4 ft. White Fluorescent Strip Light Fixture with 2 T8 Light Sockets

JAS

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I have a four foot fluorescent fixture in my basement that holds a pair of T8 tubes. One is bad. Should i:


-Replace just the bad one and replace the other one when it goes out, or


-Replace both at the same time under the theory that if one went bad the other one may be going out soon, also.


I know some businesses would/do replace both at once, but my understanding is that it is more because of the cost of labor than anything else.


And, truth be known, I only have a few new four foot T8 tubes remaining at home. I have decided that when other fluorescent tubes go out I will switch to LED.
 

PhotonWrangler

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If it was me, I'd replace both of them since the other one probably has the sane number of hours on it and will fail soon anyway. Down the road I would either get LED retrofit tubes for the fixture or swap out the fixture with something designed for LED lamps or strips.
 

mattheww50

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In most industrial environments all fluorescents are replaced when they reach somewhere around 75% of design life. By that point they are seriously down in lumen output, and a fair number have already failed. I have looked into LED replacements for T8's and have not been impressed. None of them have anywhere near the lumen output of a high quality T8 (you can get 3000+ lumens out of the best lamps), and none them have CRI's as high as the best T8 Fluorescents. The day may come when this is no longer true, but for the moment it isn't. The other problem is that there are at least 3 different starter/ballast configurations in service today (which one largely depends on age of the fixture) and I have yet to see a product that runs on all of them. I used to work for Home Depot and we probably took about 1/4 of all of the LED Fluorescent replacements back. They were not compatible with the ballast/starter configuration the customer had. We knew when we sold them that a lot of them would come back.
 

idleprocess

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Removing the ballast entirely is the way to go with LED floro replacement tubes. Did a few hundred at the local Makerspace using some cheap tubes from a local supplier and the only failures I'm aware of were in a fixture that ate T12, then T8 ballasts and tubes regularly.

CRI was comparable to the bulk tubes we were buying. Output was less, however we weren't depending on the dirty matte white "reflective" surface on the backside of the fixture to deliver a fraction of half of those lumens; subjectively they were the same as new floros on the T8 retrofits we used to do. They had some flicker, but we were mostly replacing >20yr old magnetic ballasts so it's not like flicker was anything new.

It's more work to remove the ballast, but it removes a superfluous component from the path that you don't want anyway. You're probably not going to see 10 years of continuous use out of them, but at ~$10 each now with DLC/UL ratings that's not as important as it was when they were markedly more expensive.
 
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Dave_H

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Interesting to find that T8 LED tubes are now available in "hybrid" design which claims to work for both
PnP and direct-wire fixtures...wonder how they manage to do it.

Dave
 

Dave_H

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......
The other problem is that there are at least 3 different starter/ballast configurations in service today (which one largely depends on age of the fixture) and I have yet to see a product that runs on all of them. I used to work for Home Depot and we probably took about 1/4 of all of the LED Fluorescent replacements back. They were not compatible with the ballast/starter configuration the customer had. We knew when we sold them that a lot of them would come back.

Interesting that store sales people seem mostly unaware of this situation. Things are not made better by lack of info on packaging.

One one low-end 2-tube fixture, there is no mention anywhere of the type of ballast...rapid start, instant-start, electronic? I assume most new are electronic.

I still want to find detail of how fixture/tube connections work, no plans to adopt direct-wire, various reasons.

Dave
 
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idleprocess

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Interesting to find that T8 LED tubes are now available in "hybrid" design which claims to work for both
PnP and direct-wire fixtures...wonder how they manage to do it.

Dave

Most 2-ended direct-wire models I've looked at did this 2 years ago. Guessing that it's not difficult to fake out the ballast when your design is rated for 110-277VAC, just difficult to do so reliably across the spectrum of ballast topologies.
 

PhotonWrangler

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Faking out the ballast makes me wonder what the actual steps are. Firing up a fluorescent tube is an electrically violent event, often involving several strong spikes of voltage to strike the arc, then a lower voltage and regulated current to maintain it.
 

idleprocess

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Aye. Arc strike is a kilovolt event as best I recall. Guessing that ballast-compatible lamps shorten this greatly by conducting that spike immediately so the ballast switches to maintenance operation in shorter order than normal.
 
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