My kitchen has 3 4-foot fluorescent fixtures, each with two bulbs. A couple days ago the bulbs in one of the fixtures started to ‘die’, that is the got dim and started to flicker. Being lazy and poor, I didn’t immediately run to the hardware store for new bulbs. Within a few hours, the other two fixtures were doing the same thing. WTF?
Am I dealing with bad bulbs, bad fixtures, or what? FWIW, there is a track light with incandescents hooked into the same circuit, and it’s working fine. But all six bulbs at once? Why? I’ve had fluorescent fixtures in my home my whole adult life and have never seen them die in groups.
Two possibilities come to mind: the bulbs were all bought at the same time from the same batch, so they could all be faulty (or simply reached the end of their lives - you don’t say how old they are).
And/or you could have a power problem in your house. Wildly varying voltages arriving at the bulbs could also cause short life.
Besides the above possibilities, it is common to see dual lamp florescent fixtures wired backwards. If you look at the ballasts and study the wiring diagram, you can check it yourself, and swap the pin holders as needed. The most common symptom is not getting anywhere near the rated life out of your lamps (though life will vary, especially based on how much they are turned on and off).
Otherwise as someone already said, bad power, especially low voltage will fry a ballast pretty easily. Another way for ballasts to go bad is keeping one dead or marginal lamp installed, waiting for the other one to go bad before you replace them.
Thanks for the replies. I know all the bulbs were changed at different times, each set purchased as needed. The fixtures themselves are old - at least 15 years. I’ll check the grounds. Interestingly, there is one light fixture in the house (different circuit) that burns out bulbs constantly, sometimes in as little as a few days. We simply don’t use it due to this.