Ballasts serve only several key functions in lighting applications. According to sources at the Lighting Research Center, ballasts are employed in light bulbs to control the electrical current drawn in from a power source. Another function of light ballasts is to provide the light bulb they are hooked into with a starting voltage. Gas discharge light bulb technology cannot regulate the amount of electricity that passes through the bulb without ballasts.
As of 2010, only two different types of ballasts are used in light bulbs: electronic and electromagnetic ballasts. Electromagnetic ballast technology has been used for decades while electronic ballasts are relatively new to lighting. Electronic ballasts are quickly replacing electromagnetic ballasts. However, light bulbs that are considered “high-output” still require electromagnetic ballasts. One of the most beneficial features of electronic ballasts is that they operate much more quietly than do electromagnetic ballasts.
In some cases, ballasted lights can flicker and produce a buzzing sound. This can be attributed to the ballast, another component of the light bulb or the electrical connection itself. Flicker is caused when the electric current between the power source and the light bulb is interrupted. A defective bulb or a simple loose fit can cause a bulb to flicker or make noise. Changes in voltage levels to the bulb can result in flicker. Electromagnetic ballasts flicker quite a bit during the span of a minute, according to California’s Energy Commission. Electronic ballasts, on the other hand, do not flicker nearly as much as electromagnetic ballasts. Electromagnetic ballasts can flicker up to 120 times per minute.
The adaptable ballast is a type of electronic ballast. Adaptable ballasts are unique in that several light sources can be hooked into a system that uses only one of them. Technological limitations prevent most lights that use ballasts from being able to be hooked into a dimmer system. Hooking a ballasted light bulb into a dimmer system increases the likelihood of experiencing flicker.
Several types of light bulbs on the market require ballasts to function properly. All high-intensity discharge (HID) bulbs, including metal halide bulbs, mercury vapor bulbs and high-pressure sodium bulbs, require ballasts. All fluorescent bulbs, including fluorescent tubes and compact fluorescent bulbs, require ballasts. If a light bulb that required ballasts were powered without its ballast, the bulb would instantly overheat and burn out immediately, according to the Lighting Research Center.