Weird fluorescent light electrical problem....

[Onewolf]

I have two zones of 8ft (2x2x4') T8 fixtures in our detached garage. One zone has 4 fixtures and the other zone has 3 fixtures. About two months ago one of the zones started having an issue that when it's hot (95+ degrees) in the garage the entire zone of four fixtures will not turn on. All 4 lights in all 4 fixtures flicker momentarily and then go out. I've tried resetting the breaker but that has no effect (Both light zones are on the same breaker anyway). If it matters, this zone of lights can be controlled by two different light switches.

If the temperature is below 90 or so the lights work fine.

Any ideas on how to debug this issue?

Thanks.

 

[matt_i]

I would check out the 3 way switches and make sure voltage is being switched. It sounds as if the issue is on the input power/primary side of the ballasts. Ideas would be a bad 3 way switch or a wire nut connection that's not well-made.

 

[Aceman]

"The ballast of a fluorescent luminaire installed indoors shall have integral thermal protection. Replacement ballasts shall also have thermal protection integral with the ballast."

Taken from here:

http://ecmweb.com/quizzes/code-quiz-112

 

[cybrdyke]

The fact that the lights work fine tells us that the lamps and the ballasts are OK. Your issue is either in the wiring to the fixtures or in the switches. And all 4 fixtures behaving the same verifies this.
If I were betting, I'd say it's one of the switches. Maybe humidity, corrosion, loose connection....
But you could also check for a loose connection in the wiring between the switch and the ballast.
Good luck.
CD

 

[wyliesdiesels]

What is the temp rating on the ballasts?

 

[Mr_fixit]

I'd look for one loose connection at one of the switches, or at the first light where the wires feed all the lights.