Fluorescent Lighting Problem

Old 07-07-13, 09:22 AM
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Fluorescent Lighting Problem

I hope someone can help. I have two 4-tube fluorescent light fixtures in my garage wired to the wall switch. I noticed the two inner bulbs in one of the fixtures, let's call it A , weren't working, so I bought two new bulbs. Then I noticed the 2 inner bulbs were blown in the other unit, let's call it B, as well.

I installed the two new bulbs in the middle positions of A, and the outer 2 bulbs suddenly didn't work. I moved the 2 bulbs that were working in the other unit (B) to this unit (A), and they didn't light up either, but the 2 inner bulbs that hadn't been working in unit B suddenly came on when they were the only 2 in the fixture.

Except for the 2 new bulbs, all of the bulbs are old and have black ends to varying degrees. They probably all need replacement, but since working bulbs aren't lighting, I realize I may have a bigger problem than simply replacing the bulbs. Before I buy more bulbs, can someone suggest what's wrong with the fixtures? Starters? Ballasts? Wiring? I'm a novice DIYer, so I'm hoping it isn't too big a problem.

Money is really tight right now as I'm unemployed, so can I just use 2 bulbs in each for now? I think I heard or read somewhere doing that can damage the ballasts...

Any advice would be greatly appreciated!
Old 07-07-13, 09:33 AM
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Lynda Jean, welcome to the forums! Each set of bulbs, inner and outer have their own ballast, so you can remove either inner or outer (whichever doesn't work) and just run the other two in the fixture. With black ends, they are probably EOL, so replacement may be necessary. HOWEVER, you get into a situation where you may need to replace a ballast. In pricing the ballasts, you will find one ballast cost more than the entire fixture would.

Whenever you can afford it, I would look into some two bulb fixtures with T8 bulbs. They will give off an enormous amount of light and the ballast is electronic. I would do this before I dumped more money into the T12's, which BTW are being phased out.
Old 07-07-13, 11:56 AM
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SOME fluorescent fixtures use four-tube ballasts. They may not make them anymore but they were common at one time.

Leaving non-working tubes in place or removing tubes can often cause a ballast to fail.
Old 07-11-13, 01:56 PM
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Make sure your fixtures are grounded. It sounds like you have magnetic rapid start ballasts, which sometimes won't work properly if the bulbs aren't mounted close to a grounded metal surface. You can safely run two bulbs in a fixture like yours by simply disconnecting the power to the appropriate ballast. Open the ballast cover and trace the wires from the bulb sockets you don't plan to use back to the ballast. Then just unhook the black and white supply wires from that ballast. This will effectively turn the fixture into a 2-lamp unit. If you ever want to replace the ballasts, you can buy a new 4-lamp electronic ballast for about $20, and a 2-lamp one for even less. A new fixture of decent quality will cost more than that, and ballasts are not difficult to wire. The wiring diagram is generally printed right on the ballast. I suggest using the old ballasts until they either fail to work or the old T12 bulbs become too difficult to find, as magnetic ballasts often last much longer than electronic ones. The advantage of T8 electronic ballasts is that they will work in almost any situation, regardless of grounding, temperature, humidity (yes, that can affect rapid-start systems), and they are also somewhat more efficient.

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