How to Replace Ballasts in Fluorescent Lights
Flickering fluorescent light bulbs; a loud hum coming from the light fixture; or the bulbs not coming on at all may be an indication of a bad ballast or one that is getting ready to fail. There are two types of ballasts for fluorescent lighting. The old magnetic type (which hum and get louder when ready to expire) or the newer electronic type (more energy efficient and no humming). If you're not sure which type your light fixture takes, remove the old one first, following the instructions below, and bring it to a hardware or lighting store to make sure you're purchasing the correct ballast for the job. Does this Spark an idea?
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Things You'll Need
- Replacement ballast
- Ladder
- Screwdriver
- Wire nut connectors
- Wire cutters/stripper
- Nut driver
Instructions
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How to Replace Ballasts in Fluorescent Lights
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1
Locate the circuit breaker to the fluorescent light fixture and turn it off. If the fixture is plugged into an outlet, you can just unplug it.
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2
Get a ladder to reach the fixture if necessary and remove the light bulbs. Carefully place them aside out of the way so you can put them back into the fixture once the ballast has been changed.
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3
Locate the panel at the bottom of the light fixture. You will notice two to four screws retaining the panel to the bottom of the fixture. Remove the screws in the panel to expose the position of the ballast or ballasts inside the fixture.
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4
Locate the ballast. It's a rectangular component (usually black) with two to four wires coming off each end of it. Cut the wires of the ballast on each side with wire cutters about 8 inches from the ballast. If the ballast has been replaced before, it is likely that the ballast is connected to the wiring with wire nut connectors (cap screws). If so, unscrew the connectors instead of cutting the wires and separate them from the fixture wiring.
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5
Locate the two or four retaining nuts of the ballast. They are on each end of the ballast or all four corners. Some ballasts may have retaining nuts on one side and a hinged retainer on the other that will slide out of position once the retaining nut(s) have been removed. Remove the retaining nuts with a nut driver. Be sure to hold the ballast with one hand while removing the nuts with the other. The ballast is heavy, and you do not want it to fall on you. Remove the ballast.
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6
Compare the ballast to the replacement ballast (or bring the old one to the store to compare and ensure you're buying the correct replacement). Ballasts have information labeled on the base of them that will display the current they use, the wiring diagram and the voltage. Be sure the new and old ballasts match.
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7
Place the new ballast up into the light fixture and replace the retaining nuts.
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8
Match the wire colors of the ballast to the light fixture wires. Strip the wires about a half an inch (if you had to cut them) and then twist the same colored wire ends together. Place a nut connector over each pair of twisted wire connections. The connector has a hole that the wires go into, and tightening the connector holds the wires together better than just twisting them. More importantly, it safely covers the exposed electrical wire connections.
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9
Replace the fixture panel and screws.
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10
Replace the bulbs.
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11
Plug the fixture back into the outlet or place the circuit breaker back to the on position and turn on the light.
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