How to Replace a Fluorescent Light Bulb

Fluorescent light fixtures are durable and virtually maintenance free, but occasionally service and repair are required. You’ll typically run into three DIY-friendly problems with fluorescent light fixtures: the fixture won’t light up, the bulb flickers on and off or the bulb won’t stay in the socket. Luckily, replacement parts are easy to install and can be found at home centers and hardware stores. Ahead, we’ll show you how to troubleshoot problems with fluorescent lights and complete the appropriate repair.

Troubleshooting Guide

• No power: If the fixture doesn’t light up at all, it may not be getting power. Check the circuit breaker or fuse box, and reset or replace the necessary equipment.
• Replacement bulb: Fluorescent light bulbs typically last many years, but when one flickers on and off, or the end turns light gray to black in color, you’ll just need replacement light bulbs. Replace the bulb with the same size bulb.
• Cracked sockets: Another common problem is cracked sockets, caused by bumps from other objects or stress from removing a bulb. Shut down power to the light, remove the bulbs and then open up the fixture to gain access to the broken socket. There will be two or four wires coming into the socket. Keep the wiring straight by swapping wires from one side of the socket at a time.
• Broken ballast: If the fixture still doesn’t work, then the ballast is probably shot. The ballast boosts the incoming voltage to start the tubes, and then regulates the current to provide continuous light. Ballast replacement can cost as much as a new fixture, so buying a new fixture may be a better investment.

Servicing a fluorescent light: Pull the bulb

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Unplug the light and twist the bulb 90 degrees with both hands. Pull one end straight down to free it from the socket and then lower the entire bulb.

Insert the replacement bulb into the socket and twist the bulb 90 degrees with both hands until the bulb hangs securely. You should feel it click into place.

Remove the end cover

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If a faulty socket is the issue, first unscrew the fixture end cover. Screw locations will vary, but double-bulb units typically have a screw on each side, and four-bulb units typically have an additional screw on the top center edge. Remove all screws and pull off the cover.

Remove the fluorescent light socket

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Slide out the fluorescent light socket to expose the wiring. It’s very important to keep the wiring order straight, so cut one side of the old socket wiring loose at a time. Strip the wiring back 1/2 in., then press the bare wire ends into the terminal slots on the new socket. The terminal slot works like a barbed fishhook; once a wire is pushed in, it cannot be pulled out. Repeat the process for the remaining wires and then replace the socket.

Close up

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Push the stripped wire into the new terminal, being careful to insert the correct wire into each terminal. Replace the end cover and bulbs.

FAQ

What should I do with my old fluorescent light bulb?

Fluorescent bulbs should be recycled due to their mercury content. To find a recycling center near you that accepts used fluorescent tubes, head to Earth911 for a comprehensive national list.

What are the pros of fluorescent light bulbs?

Fluorescent bulbs are a cost-effective and energy efficient lighting source that’s produces a bright light that’s great for task lighting.

What are the cons of fluorescent light bulbs?

Fluorescent bulbs have a higher initial cost than other lighting options. Also, many are not dimmable, so if your space does not need a bright light, a fluorescent bulb may not be your best option.