Lighting, Light Fixtures, Ceiling and Exhaust Fans - Flourescent Fixture Problem

My 4 tube flourescent fixture got really dim, so I replaced the tubes. It still was dim. The two outside tubes were very dim and flickering and the two inside tubes were not lit. I bought and installed 2 new ballasts. Now the outside tubes are great, but the 2 inside tubes are still not lit. What can I do?:wall:

Flourescent fixtures are harder (more stuff to check, but not difficult) to diagnose than incandescent ones. But you are dealing with a relatively low number of parts to inspect.

Inspect voltage (probably okay, being that two of the 4 light good).
Inspect/try different bulbs. (Good to have new ones on hand anyway).

Inspect/replace balasts (you have done that).
Recheck all the wires in the wire nuts.
Check socket ends for out of position/missing metal tangs.
Remove sockets to see if wires came out of them (as they may be stab connections).

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*I* had the last thing mentioned, occur in a fluorescent recently. I was able to just shove the wire back in the stab connection in the socket and it 'took' good, and that fixed my partial outage in the fixture. (I work on a building with lots of T8 fixtures on 277 current.)

Did you replace all four tubes at the same time? And did you replace them with brand new ones? And were the new ones of the same type as the old ones?

Thanks. I did evertything except to take the sockets loose to see if the wires were stabbed in all the way. The wierd thing is that this fixture has been there for about 10 years, so it doesn't seem like the wires would be loose, I might try to disconnect the wires and test continuity.

did you check the ground wire is good due most flourscent luminaires are very senstive with ground and they need good ground to get them lit up

Make sure you follow the ballast connection diagram very carefully due some of the flourscent luminaire they will not work if you get one of the wires crossed over.

once a while it do happend you can get a bad ballast.

after you check the tombstone for good connection if that is good and swap the tubes and still fail to lit up then you got bad ballast. if that is brand new one make sure you read the label if if that is correct supply voltage most will marked either 120v or 277v some case both on electronic verison.

if new one is bad take it back and exchange for other new one.

it happend to me once a while i will hit a bad one along the way.

Merci,Marc