Fluorescent tube lighting and its penchant for orneriness

I (and maybe you) work in a building lit by fixtures of paired fluorescent tube lights. They generally work well, until one day they don’t. Trouble begins when you flip on the switch and one of the pair of lamps flickers, or refuses to light at all. You get up on a chair and try jiggling and tapping and twisting the bulb - this sometimes revives it, but even if comes back to life, chances are good it will be dark again the next time you try to cold start it.

I always wondered if the spring-loaded contacts that hold these tubes in place are to blame - that they are simply a poor design, and some kind of clip that got a firmer grip on the ends of the bulb would prevent these problems. Still, if it were that easy then why wasn’t this done years ago? What other factors cause lamps to fail? How long should they last? What drives me (and maybe you) crazy is not that they go bad, but that they seem to fail in stages, and you always think you ought to be able to squeeze more life out of them. Incandescent bulbs don’t do this - they just go pip, then you go looking for some members of your favorite ethnic group to change them.

that lamp type has a number of actions occurring in the tube and different factors affect each. there are a couple of different versions of that lamp type as well.

they can last long enough to build up a huge amount of dust on the bulb, they can go their full lifetime which is longer than an incandescent bulb.

the glass of the bulb is thin, stronger springs would cause people to break the bulbs during installing or uninstalling which is a danger.

There’s your problem. You have a faulty understanding of their failure modes which leads to a faulty expectation.

Traditional long-tube flourescents last far longer than incandescents. They fail not by going suddenly to dead black, but by failing to operate perfectly. Once they fail to oerate perfectly, they’ve lived out their long useful life. The correct response to a flickering or slow-starting tube is to put it in the garbage, not to mistakenly try to squeeze more life out of something which has already failed.

Flourescents should be replaced while they are still working. As they age, they produce less and less light and take more voltage to light. An additional problems is that eventually the contacts oxidize producing resistance. Wiggling the bulb scrapes a little oxide off allowing the bulb to light. Letting the bulbs go is false economy when it leads to the ballasts failing. You can buy many bulbs for what you have to pay for a ballast, let alone if you have to pay an electrician to instal it.

Note, old flourescent bulbs should go to a recycling center, not in the garbage.

Flourescents have had a good run, but the LED is coming. I am actually working under LED’s some now. Somebody donated some to the center where I volunteer sometimes. They were retrofitted into the flourescent fixtures. The ballasts were removed and long tubes with many LED’s installed. I will see if the same problems of oxidizing contacts develop. The fixtures are fairly new, about 7-8 years.

Older fluorescent fixtures have three primary components: ballast, starter, and bulb(s). As mentioned by others, the bulbs don’t last forever; they need to be regularly changed. When I have a problem with an older fluorescent fixture, I will usually change out the bulbs first. If that doesn’t work, nothing is lost - I’ll simply save the older bulbs and then focus my attention on the ballast and starter.

Newer fluorescent fixtures only have two primary components: an electronic ballast and bulb(s). The electronic ballasts are pretty reliable, so most problems can usually be resolved by replacing the bulbs. Also note that many newer fluorescent fixtures require the fixture’s metal reflector to be connected to ground. Failure to connect it to ground may cause the fixture to behave in an erratic manner.

Correct me if I am wrong, but aren’t fluorescent bulbs more efficient than white LEDs (power vs. lumens)?

I am looking forward to LEDs. Do they flicker?

I think a design improvement for fluorescents would be to give up trying to light after a while, the flickering is more irritating than an unlit bulb.

white ones that produce light using phosphors don’t.

From http://www.pewclimate.org/technology/factsheet/LightingEfficiency

''A CFL produces between 50-70 lumens per watt

LEDs produce in the range of 27-150 lumens per watt, depending on the type of LED.‘’

The LED’s I have worked under don’t seem to flicker.

I have wired LED’s to house current with nothing in the circuit but a resistor and not seen any flicker even with the current being interrupted 60 times a second.

The “150 lumens/watt” for LEDs is a typo; they accidently included low-pressure sodium lights. According to their cite,

Straight Tube Fluorescent: 30-110 lumens/watt
CFL: 50-70 lumens/watt
Cool White LEDs: 60-92 lumens/watt
Warm White LEDs: 27-54 lumens/watt

So while there are white LEDs that are more efficient than fluorescent lamps, the opposite is also true. I also wonder if they are including the power supply for the LED lamps when they measure the power.

I suspect this site is using the power delivered to the socket, http://www.energysavers.gov/your_home/lighting_daylighting/index.cfm/mytopic=11975

The best LEDs exceed this. For instance, Cree reports 208 lm/W in the lab.

Their shipping XM-L exceeds 100 lm/W, even for the warm white config. With a low enough driving current, you can even hit 150 lm/W for cool white.

Did you rectify it, otherwise it should be 30 times a second, with it off half the time?

An LED does rectify one half wave AC current. And the half wave where the polarity is wrong comes 60 times a second. I am not sure if it is the LED or my vision, but the light appears to stay on constantly.