Fluorescent fixture problem

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  #1  
Old 02-22-06, 08:55 AM
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Fluorescent fixture problem

Every now and then I run into a fluorescent fixture that will not cut on unless the fixture can is tapped or a tube is wiggled. I have found with some 2' strip or circleline type fixtures that the fixture can needs to be grounded for the fixture to operate properly. I've never found that problem with 4' fixtures.

The latest example is a head scratcher. I have a friend who has a 4-tube, 2-ballast fixture in his garage and I've been trying to lead him through the troubleshooting process. He had the ususal problem - black and / or glowing tube - and I told him he needed to replace the bulbs and if that didn't work, he needed to replace the ballasts. He has now replaced all bulbs, ballasts and sockets, but still has intermittent performance of the fixture. Either flipping on & off the switches a few times, or wiggling the bulbs (sometimes just touching the bulbs) is required to get the fixtures to come on (they glow on the end, but require extra effort to cut on).

The fixture is in an unheated space, but he lives in Gainesville Fl. I don't think he would need an HO fixture. The fixture is not grounded, so I had him temporarily pigtail the neutral to the can to see if that would help, but it doesn't.

Does anyone have any suggestions for what might be causing his problem?
 
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Old 02-22-06, 09:46 AM
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Things to check.....

1.) Is the black wire from the ballast connected to the hot side of the line? If not, you will have starting problems with rapid start lamps.

2.) Also, this fixture must be grounded for reliable starting. While it may not be an issue in every case it's still necessary.

3.) Are the bulbs correct for the ballast? Check the Ballast label and the bulbs.

4.) Are all covers in place? The cover aids in starting on rapid start circuits.

5.) Check all connections carefully. Clean lamp contacts and socket contacts (fine sandpaper works well to remove oxide coatings....Turn Off Power.

6.) Rarely, the gas mixture in the bulb causes starting problems. Substitute different brand lamps.

Let us know what happens.
 
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Old 02-22-06, 09:56 AM
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I'm going by what I've been told - the fixture is 500 miles away from me.

1. Black line wire is connected to black fixture wire.
2. Fixture circuit has no ground. I had him pigtail off the neutral to the can temporarily.
3. Ballast is standard magnetic rapid start, tubes are F40T12
4. Covers are in place.
5. Sockets are new.
 
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Old 02-22-06, 10:02 AM
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An ungrounded fluorscent fixture will operate unreliably.

Pigtailing the ground off the neutral is more dangerous than you can possible imagine, even temporarily. Remove it immediately.
 
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Old 02-22-06, 10:21 AM
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Pigtailing the neutral was done to provide a "ground" for troubleshooting purposes. It didn't help, and the pigtail has been removed.
 
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Old 02-22-06, 06:33 PM
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Originally Posted by mcjunk
and I told him he needed to replace the bulbs and if that didn't work, he needed to replace the ballasts. He has now replaced all bulbs, ballasts and sockets, but still has intermittent performance of the fixture.
What is your time, all those parts and head scratching worth vs. a new electonic ballasted fixture?
 
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Old 02-23-06, 05:47 AM
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Replacing the fixture is not my call. Labor and head scratching is insignificant to me, as I've merely been going back and forth via email with my friend trying to help him get the fixture working. Material costs are insignificant to him - I gave him a couple of brand new magnetic ballasts when he was visiting me a month ago (I had bought them on clearance for $1 each at Lowes). He's had to buy some new tubes, which he needed anyway and some tombstone sockets (which he probably didn't need). Furthermore, labor and head scratching are always part of the equation unless you own a crystal ball. If I would have told him before he started that he was going to spend 5 hours trying to fix this problem, without success, or he could spend 2 hours and replace the fixture with completely successful results, then yes, he may have chosen to replace the fixture. Neither of us have a crystal ball, and we can't go back in time, so we are where we are.

If he did buy a new fixture and install it on a circuit with no ground, would he still be in the same position? Would he have an intermittent starting fixture, or do electronic ballasts not require a fixture to be grounded"?
 
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Old 02-23-06, 07:31 AM
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If all the items that I listed were checked and re-checked, then I suspect you are dealing with the symptoms rather than the problem. The problem being substandard building wiring. Rapid start ballasts sometimes can be sensitive to low line voltage (anything under 110 volts), poor grounding (or none), incorrect polarity (ballast black wire to hot, check with good digital meter and don't assume anything) or a combination of the above.

It might be best to call an electrician to deal with this and other potential hazards as well.

Good luck and be safe.
 
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Old 02-24-06, 08:38 AM
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I can think of a couple of things:

Check for low voltage as previously suggested. Also check the voltage rating on the ballast.

Check to make sure that the wiring did not get mixed up when the ballasts were changed. This is very common in a two-ballast fixture - the lamps end up with wires from different ballasts on each end.

If the fixture is really, really old, it's possible that the wiring of the tombstones is not set up as is required by modern ballasts. There is a wiring diagram on the ballast, make sure the fixture matches it. You'll have to take the tombstones out to do this - some of them are set up where both "pins" are common, others are setup where each pin is isolated. It's also possible that he bought tombstones that are not of the right type.

Try a different ballast. $1 close-out ballasts don't sound like something I'd trust. You can get a new Advance ballast from HD for about $13. Try one of those.
 
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Old 02-24-06, 08:54 AM
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The voltage rating of the ballast is 120V. The ballasts originally sold for around 15 bucks each - the reason I got them so cheap is because they are magnetic and Lowe's was phasing them out to sell electronic ballasts. They are "new" in the box, even though I bought them several years ago.

I will get my friend to check the voltage at the fixtures, if he has a voltmeter. I know he has a hot stick, not sure about a voltmeter.

He changed the ballasts one at a time - therefore, I don't think he could have mixed the two "circuits" up. I'll tell him to check the wiring diagram closely to make sure everything's OK.

I'll ask him about the tombstones, and whether they match the original ones or not.

The last time he emailed me, he told me that he didn't have the belly pan on the fixture. I told him to install it - that it's supposed to be on for proper startup. Of course, I know that the fixture is supposed to be grounded and is supposed to obtain some kind of capacitative field between the tubes and belly pan, but I've never really experienced that in real world conditions. I've never witnessed startup problems when the fixture wasn't grounded or when the belly pan was off on 4' 2-tube ballast fixtures.
 
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Old 03-07-06, 10:36 PM
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Originally Posted by mcjunk
I've never witnessed startup problems when the fixture wasn't grounded or when the belly pan was off on 4' 2-tube ballast fixtures.
I have. It's pretty common with U-tube fixtures, and not all that uncommon in 4' fixuures using "inexpensive" ballasts.

Perhaps he should try an gen-yew-wine Advance ballast (Home Depot - $13) and see if the problem goes away.
 
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