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There are actually 4 things that can cause fluorescent light fixtures not to work. Bulbs, ballasts, tombstones, or no power.

• Bulbs- This is usually the culprit when fluorescent light fixtures will not work.  Try changing the bulbs first to see if this corrects the problem. Also remember that even if a bulb is working but has turned black on the ends it should be replaced because these bulbs put added pressure on the ballasts trying to burn them.
• Ballasts- A fluorescent ballast will last for a good long while but eventually will fail. Sometimes these ballasts will emit a strong odor that will verify the need for replacement. If you see any leakage coming from the ballast that resembles tar that is another verification for replacement.

1. The most common fluorescent ballasts are for 4′ and 8′ fixtures. Most 4′ ballasts will burn two bulbs with a four bulb fixture having two ballasts in it. One ballast will feed the two inside bulbs and the other ballast will feed the two outside bulbs.

Changing the ballasts is not a difficult job but can be somewhat dangerous if not done properly. You should always make sure the power has been turned off to the circuit before attempting these repairs.

A 4′ 2 tube ballast has 8 wires coming from it. 2 reds, 2 blues, 2 yellows, 1 black and 1 white. The black is the hot feed and the white is the neutral. These two wires should be removed first. Then you can cut the the remaining wires loose one at a time and take out the ballast.

Match the colors from the ballast to the same colors from the fixture. It doesn’t matter which two colors hook to each wire as long as the colors match.

8′ 2 tube magnetic ballasts only have 4 wires and they just match up to the colors in the fixture.

• Tombstones- These are the end sockets that the bulbs fit in to and they tend to break sometimes if the pins from the bulb are not inserted properly.  If you have to change any of these the wires just push into the bottom  of them.

Bulbs or ballasts are usually the problem in these fixtures and neither ones are very hard to change.