How To Change a Fluorescent Light Bulb in Minutes

Different fixtures require different light bulb types to work safely and efficiently. U.S. legislation is phasing out CFLs (compact fluorescent lights) and fluorescent lights in alignment with consumer safety.

While older fixtures often require T12 bulbs (1.5’’ diameter), the newer energy-efficient fixtures commonly use T8 bulbs. The T stands for tubular and the number is the diameter in eighth fractions of an inch, not the length in feet. The T12 is 12/8 of an inch or 1.5 inches, the T8 is 8/8, and the T5 is 5/8 inch. 

Before updating your old bulb to an LED or from an incandescent vs. fluorescent light bulb, you may need to retrofit your ballast to ensure bulb-to-fixture compatibility. The ballast is the small machine that stores the charge that lights the bulb and distributes the voltage evenly to keep it from overloading. 

A safety-minded DIYer might deem this step obvious, but make sure the power to the fixture is off before anything else. Depending on the bulb you are replacing, do the following:

• Flick off the wall switch. 

• Disconnect electricity to the fixture via your fuse box. 

Test that the electricity is off by flicking the switch again. Then, confirm that you can safely and comfortably reach your fixture without straining. Ask someone to spot you on a stepladder if the fixture is located high above you.

Hop over this step and skip on to number four if the type of light fixture you have is uncovered.

If your light does have a cover, you can usually remove it by twisting the caps or seals counterclockwise using your pliers until they pop off. Have your hand ready to stabilize the cover once it's loose to avoid being hit by it. Gently slide the cover off the fixture.

Double-bulb units typically have a screw on each side, and four-bulb units typically have an additional screw on the top center edge. So, remove screws if needed. 

At this stage, you should be looking at an open fixture that exposes the light bulb you want to change. Here's how to safely remove the bulb:

• Test that the bulb isn't hot to the touch before grabbing it.

• Keep your hands near the ends or base of the bulb.

• Gently rotate the bulb clockwise to loosen it.

• Identify the pins holding the bulb in the fixture.

• Rotate the bulb toward you.

• Bring the bulb into vertical alignment.

• Slide the bulb toward you.

With the cover off, inspect the sockets at either end. Use a screwdriver to tighten loose sockets, and replace any broken ones. You can now set the tube in a safe place unless it didn’t come out cleanly—then you’ll need to learn how to remove a broken light bulb. Compare the type of light bulb base of the old light with your new bulb. If they match, you can move on to the next step.

Now it’s time to bring in the replacement bulb. Here's how to install it:

• Align the bulb's prongs with the socket slots.

• Lift the tube into the sockets.

• Rotate the tube 90 degrees.

• Confirm that it "locks" into place.

• Do a gentle tap to ensure it's secure.

You can repeat this process for as many bulbs as you need. Just make sure to focus on handling one bulb at a time to avoid shattering. 

Test that the new bulb works correctly by reversing your steps to flip the fuse box and light switch back on. If it lights, you’ve successfully repaired the bulb. 

If you’re still in the dark, consider troubleshooting the other ballast or sockets. A faulty ballast can make a humming sound, cause the lights to flicker, or short the bulb out as soon as you power it up. Older ballasts and ballasts exposed to cold air tend to burn out more frequently.

The good news is that if you do need to replace your old ballast, the modern designs are electronic and an excellent energy-saving lighting option. And who doesn’t love a lower electricity bill?