Dimmable bulbs in 3-way lamps will work to produce light, but they will only work as regular on/off lamps. The 3-way output is prevented by the incorrect number of connection points and filaments. The dimming output is prevented by the lack of oscillating or varying electrical input.
There are times when you may not have the exact right tool for a job, but you find something close to the mark. If you are looking for a lightbulb to put in your three-way lamp, a dimmable bulb may seem like it would do the trick. After all, a dimmable bulb can switch between brightness settings, and so can a 3-way bulb.
While putting a dimmable bulb in a 3-way lamp is possible, the resulting light will not be able to switch between multiple brightness levels, even though it seems like it should be able to. Since the bulb and the lamp are not idealized for each other, the light will only have on and off functions.
Difference Between Dimmer and 3-Way Circuits
Incandescent dimmer bulbs are the cheapest dimmable light bulb option and rely on very simple circuitry. There are two connection points within the socket, one for on and one for off, and the dimmed effect is created by altering the voltage to the bulb while it is in the on position.
LED dimmer bulbs have more complicated circuits. At a brighter setting, the lightbulb allows current to flow relatively uninterrupted. But at dimmer settings, the current is interrupted for a fraction of a second repeatedly.
The dimmed effect of the bulb is created by this hyper-speed flickering that is unnoticeable to the human eye. Further dimming of the bulb results from increasing the intervals that the light bulb is turned off. It still occurs fast enough that you will not notice any flickering.
Comparatively, 3-way bulbs have three connection points within the socket. These three connections determine the brightness of the bulb. There is one connection for low, one for medium, and one for off. When both the low and medium are connected, that signifies the high setting. On each of the three connections, there is a steady input of electricity (unlike the dimmable LEDs).
Comparing Dimmer Bulbs and 3-Way Bulbs
Dimmer bulbs have one filament that can function at a variety of brightness levels. In an incandescent bulb, this is done simply by shifting the amount of voltage to the filament, while in an LED, the dim effect is created through rapid on-off oscillation.
Both bulbs require the correct type of socket and lamp to create the desired dimming effect. Incandescent bulbs require incandescent dimmable lamps and LED bulbs require LED dimmable lamps (you do not want to try putting a regular LED bulb in a dimmer!).
3-way bulbs have two filaments. One of these filaments operates at medium wattage while the other operates at low wattage.
The three levels of brightness are operated by turning on just the low filament (lowest setting), just the medium filament (medium setting), or both filaments (highest setting).
Dimmer Bulb Will Work
For a light bulb to work, it needs a connection point to complete the circuit. There is still a connection point within a 3-way lamp for the dimmable bulb; in fact, there are three. This means that the light will turn on.
No matter which connection point the bulb connects with, it shouldn’t be affected because it is designed to handle greater or lower power input. The bulb should operate at a singular brightness, equal to the power of whichever connection point it is in contact with.
This may seem confusing, but it is all to say that you can put a dimmer bulb 3-way lamp, as long as you don’t mind the fact that it loses its dimming function.
Ensure the Power Supply and Wattage Are Compatible
Make sure that your bulb’s wattage does not exceed the highest setting on your 3-way lamp. While the dimming capacity should yield a wide range, since the bulb is designed to produce many levels of brightness, it is still important to make sure of this to avoid any problems.
If the bulb’s lowest setting exceeds the wattage of the lamp, the system can overheat. This can lead to an explosion if not dealt with. If the power supply exceeds the wattage of the bulb, the light will likely burn out quickly.
The settings on your 3-way lamp can likely be determined by the user’s guide.
Bulb Will Not Dim or Switch Between 3 Levels
Dimmable bulbs require dimmable lamps, and 3-way bulbs require 3-way lamps to function to the best of their abilities. While a dimmable bulb will work in a 3-way lamp, the function of both the bulb and the lamp will be impaired. The same applies when using a regular bulb in a 3-way lamp—you lose the 3-way function.
A 3-way lamp is supposed to switch between three levels of brightness. It doesn’t have the correct hardware to control a dimmable bulb’s continuous spectrum of brightness levels. It does not even have the correct hardware to give a dimmable bulb three different levels of brightness.
It requires a specific bulb with multiple filaments to create the three varying levels of brightness.
Since the dimmable bulb only has one filament rather than the two required for the operation of a 3-way lamp, it will not be able to switch between three brightness levels. One filament can only show one level of brightness without the proper circuitry to make it dim.
Therefore, if you attempt to use a dimmable bulb in a 3-way lamp, it will not dim or switch between levels of brightness. It will only have on and off variations.
What About Dimmable LEDs
Dimmable LED bulbs do not necessarily require a special type of socket to function. They will work in regular sockets designed for incandescent bulbs as well. They will also work in a 3-way lamp.
However, their dimming function will not be supported by certain types of sockets.
The 3-way lamp will not be able to support the dimming function of a dimmable LED bulb. The bulb is designed for connection with a system that breaks the electrical current rapidly to create a dimming effect. It is not designed for this purpose and will not be able to function in this way.
Therefore, it will not be able to support the wide continuum of brightness offered by a dimmable lamp.
When placed in a 3-way lamp, it will operate at one level of brightness, the highest level supported by the bulb.
If a dimmable bulb is the only type of bulb you have for your 3-way lamp, then, yes, you can use it in this setting. It is not ideal, because the dimmable effects of the bulb and the three-way effects of the lamp are both negated in the process of combining the two.
What you end up with is a regular lamp with on and off settings. And this is only if you have made sure the wattage of your lamp and bulb are a correct fit.