I have a client with undercabinet 1/2" fluorescent lights. She has them on approx. 12 hours per day, and after 2-3 months they start a very irregular flicker. I tried them today & it flickered a little at the start, then seldom, but occasionally.

Are these bulbs dying normally after only 750-1000 hours?

This is a replacement fixture. The previous was doing the same thing. It's not from a motor surge, and other fixtures in the room aren't having this problem. Pounding on the fixture doesn't make it flicker.

Thanks,
Dave

Try thoroughly cleaning the florescent tube. There's a very intricate relationship with the metal ground of the fixture that sometimes can be interfered with due to dirt/dust buildup on the tube.

I would verify the grounding of the fixture, all the way back to the GEC if necessary. Sounds like a bad ground.

Sounds like loose terminations at the Lamp Holder - either holding the Lamps' Bipins, or the Wire(s) connected to the Lamp Holder.

They would loosen up in operation, due to heat.

Fun for Troubleshooting!

Scott35

Cheap fixture? (Not a name brand electronic ballast)
Cheap bulbs? (maybe same lot or batch as the old one?)
Cheap ballast? (Same deal as with bulbs)
Grounding of the fixture can be an issue...
So can low available input voltage...
All of the above...

Then my favorite... improper burn in time of the lamps. Try leaving them on for 24 hours or more for the first start up, it helps... It is actually required for dimming lamps, but have noticed a difference in non dimming...