Ballast or tubes in the kitchen fixture ?


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Old 01-19-16, 10:13 PM
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Ballast or tubes in the kitchen fixture ?

Hello we have a couple of overhead fluorescent light tubes in the kitchen ceiling. We are replacing the tubes almost every month. My question could it be the ballast or is it just the tubes which are going bad ?
 
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Old 01-19-16, 10:18 PM
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It could be a mismatch between the tubes and the ballast. The newer type fluorescent tubes require higher starting voltage and work best on electronic ballasts.

With the disappearance of the old style T-12 lamps it makes good sense to upgrade fixtures to new electronic ballasts and T-8 tubes. The T-8's will fit in the same sockets as the older T-12 tubes.
 
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Old 01-19-16, 11:02 PM
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Or switch to LED tubes. Costs about the same as two new tubes and a T-8 ballast. (Approximately $35 for two tubes from Amazon and you won't need a ballast.)
 
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Old 01-19-16, 11:13 PM
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I haven't got the opportunity to check out the LED tubes. I have to get some.
Unfortunately a full case of T-8's followed me home several weeks ago.
 
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Old 01-21-16, 06:26 PM
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There are many possibilities. It'd be good to know if the tubes are darkening at the ends (and if so, all ends or just one and is it always the same one?). Besides checking what size they are, it'd also be useful to know how the behave (completely dark, dim across the length of the tube, dimly lit at the ends). And it helps to know what's printed on the label of the ballast, if it's not too much trouble to access it.

It could be a mismatch, though I've seen T8/T12 mixups and while it shortens lamp life, they still typically make it more than a few months. Normally the starting issue with the newer low mercury lamps is only a problem when they're fresh out the package, but it's possible.

A bad/missing wire connection to one socket will result in unreliable starting shortly after installation. Any time you see a rapid-start fixture go dim and flickery a week to a month after relamping this is usually the cause. Whichever end is blackening has the bad connection. Rarely it's caused by the ballast not supplying heating voltage rather than a socket connection.

If the ballast capacitor is bad and it's underdriving the lamps, that can also cause early failure, but not if it's rapid start ballast (cathode heating allows tubes to be underwpowered - it's why dimmable fluorescent are always rapid/programmed start). This is most commonly a problem with instant start slimline (single-pin) fixtures.

It's also possible that the tubes aren't burning out but are unable to start due to a missing ground connection or high humidity or other reasons. If this is the cause and the fixtures are in fact grounded, this can be a tough one to fix. There are workarounds but the most surefire solution is an electronic ballast.

If it's a series ballast and you only replaced one bulb the first time, the other older bulb burning out could explain why both have gone dark.

Finally, if non-US is Canada everything that's been said still applies, but there are a lot of differences in Europe. They have very few rapid-start magnetic ballasts It's almost entirely preheat and electronic. Also they have a 36W T8 that's compatible with T12 ballasts while we don't have them here (our RS ballasts can't start them).
 
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Old 02-14-16, 09:43 PM
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Sorry I did not know that my very last post was moved to a new thread.
 
 

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