Lamp Ballast Replacement | How To Change Your Fluorescent Light Ballast EASILY!

  • Home Decor 101
  • Posted by: carson-rutz
  • Jun 14, 2024

A ballast, also known as a control gear, is a small component located inside the light. It provides the initial voltage needed to start the light and controls the flow of current. Various lighting types, such as LEDs, fluorescents, halogens, and HID/Metal Halides, utilize ballasts for smooth operation.

Our guide provides a detailed walkthrough of the steps required for lamp ballast replacement and discusses important signs that suggest when a ballast replacement is necessary, ensuring your lighting system works efficiently.

Project evaluation: 

Skill Estimated Cost Estimated Time
Intermediate  $15 to $25 1 hour

Tools and Materials Required for Lamp Ballast Replacement

For a smooth lamp ballast replacement process, having the right tools and materials on hand is crucial. Here's a helpful list to ensure efficiency and success.

Materials  Uses
Replacement ballast

Replacement ballast

  • Regulate electrical currents
  • 2 popular types of ballasts: Magnetic and electronic ballast
Electrical pliers

Electrical pliers

Cut, straighten, and bend wire, as well as twist wires together for splices.


Used for turning screws, tightening or loosening them to assemble or disassemble components of a lamp.
Wire cutters

Wire cutters

Enable precise cutting and stripping of wires to ensure proper electrical connections.
Voltage tester

Voltage tester

Detect live electrical currents and prevent accidental shocks or damage to equipment.
Wire connectors

Wire connectors

Connect two or more wires securely
Labelling materials

Labelling materials

Mark wires and components during lamp ballast replacement
Rubber gloves

Rubber gloves

Help protect against electrical shocks and ensure a secure grip on tools
Safety glasses

Safety glasses

Shield eyes from debris and sparks while replacing lamp ballast (applicable when replacing old lamps)

How to Change the Ballast on a Fluorescent Light?

Changing the ballast on a fluorescent light is a breeze with our 9 simple steps crafted to guide you smoothly through the process.

Step 1: Disconnect the power

Disconnect power before changing lamp ballast replacement for safety (source: powered electrical & data)
Disconnect power before changing lamp ballast replacement for safety (source: powered electrical & data)

Before starting any electrical work, ensure the power to the lighting fixture is off. You can do this by either turning off the circuit breaker or removing the fuse connected to the fixture.

  • Turning off the circuit breaker: Find the electrical panel or fuse box in your home or workspace. Open the panel cover and locate the circuit breaker for the fluorescent light fixture. Flip the switch to the “off” position to cut off power.
  • Removing the fuse: If the fixture is connected to a fuse, use insulated pliers or fuse pullers to carefully remove the fuse. Handle the fuse with care to avoid injury or damage.

Step 2: Remove the tube and fixture cover

Carefully remove the lens or diffuser cover from the fixture to access the lamp and ballast. Here’s how:

Remove the cover: To remove the lens or diffuser cover from the fixture, start by identifying the type of fixture you have. If your fixture has a clear plastic lens on the outside, simply grab the outer edge and gently pull it away from the fixture, then down. For fixtures with a lens inside a framed lid, look for locking clasps that can be pulled down to allow the lens to swing down.

Remove plastic fluorescent light cover (source: youtube)
Remove plastic fluorescent light cover (source: youtube)

Remove the fluorescent tube: To remove the fluorescent tubes, twist each bulb about 90 degrees until you see the metal contacts at the ends. Then, gently pull down on one end to release the contacts from the socket. After that, take out the bulb from the fixture, and repeat the steps for any other tubes. It is important to handle it with care to avoid breakage. 

Remove the fluorescent tube (source: youtube)
Remove the fluorescent tube (source: youtube)

Remove the cover plate: Inspect the fixture to determine how the cover is secured. It may require unscrewing screws, releasing clips, or gently sliding it off. Take your time to avoid damaging the cover or the fixture. 

How to remove ballast cover from fluorescent light fixture (source: youtube)
How to remove ballast cover from fluorescent light fixture (source: youtube)

Step 3: Identify the ballast

Identifying the ballast is one of the important steps in lamp ballast replacement (source: the spruce)
Identifying the ballast is one of the important steps in lamp ballast replacement (source: the spruce)

Locate the ballast within the lighting fixture. It is typically a rectangular or square-shaped component mounted on or near the lamp sockets. Take note of the ballast's make, model, and wattage rating for selecting the correct fluorescent light ballast replacement.

What about the LED tube with ballast? Here are some tips to determine compatibility to replace ballast with LED. Every LED tube, irrespective of driver type, is assigned a size designation indicated by the letter “T” followed by a number, representing the tube's diameter in eighths of an inch. For instance, T5 denotes a 5/8-inch diameter, T8 signifies a 1-inch diameter, and T12 indicates a 1-1/2-inch diameter. 

Additionally, on the ballast label, there is a number close to the UPC code known as the package description, along with a product code. These details assist in determining lamp compatibility and lamp ballast replacement properly.

A chart showing lamp and ballast compatibility (source: lowes)
A chart showing lamp and ballast compatibility (source: lowes)

Step 4: Remove the old ballast

Cut the old ballast wiring (source: youtube)
Cut the old ballast wiring (source: youtube)

Cut the old ballast wiring: To change the ballast on a fluorescent light, the first step is to cut the old ballast wiring. Using side-cutting pliers or wire snips, snip the wiring several inches from the end of the fluorescent ballast. Be sure to cut all the wires connected to the fluorescent light ballast; typically, there will be four to eight wires protruding from the ballast.

Unscrew the old ballast: The next step after cutting the old wiring is to unscrew the old ballast. Locate the mounting nut or nuts securing the ballast to the fixture and use the appropriate tool, such as a screwdriver or wrench, to loosen and remove them. The mounting nuts holding the ballast in place may be one or two, depending on the fixture. Hold onto the ballast with your free hand as you remove the nuts to keep it from falling out suddenly.

*Note: Carefully detach the wires, taking note of their positions or labeling them for easier reconnection later.

Step 5: Choose the right replacement ballast

The following essential details can help you narrow your search for ballast:

Types of fluorescent lamps 

Fluorescent lamps typically fall into two categories: compact fluorescent or linear fluorescent (tubes). These lamps display part numbers and specifications that aid in identifying their type (CF for “Compact Fluorescent” or F for “Fluorescent”) and wattage. For example, F32T8 refers to a 32-watt fluorescent tube lamp.

Besides, considering the shape of fluorescent lamps, such as T8 or T12, is important when you want to change ballast T8 or replace a ballast in a T12 fluorescent light because each type requires a specific ballast designed to match its size and electrical specifications. T8 and T12 lamps have different diameters and lengths, which impact the compatibility of the ballast. 

Additionally, considering the lamp shape helps in determining the proper installation procedure, as the mounting and wiring configurations may differ between T8 and T12 fixtures. 

Ballast’s dimensions

The size of ballasts is a significant consideration. While older troffers typically offer ample space, indirect baskets may have limitations. The recommended approach is to measure the current ballast and use those dimensions as a reference for the new one.

The number of lamps you're powering

Ballasts are designed to hold a specified number or range of lamps. So, how to change a ballast in a 4 bulb fluorescent light? If your fixture contains 4 tubes, ensure the ballast you select can power all 4. This information is often included in the product description. Most commonly, ballasts are designed to power either 2 or 4 lamps.

Types of Fluorescent Ballasts: Magnetic vs. Electronic

Fluorescent ballasts come in two types: magnetic or electronic. Electronic ballasts are more energy-efficient and quieter than magnetic ones. The majority of modern lights utilize electronic ballasts, while they may be operating on a magnetic ballast if your lamp fixture is 10 years old or older. 

You can identify a magnetic ballast if your fixture flickers when turning on and emits a hum. Additionally, magnetic ballasts are notably heavier than electronic ones.

Start type of Ballast

Each type of ballast - instant, rapid, and programmed start ballast - has advantages and disadvantages.

  • Rapid Start involves preheating filaments before fully activating the lamp, often with a brief delay. While available in both magnetic and electronic ballasts, it's more prevalent in the former.
  • Instant Start immediately powers on upon switch activation, exclusive to electronic ballasts and widely used.
  • Programmed Start represents the latest innovation, blending features of rapid and instant start to minimize the detrimental effects of instant start ballasts while extending lamp lifespan. This type is solely electronic.

Voltage Powering your fixture

When proceeding with lamp ballast replacement, it is crucial not to overlook the importance of voltage regulation. A ballast's principal function is to regulate the voltage required for lamp functioning. Understanding the incoming voltage to your fixture is essential. Electronic ballasts are capable of accommodating various voltages, commonly known as "universal voltage."

If you're unsure about the compatibility of the voltage powering your device, seek guidance from the seller or a handyman. They can provide precise information to ensure your electrical setup is safe and appropriate for your needs.

Step 6: Install the new ballast

Remove about 1/2 inch (12 mm) of insulation from the ends of each of the eight wires in the electrical wiring (source: youtube)
Remove about 1/2 inch (12 mm) of insulation from the ends of each of the eight wires in the electrical wiring (source: youtube)

First, mount the new ballast securely in the fixture, ensuring it is in the same position as the old one.

Next, strip the electrical wiring back approximately 1/2 inch (12 mm) of insulation from the ends of all 8 of the wires to expose the wire and connect the matching-colored wires from the fixture to the corresponding wires on the new ballast. Make connections between the red and the red, the white and the white, the black and the black, and the blue and the blue wires.

Then, secure the connections with twist-wire connectors, making sure they are tight and insulated to avoid electrical dangers. Check out our guide about ideas for how to hide a lamp cord to enhance both the functionality and appearance of your lighting setup.

Lastly, once all the wiring is connected, replace the ballast compartment cover, making sure it is securely fastened to protect the internal components. 

Step 7: Test the connection

Verify the new fitted ballast and turn on the power before completely reassembling the fixture (source: youtube)
Verify the new fitted ballast and turn on the power before completely reassembling the fixture (source: youtube)

Before fully reassembling the fixture, turn on the power and test the newly installed ballast. Check if the lamp lights up properly without flickering or buzzing. If everything is running smoothly, turn off the power again.

Step 8: Reassemble the fixture

Reassembling a fluorescent light fixture is the next step after having successfully lamp ballast replacement (source: youtube)
Reassembling a fluorescent light fixture is the next step after having successfully lamp ballast replacement (source: youtube)

After successfully replacing the ballast on a fluorescent light fixture, the next step is to reassemble the fixture. Begin by carefully positioning the lamp cover or diffuser back onto the fixture, making sure it fits securely into place. Take a moment to double-check all screws, clips, or other fastening mechanisms to ensure they are tightened properly, which is essential for the safety and longevity of the fixture.

Step 9: Restore power and test again

The final step is to restore power and test the fixture again. Switch on the power to the lighting fixture and observe the lamp closely to ensure it illuminates without any flickering or other issues. Testing ensures the success of the ballast replacement and the proper functioning of the fluorescent light.

Watch the video below to gain a better understanding of replacing a fluorescent light ballast replacement. It offers a visual guide to help you through the process more effectively!

In case you have successfully carried out lamp ballast replacement and then desire to enhance its appearance, our article on how to clean a lamp at home offers valuable guidance. Following these instructions will assist you in achieving a fresh and new look for your light bulb!

How Do I Know If My Ballast Needs To Be Replaced?

Check for some symptoms to determine lamp ballast replacement (source: zoro tools)
Check for some symptoms to determine lamp ballast replacement (source: zoro tools)

Most lamp ballasts last 10 - 20 years, but heat, moisture, and other factors can shorten their lifespan. To avoid problems, it's advisable to have a professional regularly inspect your lights for damage. Here are 6 signs your ballast needs replacing:

  1. Flickering lights: The flickering may be intermittent or consistent, and it can be a sign that the ballast is not providing a steady flow of electricity to the lamp.
  2. Buzzing or humming sounds: A defective ballast may cause any buzzing or humming noises coming from the light fixture. These sounds usually point to an issue with the electrical parts or the ballast's capacity to control electricity appropriately.
  3. Uneven or inconsistent brightness: If your lights suddenly look too bright or too dim, your ballast might be malfunctioning. Especially if some bulbs in a group seem brighter or dimmer, that could mean your ballast isn't spreading power evenly.
  4. Delayed or slow start: If your light takes a while to turn on or seems to start slowly, it could be a sign that the ballast needs replacing. The ballast might be having trouble providing enough power for the lamp to ignite.
  5. Burn marks or excessive heat: Examine the ballast and its surroundings for any indications of burns or overheating. Excess heat produced by a malfunctioning ballast may harm the ballast itself as well as other parts of the fixture.
  6. Shortened lamp lifespan: A malfunctioning ballast could be the cause of your lamps burning out more frequently than normal or lasting a lot less time. A defective ballast's inconsistent power supply can overstress the lamp and cause it to fail before its time.
  7. Swollen casing: When the heat from a ballast's internal components exceeds the casing's capacity, it may cause swelling. If you see a swollen casing during the inspection, you need to have the lamp ballast replaced to avoid potential hazards or further damage.
  8. Leaking oil: The oil serves to cool the ballast components and maintain their performance. Leaking oil indicates that the ballast's components are aging and may fail over time. 


In summary, we outline 9 straightforward steps for lamp ballast replacement with ease. By following these steps, you can confidently address any issues with their ballast. Furthermore, the article provides insights on identifying when a ballast requires replacement, empowering individuals to troubleshoot effectively. 


How often does a ballast need to be replaced?

Ballasts usually need replacement based on their lifespan. Magnetic ballasts tend to last around 10 to 15 years, while electronic ballasts have a longer lifespan, ranging from 15 to 20 years. Regular maintenance and monitoring can ensure optimal performance and timely replacements when needed.

How can you tell how old a ballast is?

Look for a four-digit number on the ballast label or stamped on the back of the case. Swap the first two digits to get a date in YYMM format. For instance, if you have 2811, it means November 1982.


Leave a comment

Your email address will not be published. Required fields are marked *