My bathroom has a fixture for twin 48" fluorescent bulbs. About every six months, the bulbs start to go bad. At first they will only come on about half way, and they flicker dimly for a few seconds before reaching full brightness. After a few weeks they just stay dim no matter how long they are on.

I have already replaced the ballast in this fixture, thinking that might help. No joy. I have replaced the bulbs twice a year for four years. I use the same bulbs in my other bathroom with no issues. Any suggestions?

  • What else do you have on that circuit: like fans, etc? Anything with a motor can feed voltage spikes back into the circuit.
    – Niall C.
    Commented Sep 3, 2011 at 19:55
  • Is the condensation worse in this bathroom?
    – ChrisF
    Commented Sep 3, 2011 at 20:11
  • What kind of switch is on this fixture? Is it a digital switch, or one with possibly with a timer, dimmer, or a glowing backlight to help find the switch in the dark? Commented Sep 3, 2011 at 23:13
  • I'm not sure what else is on the circuit. I'll have to check.
    – Josh Earl
    Commented Sep 4, 2011 at 0:19
  • There is more condensation in this bathroom, but it doesn't seem excessive.
    – Josh Earl
    Commented Sep 4, 2011 at 0:20

3 Answers 3


Fixture ballast is bad. Time for new ones. Sorry!

  • 1
    But I've already replaced it once, and it didn't stop the problem. Seems unlikely that I had two bad ballasts.
    – Josh Earl
    Commented Sep 4, 2011 at 0:14
  • 2
    are you sure you have the right kind of bulb? Some fixtures will not work well with the ES, energy saver reduced wattage bulbs or the Rapid start types. Check the spec for the type of bulb required. Commented Sep 4, 2011 at 9:47

Are you using T8 bulbs in a T12 socket? The bad performance and short life span is often for this reason.

  • I have seen this cause short lamp life the ballast should say the type of lamps to use. Since t8 & t12 will fit in the same fixture, I would switch to a ballast bypass led tubes and then you should be good for years with even more light ( I use 20 & 22 w LED' s ) way brighter have been changing all t8 & t12 for 2 years now as the old ones die.
    – Ed Beal
    Commented Jan 25, 2018 at 22:59

FWIW, I once bought a GE Circline fluorescent bulb, and it lasted only 6 months. I got a replacement, and that lasted only about 6 months. They were just two defective bulbs, by chance. That might have also been about 10 years ago, same was with this OP -- maybe there were bad batches.

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