We live in Florida, and the fluorescent lights in the kitchen turn on very slowly (if at all) in the summer. Other clues are:

  • They work fine in the early morning
  • Later in the day (hot day) they will not turn on immediately
  • These are ceiling light fixtures, above the ceiling is the (hot) attic
  • If you flick the switch back and forth rapidly, you may get lucky and the light comes on
  • This house was built in 1992, therefore probably an electronic ballast
  • Our Air Conditioning went out for all of last week, it stayed 85 degrees F in the house as a minimum and they never came on.

Is it the ballast?


2 Answers 2


Almost certainly the ballast, unless old enough to actually have a separate starter, at which point it becomes a tossup between ballast and starter - probably not from 1992. But a 1992 ballast is certainly ripe for replacement 22 years later. They don't live forever.

I have a few older ones I have not gotten around to replacing that are very humidity-sensitive (a little bit heat, a lot humidity...at least in my case.)

  • If you can look at the ballast its self it should have printed information about the lamps that can be used. Usually T8 for electronic ballasts and T12 for older magnetic ones. The wrong type of lamps will not work correctly if at all.
    – user24125
    Aug 24, 2014 at 16:22
  • 2
    Or if T-12, just do a T-8 conversion. The T-12 and T-8 use the same bi-pin socket. Buy a new energy efficient electronic ballast for the number of tubes in the fixture and T-8 tubes. Rewire the fixture per the wiring diagram on the ballast and enjoy flicker free, more efficient lighting. Aug 24, 2014 at 16:58

The problem may possibly lie in the ballast, the tube(s), or the switch. The simplest initial test is to replace the tube(s) with (a) new one(s) and see if the problem goes away. If so, the problem was in the tube(s).

Testing the ballast and the switch is a little more complicated, but made simpler by ensuring that the fixture is equipped with (a) known-good tube(s), then switching the light on during the morning hours when the light works as expected. Now find the circuit breaker that controls that light and turn that breaker off. Wait until the house warms up to a temperature known to cause failure in that fixture, then turn the breaker on. If the light can be controlled reliably by the breaker but not by the switch, then the switch is at fault. If the light cannot be controlled reliably by the breaker, then the ballast is at fault.

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