GU10 Fittings - Bulbs not working

Discussion in 'Electrics UK' started by Mac Sami, 3 Mar 2012.

  1. Mac Sami

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    New build apartment, around 4 - 5 years old.

    I have 4 x GU10 fittings in the kitchen which are controlled by a switch on a 4 x wall gang of switches (one switch turns all 4 x bulbs on or off, other switches are a dimmer for the living room area, switch for desk area and a 4th unknown switch).

    About 3 weeks ago one bulb blew, tripped lighting circuit at fuse box (happens with GU10 bulbs from time to time). Replaced bulb, didn't work. Replaced with another new bulb, still didn't work.

    About 2 weeks ago a second bulb blew, same as above - so 2 of the 4 aren't working.

    Fast forward to yesterday and third has now gone, same as above.

    On checking the the 4 x gang wall switch:
    - 2 x switches have brown and blue going to them (makes sense to me).
    - Third switch (kitchen) has blue, with brown being a short cable connected to same connection on fourth switch (which doesn't control anything)
    - Fourth switch in turn has blue and brown as well (but as above this switch doesn't switch anything on / off?)
    - I also have 4 x yellow/green going to a corner of the blanking plate (ground?)

    Image attached, from left to right:
    - 4th switch, unknown
    - 3rd switch, kitchen area
    - 2nd switch, desk area
    - 1st dimmer, living room area


    Two questions:
    1. Why would the bulbs stop working in the fashion described - what should I check for?
    2. Why on earth would the 3rd + 4th light switches be wired as described above?

    If this is a job above me please do say - would rather get an electrician in to get it put right.

    Any advice much appreciated.
     
  2. sparkiemike

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    A lot of the GU10 are only rated for 1000hours, so when one fails the others can follow soon after. (EDIT:) assuming they were installed at the same time you could expect them to fail at about the same time - if you have got 4/5 years out of them that is good!

    The designers must of intended for the 4th switch to control something, maybe undercabinet lighting, and never got connected for some reason. It looks like the cable from the 4th switch is suppling the live feed to the 3rd switch. Further testing with instruments would confirm it. There is probably a hiddend JB somewhere.
     
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  3. Mac Sami

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    The bulbs normally last between 6 months and a year, which is expected.

    What I don't understand is why 3 of the fittings no longer work, even when I put new bulbs in them. Are you saying it's normal for the fittings to need replacing?

    What concerns me about the fourth switch which I forgot to mention in my opening post is that you have the brown cable running from 3rd to 4th, but then both cables from 4th are brown.
     
  4. sparkiemike

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    You said the "bulbs" stopped working/blew. Are these bulbs on the same light fitting or are there 4 fittings? Are they downlighters ?
     
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  5. Mac Sami

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    There are 4 separate GU10 downlight fittings in the ceiling, controlled by a single light switch.

    Three of the fittings do not work. Initially one fitting did not work, then two fittings did not work, now three fittings do not work.

    Have replaced bulbs in said fittings but still no light.

    Fourth fitting does work however.
     
  6. Chri5

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    Are you puuting the correct bulbs in?

    Gu10's come in 240v direct mains and 12v via transformer,hence bulbs need to be the right sort..
     
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  7. Mac Sami

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    I'm using 240v GU10 50W bulbs.

    Fittings have 250v 100W printed on them.
     
  8. xr4x4

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    have you pulled the fitting out and checked the connections/lamp for burning?
     
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  9. sparkiemike

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  10. riveralt

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    Yes but are they the correct bulbs for the fitting - Sparkiemike pointed you in that direction with his link.
    There are two types of GU10 halogen lamps cool beam and aluminuim reflectors - putting a cool beam lamp in the wrong fitting will eventually cause damage to the lamp unit.
     
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  11. Mac Sami

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    Sorry for the continued obvious questions and statements:

    Fittings are JCC Lighting JC94002, with required lamp replacement being a GU10 50W aluminium reflector forward heat bulb.

    In the last couple of months, I've been fitting them with Philips GU10 50W Twistline halogen bulbs. Nothing on the box says if they are aluminium reflector or dichroic / cool beam - but is halogen = cool beam dichoric reflectors?

    If so, clearly it's my fault as I've unknowingly put the wrong bulbs in.
     
  12. riveralt

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    I am sure that Twistline energy saver halogen bulbs are aluminium reflectors so they are the correct lamps for your fitting.
    If only one of the lamps is working then that suggests one of two things.
    Each of the light fitting has developed a fault either through a loose or broken conductor in the terminal (either lamp or switch) or the ceramic lamp holder has broken. Highly unlikely for all three to go but you never know.

    Assuming no work has been conducted on the circuit then the other possibility - though very remote - is that the original circuit was incorrectly wired in series.
    Failing that you will need to dead test the circuit to establish that you have continuity throughout or live test to establish that you have 240v at each lamp. Do you own a multi-meter and do you know how to use it.
     
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  13. Mac Sami

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    I've got an electrician to come and look at the issue on Monday (I'm just not confident with electrics). Could be as simple as the fittings being faulty or as you say something more.

    Thanks for your advice and to everyone else who has contributed.
     
  14. ban-all-sheds

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    Can you get 12V GU10s?

    I thought that all ELV MR16 lamps had GX5.3 bases?
     
  15. SSOTN

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    True. MR16 are the 12v lamps.
     

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