LED Tube Lights Randomly 'Dropping Out' under High Load Conditions

[kbuhagiar]

Hello Folks,

Earlier this year I converted all of the eight-foot fluorescent fixtures in the rear portion of my garage to no-ballast LED tubes (all ballasts removed and fixtured re-wired), sixteen tubes total installed on eight two-tube fixtures. Yesterday was the hottest day of the year in our neck of the woods, and we had all four AC units (two conventional and two mini-splits) going for a few hours in the afternoon. During that time, one or two of the LED tubes would randomly 'drop out' (go dark) for a few seconds, and then re-light. There doesn't appear to be any rhyme or reason to this, except that it only happened during high load conditions when all of the AC units were running at once.

All of the AC units are on separate circuits from the LED tubes, and out of all of the 16 tubes only five or six exhibited this behavior, all on separate fixtures. And, FWIW in the front portion of my garage I have sixteen four-foot fixtures, populated with thirty-two LED tubes, and not a single one of these ever flickered at all during the same high-load periods.

My research has indicated that the circuitry that drives LEDs can be sensitive to voltage fluctuations, and that the lower-quality units will exhibit this behavior more frequently. So my theory is the 8ft LED tubes I installed are of inferior quality and some of them are overly sensitive to voltage fluctuations. If so, is it just a matter of replacing the tubes with better-quality items? Or is there something inherent to an 8ft tube (as opposed to a 4ft tube) that would make it more susceptible to these variations?

Thanks in advance.

 

[BrandonV]

What brand tubes did you install?

**** LED driver circuitry is all too common these days.

 

[Chuckster in NJ]

Did you get any voltage readings?

 

[kbuhagiar]

I purchased the in-house brand ('PLT') from an online retailer (1000bulbs.com). And yes, it was the least expensive (by about half) of all of the available selections.

In an attempt to evaluate performance I first ordered a case of 10 (minimum quantity allowed), then rotated the entire batch on a 'test' fixture, for 72-hour periods, for a couple of weeks. (FYI 72 hours used to be our standard burn-in period when we purchased PBX electronics back when I was a telecommunications manager). All tubes performed flawlessly, and no problems were observed so I ordered another case.

In hindsight it perhaps wasn't the most exhaustive test platform; never thought about voltage fluctuations. Mea culpa, that's on me, I've already given myself 20 lashes with a wet noodle, lol.

So here we are now, and if purchasing higher-quality tubes is the solution, so be it. Lesson learned.
It would be nice, however, if I could get some kind of assurance that this problem will not occur with the higher-priced tubes...

 

[kbuhagiar]

Did you get any voltage readings?

Nope, haven't dug down that deeply yet.
The wiring in this house is robust and code-compliant and hasn't warranted any further investigation - yet.

 

[BrandonV]

Nice test procedure, but I would hope any light would last that long. The problem I find most of the time when I dissect a failed LED light is that the driver components are running hot, either thermally or in terms of the current they're passing. Compared to the datasheet, it's understandable why these things die prematurely. Sometimes, you see the manufacturer pushing the LEDs themselves. It's all penny-pinching. If manufacturers wanted these things to last, they could. See the video on Dubai lamps.

 

[Chuckster in NJ]

Nope, haven't dug down that deeply yet.
The wiring in this house is robust and code-compliant and hasn't warranted any further investigation - yet.

Need to take some voltage readings (while this is happening) to see if you may be a "victim" of low utility voltage.……. Very common problem during peak summer time cooling loads.

 

[kbuhagiar]

***UPDATE***

Took some preliminary voltage readings yesterday in the garage. During most of the day the voltage was a steady 121VAC, but during prime time (6-8PM), when the flickering is the most prominent, the average voltage dropped to around 108VAC, and sometimes dropped as low as 106VAC.

 

[kbuhagiar]

UPDATE UPDATE:

1) The local utility acknowledged problems, and replaced a splice close by, and that made a huge difference - no more dropouts!

2) I replaced one of the 3-way switches on the light circuit; after being on for a few minutes it would get really warm. Probably contributed to the problem as well.

 

[Death Row Dave]

I have 44 8 ft LED tubes in my shop , life expediency has been a total train wreck . Lighting is top shelf . They are way better than what I replaced , just not pleased with life of the LED