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Max wattage for LED bulbs in new light fittings

Discussion in 'Electrics UK' started by darrenbgray, 8 Nov 2020.

  1. darrenbgray

    darrenbgray

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    Hi - I have just fitted a triple spotlight and it says Max 3.5w GU10 LED build required.

    I have a whole bunch of 4.6w bulbs, will they be OK to use? Its hard to imagine an extra watt per bulb is going to be an issue?
     
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  3. winston1

    winston1

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    Don’t look at it as 1 watt, look at it as a 33% overload and make your decision.
     
  4. JohnW2

    JohnW2

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    Mathematically true.

    However, I have to wonder how (even if one wanted to!) one could manufacture a light fitting which could not tolerate more than a 3.5W lamp/bulb - particularly given that it might well not look appreciably different from one which, in days of old, would have said that it could take a 40W or 60W (very inefficient) incandescent lamp/bulb!
     
  5. darrenbgray

    darrenbgray

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    Yep, that's what I couldn't understand. The numbers are so small compared to even halogen bulbs I can't see what the issue would be.
     
  6. SUNRAY

    SUNRAY

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    They may be less efficient but the cost of LEDs and their more frequent replacement is very similar to the cost of running old fashioned stuff. Add the manufacturing carbon and the horrible chemicals used...
     
  7. JohnW2

    JohnW2

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    Welly, I was only talking about the heat generation, but ...

    ... "more frequent replacement" (of LEDs as compared with incandescents) - where did that come from? LEDs certainly tend to last less long than many people expect (particularly those who don't understand what "median life expectancy" means) but nevertheless far longer than incandescents. I have a very large number of lamps/bulbs in my (large) house, and I literally used to buy incandescent bulbs (quite frequently) in batches of 50 or 100. These days I very occasionally buy a dozen LEDs.

    As for (financial) cost-saving, experiences will obviously vary. In my kitchen, I inherited a rather unusual situation which involved a total of 16 candle bulbs. They were original 25W incandescents (hence 400W total) but are now 3W LEDs (48W total). That 352W different would, for 6 hours a day and, say 14p/kWh, equate to a difference if about £108/year. That would buy a good few LEDs (I never buy other than cheap ones) and, in any event. most last for well over a year - and that's just one room. Environmental etc. costs are a different issue.

    Kind Regards, John
     
  8. 333rocky333

    333rocky333

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    Im thinking it may be more to protect the bulb than the fitting, especially with a shade fitted, leds do generate some heat and the electronics in the bulb base i would quess would take a lot less heat lto damage than it would to damage the fitting or wiring, as you imply has not likely changed since the halogen era.
    I wonder if they even still use Heat resistant wires to the holders.
    I recently had some lights tripping in a shop, on taking off the globe shade the G9 led had got so hot it was a blob of molten plastic, the ceramic holder was fine.
     
  9. JohnW2

    JohnW2

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    Maybe, but I think you're perhaps being fairly generous in assuming that the manufacturers of the fittings are particularly bothered about how long lamps/bulbs will last in their fittings!

    Kind Regards, John
     
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  11. JohnW2

    JohnW2

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    In addition to what I recently wrote, it occurs to me that, unless the fitting in question is, say, particularly poorly ventilated, there is no real reason why the base of an LED of any wattage should get hotter in one fitting than another - so if an LED >3.5W were deemed to be unsuitable for use in one fitting, it would probably be unsuitable for use in most fittings, wouldn't it?!

    Kind Regards, John
     
  12. bsr

    bsr

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    I think it'll be fine. I reckons it used to say "max 35W" back when it was designed for halogen and someone just converted it to the equivalent led rating without thinking.
     
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  13. Harry Bloomfield

    Harry Bloomfield

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    I would have absolutely no concerns about using any 'normal' LED lamp in any open fitting, with a reasonably free, cooling air flow.
     
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  14. darrenbgray

    darrenbgray

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    Thank you every one for your views. It is an open fitting as it is IP20 and the instructions were a but rubbish as the box said 3.5 and the piece of paper inside said 3 so I agree that not a lot of thought has gone into it ;)
     
  15. winston1

    winston1

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    Just yet another example of manufacturers instructions being wrong then!
     
  16. Munroist

    Munroist

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    I thought LEDs lasted for about ever.

    I replaced 8 x 60w halogen with 8 x 6.5w LEDs in our kitchen 7 years ago. (I kept the 5 year guarantee that come with the LEDs as I thought they would never last, hence I know how long they have been in). All 8 are still working.

    As to cost, lets say 14p per kwh and on 4 hours a day

    8 x 60w = 480 w = 1.92kwh per day = £686 over 7 years

    8 * 6.5w = 52w = 0.208kwh per day = £75.40 over 7 years

    therefor saving of £611 so far.
    and more importantly just over 1 tonne of CO² saved

    the LEDs were £9 each back in Jan 2014, think they are about £3 each now.

    And that is just for one room !
     
    Last edited: 9 Nov 2020
  17. winston1

    winston1

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    But you have not considered the CO2 generated by their manufacturer compared with halogens!
     
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