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My kitchen has 9 26W fluorescent can lights (not CFLs - they have external ballasts). Often when I turn the switch on, particularly after they've been off for at least several minutes, about 4 of them won't light. They'll flash momentarily then stay dark. If I unseat the bulbs (handy being very tall :) ) and reseat them a time or three, the lights will come on. I've tried replacing bulbs, to no avail.

I'd assume bad ballasts, but a couple of things make that less likely in my mind:

  • While it's usually about 4 lights that don't come on, it's not the same 4. Some more commonly have the problem, but all 9 have at some point.
  • This has been happening since the ballasts were new (about 2 years ago). It might be getting a bit worse (i.e., more lights out on average) over time.

The lights are on a dedicated 15A circuit. They're switched by a 3-way switch. The ballasts are Sylvania QTR1x26T4. The wiring, circuit breaker, fixtures, ballasts, and bulbs are all about 2 years old.

Anybody know of possible causes for this behavior?

  • It would have been nice to deal with this when they were new. Have you called the service center number? Have you checked the date stamp on the ballasts or have the receipt to see if they're still under warranty? – ChiefTwoPencils Jan 19 '15 at 9:35
  • Any chance it's the starters, little plastic things that are forever being replaced. At least they are cheap to replace. – Hightower Jan 20 '15 at 22:07
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Fluorescent fixtures can be rather tricky. With that many installed on the same circuit, what you might be seeing is an unbalanced load on the circuit, causing some of the fixtures to have full current and others, less, and quite simply a ballast, or any fluorescent will not work without full current. With the warm up times of older ballasts, combined with different features of newer electronic ballasts, this could be the answer.

Isolating part of the fixtures on the circuit from each other quite possibly will solve this. The simplest way would be to install two (or more) switches instead of one, preferably running from different circuits.

You might also consider replacing some, or all, of the can lights with LED. This would considerably lower the load, as well as saving energy. Quite interesting that you have can lights with an external ballast, as well. I've never seen that. What type of bulb do these use if not a CFL? Is it possible that what you think is a ballast is simply a wiring box where the can lights connect to the wiring, or some sort of dimmer control?

  • My intuition tells me that you're on the right track. I'm wondering if all fixtures are wired in series, and that's causing a problem. I guess the bulbs are CFLs - I thought that term referred to bulbs with built-in ballast that screw into an incandescent socket. These are 4-pin bulbs using a G24Q-3 base, and the ballast is external (data sheet linked in question). It's a little box that screws onto the wiring box. – Aron Jan 24 '15 at 17:31
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Updating this for posterity and to share our solution.

Background -- 4 pin cfls with Sylvania Quicktronics residential series ballast, QTR 1x26T4 (120v). 6 can lights on the same switch. Same bad behavior as the OP -- some lights came on; others didn't in a totally random fashion.

On the possibility that there were simply too many lights on that circuit, we tried removing 3 bulbs as an experiment. It looked good initially, but didn't reliably light all 3.

Fast forward a year... we found some 4 pin LED retrofit bulbs that do not require a ballast bypass. (This is key -- some do, some don't, and some of our lights were under a very short area of roof, so a ballast bypass would have been a curse.) GE makes them; so do others. This isn't a shopping recommendation, but we happened to get GE's model LED12G24Q-V/827. At just shy of 20 bucks each, you wouldn't call them cheap, but compared to hours on your belly in the attic to bypass ballasts, they're probably priceless. They are non-dimmable. These have a ballast compatibility chart that our ballast didn't appear on. However, things are working perfectly after a few days.

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I've had a similar problem in my basement fixtures. Check the contacts on the tubes for corrosion and remove it with sandpaper. You can also check the contacts on the fixtures and run some sandpaper in them but make sure the power is off first.

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