Replacing an Electrical Ballast

What Are Electrical Ballasts?

An electrical ballast is a device that controls the current flow in an electrical circuit. It does this through electromagnetic induction, which means that it uses an electromagnet to control the current flow. This type of device is used to regulate lamps and circuits with alternating currents (AC). They are commonly used in fluorescent lighting fixtures. 

Types of Electrical Ballasts

Different types of ballasts are available for commercial and residential use, so conducting the proper research before buying is essential. They come in two different primary types: magnetic and electronic. Both types have distinct uses and installed bases. A magnetic ballast, for instance, uses a transformer to control the electric current. The transformer consists of a coil wire called an inductor that produces a magnetic field. The magnetic field slows down the current which allows the fluorescent bulb to properly put out the correct amount of light. When the ballast is wrong, it can cause flickering and buzzing. Unlike magnetic ballasts, electronic ballasts have no moving parts within the circuit. The high voltage that triggers a fluorescent light activates a small circuit board to power the bulb. Generally, it lasts for 10 years or more, as opposed to 2-4 years with magnetic ballasts. In addition to instant starting, electronic models do not require special sockets, making them easy to replace. In addition, they offer better dimming capabilities than magnetic models. If a customer wants a large area lit, but does not require full brightness, they can choose low-level lighting that will remain constant without flickering. 

How Does An Electrical Ballast Work?

An electrical ballast works by converting electrical current into alternating current (AC). It also regulates voltage so that it remains consistent throughout the operation. This means that all lamps connected to the same ballast will ignite at the same time. In addition, the ballast limits current flow so that it does not exceed a certain threshold.

What Is the Necessity To Replace Ballasts?

If you notice any of these issues with your fluorescent light fixtures, you should consider replacing the ballast.

Frequent cycling of lights

This happens when the lighting dims for a short period, then goes completely dark or very bright. 

One lamp remains lit while all others go out 

This usually means there’s nothing wrong with the lamp but only that the ballast needs replacement. If you were to remove one of the lamps, another would most likely stay on as well. 

Unusually high electric bills

This often occurs because magnetic ballasts are not properly regulating energy use which can waste up to 30% more than electronic models do. 

No lights at all 

If the fluorescent bulbs never turn on when they should, it’s most likely because one of the parts is faulty and needs to be replaced. 


When a ballast starts to fail, it can produce a buzzing or humming noise. The noise is the ballast incorrectly handling the amount of current coming from the circuit panel. You should call an electrician so they can find out what’s happening. Although it’s most likely your ballast, it can also be a sign of something worse.

Changing colors 

The color of the light coming from fluorescent bulbs changes as they age. They begin to emit a dim orange or red glow which can be fixed by replacing the ballast.

Swollen casing

You do not need to remove the cover to find out whether the ballast is bulging. If it is, then your only option is a light ballast replacement.

Burn marks 

Burn marks may be visible on the wires extending from the ballast. Don’t stick anything around the wiring to get a better look. If you can’t see it, call for a qualified technician to help you.

Water damage 

Water damage can come from anywhere. Simply look to see if there is excess moisture on the ballast. If you see any of these issues, then your ballast is shot. Call for a light ballast replacement before more damage is done. 

Leaking oil

If your ballasts are leaking oil, it may be the sign of a faulty capacitor that needs replacement.

When Is the Right Time To Replace Ballasts?

Electrical ballasts do not last forever. They eventually wear out through constant exposure to heat and vibration. The best time to replace ballast is when one of the above issues presents itself, but professionals agree that there comes a time in every fluorescent light fixture’s life when it’s convenient to simply replace them altogether. While aging bulbs will dim over time, energy-efficient electronic models do not have this issue. However, even if they are dimming or seem weak, they shouldn’t be removed since you cannot predict how another bulb will behave afterward. It’s also important to note that even if your lamps are still operating efficiently, over time their color will change from white to orange or which can be fixed with the replacement of the ballast itself.

Why Ballast Replacement is Safer than Repair

The method used to reduce the voltage inside the ballast will be dependent upon the lamp is lit and the light components inside. The different types of lights that include ballasts are LEDs lights, fluorescent lights, halogens, and HID/Metal Halides. In these lighting sources, resistors, inductors, and capacitors are used, sometimes in combination, to provide the required voltage at a consistent rate. Incorrectly replacing the elements in the wrong order or wiring the new ballast incorrectly could create a very unsafe environment with the lamp malfunctioning. So when it comes to ballast repair vs ballast replacement, replacement by a certified electrician is a more sensible and safer alternative. If needed, your electrician can upgrade your lighting in addition.

How To Replace A Ballast

When it’s time to replace the ballasts in your fluorescent lights, follow these steps for an easy process. Please do not proceed if you are not experienced with electrical work. Call a residential electrician instead or if you need to replace numerous ballast’ then call a commercial electrician. If you proceed you do so at your own risk. Gather Tools & Materials, such as:
  • Voltage tester
  • Wirecutter/stripper
  • Wire nuts
  • Socket wrench
  • Smartphone/camera
Cut Power Turn off the fluorescent light fixture if it is possible to do so. Or, if that is not an option, turn off the power at the circuit breaker. Take the Cover Off the Fixture On fixtures with a clear plastic lens surrounding the fixture, remove the cover. When the lid of your fixture has a frame, look for the clasps. You will be able to swing the lens open by pulling the clasps down. Remove the Fluorescent Light Tubes The bulbs should be rotated 90 degrees. You can gently pull down on the metal contacts located at the ends of the bulb until you can pull them out of the sockets. While you’re in there, check the sockets holding the bulbs, tightening or replacing them as necessary. Take Off the Cover Plate For the wires to be exposed, the wiring cover plate needs to be removed from the center of the fixture. Visually locate the tabs that hold the cover in place, then squeeze in the sides of the cover to release the tabs from the slots, pulling down to remove the cover. Check for Voltage Using a non-contact voltage tester, verify there is no power flowing to the fixture before touching any wires/connections. Take a Picture Take a picture of the wires so that you can refer to them when connecting the new ballast. Disconnect the Ballast Wires Remove the connectors or cut the wires as close as possible to the ballast to disconnect each ballast wire. Remove the Ballast While using your socket wrench to remove the mounting hardware, support the ballast with your hand to prevent it from falling. Afterward, remove the ballast from the fixture. Find and purchase the Replacement Ballast You can find a replacement ballast either by taking the part number or the ballast itself to a lighting supply store. Ensure the wiring diagram, voltage, and current of the new ballast match those of the old one. If possible, use electronic ballasts, which are more efficient and quieter than older magnetic ones. Preparation of wires for the new ballast Remove damaged or crimped portions of ballast wires, stripping ½ inch insulation from the ends using wire strippers. Then install the new ballast Install the new ballast into the fixture using mounting hardware and your socket wrench. You will need to use wire nuts to attach the new ballast wires, referring to your photo and ensuring that they match the original wiring. Reinstall the light components Replace the wiring cover plate, followed by the fixture lens and the bulbs. Restore the power Upon resetting the circuit breaker, plug in the light and check for proper operation. Ensure that the old ballast is disposed of properly Ballasts made before 1979 often contain polychlorinated biphenyls (PCBs), a known environmental toxin. If your old ballast leaks a black substance, handle it gently and avoid skin contact. For proper disposal of old ballasts, take them to the nearest hazardous waste recycling facility.

Final Thoughts

Electrical ballast replacement can be a do-it-yourself task that you can accomplish on your own with the right tools and knowledge. However, if you suspect your electrical wiring or the environment is complicated enough to challenge your skill level, hire a licensed electrician for help.

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