LEDs over work bench.

Discussion in 'General Electronics Chat' started by markdem, Jan 14, 2015.

  1. markdem

    Thread Starter Member

    Jul 31, 2013
    Hi all,

    Not sure where else to ask this, so here will do I guess.

    Has anyone built a LED light fixture over there workbench? Question I have is how may LEDs did you use?
    I am planning on using Cree XM-L2 LEDs that have a output of about 1000 lumens, but not really knowing what that means makes it hard to decide how may I should have.

    I guess the best way is to test 1 or 2 and see how much light they pump out, but then I need to place 2 orders with the supplier.

    Any recommendations or ideas?

  2. #12


    Nov 30, 2010
    My box of 60 watt light bulbs is labeled 840 Lumens.
    I have two kinds of 75 watt outdoor light bulbs. The, "floodlight" is labeled 1130 Lumens and the, "spotlight" is labeled 1000 Lumens.

    ps, I have recommended that the moderators move your post to Chat or Projects. They will probably respond soon.
  3. KJ6EAD

    Senior Member

    Apr 30, 2011
    You're getting ahead of yourself a little and going in the wrong direction as well.

    Think about how brightly you want the work surface and objects on it illuminated. That surface illumination is called incident light and it's measured in units of lux. You can buy incident light meters fairly inexpensively if you want to get a number to match your perception of the right level of illumination. Once you have that number, save it for comparison to the calculated lux you can expect from any proposed light source.

    To calculate the lux level produced by a source, you need it's radiation angle, distance from the surface and lumen output. Put these into one of the many online calculators or look up the formula on Wikipedia to find out if your source will meet your requirements.

    Lux is a measure of incident light striking a surface while lumens are a measure of light transmitted from a source. Look up the Wikipedia article on "lumen" for the conversion formula.
  4. sirch2

    Well-Known Member

    Jan 21, 2013
    Rather than a few bright LEDs you should consider LED light strip, lots of LEDs in a self adhesive strip, usually runs on 12v. I think this would give a much more even light and does not blind if you look at it.
  5. markdem

    Thread Starter Member

    Jul 31, 2013
    Thanks guys.

    Sorry, maybe I should of the question clearer. The workbench is 2.4 meters long so there will be a strip of LEDs installed above.
    I don't really want to over think this one, I just wanted to know if anyone else has done something like this. I agree that using a PAR meter would be the best way to go but I really don't need to be that technical. I was thinking of using 12 LEDs, but I just don't know if this is too many or not.

    Thanks again.
  6. #12


    Nov 30, 2010
    I told you a 75 watt spotlight (old PAR outdoor light bulb) has the same lumens as your XM-L2 LED idea. This is so you can think about how many outdoor spotlights you would need to get the right amount of light. I think 3 or 4 would work well enough. If you want 12 LEDs you should choose smaller LEDs.
  7. ian field

    AAC Fanatic!

    Oct 27, 2012
    Apparently, the latest thing is LED replacements for florescent strip-light tubes.

    A fitting might still be able to get cheap - you have to strip out the ballast and rewire for the LED unit.