I have a problem my friend has a fluorescent light fixture when he turn on the lights they stay bright for a while and then they go dim. This is what I did so far I change the Ballast light clips and the blubs but I am still having the same problem. Is there anything I might be over looking

Thanks Michael

Do they go bright after they have gone dim?

How much load is the circuit carrying? When the go dim, cab you test the voltage level going to the light at the switch?

Did you match the ballast's for the correct size and make of the originals?

Mike,

Please do not answer questions via private mail. Just append your responses to this thread. Thanks

The below information was provided by Mike:


Hi there ,yes, the ballest is the right name and same number .
The only way they go bright again is when you shut them off and turn them back on but you might have to turn it off and on a few times for it to go bright or it might do it right away

What do you mean check the load are you talking what is hook up to the curcit breaker far as all electric items to the one breaker

What do mean check the switch with a meter do yo mean the on off switch or can I check where the blubs holder to see how much votage is going the lights

How about the order of magnitude of the time they stay bright?

Minutes, 10's of minutes, hours etc.

Any hard starting problems?

Is the ballast hot to the touch about when it happens?

The fixture is probably not grounded properly, or at all. Check to be sure, if you have Romex NM-B cable, that the bare wire is grounded, and connected to the frame of the fixture using a machine thread screw. A new fixture is supplied with a green screw just for this purpose.

If using BX (AC) cable, be sure the sheathing is grounded, and the cable is connected to the fixture using the proper cable connector.

If there is no grounding wire grounding the fixture,(equipment ground) either a bare, green wire or the metal sheathing of a cable or conduit assembly, the fixture will always having problems operating properly, no matter how many parts are changed.

What Don is referring to is voltage drop caused by a heavy amp load on the circuit, that would cause the voltage at the fixture to drop dramatically.

I doubt this is the case, but it is possible.

There will need to be a large reefer, or AC unit, or a high wattage electric heater, or something along those lines, that comes on every time the light does not worked properly. Or a loose connection in the circuit causes a voltage drop, this is somewhat likely.

If you notice the light works well on damp humid days/nights, and not so well on dry low humidity days, grounding is the cause.

Re-reading your post, you state that turning the switch off and back on again helps bring the light on again.

I stand by my defective ground advice. I have seen that symptom many times.

Yeah, I have handled a couple fixtures in my time, a few hundred thousand I would guess. That comes from installing lighting systems and working lighting maintenance for years.

If you need more detail to troubleshoot and/or repair, get back with more detail of the wiring and fixture. Pictures tell a thousand words.