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Downlight Heat

Discussion in 'Electrics UK' started by bcfcjwb1, 18 Aug 2021.

  1. bcfcjwb1

    bcfcjwb1

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    Hi,

    I posted a question about the recommended wattage of LED bulbs recently and the answers made me check other fittings in the house!

    I've noticed that the Deta downlights in the bathroom get very hot. The bulb, holder and chrome facia are all affected. Is this normal for this type of product?

    One is fitted with a Megaman 4.5W GU10 LED bulb and the other with a Kosnic 6W GU10 LED bulb. A sticker on the unit says 40W max, plus no cool beam. Weirdly the unit with the 4.5W bulb seems to get hotter than the one containing the 6W bulb.

    Any advice gratefully received.
     
  2. bernardgreen

    bernardgreen

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    There are instances where a lamp holder rated at 40 Watts incandescent overheats when a much lower wattage LED lamp is used in the holder.

    This may be because :-

    In an incandescent lamp the majority of the heat produced in the filament is radiated into free space from the glass / quartz envelope and does not significantly heat the lamp holder

    In an LED the lamp's integral driver module is in the cavity of the screw or bayonet cap of the lamp. The heat from the driver heats the cap and the lamp holder is then heated by the heat passing from the cap.
     
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  4. bcfcjwb1

    bcfcjwb1

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    Thanks for that.

    I've no idea where to find the recommended wattage for LED bulbs for this fitting. The only thing I know is that they were only fitted 2 years ago.

    Does anyone know where I can find that information?
     
  5. ericmark

    ericmark

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    I have found there are many ways to control LED's, we call it a driver, the bit which turns AC to DC and controls the output, but it can be anything from a simple capacitor to a pulse width modulated integrated circuit used to limit current. I had a 4.8 watt 350 lumen GU10 in the kitchen, swapped for a 5 watt 500 lumen smart colour changing GU10, forget the smart capability, one is 73 lumen per watt the other 100 lumen per watt, so if not producing light it must produce heat.

    As to heat limit I don't know, but I can touch most LED packages but not grip many for any length of time. Never tested degs C.
     
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  7. bcfcjwb1

    bcfcjwb1

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    I can definitely touch anywhere on the unit when it's been on for a good while, but I wouldn't want to grip it for too long - although I could. This seems to match your experience so gives me confidence that it's within a normal range.

    Thanks for the advice.
     
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