Master electrician Heath Eastman takes us on a road trip to solve a homeowner’s dimmer problem. After the homeowner explained that she upgraded the switch to a dimmer and that her track lighting is now flickering, Heath knew just where to start. After checking out the switch to ensure that it was compatible, the two discuss the different types of dimmable switches available.
Flickering Lights are a Common Problem
Dimmable lights are a desirable feature. They allow homeowners to adjust the lighting for the time of day, conserve energy, or even set the mood for a movie or romantic dinner. Many homeowners install dimmable switches to achieve this effect, but they end up with lights that simply flicker rather than dim, or switches that don’t do anything at all. Both issues are very common.
Start with the Light Fixture
If the switch is already installed and the lights are flickering or not doing anything when the dimmer is adjusted, start with the light fixture and its transformer. There are two common types of fixtures: standard voltage (120VAC) and low voltage.
Standard voltage can utilize a dimmer designed for a specific light bulb. On the other hand, low voltage fixtures have a transformer that converts the electricity to a lower voltage. This requires a specific type of switch, those being either magnetic or electronic. If the fixture requires one switch and the wrong type is installed, it’s likely that the lights won’t do anything at all.
Pro Tip: Ken Fairbanks, SmartHome’s vice president of business development, notes that low-voltage lighting systems are particularly prone to dimmer issues: “Depending on the transformer, a product may or may not like being dimmed.” If you’re hearing an electric humming sound from a low-voltage fixture, the transformer and dimmer may simply be incompatible.
Watch for Three-Way Switch Mix-Ups: A common cause of dimmer problems occurs in rooms with two switches controlling one light, such as a kitchen or dining room. As explained on This Old House, people often install a single-pole dimmer—which only has two screw terminals—when the setup actually requires a three-way dimmer with three terminals. The result: the dimmer works in one switch position, but the other switch becomes completely useless because the second runner wire isn’t connected.
Choose the Right Switch
If we determine that the light fixture itself is paired with the wrong switch, the switch needs to be replaced. There are several types of dimmable switches:
- Incandescent dimmer switches. These switches pair with old-style incandescent bulbs and standard light fixtures to adjust the bulb’s brightness.
- Universal dimmer switches. Universal dimmer switches work for several types of light bulbs, including LED, compact fluorescent, halogen, and incandescent bulbs.
- Low-voltage: Certain fixtures require low-voltage switches. Among the types of low-voltage switches are magnetic and electronic, and they’re not interchangeable.
- Universal with low-voltage: There are universal switches that handle not only the standard variety of light bulbs but also electronic and magnetic low-voltage dimming.
It Could Be the Bulb
LEDs are becoming increasingly popular, offering the flexibility of dimming and color temperature while also being energy efficient. However, these bulbs come in both dimmable and non-dimmable versions. If the switch and the fixture are paired correctly, but the light flickers or won’t adjust, likely, the bulb isn’t dimmable. Swapping the current bulbs out for a dimmable version will usually solve the problem.
Pro Tip: Heath, a This Old House electrician, explains that LED bulb compatibility is the most common flickering issue he encounters: “Everyone’s putting LED bulbs in, which is great. Two issues, though. Not all of them are dimmable. Some are non-dimmable. And if you have an older dimmer, it may not be LED-compatible.” He adds that you want to make sure you get a dimmable LED lamp and an LED-compatible dimmer to avoid the flickering.
