Dimmer switches are useful for setting a mood, creating lower light situations at night while still maintaining visibility, lowering energy costs, and just generally controlling the ambience and environment. However, not all light bulbs are compatible with dimmer switches and it can be confusing for homeowners. Previously, before improvements in lighting technology, any dimmer switch would dim a light bulb. This is no longer true and people need to know how to match light bulbs and dimmers to make them compatible.
Dimming switches work by affecting the voltage and not the wattage. With the incorrect dimming switch, certain light bulbs will get the wrong voltage and create problems. Before buying dimmer switches and light bulbs, people should be knowledgeable about the different types of light bulbs, dimmer switches, and how to choose compatible light bulbs and dimming switches.
Types of Light Bulbs
Light bulbs have a wattage and a voltage. The wattage is the strength of the current while the voltage is the type of current. Consumers have a choice of incandescent, halogen, fluorescent, and LED light bulbs. The incandescent and halogen bulbs are easy to control with a dimmer switch, while the florescent and LED bulbs save more energy, but they are more difficult to deploy with a dimmer switch and are more expensive.
Incandescent Light Bulbs
Incandescent light bulbs work because an electric current runs through a wire filament, which heats the filament and makes it glow. The incandescent bulb and its close relative the halogen bulb are the most utilitarian light bulbs because they work with any dimmer switch. They only burn out if the voltage is too much for them but not if the voltage is underneath their capacity. Consumers wishing to conserve energy and increase the lifespan of the light bulb can lower the voltage to the bulb. These light bulbs can represent a real savings to the homeowner initially, as inexpensive light dimmers work just as well as expensive dimmers. Incandescent light bulbs also dim almost completely when just above the off position.
Fluorescent Light Bulbs
Fluorescent light bulbs run electricity through an argon containing tube with mercury vapor. The ultraviolet light generated excites the phosphor coating inside the tube to emit visible light. Some fluorescent light bulbs, also called CFLs, which stands for compact fluorescent light, are not designed for use with a dimmer; if the homeowner puts a lower voltage through it, the bulb will shut off and never dim. To use a dimmer with a fluorescent light, the bulb must have a dimmable ballast, which will be written on the package or should be advertised if the homeowner is buying online. Some standard dimmers will then be compatible with a fluorescent bulb but not all are. Instead, consumers should get a dimmer that specifically says that is compatible with fluorescent lights. Even with a dimmable fluorescent bulb, at the lower light range, the bulb may just turn off. Another issue is that they may not turn on correctly when using one or more dimmers in different locations.
LED Light Bulbs
LED light bulbs work by a using a light emitting diode to induce electrons that interact with positively charged holes and release photons to produce luminescence. They dim lower than fluorescent bulbs but the dimming range is determined by the bulb’s circuitry. The LED also is prone to turning off at the lower light range, and it too may perform incorrectly with one or more dimmers. While an incandescent bulb will flicker with voltage fluctuations, an LED may shut off or flicker excessively.
Choosing the Right Bulb and Dimmer Switch
Depending on the manufacturer, bulb and dimmer performance will vary. Choose manufacturers that rigorously test their bulbs and dimmers for performance and compatibility. When in doubt, consult the manufacturer’s website and technical materials, or a consumer can contact the company directly with any questions. Also, stay updated on your bulb and dimmer and the manufacturer’s technological improvements over time, as they may be able to improve the functionality of the bulb and dimmer or add extra features.
Choosing the Right Bulb
Consumers looking for compatible bulbs should keep the above mentioned in mind and compare bulb performance and expense. The proper bulb will stay on as it is dimmed and will perform as expected at each level of illumination. The bulb will turn on even if there are one or more dimming switches and not flicker excessively during voltage fluctuations.
When buying, a consumer should remember that incandescent bulbs dim from zero to 100 percent while fluorescent and LED bulbs can only lower to 10 to 20 percent of minimum value, so homeowners may not be able to achieve the level of ambience desired. In addition, fluorescent and LED bulbs require more expensive and complicated dimming switches. However in the long run, LED and fluorescent bulbs provide significant energy savings.
Choosing a light bulb is also a matter of choosing a color that fits the homeowner’s usage of the space and ambiance preferences. Bulbs are available that range from completely white to yellowish to a bluish light. Light color is measured in Kelvin (K). Lower numbers glow more yellow, while higher numbers glow more white or bluish.
- Warm soft white ranges between 2700 K to 3000 K
- A neutral, cool white is between 3500 K and 4100 K
- A natural daylight illumination, which is good for reading, is between 5000 K and 6500 K
To get the best of both worlds, use an incandescent bulb, which is easy to deploy with a dimmer, and to save energy, consumers should consider getting ENERGY STAR qualified light bulbs. Following is a chart, adapted from ENERGYSTAR.gov which outlines the savings in wattage.
ENERGY STAR Qualified Bulbs
Regular Incandescent Bulbs
9 to 13 watts
13 to 15 watts
18 to 25 watts
23 to 30 watts
When comparing, consumers should focus on the lumens, which is a measure of the visible light emitted by the light bulb, in order to choose the right light bulb.
Choosing the Right Dimmer
Dimmers have varying features including different types of photocells, motion sensors, and timers. When investing in dimmers, people should keep in mind that advanced dimming circuitry is available with high efficacy light bulbs. While inexpensive dimmers are adequate for incandescent and halogen bulbs, consumers may want to invest in dimmers that are capable of handling mixed load sources including LEDs and CFLs on the same circuit.
Keep in mind that a dimming switch is different from a three-way light switch. The dimmer is designed to allow the user many gradations of illumination, while the three-way switch lights at only three different levels. To use a three-way switch, buy a bulb specifically for three-way technology. Three-way bulbs are more expensive than regular CFL bulbs.
People looking for bulbs and dimmers should keep in mind that incandescent and halogen bulbs are easier to use because any dimmer switch is compatible. The initial costs for incandescent and halogen bulbs are lower, but with regular light bulbs the energy savings is not as good as fluorescent and LED light bulbs. Consumers who choose to use fluorescent and LED light bulbs need to be very sure that the light bulb specifically states on the package or advertising that it is compatible with dimmers or three-way switches. Without taking the time to make this critical distinction, voltage problems may occur, as well as a voiding of the light bulb or dimmer warranty. Additionally, fluorescent and LED bulbs can cost as much as three times more, and the dimmer will cost more as well. Finding light bulbs and dimmer switches is not difficult as they are sold at lighting stores and home improvement stores.