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Thread: LED T8 fixture/tube compatibility

  1. #1
    Flashaholic
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    Default LED T8 fixture/tube compatibility

    The market for 4-ft T8 LED replacement tubes seems to be getting less predictable as far as compatibility with
    fluorescent tube fixtures, even those meant for LED tubes.

    I just bought a dual-tube 4-foot T8 LED shop-light for good price, $42 plus tax, including two tubes; this despite packaging
    almost devoid of specs including luminosity, tube life, and type of ballast. 22W tubes are replaceable, whereas a
    lot of new LED T8-type strips or "fixtures" have non-replaceble LEDs, in other words toss the whole thing when the
    LEDs go; which goes against my grain. I am not confident of all claims for 30k-50k hours of life.

    I tried other T8 LED tubes including Philips, Honeywell, and Globe brands; none worked in this fixture. The
    manufacturer seems to have created a captive market for their replacements. Fixture label warms that its has been
    modified for LED tubes and to not use regular fluorescents. It works fine with supplied tubes, so will keep it, though
    this kind of restriction seems heading in the wrong direction.

    Previously I bought a regular fixture with "instant-start" electronic ballast but it did not work with any of the
    above LED tubes. I decided to put regular fluorescents in (works fine), then donate it (if I only could, all second-
    hand shops are closed and not even taking donations).

    Yet another cheap ceiling fixture seems to like LED tubes, but only works when both are installed and working.

    So I guess this strengthens the case for direct-wire tubes; in fact some now are dual-mode, albeit a bit
    more expensive. Is it correct to say that these tubes are internally ballasted and if used in a ballasted fixture,
    the two in series should work i.e. limit current to the lowest limit of the two? I so that would give overall
    lower efficiency.

    Dave

  2. #2

    Default Re: LED T8 fixture/tube compatibility

    Does the tubes have any information on them like voltage and current draw? The way I see it there could be 3 varieties of these LED tubes.
    1)works using ballast voltage
    2)works using wall (mains) voltage
    3)works using a power supply
    In case 1 or 2 you either need to do nothing but swap tubes out or have to bypass the ballast. In case 2 the power supply must match the tubes needs. Not sure of what circuitry is in these different types of tubes or how they are wired.
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  3. #3
    Flashaholic
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    Default Re: LED T8 fixture/tube compatibility

    Fixture was found to be direct-wire, verified it works with another direct-wire tube. Not at all unhappy,
    now have one of these which can take other replacement tubes. Disappointed by lack of specs and documentation,
    the direct-wire could be deduced from some clues:

    (1) Fixture label warned against use with regular fluorescent tubes.

    (2) Fixture indicated "power supply" end of tube (not clearly indicated on tubes themselves). Tubes plugged in one
    way worked, turned around the other they did not; indicating powering from one end.

    (3) Buzzed out fixture (power off, switch on) and found dc continuity from plug to sockets.

    (4) Decided to open fixture (two screws) and found only wire, switch, and sockets wired at one end.

    Tubes are labelled with power (22W) and voltage/current (100-277v, 245mA) but no luminous info or indication of lifetime.
    CCT looks about 4000K by side-side with another tube. Not a problem for some people though I prefer 5000K for
    work areas.

    I am also happy to not pay full price (40% off) as fixture does not need a ballast, and has less/simpler internal wiring, and by
    all rights ought to be cheaper than a ballasted one, but that's not always how things work...


    Dave

  4. #4

    Default Re: LED T8 fixture/tube compatibility

    Sounds like you got a good deal then. I don't have any LED tube lights yet as I'm using up all my fluorescent stockpile before dealing with upgrading I figure by that time the market will have ironed out all the bugs with LED technology but I have gleaned a lot of information. I looked at swapping tubes in old fluorescent fixtures vs buying LED fixtures and overall cost and think I may go with the tube swap as they are easily replaceable vs when an LED fixture goes bad you have to replace the whole thing and the cost for a tube or two is lower than a whole fixture is. I didn't know that they had the power in some lights/fixtures in one end of the tube but it makes sense to do it that way easier to make and less things to go wrong but does require a new keystone (I think that is what the ends are called).
    My big issue with these tube swaps is longevity and output vs tubes and efficiency gain. I have a tube that I pulled out of a dumpster that one end is gone and it has a line of chip LEDs and they best chip efficiency that I've seen (cheap chinese) is about 100-120 lumens/watt and most likely you would see around 80-100 lumens/watt. Never having seen any of these tube swaps in use I have no comparison.
    I did scavenge a 2x4 foot LED fixture (drop in grid) from a dumpster that after tinkering found out that a wire pulled loose from the power supply I repaired that and hung it in my garage replacing a 4 foot 80 watt fluoro twin tube fixture and both fixtures were about the same wattage but the LED one looked about 50% brighter I found that I could see better in a dark area of the garage that I didn't need to turn on the other fluoro fixtures. I guess my problem is being a flashaholic and living alone I often don't use ceiling lights to do quick things so my bulbs rarely burn out and I have a bunch of spares and a bunch of incans that I swapped out flouros for still.
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  5. #5
    *Flashaholic* PhotonWrangler's Avatar
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    Default Re: LED T8 fixture/tube compatibility

    I bought a T8 LED replacement lamp that was rated for magnetic and electronic ballasts. I had a suitably rated electronic ballast sitting around so I wired it up to try it out. I applied power and it went kapow.

    At this point I completely distrust the marketing language on the lamp's packaging.

  6. #6

    Default Re: LED T8 fixture/tube compatibility

    I was looking for a smaller LED lamp replacement for a table lamp but the smallest I found was a 15 watt 18 inch tube.
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  7. #7
    Flashaholic
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    Default Re: LED T8 fixture/tube compatibility

    Quote Originally Posted by Lynx_Arc View Post
    Sounds like you got a good deal then. I don't have any LED tube lights yet as I'm using up all my fluorescent stockpile before dealing with upgrading I figure by that time the market will have ironed out all the bugs with LED technology but I have gleaned a lot of information. I looked at swapping tubes in old fluorescent fixtures vs buying LED fixtures and overall cost and think I may go with the tube swap as they are easily replaceable vs when an LED fixture goes bad you have to replace the whole thing and the cost for a tube or two is lower than a whole fixture is. I didn't know that they had the power in some lights/fixtures in one end of the tube but it makes sense to do it that way easier to make and less things to go wrong but does require a new keystone (I think that is what the ends are called).

    My big issue with these tube swaps is longevity and output vs tubes and efficiency gain. I have a tube that I pulled out of a dumpster that one end is gone and it has a line of chip LEDs and they best chip efficiency that I've seen (cheap chinese) is about 100-120 lumens/watt and most likely you would see around 80-100 lumens/watt. Never having seen any of these tube swaps in use I have no comparison.
    I'd say if you are happy with linear fluorescents and not in a hurry, why not use them up. Typical efficacy seems to
    be 75 lumens/watt e.g. 32W/2400 lumens which is not at all bad compared to incans. Unless running lots of tubes and/or
    long run times, probably will not have any profound cost impacts.

    Current LED tubes spec. at least 100 lumens/watt, ~120 more typical. e.g. Philips 17W/2100 lumen.

    Small downside of self-ballasted LED tubes is the extra circuitry transferred to the throw-away part; not sure how
    much extra is involved. This is somewhat similar to early CFLs prior to electronic ballasts (~30 years ago) which used
    pluggable tubes with separate iron-core bases (weighed up to a pound), so ballast was re-usable.

    Upside is LED tubes can (but not always) have plastic shell v. thin glass, and of course no mercury. If/when you want
    to retrofit, suggest you obtain 1-2 tubes to check compatibility with existing fixtures.

    Dave

  8. #8

    Default Re: LED T8 fixture/tube compatibility

    I figure I have many years of replacement fluoros. The only LED lights I want for now is 150+ watt screw in bulbs for the living room especially a high output 3 way would be very nice but alas if you want 150 watts you have to hunt like mad for a CFL or incan.
    What would be excellent is a circular LED "tube" for some of my torchiere lamps it would have to do as well as a 300 watt incan bulb or better though.
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  9. #9
    Flashaholic
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    Default Re: LED T8 fixture/tube compatibility

    Quote Originally Posted by Lynx_Arc View Post
    I figure I have many years of replacement fluoros. The only LED lights I want for now is 150+ watt screw in bulbs for the living room especially a high output 3 way would be very nice but alas if you want 150 watts you have to hunt like mad for a CFL or incan. What would be excellent is a circular LED "tube" for some of my torchiere lamps it would have to do as well as a 300 watt incan bulb or better though.
    Philips now has a 200W eq. LED E26 bulb, rather large (A35), non-dimmable, and pricey (at HD here is >CDN$20). I picked up a LED tri-light 50/100/150W eq. which like most these days has a small base, but my older floor lamp uses the larger Mogul base. Base adapters exist but ones I have found locally have only two contacts, so lose the tri-light capability; I think it will come on at 100W eq. The adapters are $10-$12 each, should be something better out there. I just like stuff OTS where possible. Dave
    Last edited by Dave_H; 06-01-2020 at 09:13 AM.

  10. #10

    Default Re: LED T8 fixture/tube compatibility

    Quote Originally Posted by Dave_H View Post
    Philips now has a 200W eq. LED E26 bulb, rather large (A35), non-dimmable, and pricey (at HD here is >CDN$20). I picked up a LED tri-light 50/100/150W eq. which like most these days has a small base, but my older floor lamp uses the larger Mogul base. Base adapters exist but ones I have found locally have only two contacts, so lose the tri-light capability; I think it will come on at 100W eq. The adapters are $10-$12 each, should be something better out there. I just like stuff OTS where possible. Dave
    I've seen 300 watt (equiv) fluoro bulbs but the screw base was larger (maybe A35?) so not useful to me and LED bulbs that aren't standard size setsup you are better going to LED native designs to get away from socket heat sinking limititation and cost.
    I think LED lighting needs to come up with worldwide standards for sockets and power supplies connectors so you can swap them into existing fixtures easily upgrading and replacing the bulbs etc without replacing the fixtures. Today retrofitting lights and fixtures is too difficult to source parts and LEDs at decent prices to warrant them over buying new ones.
    I would love to see a 3 way lamp that is 15/100/300 equiv watts in LED format but probably not doable as it would require some sophisticated electronics to handle the switching as normal 3-way bulbs are just adding filaments together not sure how CFL 3-ways do it.
    I would also like to see an LED setup that could replace a dimmable torchiere halogen lamp setup so that you could have 10 lumens on low and 3000-5000 or so on high using LEDs.
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  11. #11
    *Flashaholic* idleprocess's Avatar
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    Default Re: LED T8 fixture/tube compatibility

    Quote Originally Posted by PhotonWrangler View Post
    I bought a T8 LED replacement lamp that was rated for magnetic and electronic ballasts. I had a suitably rated electronic ballast sitting around so I wired it up to try it out. I applied power and it went kapow.

    At this point I completely distrust the marketing language on the lamp's packaging.
    I recall hearing that there are three major flavors of electronic ballast topology and that building a LED tube that's compatible with all three is ... impractical. Mains-powered removes this ambiguity, however those tend to require non-shunted tombstones (sockets) which are not standard for most floro tubes thus the retrofit process is more involved than simply cutting the existing tombstones to mains power. As such I would recommend going with AC-powered tubes since most applications are for utilitarian applications where replacing the fixture isn't cost-effective but you'd also like to get out of the ~annual relamping cycle until such time as you replace the fixture with something purpose-built that has the performance and durability to justify the upfront cost.
    I apologize that this letter is so long; I did not have time to write a short letter

  12. #12

    Default Re: LED T8 fixture/tube compatibility

    I would say skip the tubes that require a fluoro ballast as when the ballast goes out you have to either replace the tubes without one or buy another ballast and also stepping voltage up with a ballast then down again for LED powering reduces efficiency, increases heat also and could possibly do interesting things if the ballast starts to act up.
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    Psalm 112:4 Light shines in the darkness for the godly. They are generous, compassionate, and righteous.

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