Fluorescent Light Fixture Troubleshooting

Old 08-13-05, 11:22 PM
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Fluorescent Light Fixture Troubleshooting

I am having a problem and any help would be greatly appreciated. I have a pair of hard-wired rapid-start fluorescent lighting fixtures (2 bulbs in each, 4 total) which have been troublesome for a while and I finally got around to working on them. I had one fixture that worked fine, while the other did nothing. I thought that the ballast might have been the problem and I replaced it. Now neither fixture works well. They light but are incredibly dim. I have replaced all 4 bulbs. I have replaced all 8 sockets/lampholders. I have replaced both ballasts. I have tested the live voltage and get 122 volts coming into each fixture. And I still have incredibly dim light coming out.

Any ideas?
Old 08-14-05, 08:01 PM
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I would check to make sure the wiring to the lampholders is tight. I've had it come loose on me before.
Old 08-15-05, 10:36 PM
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Fluorescent fixtures do weird things when they're not grounded.

Are they grounded?

There are several types of tombstone out there, too. Make sure the ones you have are connected internally as shown on the schematic printed on the ballast. Some tombstones are internally wired so one wire will energize both pins, others require a separate wire for each pin. Some use a little jumper from one side of the tombstone to the other. Use the ones called for on the ballast schematic.

Are your ballasts the right voltage?

Did you by chance mix up the wires when you replaced the ballasts such that the yellow wires on one end of a lamp are coming from a different ballast than the red or blue wires on the other end of the same lamp? (a very common mistake).

Is the ballast listed for the lamps you are using? (25 watt ballasts will not start 34 watt lamps, magnetic ballasts will not start T-8 lamps, electronic ballasts will not start T-12 lamps - for the most part. They'll only start the type of lamp listed on the ballast)

Are your ballasts/lamps some imported brand no one has ever heard of before? (I like Advance ballasts myself - never had a DOA - although they're probably imported these days as well). Are the ballasts full-size or are they the midget jobs favored by manufacturers of $8 shop-lite fixtures? The midget ballasts can be troublesome.

Have you considered replacing the fixtures? (You surely have enough labor invested in these to buy new ones by now... )

Last edited by Cheyenps; 08-15-05 at 10:55 PM.
Old 08-16-05, 11:15 PM
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Cheyenps and HandyMan: Thank you both for your help.

Cheyenps - I really appreciate the thorough response. Honestly, before I heard back from you, I had already gone out and purchased a new fixture. Still nothing. Then I decided to (again) check the grounding. It turns out the grounding feed wasn't securely fastened in the ceiling. Although I am a little hesitant to declare success, as of now I have four fully fuctioning bulbs. So thanks again. I appreciate your willingness to offer advice.

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