Fluorescent Lamps On When Switch is Off

Old 03-01-15, 09:52 AM
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Fluorescent Lamps On When Switch is Off


One of the three fluorescent lamp fixtures in my basement would not turn on so I figured the lamps blew. I changed the lamps with new and still would not illuminate so I guessed the starters needed to be replaced but I didn't have them.

I pulled the starters out, placed them back in and put the lamps back in and they lit up! Problem is; the switch to the lamp was in the Off position! On or Off, the lamps stay lit so I pulled them out. Do I need to change the switch or could there be an issue with the fixture itself?

The fixtures themselves are several years old and you can hear the ballast humming. I have since read that I will need to tighten the wiring and that should stop the humming but am not sure if changing the switch will resolve the issue.

Am I on the right track? Any/all advice is appreciated!

Old 03-01-15, 10:47 AM
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Older ballast do hum, that is just a fact of life with them, they are a transformer so they hum.

I suggest taking meter and seeing if you have voltage at the light when the switch is off. If you do, your switch is bad. If this is a illuminated switch, this can cause fluorescent lights to turn on or flicker when they are off.

If your lights really do have starters they are quite old and likely not worth repairing.
Old 03-03-15, 05:54 AM
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Did you just install or change any wiring?

Some older fluorescent fixtures with starters have a funny kind of on-off switch built in that does not really switch off the power but rather just interrupts the power in a manner that the light will go off until the switch is flipped back on and the starter goes through its motions. The switch could be worn out in a manner that flipping it off does nothing at all. Most of these switches are in the form of two buttons rather than one toggle.

A wall switch should cut the power completely. It too could fail in a manner whereby it stays in the on position regardless of the toggle position.

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