Kitchen light keeps going bad !!!


Hello all, I replaced my kitchen "cheapo" fluorescent light last year with a nicer model that uses F32T8 style bulbs.
After about 4 months, one of the bulbs went bad. These are supposed to last 5 years. I replaced it. Then the other went bad 3-4 months later. I went through this a few times.
I tried different bulbs from different brands and stores. No luck. I thought maybe the ballast went bad so I bought new, good quality, and replaced that. I did that this past September and now one of the bulbs is going bad again!
The wiring is fine, all the connections are tight and in correct order. No signs of burning or charring.
What is going on? How can I fix this? Now I don't even care about the light...as much as solving my curiosity!!! lol
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Seems like you've been through this too many times for it to be coincidental.
Turn on the lamps for a few hours and then remove the diffuser to see if there's a build up of heat in the fitting. It could be warm enough to cause premature failures without being suffiently hot to show any scorch or similar marks.
I guess you can check for moisture at the same time although I wouldn't expect humidity to be a factor.
Remove and reinstall the tube that is showing signs of failure. Does that help? Perhaps you have some corrosion or other contaminent building up on the contacts?
Also, is the fitting installed close to a fan, or other source of vibration? That will certainly shorten the life.
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Brian wrote:

Make sure your ground is good. Fluorescent lights are said to be prone to failure if not grounded properly. Not sure, just propogating a rumor I heard.
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Check your manual and check for stickers on your fixture. Often, these kind of fixtures are very picky on what type of tube they use. Pay attention to any requirement for a "rapid start" tube, etc. Sometimes they can be hard to find because they sell out quick.
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Other than heat I can't understand what would shorten their life so much. I have small under the counter fluorescent lamps that only last 6 months or so. While buying more at HD somebody else was buying the same bulb, I asked him if he had the same problem. Yep. I replaced two small fixtures under one cabinet with a longer one (takes a 34" long bulb). On the box GE claims will last 15,000 hours. Time will tell.

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Brian wrote:

. Sounds like defective lamps! I have just bought ten T8s, mixture of two manuafacturers. No problems do far. But btw i tried a couple of T8s in an older fixture which uses the older non-electronic ballast and while they worked the ballast overheated after a while and became intermittent. The newer fixtures which use the T8s have electronic ballasts.
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I have the same issue with florescent lamps, and in particular with circle line, and compact fluorescents. The rating on lamp life is based on continuous burn hours but once you starts turning the fixtures on and off, it will kill the fluorescents. Remember years ago before the energy crises, you see floors all lit up 24/7 in high rise buildings - that is for maintenance so they don't have to change out the lamps as often. My lamps, like the ones in the hallways and bathrooms where its switched a lot, may last only six months with a burn life of only 10 or so hours. So at some point, incandescent lamps will be much more energy efficient than fluorescents if you take the life-cycle energy cost into account including the energy to manufacture the lamps.
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Actually, lamp manufacturers generally rate fluorescent lamp life based on three hour starts (3 hours on and 20 minutes off), in accordance with IES LM-40-1987 testing standards.
Lamp life can be extended by increasing burn cycles but perhaps not as much as you might expect. For example, a standard GE F32T8 has a rated life of 20,000 hours based on 3 hours per start and a 24,000 hour life expectancy at 12 hours per start.
Source: http://www.gelighting.com/na/business_lighting/education_resources/literature_library/product_brochures/downloads/product/85067_linear_fluo.pdf
A typical CFL would have a rated service life of anywhere from 6,000 to 15,000 hours, based on the aforementioned 3 hour testing cycle. By comparison, a standard incandescent bulb has a rated life of just 1,000 hours.
A 100-watt incandescent bulb would consume approximately 100 kWh over its normal life. At $0.10 per kWh, a consumer would expect to pay $10.00 in electricity costs to operate this bulb. An equivalent 23-watt CFL would consume 23 kWh over this same timeframe, for a net savings of $7.70.
A good quality, name brand CFL now costs as little as $2.00 to $3.00 when bought in multi-packs. Given that the cost of energy in the manufacture and distribution of these bulbs would be a small fraction of its retail price, even if a CFL were to fail at one-tenth its rated life (i.e., 1,000 hours versus 10,000 hours), the value of energy it would have saved would still exceed that of its purchase price.
In any event, I would expect a CFL with a rated life of 10,000 hours to be capable of withstanding over 3,000 starts (i.e., 3 hours per start x 3,333 starts = 9,999 hours). If you were to turn this CFL on and off an average of ten times per day, it should (presumably) continue to provide service for close to a full year.
If you turn lights on and off more frequently than this, you might consider a "cold cathode" CFL. These CFLs can be turned on and off as frequently as you wish, with no material impact on lamp life.
See: http://www.tcpi.com/PDF/495_01116%20Revision%20CC%20Globe%20SS.pdf
Cheers, Paul
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wrote:

According to my Sylvania catalogue, a standard "general purpose" 60-watt A19 bulb has a rated life of 1,000 hours and its 100-watt A19 counterpart is rated at 750 hours. Sylvania's "double life" bulbs have a life expectancy of between 1,500 to 3,000 hours depending upon the wattage. The trade-off in the case of longer life incandescent bubs is lower light output (fewer lumens per watt).
[...snip...]

If you have duty cycles as short as five seconds and you turn your lights on and off an average of twenty times a day, you should stick with a halogen or incandescent bulb. Cold cathode CFLs are another option but as Don points out, these lamps are currently available only at the lower end of the wattage scale. A 5-watt TCP CC-CFL produces just 230 lumens or about the same amount of light as a standard 25-watt incandescent. In a six bulb bathroom vanity light that may not be a problem but for a single socket stairwell fixture it would be a rather poor choice.
Cheers, Paul
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I can see that others have been down this road. I also have a small "under the counter" light that fails regularly too. The bulbs last for maybe 6 months at most. They are the T F8 style bulbs. I think they are 9 or 10 inches. I am going to replace the lights completely and go with what I had before. They may not have been energy savers, but they sure lasted for years before I had to change them. That alone is going to save me a lot of money at the rate I am currently spending on bulbs, ballasts, etc.
Thanks everyone for all the great advice. I appreciate it. Great group!
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Hi Brian,
For what it's worth, I installed six 20-watt T4 fluorescent cabinet lights about four and a half years ago. The fixture over the kitchen sink is left on six to eight hours a day, while the others might average perhaps two or three. So far, I've had to replace just one tube (the one over the kitchen sink). The lamps have a rated life of 10,000 hours and that seems to be in line with my own experience.
The fixtures are very similar to the ones shown here: http://www.brodwax.com/SleekT4.htm
I did remove the plastic sleeve/diffuser so that these fixtures operate at a lower temperature and I'm hoping this will help extend the life of both the bulb and ballast (heat being the major killer of all things electronic).
Cheers, Paul
On 15 Dec 2006 08:25:48 -0800, "Brian"

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