Do fluorescent lights ‘cycle’?

[RedSS454]

As i sit in my garage drinking a cold one after a few projects, I’m noticing that a very old fluorescent shop light i have seems to be ‘cycling’. The ballast hums, and produces normal light. After awhile it will stop humming, sound like it shuts off, and light output dips slightly. Is this normal?

I’ve been debating swapping this 8’ fluorescent (4 bulb) out to an 8’ (or 2x4’) LED, but if it isn’t broke i won’t fix it.

 

[Bert_]

If two of the bulbs shut off it could be one of the ballasts tripping the thermal protector. A failing ballast can run hot a trip it.

 

[RedSS454]

They don’t shut off, but light is noticeably dimmer. This is the first time I’ve really noticed the change in light as i was always preoccupied, but have noticed the sound. I guess my real question is, should i be looking at replacing it?

 

[James-W]

I think you would be better off replacing the fixture with a brand new LED model.

 

[Bert_]

It's definitely not normal. Could be that the ballast is developing a shorted turn in the winding.

*edit, if this is T8 electronic, which most of the 8' 4 lamp tandem fixtures usually are, then I don't have a clue. Still probably a failing ballast but why I have no idea.

 

[Chilliwack Murray]

It sounds like it is dropping back to start mode.

Ballasts have two modes of operation, starting, where they excite the gas enough to conduct (like the pre-heat on old fluorescent desk lamps etc) and run where they maintain only enough current to keep the lamp on.

It could be a failing ballast but equally likely you have a failing tube that is putting the ballast back into start mode. Try new tubes first unless it’s time to upgrade anyway.

 

[CJ7VFR]

Do you have anything else in the garage or house that cycles on and off at the same regular interval, such as a refrigerator or freezer or other piece of equipment?

I have noticed the same thing you are describing with the last of the fluorescent shop light fixtures in my basement. I never really noticed it before I replaced most of them with new LED shop lights.

The old fluorescent lights do indeed dim a bit whenever my refrigerator cycles on, and then they get brighter again when it cycles off.

Maybe it is something like that. But like you said, I never actually noticed it before, as I was always doing something to keep my mind busy.

Jim

 

[tfi racing]

How old is "very old"? If it is older than about three years, it is likely time for an update, don't waste any more time or beer pondering it.

 

[johnnyradiant]

Anytime either an old tube or a ballast starts to act up that is the always the time to upgrade unless the stores are closed and/or your in the middle of a project.

There's another side to the time/beer wasting on pondering it. It might be the 'right excuse' for a break to have one while you 'ponder it'.

 

[RedSS454]

How old is "very old"? If it is older than about three years, it is likely time for an update, don't waste any more time or beer pondering it.

Whole unit is, at minimum, 15 years old, and likely older. So I’m leaning towards just replacing it at this point.


Nothing else cycles on and off, just this. Probably best to just go with new LED at this point. Guess i have my weekend project for this week. Thanks guys!

 

[SGKent]

tubes go bad. Replace them or go LED. LED run cooler.