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Poor reliability of AC powered LEDs

Discussion in 'Electrics UK' started by tuck1s, 2 May 2021.

  1. tuck1s

    tuck1s

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    Daughter has replaced most of the bulbs in their house with LEDs, initially cheap no-name ones from https://cpc.farnell.com/. Many of these are the "candle" style ones in fittings that take 3 bulbs.

    We saw a lot of early life failures. Thinking that "you get what you pay for" we've gradually replaced these with Philips equivalents https://cpc.farnell.com/philips-lighting/45479400/lamp-led-candle-nd-5-5-40w-e14/dp/LP10214.
    These have been better, but still seeing more early life failures (less than 1 year old) than I'd expect.

    I suspect candle style bulbs are less good at dissipating heat than larger bulb styles, but this is still surprising.

    I wonder if the mains supply to their house is perhaps over-voltage at times?
    I assume there's not much they could do about this, if it's within spec (is that 230v -6% + 10%)?

    Presumably all neighbours on the same substation feed would see the same (or similar). Worth getting her to ask around in her street and see if anyone else has experienced the same?

    Is it worth getting a data-logger to record the voltage over time, just plugged into a socket, and see if that's a factor?
     
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  3. flameport

    flameport

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    Does the consumer unit have surge protection installed?
     
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  4. tuck1s

    tuck1s

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    Good question. It's a fairly primitive-looking MEM one from c. 1995 when the property was built. Will look up the model when we (finally) can visit her.
     
  5. Jackrae

    Jackrae

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    The question about surge protection raises an interesting point.

    What's gone wrong with the UK's generation and distribution system in recent times that suggests 'surge protection' is becoming a commonplace 'essential'.
     
  6. echoes

    echoes

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    They fail by design. The LEDs are driven at a current which results in them running bright, hot, and having a short life.
     
  7. bernardgreen

    bernardgreen

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    I would say that nothing has gone wrong in the distribution system, the perceived need for 'surge protection' is there because modern mains operated equipment is much more prone to being damaged by transients than older equipment is.
     
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  8. bernardgreen

    bernardgreen

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    That is a definite truth for a lot of LED lamps.
     
  9. echoes

    echoes

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    I'm doing an experiment at home with sainsburys led lamps.
    I'm changing the resistor which determines the drive current, and I'm going to see how much longer they last being run cooler (but slightly less bright).
     
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  11. JohnD

    JohnD

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    without even looking at the house, I would guess the chances are at least 100,000 to one against.
     
  12. AndyPRK

    AndyPRK

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    From this, I would say its 100% No

     
  13. reds42

    reds42

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    Need to get yourself some philips Dubai lamps, there are more LEDs run at lower current which improves efficiency and will last longer.

     
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  14. echoes

    echoes

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    Are these generally available?
     
  15. reds42

    reds42

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    I don't think they are, which is a shame as they are LED lamps built properly. Suppose theres less money to be made for manufacturers selling lamps that last rather than need constantly replacing...
     
  16. JohnW2

    JohnW2

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    Indeed, but, at least as far as I am concerned, it remains very much a "perceived need". I have yet to find anything approaching 'chapter and verse about this', and I have personally experienced so few failures of 'modern mains operated equipment' (of which I have always had a lot) over the years/decades (few, if any, of which failures were probably due to supply transients) that I do not perceive it (at least at present) as an issue of any potential concern to me personally.

    Kind Regards, John
     
  17. JohnW2

    JohnW2

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    If personal anecdotes mean anything .... I have a lot (probably 50+) LED candle bulbs, many in 3- or 5-bulb fittings such as you describe.

    When, in days of old, they were all 25W incandescent bulbs, I usually had to replace some at least every week. With the LEDs, it is now generally 'one every few months'. Until recently, I had not marked the bulbs with 'date of installation', so I'm not sure how long they have been lasting, but I would guess that the average (of those which do not fail very early) is at least 2-3 years, often more.

    Over the years, I've experimented with a range of brands/prices, and have found that expensive 'respected brand' ones are at least as bad as cheapo ones - to the extent that for a long time I have only bought the "cheapest and nastiest" I can find!

    I have occasionally had problems with 'bad batches' (all failing very early), and for that reason now buy in small quantities from multiple sources.

    Some 'early failures' will always occur with things like this, and one has to be careful not to be misled in one's expectations by quoted 'life expectancies'. The figures quoted are usually median survival times. That means that, of a large number, an 'expected life expectancy' of, say, 10,000 hours, means that half will survive for at least 10,000 hours, and half will fail in less than 10,000 hours. However, such a statistic tells one nothing about survival in those which do not make it to 10,000 hours - for example, if half failed within the first 100 hours but the other half lasted for at least 10,000 hours, the median life expectancy would still be quoted at "10,000 hours".
    Nothing is impossible, but I would say that was an extremely unlikely explanation. One would hope that anything sold in this country would work satisfactorily with the maximum permitted supply voltage (as you indicate, 253V). In any event, as you go on to say ...
    As you say, that would be the obvious way of ascertaining whether there was any local supply issue (which I very much doubt).
    As above, I would personally think that would be a waste of time/effort/money. Furthermore, such monitoring would not detect the transients/surges which (predictably!) others have mentioned in response to you - but again (for what it's worth), I personally think it pretty unlikely that such would be the cause of your experiences.

    Kind Regards, John
     
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