Two q's about CFLs

[Higgs Boson]

In my garage, I have a fluorescent light -- the long kind with two "bulbs" -- nd two CFLs-- the spiral type.

Q #1: When I put on the garage lights, the fluorescent buzzes horribly. Today, it didn't buzz. I looked around and saw that one of the CFLs was out. I replaced it and the fluorescent buzzed again. What's the connection? Why did this happen?

Q #2: Is there a way to tell that a CFL is burned out? With an incandescent, you can tell by shaking it. But i had to screw that CFL into another lamp to make sure it really was burned out.

TIA for any help

HB

[Jeff Thies]

I really don't know. But with something screwy like that I'd be looking at the wiring, specifically the grounding.

Not really. They age and will produce less light at the end of their life. You can see the tubes darkening at the ends. It used to be you could tell when those dollar store CFLs went bad because they would catch fire.

Jeff

But i had to screw that CFL

[hrhofmann]

There are two ways CFLs die. One is the ends of the glass spiral tube darkening, as the filament vaporizes and deposits on the ends of the spiral. Eventually the light will fail to light because the filaments either open and don't heat up at all, or the filaments lose the ability to give off enough electrons to start the arc inside the tube. The second failure mode, all too common, is for the electronics to fail. When the electronics die, it can be a simple failure to light the CFL, or it can be more spectacular, ie, smoke and little flashes of light inside the base of the bulb where the electronics reside. The electronics tend to run hot because there is little space in the base of the CFL, and if the CFL is used in a very confined space, like upside down in a ceiling recessed light, the probablility of the more spectacular failure is increased.

[Iowna Uass]

I'll throw this at Q#1. Chances are, the CFL had a faulty diode or capacitor and was creating "noise" on your electrical circuit. That would be enough to cause an unfiltered device such as a flourescent fixture to buzz. Most electronics are have filters in the power supply to clean up line noise today. If you are old enough, you might remember when mom would be mixing a cake in the kitchen and you'd have fuzzy lines across the old Electrohome. That would be the same principle.

[Frank]

I've noticed that CFL's buzz too - some more than others. They can also be annoying.

One's I've had burn out, just dimmed down, losing light at ends.

[Higgs Boson]

OK in theory, but that would mean that the replacement CFL had the same problem. Statistically, not too likely?

I replaced the CFL because I didn't think I had the skill to trace possible problems with that fixture and/or extension cord, which plugs into the main outlet. Especially after the replacement CFL also seemed to cause buzzing in the fluorescent fixture.

But on second thought, that's no biggie, even for a non-tech, so I think I will replace those two elements and see what happens.

Another interesting experiment would be to remove bulbs from both CFLs and see if buzzing ends. Will report back for anyone interested.

Tx to all who responded.

HB

[Don Klipstein]

If each of the CFLs are pin-base ones with separate external ballasts, then the explanation is almost certainly a ballast that can be quieted by tightening its mounting. Slight chance the ballast needs to be replaced to shut it up - fair chance hard or inconvenient to do without replacing the fixture.

Fluorescents including CFLs usually have one end, sometimes both ends of their tubing, significantly blackened when they kick the bucket. Much less frequently, a small region of the glass tubing around the filament at one end cracks. Sometimes a plastic base or ballast housing has visible minor melting or minor scorching around one or both ends of the tubing. If you see this at one end and not both, then the usual cause is that the bulb has sung or is singing its swan song.

Sometimes a CFL with an integral electronic ballast will croak with ballast failure being either the cause of death, or ballast failure being caused by an early stage of the bulb going into a terminal condition. Then, the only sign that the CFL is dead is that it refuses to work.

[Higgs Boson]

Thanks for that tutorial on dead or moribund CFLs. Very helpful!

HB