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How to Retrofit LED T8 Tube Light?

Discussion in 'Electrics UK' started by devs, 26 Nov 2018.

  1. devs

    devs

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    Hi guys can someone please explain how I rewire this to accept LED bulbs?

    Many thanks,

    Devs.

    IMG_0547.JPG
     
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  3. flameport

    flameport

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    Depends on the tube, but that electronic ballast inside will need to be removed and wires connected directly to the tube sockets at the ends.

    In reality it's cheaper and easier to sling that fitting away and buy a dedicated LED one.
     
  4. winston1

    winston1

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    It may be easier but I can't see how a whole fitting is cheaper than a tube.
     
  5. SFK

    SFK

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  6. ericmark

    ericmark

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    The normal way with LED is all pins in series with a special fuse instead of the starter, the problem is some one may fit a fluorescent back in to the fitting so needs the fuse just in case, and one end of LED tube is a short circuit the other end is power in, so wiring in series means it can be fitted either way around.

    However in the main LED tubes are half the lumen output to the tube it replaces, so unless over sized to start with, may need to change to a double tube fitting, also compared with fluorescent with electronic ballast LED is claimed to have same life, and only marginal more efficient, LED approx 100 lumen per watt, fluorescent with electronic ballast 94 lumen per watt, and the LED tube is far more expensive.

    I swapped one in my house because old tube was fat 65W and now only 58W made so would need a new ballast, so LED seemed a quick fix, however in spite of house hardly being used, had to go and live with mother, within 2 years the LED tube had failed, this is still the only 230 volt LED lamp I have had fail, had to replace with another LED tube as it had been rewired removing ballast.

    Wish now I had done the job proper and fitted a HF ballast as 58W tube, dropping from 5800 lumen to 2400 lumen is a huge drop in light output.
     
  7. SFK

    SFK

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    Eric,
    Completely agree, LED tubes are not yet comparable to Florescent tubes in terms of light output.
    I tend to keep an eye on the changing numbers, and depending on application sometimes change florescent for florescent and sometimes change florescent for LED.
    (And sometimes simply get 600x600 LED panels).

    For a 5ft tube I watch the following parameters (these are correct as of today):
    Florescent: £3.30, 58W, 5,200lm, = 89lm/W or 1,575lm/£
    LED: £10.00, 24W, 3,350lm, = 139lm/W or 335lm/£

    LED tubes are now producing more light per Watt (although at a narrow wavelength), but LED tubes still cost more per lm.
    And as a direct replacement, you do need 1.5 x LED tubes for every florescent tube (5,200lm / 3,350lm).

    SFK
     
  8. Lower

    Lower

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    Don't forget that fluorescent tubes output light through 360 degrees and LED 's only output light through 120 degrees. You get the benefit of the reflected light that comes out the back side of a fluorescent, but you can't just compare lumens for lumen.

    When we specify LED tubes instead of fluorescents we allow 1.25 LED tubes for every fluorescent and that is proving to give a similar lux level in the end installation.
     
  9. SFK

    SFK

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    Lower,
    Completely agree, and also agree with the "you can't just compare lumens for lumen", for the additional reason that LEDs have a very narrow wavelength that changes their illumination profile when compared to LED tubes.

    Interesting to hear that you allow for 1.25 LED tubes for every fluorescent tube, compared to my 1.5 LED tubes for every fluorescent tube. That actually suggests that you slightly happier with light output of LED tubes than I am.

    SFK
     
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  11. devs

    devs

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    Thanks a lot guys for all the help. If I can make use of the old fittings rather than slinging them I'd feel better about that.

    I've just had a go at rewiring but unable to get them to light. Attached are photos of my wiring along with the new bulb. I notice that the new bulb comes with a starter but assumed that this is optional if ness as my fitting does not have a starter point. Thanks again, Devs.

    IMG_7454.JPG IMG_7810.JPG IMG_7168.JPG
     
  12. SFK

    SFK

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    Devs
    The wiring to the tubes looks correct, L to one side and N to other side of the LED tubes (of which there are two).
    You are correct that you do not need their starter (which in this case is simply a wire to join the two connections together and to replace a real starter).

    BUT Very small image, it looks as if you have cut the Earth (which has to be connected to middle choc block) and the Live should be to the right choc block with the fuse. Do not use wired like this, it is v dangerous as it makes all the metal live.

    Have you put LED tube in correct way around? You might have four options.

    By the way, I notice you have not read the instructions that came with the LED tube :>
    Could you take a photo of the wiring in that?

    SFK
     
    Last edited: 30 Nov 2018
  13. Lower

    Lower

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    The lighting we use is designed to light a specific size enclosure with white walls and roof so the results of different types of lights are directly measurable.

    We have our own design of LED board that we use as our primary lighting system nowadays but it costs more than LED tubes so we do fit LED tubes periodically. The output of the LED tubes vary drastically depending on manufacturer and price so that 1.25 figure is based on a decent quality tube as well.
     
  14. flameport

    flameport

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    Your wiring is wrong and dangerous.

    You have line connected to the earth terminal, which is also connected to the metal case via the metal tab on the lower side of the connector.

    fatal_wiring.jpg

    The correct terminals left to right are N - E - L,

    L being the one with the fuse in it.
     
  15. SFK

    SFK

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    Flameport - dam! and well spotted.
    Dev, connecting Live to the outer metal of the light could/should have easily killed you or someone else.
    Hopefully you will respond and are not now hurt.
    SFK
     
  16. AndyPRK

    AndyPRK

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    whoops.

    So why can't an energizer LED tube (and supplied LED starter/bypass) be fitted? THey are around £20 each though.
     
  17. SFK

    SFK

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    Andy,
    The Ballast in Dev's lamp does not have a Florescent Starter, so cannot use the "LED starter/bypass" as no-where to fit it.
    And as the Ballast is not realy needed and yo have to re-wire anyway, normally best to remove ballast as makes slightly more efficient.
    SFK
     
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