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General: Lumen confusion

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  1.  
    • CommentAuthorRex
    • CommentTimeAug 30th 2025
     
    What ho one and ll,

    I have two units with three 10W (900 lumens) LED E27 bulbs in each, pointing at the sloping ceiling to reflect light into the bathroom. The original purchase was a pack of six with the standard LED lifespan for the rest of my life.

    Of course, one has failed!!! And trying to buy a replacement is confusing. The bathroom is bright with only five bulbs at the moment, but the current empty hole or one bulb not matching is visually, rinky-dinky.

    I either buy another pack of six (but don't need five extra) or a pair. The 10W replacements have a lumen value of generally around 1055, while 9W bulbs are around 805 lumens.

    But will either 1055 (10W) or 805 (9W) lumens but noticeably different?

    I would of course, like them all to be the same brightness.

    Thanks
    •  
      CommentAuthordjh
    • CommentTimeAug 31st 2025
     
    So buy a pack of six and replace all the lamps in one fitting. Keep the two old but good ones as spares as well as three new ones.
  3.  
    Perhaps more important than the lumens of the light bulb is the colour temperature of the light. In all probability a new light bulb will show a different colour light compared with the old. (even the same colour temp. will probably have a difference between the old and new)
    If you want to avoid light differences it would be best to replace all the bulbs as a set and use the old good bulbs in places where there is only one bulb.
    •  
      CommentAuthordjh
    • CommentTimeAug 31st 2025
     
    Posted By: Peter_in_HungaryIf you want to avoid light differences it would be best to replace all the bulbs as a set and use the old good bulbs in places where there is only one bulb.
    Yes. If the difference between the two sets is annoying then it is clearly possible to use all six I suggested to purchase at once and discard all the old ones. I had an odd effect when I replaced two LED lamps in a fitting with 'identical' ones of a different colour (as a temporary measure). I expected the colours not to match, of course, but was really surprised to discover a strange flicker that occurs when they are turned on. I suppose that the different colours have slightly different start-up times that results in the effect.
  5.  
    6000 lumens / 60W is a lot of light, and electricity!

    Typical level is 300 lumens per m2 of floor area, for a bathroom.

    Also, LED efficiency has improved far beyond what you're being quoted, should be looking for 150-200 lumens per watt nowadays for A-rated lamps, so around 4W per 800 lumen lamp.

    Is it time to update the fittings for fewer and lower-power lamps? Some of the best have integrated LEDs rather than a screw-in 'bulb', because that dissipates heat better than having the LED driver crammed into the 27mm lamp base.

    Remember also the bathroom zoning rules, shouldn't be able to reach any 230V screw fittings while standing in the bath or shower, 12V SELV is ok.
    • CommentAuthorRex
    • CommentTimeAug 31st 2025
     
    Gentlemen,

    Thanks for the input. The colour temp is 2700k but you are correct that any replacement single bulb, listed as 2700k is likely obviously not the same as the current installed. And that would be as annoying as a single bulb being brighter / dimmer.

    So perhaps best to bite the bullet and replace all six.

    Why do i need six? When I built, these units had compact florescent bulbs which where certainly not as bright as LED bulbs. I just replaced the 10W florescent with 10W LED; and yes, there is certainly more than sufficient light.

    To answer the other point, the bathroom has a kinda 'vaulted' ceiling and the fittings are well beyond a reachable distance. They are probably around 1 meter beyond my highest stretch and need a three step hop-up to change or clean. The BCO was quite happy.
  7.  
    Wot WillInAberdeen said +1

    6 x 10W led bulbs is a lot of light, probably 50% more than CFLs and in addition LEDs don't fade over time as much as CFLs

    So perhaps consider using 6W LEDs
  8.  
    CFLs were 50 lumens per Watt, whereas LEDs are now pushing 200 lumens per Watt, so 4x brighter. (And CFLs fade as PiH said)

    So if there were originally 10W CFLs, then the correct LED replacement would be 2 or 3 W. (Edit: this would be called 'equivalent to a 40W incandescent'.)

    Something like this, Philips 2.3W 485 lumens?
    https://amzn.eu/d/gDv2esX
    Other makes and styles available ofc.
    • CommentAuthorRex
    • CommentTimeSep 1st 2025
     
    The fittings are Ikea's finest and did not come with bulbs. During the build, and to hit the environmental numbers, I bought 11W CFL bulbs. X years ago, I replaced them with the wattage equivalent (10W) LED. Yes, they are sooo much better in every respect and I probably don't need that amount of light, but....

    We are now so used to a bright bathroom, dropping to a lower brightness may not go down too well. Part of the reason for originally, so much light is that the units are mounted on a vertical section, and although some of the light inevitably emits downwards, the lights are pointed to the sloping ceiling to provide a soft, reflected light rather than a hard, shadowy light.

    Will get a pack of 800 lumen bulbs and see how it goes. If bought from Amazon, I cna return them if necessary.
    •  
      CommentAuthordjh
    • CommentTimeSep 1st 2025
     
    You could always try just installing two new lamps into each fitting and see if that is bright enough.
    • CommentAuthorRex
    • CommentTime1 day ago
     
    As a final note, I bought a set (6) of China's finest, 8W, 900 lumen and 3000K LED bulbs. Slightly different from the originals (10W, 900 lm, 2700K) and tried just one in the empty slot.

    It looks the same as the other five, so now I have five new bulbs for future use.

    Gentlemen, as usual, thanks for the suggestions

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