A ballast is an integral part of fluorescent light fixtures, helping to power the individual fluorescent lamps. The fluorescent ballast is designed to provide the right amount of voltage that is needed to start the lamps and helps regulate the electrical current that flows to them once they're powered on. For a fluorescent bulb to be started, an arc must be produced between the two electrodes within the lamp. The arc occurs from the ballast quickly supplying the right amount of voltage and current that's needed to strike the arc. Then the voltage and current are limited to produce continuous, steady light output. If there was no ballast present to control regulation, the fluorescent tube would be drawing power directly from the high voltage power source coming into the fixture, resulting in uncontrollable current draw, which would cause the lamp to quickly overheat and burn out within a few seconds. Ballasts are designed to operate a specific number and type of fluorescent lamps at a specific voltage. So, this means that not all ballasts are not compatible with all fluorescent lamps.
Fluorescent ballasts are available in two types, magnetic and electronic. Magnetic ballasts are the older technology of the two, and are available in either preheat start or rapid start methods. They are less expensive, but they tend to flicker and hum, which can create an uncomfortable working environment. Electronic ballasts operate more quietly, they eliminate the annoying humming sound and flickering that are associated with the magnetic ballasts, and they're also more energy efficient as well. This type of ballast utilizes instant start, programmed start, or rapid start methods.
Instant start ballasts are designed to start fluorescent lamps instantly by sending around 600 Volts through each lamp to start the cathodes. Even though they turn on lights the quickest, but they are intended to stay either on or off for longer lifespans. Also, if they're constantly being switched on and off, their useful life will be drastically reduced. Programmed start, also known as programmed rapid start, ballasts have slower start-up times, but do not sustain the same effects of instant start ballasts when being used in frequent on-off cycles. This type of ballast could even be classified as a smart rapid ballast, since it can sense the temperate of the fluorescent lamp cathodes and uses the minimum amount of power to ignite them. Since cold cathodes require a significant amount of power to ignite, these ballasts are the most efficient of fluorescent ballasts. They're also perfect for areas like bathrooms, hallways, and stairwells that are outfitted with occupancy or vacancy sensors to constantly cycle the fixtures on and off.
Most fluorescent ballasts do not need to be replaced for at least three years. However, the performance of the fixture is gradually reduced as they continue to age. For example, as ballasts start to fail, the light output of each fluorescent lamp will continue to be reduced until complete failure. Ballasts are not designed to last forever, so it is important to know when they are nearing the end of their useful life. If your lights have a buzzing sound, changing color, have constant flickering, or are becoming more dim, it's probably time to consider replacing the ballast in your fixture. If you have any additional questions about fluorescent ballasts, or about which type would be most appropriate for your fixture, feel free to reach out to one of our lighting specialists today.