Why Is the Ballast Overheating?

Fluorescent light fixtures use a special device called a ballast to start the electrical current that creates light within each bulb. This ballast wears out over time and begins to show signs of wear, such as overheating. Other common problems can cause the ballast to overheat, which poses a fire risk.

Each fluorescent lighting fixture ballast is designed to send a specific amount of voltage through the bulb. When a bulb of the wrong size or voltage is used in the fixture, the ballast often overheats, causing the light to shut off. The bulbs and the fixture must also match in frequency, or the ballast becomes overworked and overheated. Other signs of incompatible bulbs include slow and obvious flickering or a loud whine.

While many newer fluorescent fixtures feature instant or rapid starting mechanisms, some older models use separate starters to help the bulb light up when the switch is flipped. These starters can become stuck closed and fail to open when electricity is sent to the ballast. This causes the ballast to overheat as it continues to send power to the starter that has failed to send electricity through the rest of the bulb.

When a lightning strike or power line issue causes a sudden spike in the amount of electricity being sent through your house or building, it can damage all of your appliances. The ballast on a fluorescent lamp is particularly sensitive to spikes in power, and even a short surge can heat up the ballast enough to break it. Installing surge-control devices between the lighting fixture and its connection to the electrical line can help prevent or stop this problem from recurring.

Any issue that causes excess voltage to run through the fluorescent bulb ballast leads to overheating, and incorrect wiring during the construction of the fixture or installation is one of the most common causes of this problem. If a certain fixture keeps overheating the ballast no matter what you do to prevent it, there is most likely a problem in the wiring. Rewiring the fixture is required, or the ballast will continue to overheat and have to be replaced.