How to Change a Circular Fluorescent Light Bulb

Co-authored by Daniel Stoescu and Christopher M. Osborne, PhD

Last Updated: April 8, 2021

Circular fluorescent light bulbs can be a great decorative feature, and changing the bulb is only slightly more challenging than a standard screw-in light bulb. It only takes a few minutes to switch bulbs if you use a matching replacement bulb and prioritize safety by shutting off the power supply and being careful not to break the bulb. After that, your ring of light will glow brightly once more!

Method 1

Method 1 of 4:

Removing the Old Bulb

1
Turn off the power to the light fixture at the electrical panel. Head to your home’s electrical panel and turn off the breaker switch that controls the circuit that the light fixture is on. If your breaker switches aren’t labeled clearly or you aren’t sure which circuit the light is on, turn off all potential circuits or the entire electrical supply to your home.^{[1]
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- For extra safety, get a no-touch voltage tester and hold it as close as possible to the light fixture. If the tester lights up, electricity is still flowing through the fixture.
- It is possible to change the bulb simply by turning off the light switch while you work, but it’s best to completely avoid the small risk of electric shock. If you do choose this route, post a clear note at the light switch so that the light is not accidentally switched on while you work.
2
Remove the light fixture’s cover to expose the bulb. Most circular fluorescent light fixtures have a translucent glass or plastic diffuser that conceals the bulb. If you have the product manual for the fixture, follow its directions on how to remove the cover. You’ll often have to do one of the following:^{[2]
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- Unscrew the decorative knob at the center of the cover.
- Twist the entire cover counterclockwise.
- Loosen several small screws located along the perimeter of the cover.
- Lift open several clips found along the perimeter of the fixture where it meets the ceiling.
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3
Release the spring-loaded clip or clips that hold the bulb in place. Circular fluorescent fixtures typically use 1 or 2 J-shaped, spring-loaded metal clips to hold the bulb in place. Use one hand to hold the bulb and your other hand to flex each clip—1 at a time if there are 2 or more—away from the bulb. Lower the bulb enough to keep it clear of the clips, but not so much that you put tension on the wire that’s still connected to it.^{[3]
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4
Pull out the plug that connects the bulb to the fixture’s ballast. Once free from the clip(s), the bulb will still be connected by a wire bundle to the ballast—a small box at the center of the fixture that regulates power flow to the bulb. Grasp the plug that connects the wire bundle to the bulb and pull it free of the bulb.^{[4]
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- The plug has multiple slots (usually 2 or 4) that line up with a set of metal pins sticking out of the small, opaque section of the bulb that doesn’t illuminate.

Method 2

Method 2 of 4:

Choosing a Replacement Bulb

1
Write down the bulb’s model, wattage, and T-number. Unfortunately, there’s little standardization when it comes to circular fluorescent bulbs. To ensure that the replacement fits and works properly, get as much information about the old bulb as you can. Start by reading the info printed on the bulb, such as:^{[5]
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- The manufacturer. Your best bet is to get a replacement bulb made by the same manufacturer.
- The model number.
- The bulb’s wattage.
- The T-number. Fluorescent bulbs use a T-number to denote the diameter of the bulb tube. Dividing the T-number by 8 gives you the tube diameter in inches. For example, a T8 bulb has a 1 in (2.5 cm) tube diameter.
2
Sketch the layout of the bulb’s plug-in pins. The number and positioning of the pins can vary from brand to brand or even model to model. To make it easier while shopping for a replacement bulb, jot down a quick sketch of the pin placement on your piece of paper with the other bulb info.^{[6]
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- Many circular fluorescent bulbs have 2 metal pins to accept the plug coming from the ballast, others have 4, and a few have some other number.
3
Buy a new bulb that’s as close to an exact match as possible. If you’re heading to the hardware store, bring the old bulb with you if at all possible. Otherwise, bring your notes and sketches regarding the old bulb. If you’re buying online, check the product description carefully against your info on the old bulb.^{[7]
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- Circular fluorescent bulbs range in price from roughly $5-$30 USD.
- Consider switching to LED lighting. LED technology uses less power, is more efficient, costs less long-term, and does not contain mercury.

Method 3

Method 3 of 4:

Installing the New Bulb

1
Insert the plug firmly into the pins on the new bulb. Grab the plug at the end of the wire that connects to the ballast. Press it firmly so that the pins on the bulb are inserted completely into the plug. Work carefully, though, so you don’t accidentally break the bulb.^{[8]
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- If you left home for a little while to pick out a replacement bulb at the hardware store, confirm that the power to the light fixture is still switched off at the electrical panel before installing the new bulb.
2
Hold the bulb in place with the spring-loaded clip(s). Flex the clip out of the way so you can position the bulb in place above it, then guide the clip back into place so that it holds the bulb securely. If there is more than one clip, repeat the process.^{[9]
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- Once again, remember to work carefully, since fluorescent bulbs break easily and clean-up is a chore!
3
Turn on the power and test the new bulb. Go to the electrical panel and turn on the circuit that supplies the light fixture. Head back to the light fixture and flip the switch on the wall—the light should illuminate fully and evenly within 1-3 seconds. If it lights up slowly or unevenly, turn the power back off at the panel and check the plug connection to the ballast.^{[10]
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- If the fixture won’t light up at all, there may be a problem with the new bulb, the ballast, or your home wiring.
- You can replace a bad ballast, but it’s usually no more difficult to replace the entire light fixture. In this case, you may want to take the opportunity to switch to an LED fixture that replicates the look of a circular fluorescent light.
4
Put the fixture’s cover back in place securely. Reverse the process you used to remove the cover—for instance, by tightening the decorative knob in the center of the cover to secure it in place. Once the cover is snug and looks right, you’re all finished!^{[11]
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Method 4

Method 4 of 4:

Dealing with a Shattered Bulb

1
Isolate and ventilate the room if you break a bulb. Fluorescent bulbs are fragile and contain a small amount of mercury inside. If you accidentally break a bulb, do the following before starting the clean-up proces:
- Close all interior doors and vents in the room.
- Open all exterior doors, windows, or vents in the room.
- Put on disposable cleaning gloves, if available.
2
Remove and dispose of all visible pieces of the broken bulb. Use 2 stiff pieces of cardboard as a makeshift brush and dustpan. Scoop the broken pieces into a rigid container with a tight-fitting lid, like a large mayonnaise jar. Use wadded-up masking tape to pick up small fragments, then put the tape in the discard container.
- If you need a bigger discard container, like a coffee can or a 5-gallon bucket, seal the lid completely with tape when you’re all done with the clean-up process.
3
Clean where the bulb shattered with wet wipes and a vacuum. Wipe solid surfaces in the immediate area with damp cleaning cloths and dispose of them in the discard container. Shake out removable rugs outdoors and leave them to air out for at least 2 hours.
- Vacuum any carpeting in the immediate area while the room is sealed off and ventilated, empty the vacuum outdoors and put the debris in the discard container, wipe down the vacuum, and leave it outdoors for at least 2 hours.
4
Dispose of the trash safely and keep the room sealed off for 2 hours. Double-bag the discard container, put it outdoors in a non-accessible area, and contact a hazardous waste remover for proper disposal. Keep the room sealed and ventilated and keep out pets, children, and pregnant women for at least 2 hours.
- Unbroken fluorescent bulbs that simply don’t work anymore should also be hauled away by a hazardous waste remover or dropped off at a designated location.

Warnings

Play it safe and shut off the power supply at the electrical panel before changing the bulb. It only takes a minute!

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Follow the proper clean-up procedures if you break a bulb. Even though fluorescent bulbs contain only a small amount of mercury, it can be harmful to pets, small children, and pregnant women.

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