I changed the bulb of a fluorescent light but it does not turn on. So, my first assumption is that the ballast has died. Is there any other way I can test the ballast? I am wondering perhaps the issue is in the wiring, as another light with similar characteristics is still working (so it looks like a premature death of one ballast).


It is an 8-foot push-pin type 1.5 inch wide. I do not see any starter. The end of bulbs are not darkened.

The light was on and stopped working while we were on a long vacation. Before that there were no flickers.

  • Thanks for the edit, but you didn't answer the musings about flicker. I added a new bit to the answer - for those designers who will burn in hell forever for putting the starter inside the casing.
    – Tetsujin
    Commented Sep 30, 2023 at 17:44
  • 2
    I haven't yet met a fluorescent fixture that could not and should not be gutted and replaced with modern LED lighting. Commented Sep 30, 2023 at 18:18
  • @JimmyFix-it Now I tend to agree, with ballasts running at $50 and a pair of bulbs at $25. And ballasts not lasting as long as one thinks.
    – Maesumi
    Commented Sep 30, 2023 at 20:59
  • 1
    @Maesumi depends on the ballasts, but I get F32T8 ballasts quite cheaply and tubes for $2.50, and are happy to stay fluorescent there. For other sizes, the ballasts are odd ducks, and the tubes are odd ducks, and they're too darn expensive to be fooling around with old tech. Commented Oct 1, 2023 at 19:50
  • @Harper-ReinstateMonica: Then again, based on a quick Google search, T8 LED replacement tubes seem to go for around $10 (with a few results way below that, though I tend to get a bit suspicious of the quality at such lowball prices) and probably last longer than the original fluorescents (at least if you don't buy the absolute cheapest no-name ones), so even there the long term TCO might be starting to favor the LEDs. Commented Oct 2, 2023 at 11:12

2 Answers 2


If you didn't change the wiring of the ballast, then if the fixture was working until the tube went out, and a new tube does not work, that points to a bad ballast, unless you open the fixture up to have a look and see disconnected or broken wires. I guess it might be worth going through and checking all the wire nuts to be sure none are loose, if they might have been installed poorly.

If you have a sufficiently similar working fixture you can test the new and recently removed tube in that. I suppose you could also try moving the suspect ballast there, but that's a lot of work for little chance of reward.


You can answer these to yourself, but it's a matter of elimination, financially & methodically.

Does it have a separate starter? Does it flicker when switched on or do nothing? Did the old lamp spend some time in the flickery phase near end of life? Did it have blackened ends?

Generally, the ballast will far outlive starter & tube; but it's always wise when changing a tube to pre-emptively change the starter too. Leaving a poor starter banging away at the tube will do neither tube nor ballast any good, long term.

If you change both starter & tube & it still doesn't work [and you've checked the power is good] then it's time to change the ballast too.

Note: sometimes the starter is inside the housing next to the ballast, rather than being easily accessible on one edge, making them much harder to find/change. The cover is usually easy enough to take off, two plastic 90° turn screws, but it's a nuisance if you've got 50 to do today:\

  • 1
    I haven't seen a starter required in any ballast I've bought in the past 15-20 years. Some of the 40-50 year old fixtures have them, but they won't when the ballast gets replaced.
    – Ecnerwal
    Commented Sep 30, 2023 at 17:57
  • Until they started replacing them all with LEDs, every fitting I ever serviced had a starter. Some of them were brand new.
    – Tetsujin
    Commented Sep 30, 2023 at 18:15

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