The Workbench

Bizarre fluorescent light problem. Google no help. No guitar content.


Read carefully. I don't need a tutorial on changing ballasts. This is a very specific behavior.

We have a dozen or so fairly new 8-ft dual-tube fixtures, with electronic ballasts and the newer lights with molded ends that insert into spring-loaded sockets.

I've successfully replaced the ballasts in these, and the lights work properly - so my incompetence would not seem to be a factor.

The problem is with one fixture. Important to know: this fixture cannot be switched off, the lights burn all the time. Symptom was that one bulb was out. Replaced with known good new bulb, still nothing. Whether using the functional original bulb and a new bulb, or two new bulbs, here's the significant behavior:

One bulb in place, no light. Stick ONE end of the other bulb into its socket, and both bulbs (or only one bulb if one is bad) FLASH once - and that's it. Finish installing both bulbs, nothing lights. It doesn't matter which bulb is plugged in second, nor which end is plugged in - still, when the first end of the second bulb is plugged in, both bulbs light briefly and then go out.

Replaced the ballast - and EXACTLY the same behavior.

All wire-nut connections have been visually checked and tightened. We've inspected the sockets themselves, and the wires seem snugly inserted. The only clue is that the socket for one end of one bulb appears to have a light surface flash burn. Contacts have been cleaned, however, and the wire feels snug.

The ground wire (which connects to a screw into the housing of the fixture) seems tight. I have not loosened it to check that it's making good contact.

We know the fixture is getting electricity. We know the bulbs are good. Same behavior with either the original or a new ballast (and I have a hard time accepting that two ballasts would fail with exactly the same behavior).

The fact that the bulbs flash ONCE when the second one is connected at one end has to be a clue - but to what?

I only ask here because the GDP membership often answers non-guitar questions that the wider internet fails.


Short to Ground within the unit whereby threshold voltage goes below that needed to fire up the bulb(s)...possibly propagated by a momentary High Resistance?

A similar flash burn happened in our Laundry/Utility Room this past May....melted the end of the fixture beyond have the LED version.

That burn remnant is suspect beyond what you can see...


Swap tubes with another fixture that works. It could be the lamp connectors, it could be the tubes themselves. I'd replace the fixture and go to LED.


While not directly related to your issue, I recently had a situation where a light fixture in my closet was causing the circuit breaker to pop by just switching on the light. I investigated and found that it was one of those terrible compact fluorescent bulbs I forgot to replace. Replacing the CF bulb with a reliable LED fixed the problem.


It failed over about 6 weeks time, one final bulb change then "kaput".

What was odd is the burned and melted side was the good side until the total failure. It was the bulb position that is seen "On" in this photo that failed the two other bulbs before the shorting.

The unit had failed another bulb ~6 months earlier...


Like Wabash and Twang suggested, I'd go to LED on all the fixtures. I did that with two 2 foot fixtures in our bathroom that were problematic for a long time. First I tried the LEDs (from local home improvement store) that were supposed to be compatible with existing ballasts. Those didn't work. Then I got the type were you remove the ballast all together. They've been working great for a couple of years now!

Just looked up my old order.. Made by Lunera, sold by 1000 bulbs. Were $10.00 at the time.


Those “tombstone” sockets are the cheapest possible connectors. If there are any carbon traces just replace the whole fixture and convert to LED. I’m in that process right now. Get it right and you won’t ever mess with it again.


Does it use a starter, or starters?


Have you tried switching the breaker off, inserting the bulbs, then putting power back on?

Essentially using the breaker as a light switch...

If in that moment while inserting the second tube you are getting an odd response, resistive or otherwise, you might defeat it with everything in place.


Fluorescent tubes are as bad for your eyes as ear buds are for your ears.


I'd say it's because fluorescent lights are wrong.


Tim, just replace the darn thing. I've had baffling problems with the 6' fluorescent lights in my garage. Home Depot is probably the best option at this point. Perhaps you can save yourself anymore frustration, by safely storing the tubes, and getting yourself a new fixture.

EDIT : I replaced my garage fluorescent fixtures with LED's. I like the color of the light better, they're much safer, and they don't have that 110 cycle flicker. The LED's can last 10 years or more, depending on the amount of use.


Fluorescents still use a ton of electricity compared to LEDs, and they still generate a lot of heat like an incandescent, and aren't that much more efficient. I like what lx said---they're not good for your eyes. I personally find the 120Hz flicker annoying, as well as the blue/green color temps. The mercury in them isn't good for the environment either. I think that the issue you're having is due to the lamp connectors.

Seriously, just go LED. Chances are, once you do, you'll likely never have to replace them due to their longevity.


I have a fluorescent light horror story, that made me fear fluorescent tubes ever since :

About 25 years ago, I was working in a commercial print shop, that was in a warehouse type building. I had been retired from the Army (medical) and I was working on finishing my college degree in the evening, and running a large Heidelberg 4 color press during the day. The owner had just replaced the 10' fluorescent tubes, in the fixtures over my press. It was summer time (Phoenix), and I was wearing shorts and a tee shirt.

One of the tubes was cutting in and out, since being replaced. It suddenly fell 20 feet, from the ceiling, and exploded on the cement floor right behind me. It felt like a handful of wet sand hit me, and it blew glass from one end of shop to the other.

EDIT : OSHA ended up getting involved, due to the workers comp claim, and forced a cleanup of the entire facility, with industrial HEPA filter vacuum cleaners. Much of the the glass had powdered, due to force of the tube falling 20', and had settled all over the place. It was a respiratory hazard, that needed to be addressed fully.

The glass in fluorescent tubes, are coated inside with toxic phosphorus. It has an extremely irratating, buzzing feeling, when it is embedded in the skin. A doctor, at an urgent care facility, used a black light, and picked out all that he could, but my wife and I picked out pieces, that surfaced, over the next year.

During that year, my skin was buzzing and twitching. It felt really weird, and painful. Some of larger pieces caused wet skin lesions, until they resurfaced. Finally, most if not all, of the glass was extruded from my skin.

I've had a cautious fear of fluorescent tubes since then. Until recently, they were everywhere, and I am extremely cautious when disposing them, taking extreme care not to break them. I've been replacing every fluorescent tube and bulb in my house, with LED's, ever since they became available.

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