12v Downlighters

Discussion in 'Electricians' Talk' started by Keenbutgreen, Jan 28, 2004.

  1. Keenbutgreen

    Keenbutgreen New Member

    Sorry if this is a dump question.
    With 12v halogen lights that need individual transformers
    can you put more than 1 light on a transformer if it provides enough power. i.e. if you had a 35w lamp on 105w transformer could you connect 3 lights?

    I also wondered what a link bar is for which is provided with the lights?

    thanks for you help

    KBG
     
  2. Kirby Castle

    Kirby Castle New Member

    In essence, yes - they need to be wired in parallel.

    ...but...

    why do you say "lights that need individual transformers"?

    It kinda rings alarm bells especially when you talk about the "link bar"

    where did you get the lights from?
     
  3. Keenbutgreen

    Keenbutgreen New Member

    I'am looking at the lights on TLC and they say buy transformers seperately. They also say that some lights come with a Bridge and Connector for low voltage lights which to me looks like it links to something.
    So does each light not need its own transformer?

    thanks for your help
    KBG
     
  4. ban-all-sheds

    ban-all-sheds New Member

    This bridge and connector?:

    http://www.tlc-direct.co.uk/Images/Products/size3/QLBDG.JPG

    It looks to me like it's main purpose is mechanical, it certainly doesn't look as though it provides an electrical connection from 1 lamp to the next.

    As to how many transformers - 1:1 is preferable, because sometimes the multiple bulb ones rely on all the bulbs working to get the voltage right, so when one blows the voltage to the rest goes up. I don't know if this applies to the TLC ones, but I do know that they are very good at answering technical questions about their products, so ask them what they would advise.

    Also, if you do fit multiple lamps to one transformer, remember to do the calculations for cable size, as the current is high with 12V bulbs.
     
  5. Keenbutgreen

    Keenbutgreen New Member

    thank you
    I'll ask TLC. The only reason I was asking about multi lights on one transformer was that I am putting in about 30 downlighters in new extension with 5 rooms and if I have to buy a transformer for every one it makes it very expensive.
    Any ideas would be good.

    KBG
     
  6. eyetry

    eyetry New Member

    single or double storey? Hoods & flower pots? Lets not go there again.

    :)
     
  7. Damocles

    Damocles New Member

    Don't like to spoil the decor, and maybe you dont care about saving the planet, but all that lot starts to get a bit heavy in power consumption? sounds like 6 bulbs per room on average, so guess id do 1 or 2 transformers each room. Would depend on fixing convenience and stuff as well as what loading you intend. Also nice if the transformers have a bit of space to dissipate heat
     
  8. Keenbutgreen

    Keenbutgreen New Member

    This is going in a bungalow so room above in loft for heat to escape. I am lighting a new kitchen, dining room, corridors, bedrooms and utility room etc thats why a lot of lights.
    So am I right in thinking say I had 6 35w 12v downlighters in kitchen I could use 2x 105w transformers to power 3 lights each?
    This would save a lot of expense and heat from 3 transformers as opposed to 6.


    KBG
     
  9. sparkydude

    sparkydude New Member

    Hi, right yes you can use a 105va transformer to power 3 lights, but you will find that most of that size are designed for lights mounted close to each other and the instructions will say a maximum length of cable which will probably be not long enough to serve the three points you need to run. Also if you were trying to run the three of the one ****** then you would have to keep the cables to each light the same length to avoid different voltages at each light and thus the lamps would have a subtle colour difference and some would appear to be brighter the nearer they are to the transformer and dimm the further away you go . this is due to the volt drop in the cable .Whenever doing LV downlights i always use individual trannys as at least when they go wrong its easy to change the one instead of the whole transformer affecting more lights. make sure you buy a reasonable brand too, IBL that are sold by newey and eyres and others are the best, and they come with a five year guarantee too

    hope this helps

    Nick
     
  10. finjon

    finjon New Member

    If the lamps are replaced with bigger lamps (50W), then the trafo will be overloaded.
     
  11. Keenbutgreen

    Keenbutgreen New Member

    thanks for your help.

    What is the advantage in using LV downlighters as opposed to ordinary spotlights wired in a lighting circuit.
    It sounds as if this would be a lot easier all round.
    Your thoughts would be appreciated.


    thanks KBG
     
  12. sparkydude

    sparkydude New Member

    Hi, the advantage with low voltage is the brightness and normally the length of time the lamp lasts. A mains voltage halogen downlighter is a lot dimmer and the lamps are much more expensive to buy for good quality ones. the choice is up to you , but i would always go for low voltage in a kitchen as the light output is far superior and whiter than tungsten lamps.

    hope this helps


    Nick
     
  13. Keenbutgreen

    Keenbutgreen New Member

    Again really helpful

    I think I may use the 12v Lights in the kitchen & 2 Bathrooms as you recommend but use ordinary 240v spots for the other areas.

    Thanks
    KBG
     
  14. Essential

    Essential New Member

    12v spots are economical to run. Surprisingly, group transformers generally cost the same as lots of little ones. Perhaps this has something to do with eceonomy of scale because many more little ones are made. Little transformers shouldn't generate much heat individually so, if they are spread about, the heat should dissipate more easily.
     

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