Turn off the power before you touch anything

The first step is always to cut power to the fixture. Flip the wall switch to off, then go to your circuit breaker or fuse box and switch off the breaker that controls that light. If you are not sure which breaker it is, turn off the main breaker instead — it is slower but safer. Wait a few seconds after cutting power before you touch the fixture.

If you are replacing just the tube (the long glowing part) rather than the whole fixture, you still need to turn off the power. Even though fluorescent tubes run on lower voltage than incandescent bulbs, the ballast — the box inside the fixture that controls the tube — can still shock you if you touch the wrong part while power is on.

Key Takeaways

  • Always turn off power at the breaker before touching any part of a fluorescent fixture, whether you are replacing the tube or the whole unit.
  • Fluorescent tubes twist or slide out depending on the type — check the ends of the tube to see which motion applies to yours.
  • If the tube flickers, hums, or does not light after you install a new one, the ballast may be failing and the whole fixture may need replacement.
  • Ballasts contain small amounts of PCB oil in older fixtures (built before 1979), so wear gloves and wash your hands after handling them.
  • A new fluorescent tube costs $3 to $15, while replacing the entire fixture runs $30 to $150 depending on size and type.

Identify whether you are replacing the tube or the fixture

Look at what is actually broken. If the tube itself is dark at the ends, cracked, or simply will not light even though the fixture hums when you turn it on, you only need to replace the tube. If the fixture housing is damaged, the ballast is leaking, or nothing happens at all when you flip the switch, you need to replace the whole unit.

Tubes are much cheaper and faster to swap out. A new tube costs between $3 and $15 depending on length and type. Replacing the entire fixture — the metal housing, ballast, and all wiring — costs $30 to $150 and takes longer, though it is still a job most people can do with basic tools.

How to replace just the tube

After you have turned off the power, look at the ends of the tube. Most fluorescent tubes use one of two systems: a two-pin connector (the tube twists in and out) or a four-pin connector (the tube slides straight out). Check which type yours is before you buy a replacement.

For a twist-in tube, grip the tube gently in the middle and rotate it counterclockwise about a quarter turn until it stops. It should slide straight out. For a slide-out tube, grip it in the middle and pull it straight toward you. Do not force it — if it does not move easily, check that you have the right motion.

Take the old tube with you to the hardware store or home center so you can match the length and wattage exactly. The label on the tube itself shows both. Insert the new tube by reversing the motion: twist clockwise for a twist-in, or slide straight in for a slide-out. Turn the power back on and test it.

When the tube does not light after replacement

If you installed a new tube and it still does not light, the ballast is probably failing. The ballast is the rectangular box mounted inside the fixture housing — it converts standard wall power into the lower voltage the tube needs. When a ballast fails, no tube will light, no matter how new it is.

At this point, replacing just the ballast is possible but usually not worth it. Ballasts cost $15 to $40, and you need to open the fixture housing and disconnect wiring. Most people find it simpler to replace the entire fixture, which takes about the same time and gives you a unit that will last another 10 to 20 years.

How to replace the entire fixture

Turn off the power at the breaker and wait. Use a screwdriver to remove the cover or lens of the old fixture — usually four to six screws. Once the cover is off, you will see the tube and the ballast box underneath. Remove the tube first using the method above, then unscrew the ballast from the fixture housing.

Look at the wiring connected to the ballast. Take a photo with your phone before you disconnect anything. There are usually three to five wires: two that come from the wall power, and two or three that go to the tube sockets. Disconnect each wire by loosening the terminal screws or unclipping the connectors. Write down or photograph which wire went where.

Unscrew the old fixture from the ceiling or wall and remove it. Install the new fixture by reversing these steps: screw it in place, reconnect the wires to the ballast terminals in the same order, install the new tube, and screw the cover back on. Turn the power back on and test.

Safety notes for older fixtures

Fluorescent fixtures built before 1979 often contain a small amount of PCB oil inside the ballast. PCB is a chemical that was banned in the United States because it does not break down in the environment and can accumulate in the body. If you are replacing an old ballast, wear disposable gloves and wash your hands thoroughly afterward. Do not let the oil touch your skin or clothes.

If the ballast is leaking oil, do not try to repair it yourself. Wrap it in plastic, seal it in a bag, and take it to a hazardous waste collection site. Most cities and counties run collection days several times a year, usually for free or a small fee. Call your local solid waste department to find the nearest location.

Tools and materials you will need

For replacing just the tube: a new fluorescent tube that matches your old one exactly, and a way to turn off the breaker (you already have this). For replacing the fixture: a screwdriver (usually Phillips head), wire strippers if the wires are not already stripped, a new fluorescent fixture of the same size, a new tube, and optionally a camera or phone to photograph the wiring before you disconnect it.

You do not need a electrician's license to replace a fixture yourself in most places, as long as you are working in your own home and not running new circuits. However, if you are uncomfortable working with electrical wiring, or if the fixture is in a commercial building, hire a licensed electrician. The cost is usually $100 to $200 for labor, plus the cost of the fixture.

Frequently Asked Questions

Can I replace a fluorescent fixture with an LED fixture in the same space?

Yes. LED fixtures designed to fit standard fluorescent housings are widely available and cost $20 to $60. They use much less power, last longer, and do not flicker. You install them the same way as a fluorescent fixture, and the wiring is identical. Many people make this switch when their old fluorescent ballast fails.

What do I do with the old fluorescent tube?

Fluorescent tubes contain small amounts of mercury and should not go in the trash. Most hardware stores and home centers accept old tubes for free or a small fee. Some cities also run hazardous waste collection days. Call your local solid waste department or check the store's website before you bring it in.

Why does my new tube flicker or hum?

A new tube that flickers or hums usually means the ballast is aging and struggling to start the tube. This is normal for a few seconds when you first turn it on, but if it continues for more than a minute, the ballast is failing. Replace the entire fixture rather than buying another tube.

Do I need a permit to replace a light fixture?

No. Replacing a fixture in your own home does not require a permit in any jurisdiction. If you are renting, check your lease or ask your landlord first — some leases require landlord approval for fixture changes, though most do not.

How long does a fluorescent tube last?

A standard fluorescent tube lasts 7,000 to 10,000 hours of use, which is roughly 3 to 5 years in a typical home or office. Tubes that are turned on and off frequently burn out faster. LED tubes last 25,000 to 50,000 hours, which is why many people switch when their ballast fails.