don’t require an earth connection as dbl insulated or known as ‘class 2’ (may have the symbol of a square inside a square)

    At the switch, terminate the earth core (CPC) in the lug in back box, sleeved of course.

    At light fittings, some have a 3 way connector block, others don’t. If ur fittings don’t, either terminate the CPC in a single strip connector or sleeve longer than the copper core and just dbl over and tuck alongside the cable outer sheath

    On no account be tempted to cut off CPC, even if it doesn’t need to be connected to anything - leave it there

    Check connections at 1st fitting - it’s gotta be something simple :mad:

    Above are just the muttering of a diy’er so let’s see - good luck :)
     
  4. Pollowick

    Pollowick Screwfix Select

    Also be wary of the loading on the dimmer. It may be a 250 or 400W dimmer however that does not mean you can run 250/400W of LEDs of it.

    A basic rule of thumb I was taught by a dimmer designer and manufacturer was that when calculating loads you should consider an LED to have around 10x the actual power - so a 5W LED puts a 50W load on a dimmer. However, that has recently been modified for newer LEDs to around 7x or 8x.

    Just consider that when checking the loading.
     
  5. Bazza

    Bazza Screwfix Select

    What does your two-probe voltage tester read at the first faulty light fitting?
    Not got a voltage tester? Orf to Screwfix you go.
     
  6. oddbod2

    oddbod2 Member

    Pretty hard to go wrong with that TBH. As per Bazza a quick prod with a meter should reveal all.
    Sorry, but just as a thought, you did connect the lights in parallel (Each light connected across the live and neutral) didn't you? - Only the "daisy chain" bit made me wonder.
    Photo?
     
  7. Sparkielev

    Sparkielev Screwfix Select

    Don't buy a neon screwdriver
     
  8. PhilSo

    PhilSo Screwfix Select

    Cos they don't give off much light.
    :D:D:eek::D:D
     
    Sparkielev and oddbod2 like this.
  9. DIYDave.

    DIYDave. Screwfix Select


    My thoughts exactly as in post 3 :rolleyes: when he mentioned ‘daisy chained ‘

    Although if wired in series (by mistake) then they would either glow very dim or not at all. In this case, only the 1st light is working

    Gotta be something simple innit :mad:
     
  10. Sparkielev

    Sparkielev Screwfix Select

    Mind you buying one will be an improvement on what he has now
     
    PhilSo and oddbod2 like this.
  11. Pollowick

    Pollowick Screwfix Select


    C F U
     
    oddbod2 likes this.
  12. JP.

    JP. Screwfix Select

    What does ''daisy chain the lights mean''?
     
  13. PhilSo

    PhilSo Screwfix Select

    It's nearly Christmas
    :D:D:D:D:D:D:D
    PhilSo
    Hohoho
     
  14. Bazza

    Bazza Screwfix Select

    Bah, humbug:mad:
     

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