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Thread: Linear LED Replacements are Junk - UC Davis Study

  1. #11
    Join Date
    Jul 2005
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    LA basin, CA
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    1,626
    The UC Davis study focused on LED-tube retrofits, or linear-LED lamp replacement performance, not warranty periods / lumen maintenance.

    My pensioner clients are always adverse to changing light bulbs in ceiling fixtures, especially florescent pin lamps, much less do they enjoy paying someone else to do it. So, LED tube/lamp retrofits are never sold to them, since typical cord & plug LED-shop lights sport 5-year warranty's, with no replacement lamps, or pin-sockets to fuss with.

    My trouble is the listed instructions that come with all new 4ft LED Shop lights, with a cord & plug.

    Regardless of lumen output, opening every packaged brand in Big-Box stores, to inspect instructions, yield the same restrictions.

    Cord & Plug, Linear LED shop lights all require open air circulation, prohibit confined spaces, or surface mounting. They require suspended methods for air gaps to cool the fixture housing that contains the LED driver.

    These instructions prohibit use in kitchen & bath confined-ceiling soffits, without air circulation, above most acrylic coverings, or any surface mounts. The only suitable garage/shops with proper air circulation also require chain suspension, and j-boxes converted to receptacles for the cord & plug.

    Installing per listing, and proper use still seems to require T8 fixtures for most linear-lighting maintenance, in confined or surface-mounted spaces. I doubt any linear LED's can accomplish a 5-year warranty in such spaces.
    Roger Ramjet NoFixNoPay

  2. #12
    Join Date
    Mar 2003
    Location
    Vermont
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    1,094
    I don't get it.....

    what sort of metric is being used as a comparison here?

    ~RJ~

  3. #13
    Join Date
    Apr 2009
    Location
    Williamsburg, VA
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    4,378
    Quote Originally Posted by Ravenvalor View Post
    You don't have to register to read the study and there is a link to it in the article. Here is the link to the study.

    https://cltc.ucdavis.edu/sites/defau...02017-11-1.pdf

    The study says that linear LED lamps are not as bright as linear fluorescent. They tested the 4' T8.
    There was one exception where LED out performed fluorescent though. In a wrap around fixture the trapped heat reduces the lumens of the fluorescent thus making it less brighter than the LED but only in the type of LED that has a separate driver and not integral with the lamp. It does not necessarily have to be a lamp that fits into a socket I believe. I imagine it can be some sort of a strip or a lamp that connects to a driver in the fixture. (Note: driver and not fluorescent ballast). Furthermore they say the driver has to be specifically designed for and listed for the lamp and vice versa.
    I have been looking for this type of system and cannot find it. Does anyone know where I may find a well made system like this?

    Thanks,
    In every single case where we are replacing bulbs in offices, the secretaries, receptionists, data entry, accounting, etc (office workers) do not want the amount of light that new 4' fluorescents emit. In many cases where there are more than 2 bulbs per fixture, we've seen where the 3rd and 4th bulb have been removed altogether. Thus, LEDs not being as bright as them is actually a plus. Color (Kelvin), matched bulbs (no mixing 3500K with 4000K) and no flicker are much much more important.

    As for finding replacements that use a separate driver, yes, they exist, they are called Type C. Here is a link that is much less wordy than the study which may be of some use to you and the conversation:

    http://www.premierltg.com/should-you...8-led-tubes-2/

    I dont have the time nor inclination at the moment to read a 70 page study, but some things I glanced early raised some eyebrows:

    "The study also emphatically stated that TLEDs should be used only with the specific driver equipment recommended by the manufacturer because running them on different drivers resulted in severely degraded performance."

    Well, duh. Just like running a fluorescent on the wrong ballast, or mismatching color of tubes, or replacing tubes one at a time vs a set in multi-lamp fixtures results in severely degraded performance does.

    Linear replacements are often a compromise because the LED replacements are seldom made to work with a specific fixture that was made for fluorescent tubes. Comparing them is apples to oranges. I bet LED fare much better when the entire fixture is replaced, and the comparison is all new vs all new, not all new vs replacement. The only comparison at that point is cost and time to ROI.

    Provided the time to ROI is less than how long you plan on using the building, and there are funds to go to LED, there is really no argument for not doing it.

    In a small office, changing out 20 troffers is a day or two work (which can be done off-hours), and much easier than say a grocery store (open 24/7) where there may be 25 200' rows of fluorescent lights 20' in the air, overtop of shelves and merchandise.
    Electricians do it until it Hertz!

  4. #14
    Join Date
    Oct 2007
    Location
    New Jersey
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    5,013
    Quote Originally Posted by GoldDigger View Post
    One interesting point that I had not previously given enough attention to is the more strictly downward direction of light from the LED tubes.
    I had seen it as a potential efficiency boost because the diffuse reflection from the backing surface of the luminaire caused a wastage of some light.
    What I had not considered was the balancing advantage of the distributed light source of the reflector makes for a less glaring light source with less of a point light source and therefore less harsh shadowing. For some work environments that is a big factor.
    Higher directionality in a light source leads to islands of light surrounded by darkness, like a checkerboard. This can be particularly problematic for retrofits where you can't adjust the number of fixtures. You deal with this all the time for stage lighting.

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