Easy Fluorescent Light Ballast Replacement At Home

Easy Fluorescent Light Ballast Replacement At Home

Ian Mutuli
Updated on
Ian Mutuli

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.
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Are you tired of your light bulbs constantly flickering? You might be moving to throw away your fluorescent fixture, but did you know you can do a fluorescent light ballast replacement instead?

Normally, fluorescent light bulbs use a ballast to produce the light. The ballast is important in regulating the amount of light that flows into the fluorescent light fixture. You only need to replace the ballast instead of the entire light fixture, and your light bulbs will return to normal functioning. You can also check out on how solar lights work to get more insights on a ballast.

Furthermore, the fluorescent ballast replacement will take only 10 minutes, and you are back to functioning. If you don't know how to replace a fluorescent light ballast, worry less, go through this article and by the time you are done, you will be good to do it yourself. First, let us define what a ballast is for further understanding.

What Is A Ballast?

A ballast is commonly known as a control gear -it is a small device inside a light fixture that provides enough voltage to start the light and regulates the amount of current that flows into the light.

When Should You Replace An Electronic Ballast?

1. Know If Your Light Fixture Requires An Electronic Ballast

replacing a ballast

If you want to solve your light fixture problem, you must know if the ballast wires cause the problem or need a ballast replacement. Not all fluorescent light problems could require a replacement ballast. Make sure this is the problem before you jump to a conclusion. For example, if you have incandescent LED bulbs or halogen bulbs, you will not need a ballast replacement since they are not ballasted dependent.

Another example includes the light bulbs, which have the ballast integrated on their inside, which may make it had to replace since you have to replace the ballast separately.

You may find that most fluorescent lights have internal ballasts, which also may require you to replace them separately. However, compact fluorescent bulbs often have one ballast integrated, but this case is not always common.

If you have a single bulb with an integrated ballast, you will need a replacement ballast just like any other bulb when it starts to flicker or die. You will not tear it apart since its replacement is internal. However, you can fix a larger fixture through an external ballast.

In most cases, the fluorescent light fixture such as the long strips of T12 or T8 found on business ceilings share one electronic ballast wire nuts which you can replace without swapping out the light strips. However, it can be easier to diagnose the problem before the ballast dies since it will burn the bulbs.

2. Look For Warning Signs

After you have diagnosed your fluorescent light fixture to be having a ballast, it is time to look for signs that it is failing before you go ahead and replace it. Typically, if you find that a CFL bulb is out, you can try replacing the tube. But if you notice that the entire section of the fluorescent tube is affected, then it is time to test if the problem might need a ballast replacement. Again, look for the following to help you diagnose the problem:

a). Buzzing

If you hear a funny sound coming from your fluorescent light fixture, it could be a buzzing or a humming noise. The noise is often the first sign that your light will almost die. The noise results from the light bulb struggling to maintain the current and thus causes audible voltage regulations issues.

b). Changing Colors

If your fluorescent is functioning normally, they should always shine brightly. However, if you notice that your light bulbs have a variation in hue, it could mean that the ballast might be on the fritz, and the bulb's voltage could be surging or dying.

c). No Lights At All

If you switch on your fluorescent bulbs and they fail to turn on, the only diagnosis is that they probably went out from an old ballast wire.

d). Dimming Or Flickering

If your fluorescent bulb is low in reaching its full brightness or goes out frequently, it is time to check your ballast wire connectors. The problem could also be beyond the bulb. Your ballast wire could have been damaged by water, or they could be faulty, thus unable to regulate the current, causing flickering or dimming.

3. Check The Ballast Itself

In most cases, you might be diagnosing the fluorescent lights, but the problem could be the ballast. First, you need to know when to get a new ballast wire. It could be an issue if your ballast is shot or huffing. Before looking into the ballast wires, turn off your fixture circuit breaker in the socket wrench before tinkering. Then, go ahead and remove the wiring cover plate of your light before you start examining the ballast for:

a). Swollen Casing

You will see a swollen casing even before taking the casing cover off. If you notice some plastic bulging in the casing, it will mean that your ballast is gone. It could have most likely been overloaded and damaged the box instead.

b). Burn Marks

If you don't notice any changes in the ballast, then it's time to cut it open to see any internal damages. If you notice some burn marks inside the device or wires, you need to get a new ballast. If these return, the ballast wires could handle the current and were overloaded. 

c). Water Damage

Look for any signs of moisture inside your panel or ballast. If you see some water or moisture present, it could be why your ballast wire is not working.

d). Leaking Oil

If you have an old magnetic ballast, the problem that could have caused your ballast fixture wires to malfunction could be leaking oil. You will need to clean the place very well before replacing it.

How To Replace A Fluorescent Light Ballast

Tools And Materials You Will Need

  • Replacement ballast
  • Wire nuts
  • Wirecutter
  • Nut driver or socket wrench
  • Wire strippers
  • Non-contact voltage tester


1. Remove The Cover

Remove the lens diffuser cover from the light fixture. Some light fixtures have a clear plastic lens that is used to wrap around the outside of the fixture. If you have one of these, you will grab the outer edge, gently pull the cover away from the fixture, and pull it down. If the fixture has a lens inside the framed lid, you can look for locking clasps that pull down the lens and allow it to swing.

2. Remove The Fluorescent Tubes

Remove the fluorescent tubes by grabbing them and twisting them in 90 degrees. You will see the metal contacts as it ends. You can further pull down one of its ends gently as you let the contact slide out of its socket. Next, remove the bulb from the fixture and repeat the process to the remaining tubes.

You can now inspect the socket that holds the tubes at each end of the light fixture. If you find them loose or broken, tighten them or replace them.

3. Remove The Cover Plate

Locate each wiring of the cover plate; usually, you can find it at the center of the light fixture. On each side of the cover, you will see some tabs that catch in slots in the fixture. Go ahead and squeeze the sides of the cover inward so that the tabs slip out of the slots. Then pull the cover down. You will now see the light ballast and the wiring. If you don't have an idea, you can follow a wiring diagram to ensure what you are doing.

4. Disconnect The Ballast Wire Connectors

Look for the black and white wires connected to the ballast mounting nuts. These are known as power source wires. It is worth noting that before you touch the wires or any wire connections, you should confirm that the power is off by testing each wire using a non-contact voltage tester. Ensure that the test indicates no voltage present in the wires. Apart from the source wire, four or more wires may connect the ballast to the fixture's bulb sockets.

Pro Tip; Always use your phone or camera to snap a photo of the ballast and wiring diagram for future reference when installing the new ballast.

Disconnect all the ballast wires by removing the wire connectors and separating all wires; you can also cut the wires close to the ballast using a wire cutter.

5. Remove The Ballast

To remove the ballast, you will have to support it with one hand to prevent falling. Next, you can remove the mounting nuts and bolts using a nut driver or a socket wrench. Now, remove the ballast from the fixture.

If you don't have a suitable ballast for replacement, you can bring the ballast with you to the store to find one.

6. Prepare The Wires

If the wires are damaged, or you cut them earlier, you can strip a half-inch of insulation from the end of each fixture using wire strippers.

7. Mount New Ballast

Mount the new ballast to the light fixture using the mounting nuts. You can connect the ballast wires to the fixture wires to match the original wiring. Reinstall the wiring cover plate, light bulbs and fixture lens. Restore your power by fixing your circuit breaker and testing the fixture to see if it works.

Ian Mutuli

About the author

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.
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