Why are my shop lights burning out?

I have four seperate 4' shoplight fixtures in my garage with 40 watt tubes in them. It seems about once a month I have to replace one of the tubes. They only seem to last a few months and they're usually only run a few hours a day. Why are they burning out so fast?! I'm really getting tired of replacing bulbs.

Suggest you do a websearch using the keywords flourescent and repair. There are several sites that have good info and make it easy to figure out - but you need the exact symptoms you are getting. Depends on why you are changing bulbs - orange glow, blackened ends, one side doesn't come on... Same bulb or different one each time? Buzzing, sizzling sounds heard... Really works out to one of three simple things - bad ballast, bad end connectors, or bad bulbs. The symptoms tell you what to try.

beyond just recommending that you replace the ballast, also make sure that you really have 40 watt tubes you're putting in. They sell the 32 (35? something like that) watt tubes for commercial lighting fixtures and while they look identical to the 40 watt tubes, they burn out in a hurry just like you say in a residential 40 watt fixture. These are always sitting right next to the regular t12 bulbs at home depot and look the same if you dont examine the fine print.

I usually use the 40 watt kitchen/bath tubes, so I'm pretty sure they're for home use. It doesn't seem to be one particular fixture that's doing it. They usually get black on one end and keep flickering on and off. What does the black on the ends mean?

I might just replace them all with 42 watt compact fluorescents...since they come with a 7 year warranty.

Check the following:

1. Are the lamps and the ballast matched? Simple check there, see if the text on the lamps matches that written on the ballast. Make sure that you're not using the fancy "energy saving" lamps as someone mentioned earlier. They are designed to work as traditional lamps of a slightly higher wattage - but they DO need dedicated ballasts.

2A. Are you using electronic or magnetic ballasts? If they're magnetic types, do they make a lot of noise? Sometimes that can be an indication that they're on their last legs.

2B. Do the lamps strike up easily from cold, or do they take a long time to start? If they tend to flicker a lot initially, you could have one of two things:

a) Borderline ballast voltage. I had one of these a while back, and it was brand new. The ballast, generally if it's a cheap one, cannot actually supply a high enough voltage to either strike or maintain the arc - therefore the lamp may light initally, then go out again - and keep doing this. Mine would usually strike properly *eventually* after flickering for about a minute. That thing used to eat tubes at...well, about the rate you're talking about! All of them still strike up just fine in a decent fixture, but were effectively dead in that one. The only real solution here is to replace the ballast. In my case I replaced it with one from a CFL actually! And two years on, is still working fine - with one of the "dead" lamps! ...same one I put in there two years ago!

b) Dodgy starter. Quite simple. Replace it. Worth trying anyway, they cost all of about $1. Make sure they're correctly rated though. Using a high wattage starter in a low wattage fixture (and vice-versa) can cause problems. I wholly reccomend the electronic pulse starters (the green ones). They do actually improve lamp life. And will leave a dead lamp off, rather than having it flash annoyingly and potentially overheating the ballast.

3. Check your line voltage. If it's in your garage, it could be an extension to the houses original wiring, as such, might not be of the same quality. I the voltage is either too high or love, it could be causing problems.

4. Check wiring. Many fluorescent fixtures will behave oddly if they aren't grounded correctly. The metal frame/reflector is often part of the starting system, providing a capacitive route to ground, assisting in the initial ionisation of the mercury vapour/argon gas fill in the tube.

If that don't sort it, replace the ballast or fixture.

..Failing that, replace the electrician!

Hope that helps.

Are these Lights of America fixtures? If so that's the problem-they're just a crappy design that burns out bulbs. Home Depot sells some nice shoplights for $8.95 with electronic ballasts. They can take any common 4' tube (T8 32W, T12 25W, T12 34W, T12 40W).

It's been my experience that if you have a shoplight, you need to use shoplight bulbs. The shoplight bulbs are cheaper and have a shorter life, but still should last for years.

I tried the more expensive regular tubes in a shoplight once and they caused problems almost immediately.

I have 8 T8 double-lamp 32W electronic ballast striplight fixtures hanging in my basement, and I have replaced only one tube in three years - and I think it failed prematurely. The rest of the tubes look new (no darkening of the ends) and have very good lumen maintenance (compared to the new tube I just installed).

If you decide to do away with the "shoplights" I suggest going with something T8 and electronically ballasted. The T8 lights, while slightly more expensive, have a higher luminous efficacy than the T12 lamps, better CRI (especially compared to shoplights!), and while only 32W, still put out more lumens than a 40W T12 lamp. The electronic ballasts are instant-on, no flicker at startup and no 120Hz flicker during operation, for reduced eyestrain.

I would reccomend against substituting tubes in any fixture, this will lead to nothing but problems. If the ballast is rated for two 40W T12 lamps, use two 40W T12 lamps. Even with the electronic ballasts rated for 32W T8 lamps, installing a 34W or 40W T12 lamp will result in less than satisfactory results. Typically under-driving a lamp will result in less efficient operation, at the very least.

The blackening of the ends is a result of a phenomenon known as sputtering, where the electrons coming off the electrodes literally rip metal atoms off and then deposit them on the walls of the tube. This is a result of excessive operating temperature, too much current, or a defect in the filament construction. I have seen some "rapid start electronic" ballasts that keep the filaments heated during normal operation (you can even see them glow orange) and this will accelerate the sputtering and reduce the life of the lamp. The best kind of ballasts are the electronic variety that tie the two pins of each end of the lamp together treating it as a cold-cathode lamp rather than a hot-cathode lamp (so no damaging filament heating takes place). In fact, the hot-filament startup of a magnetic rapid-start or "starter type" ballast is the most life-shortening part of a fluorescent tube's operation.

JSWrightOC said:

The blackening of the ends is a result of a phenomenon known as sputtering, where the electrons coming off the electrodes literally rip metal atoms off and then deposit them on the walls of the tube. This is a result of excessive operating temperature, too much current, or a defect in the filament construction. I have seen some "rapid start electronic" ballasts that keep the filaments heated during normal operation (you can even see them glow orange) and this will accelerate the sputtering and reduce the life of the lamp. The best kind of ballasts are the electronic variety that tie the two pins of each end of the lamp together treating it as a cold-cathode lamp rather than a hot-cathode lamp (so no damaging filament heating takes place). In fact, the hot-filament startup of a magnetic rapid-start or "starter type" ballast is the most life-shortening part of a fluorescent tube's operation.

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correct on most points.
preheating is less stressful than the cold striking most cheap electronic ballast use.
better ones are a programmed start.its the electronic version of a preheat.
starting causes more wear and tear to the cathode coating than running.
and to the op
cheap shoplites are hard on tubes due to the way they start.
i junked some liteway and loa ones that were killing tubes in less than 6 months.
and i used good tubes.ge chroma 50's.
not cheap to replace needlessly every 6 months.