Fluorescent Light Ballast Replacement

Introduction

This guide provides instructions for replacing a fluorescent light ballast and may not reflect different florescent light fixture designs. Intermediate multimeter knowledge is recommended to safely measure and confirm voltage, rewire the ballast, and remove electrical components from the ballast. Please contact a certified electrician if you are unsure what to do or do not feel comfortable proceeding.

What you need

Step 1 Ballast

Fluorescent Light Ballast Replacement, Ballast: step 1, image 1 of 2

Fluorescent Light Ballast Replacement, Ballast: step 1, image 2 of 2

Shock Hazard. Before starting this procedure, make sure the room's circuit breaker is in the OFF position.
Turn off the light switch.
Remove light fixture cover according to the manufacturer's instruction guide.

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Step 2

Burn Hazard. Light bulbs may be hot. If light bulbs were turned on, wait at least 10 minutes before proceeding.
Remove the light bulbs by gently twisting each bulb counterclockwise.
Remove the light bulb from the light bulb socket.

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Step 3

Fluorescent Light Ballast Replacement: step 3, image 3 of 3

Remove center cover to expose the wiring and ballast components.

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Step 4

Fluorescent Light Ballast Replacement: step 4, image 3 of 3

Shock Hazard. Check the fixture for voltage using the non-contact voltage reader according to the device’s instructions.
Shock Hazard. After removing wire nuts, do not touch the bare wires.
Remove wire nut by twisting it counterclockwise from the hot side (black or red wire) and the neutral side (white wire). Do not untwist wires.

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Step 5

Make sure both measure wires are not touching anything else at bare portion.
Multimeter should measure at 0 volts.
Place the red lead on the bare metal of the black or red wire.
Place the black lead on the bare metal of the white wire.

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Step 6

Switch room's circuit breaker to ON position.
Turn light switch on and repeat step 5.
Shock Hazard. Electricity should now running through wires. Only touch wires with multimeter leads.
Make sure multimeter reads between 110-125 volts.
If the measured voltage is not between 110-125 volts, do not continue. Contact a qualified electrician for further service.
Turn off light switch.
Change room's circuit breaker to OFF position.

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Step 7

Take note of wire placement or take a picture of the entire fixture to later reference when reconnecting wiring.

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Step 8

Shock Hazard. Check the fixture for voltage using the non-contact voltage reader according to the device’s instructions.

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Step 9

Take a picture of the ballast's data plate or take note of the information on the data plate to make sure you have the correct replacement part.

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Step 10

Disconnect all wires from the ballast.
Use a screwdriver to remove the ballast from the light fixture.
If necessary, cut the wires close to the ballast. The cut wires can be re-used later.

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Step 11

Fluorescent Light Ballast Replacement: step 11, image 3 of 3

Use a screwdriver to install the new ballast to the light fixture.
Ballast packaging may have a wiring diagram or may be on the ballast itself.
Make sure you strip all wire ends with a wire stripper and use ANSI approved wire nuts on all wired connections.
Reconnect all wires according to your notes or picture, add wire nuts to bare wire ends and twisting clockwise.

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Step 12

Attach center cover over the wiring and ballast components.

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Step 13

Screw in light bulb by placing a light bulb in light bulb socket.
Gently twist light bulb clockwise until light bulb is firmly in place.
Repeat until all light bulbs are firmly in place.

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Step 14

Attach light fixture cover over light bulbs according to manufacturer's instruction guide.
Move the room's circuit breaker back to ON position.
Turn light switch on to make sure the light works.

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Conclusion

Put the fixture back together by reversing the steps 1-3. Test the light to make sure it works. If it still does not function, contact a qualified electrician.