Low-Voltage Ballast Failure

About Low-Voltage Lighting

• Low-voltage lighting uses a transformer that plugs into a regular electric outlet. The transformer reduces the 120-volt household electric power to 12 volts. These devices are often called “step down” transformers because they step the electrical power down to this lower level. The more powerful the transformer the more light fixtures can be strung into the systems. Most transformers can handle 100 to 300 watts. Adding more lights or brighter lights to the system may require a strong transformer.

What Is a Ballast?

• A ballast is a device that regulates the amount of current in an electrical circuit. Ballasts come in a variety of types depending on the type of lighting used. Fluorescent lighting uses ballasts that control the amount of current that lights the tube. Some ballasts allow for an “instant start” that allows for quick lighting instead of the slow warm-up of the fluorescent tube. In low-voltage lighting, the ballast connects multiple lights in the string in order to control the correct flow of electricity to each light.

How Ballasts Work

• Ballasts carry the initial electrical current to the bulb and then regulate the amount of electricity that flows to the bulb. Therefore, they also control how much light the bulb gives off. The ability of the ballast to allow electricity to flow through it is measured as a “ballast factor” or BF. Low-voltage lighting uses a ballast with a low BF for energy savings. Using a higher BF for this application will cause the bulbs to wear out more quickly, according to the AC Electronics website.

Ballast Failure

• Ballasts generally last longer than the lightbulbs, so homeowners usually find that they have problems with lightbulbs more often than with the ballast. However, recurring problems such as flickering or outages even after changing the bulb may be caused by a malfunction in the ballast.

Troubleshooting Low-Voltage Light Ballasts

• Using an improper ballast for the type of lighting can lead to flickering or erratic operation. During the start-up period, some types of lights may warm and then extinguish because of the improper voltage relationships that are delivered by the ballast, according to the Venture Lighting website. Signs of impending ballast failure can be detected by the appearance of the part, which may be charred from overheating.