Buzz
All fluorescent light fixtures include lamps, lamp holders, ballast, and internal wiring. Some older models also have starters. The ballast is responsible for generating the voltage and current needed to start and illuminate the fluorescent lamp. Over time, you may need to replace the ballast. Continue reading to learn how to replace the old ballast with an approved replacement of the same technology. Please make sure to read the entire article and warnings before proceeding.
Steps
Determine if a faulty ballast is causing the issue.
Remove the lamps and keep them in a safe place.
Make sure to switch off both the light switch and the circuit breaker.
If you're unsure about which breaker controls the light, it's best to turn off the main breaker for the entire house to ensure safety. Rotate the metal tabs near the center of the fixture so they are perpendicular to its length. Gently remove the fixture and store it in a convenient location. Repeat this process for the other side.
Use a voltmeter or voltage sensor to check for voltage in both the hot and neutral feed wires relative to ground.
You can easily check the voltage using a voltmeter or voltage sensor. Locate the ballast and trace the wires until you find wire nuts (caps) that connect wires of the same color (red to red, etc.). If there are no wire nuts, you'll need to cut the wires about 12 inches (30 cm) from the center of the fixture on each side. Repeat this process until all wires are cut or all wire nuts are removed.
Remove the nut that secures the ballast to the fixture.
Hold it securely in place with one hand while performing this step. Use a nut driver or socket wrench for the best results. To remove the ballast, lower the side where the nut is located and slide it in that direction.
Procure a replacement ballast.
Bring the old ballast to your nearby hardware store and acquire a similar replacement. Take note of the number of tubes in your fixture, their wattage, length, and type (T8, T12, T5, etc.). Keep in mind that in a four-tube fixture, there may be two ballasts, each operating two tubes.
Install the new ballast.
To install, follow the reverse steps outlined in step 5. Ensure that the red and blue wires align with the end containing red and blue wires, and the black and white wires align with the opposite end.
- If you choose the cutting method, trim the wires so they extend about 6 inches (15 cm) beyond the fixture wires.
Remove about 1/2' (12 mm) of insulation from the ends of all 8 wires.
Utilize a wire nut to join the appropriate wires.
Match the blue wire with blue, red with red, white with white, and black with black. An alternative to cutting and wiring is to twist and pull the wires out of the lamp connectors. A slight twisting motion is required to release the wires. Take note of the wire colors during removal. To connect the new ballast, insert the wire into the corresponding hole and ensure it's firmly seated by giving it a tug, following the same method used during manufacturing.
Undo step 3.
Ensure that the tabs are inserted into the holes at the end of the fixture.
Install the new bulbs.
Switch on the light.
Helpful Tips
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This presents an opportunity to clean the fixture.
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Allow the light a minute to fully illuminate.
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When lamps don't fully light up, it could indicate: cold or low ambient temperature, faulty lamps or starters, incorrect connection of a 120V ballast, defective lamp holders, or a faulty ballast. Some fixtures also require proper grounding.
Warnings
- Choose a ballast with the same part number or a compatible replacement based on type (electronic or electromagnetic), input voltage, number and type of lamps, wattage, and sound rating. Consider whether you need a 'Rapid Start' (also known as Programmed Start or 'PS') or 'Instant Start' ('IS') ballast based on how long the fixture will be used. 'IS' is more energy-efficient for longer periods, while 'Rapid Start' prolongs bulb and ballast life with frequent on-off cycles.
- When handling electrical components, wear non-conductive shoes or stand on a piece of plywood. Avoid contact with conductive surfaces, and use a voltmeter or voltage sensor to check for voltage.
- Keep fluorescent fixtures at least 1 inch (2.5 cm) away from combustible materials to reduce fire risks due to ballast heat.
- If replacing a magnetic ballast with an electronic one, consider that the new ballast may require energy-efficient lamps and new holders. Recycling spent fluorescent lamps is crucial due to their mercury content.
- For retrofits, understand schematics and follow the new ballast's schematic precisely. Use proper wire size and insulation, and select appropriate wire nuts for connections.
