Using dimmers with LED bulbs is more complex than with incandescent bulbs. LED bulbs have more sophisticated circuitry and require special switches, as well as bulbs specifically designed for dimmers.
If you’ve fitted dimmable ceiling lights in your home with LED bulbs and the bulbs waved erratically or burned out, there’s probably a very simple reason with a very simple solution.
Bought non-dimmable bulbs
Traditional incandescent bulbs had no “dimmable” or “non-dimmable” options to worry about. Regardless of bulb type or wattage, the dimmer switch could easily dim the bulb simply by reducing the power delivered to the bulb.
Full power gave you full brightness, and anything less caused the bulb’s incandescent filament to glow less brightly until it dimmed to barely candlelight.
However, with LED bulbs, the bulb does not contain a filament but rather a light-emitting diode, a special type of circuit. This is also the reason why LED bulbs do not burn out in the same way as traditional bulbs. Adjusting the brightness of an LED is a more complex operation than simply increasing or decreasing the raw power.
That’s why you need an LED bulb specifically designed for a dimmable circuit. The hardware inside the dimmable LED bulb can handle the changes introduced by the dimmer switch. If you put a non-dimmable LED bulb into a dimmable circuit, you can expect negative results including flickering, lack of dimming, and premature bulb failure.
If you find yourself in a situation where the non-dimmable bulbs you purchased are working a bit in your dimmable fixtures (for example, they come on if you turn the dimmer up all the way, but don’t dim otherwise), we recommend replacing them. turn off and place bulbs in non-dimmable fixtures. Although the bulbs work when you set the dimmer brightness to 100%, anything below 100% is testing the internal circuitry of the bulb.
Dimmer switches work by boosting the electricity sent to the bulb, and if the LED bulb isn’t designed for that, it’s like you’re forcing the bulb to experience tens of thousands of mini “blackouts.” It’s no wonder non-dimmable bulbs fail quickly when used with a dimmer switch.
Has older dimmer switches
Normally, you don’t need to get into the weeds of dimmer switch design, but in the case of LED bulbs, the type of dimmer switch you have matters.
We’ll skip the deep dive into electrical theory, but there are some key details you need to know to understand why your dimmer switches seem to keep eating your LED bulbs.
First, the electricity that reaches your home is alternating current (AC), and its name derives from the fact that electrical current continually reverses its direction and magnitude in a pattern that can be represented by a sine wave. For our discussion here, all you really need to know is that the wave has a peak and a trough, and those peaks and troughs happen several times per second.
Second, there are different types of dimmers. Older dimmer switches (common in homes built throughout the 20th century and even into the early 21st century) are called state-of-the-art dimmers. They are so named because they cut off power at the leading edge of the electrical “wave”.
The newer dimmers are called next generation dimmers because they cut power on the opposite side of the waveform. The only reason this matters is that LED manufacturers build their dimmable LEDs on the premise that you will use modern state of the art dimmers. (In addition, some manufacturers include a manual toggle switch on the body of the dimmer so you can select which type of dimming function you want, main or rear.)
Using an older dimmer switch with dimmable LED bulbs may work well, but can also lead to issues with flickering and incorrect dimming. We recommend using a high-quality option like the Lutron Diva dimmer. It’s not worth using a cheap dimmer to save $5-$10 when you’ll likely eat up those savings the first time you have to replace bulbs prematurely.
Not only that, but when you go with an established, reputable company like Lutron, you’ll also enjoy additional support, such as the company’s extensive and detailed LED bulb compatibility database. Here is the listing for the Lutron Diva dimmer.
There is another issue to be aware of with older dimmer switches. Because older dimmer switches were designed for incandescent bulbs, the switches assume a relatively high load on the circuit.
If you have 10 x 40W bulbs in a string of recessed ceiling lights, you have a 400W peak load and a 40W load when dimmed to 10% brightness. However, equivalent LED bulbs only use around 6W each. So at 100% load the circuit only uses 60W. At 10% load it only uses around 6W. If the older dimmer (designed for incandescent lights) expects a higher minimum load, there may be erratic results such as flickering,
Finally, there is one more issue to consider if you experience frequent failure of the LED bulbs in your ceiling light fixtures. This isn’t about the dimmer switch, but if you’re looking for a solution, we want to cover the bases.
LED bulbs packaged in canister recessed fixtures often “burn out” prematurely due to excess heat. If you suspect that this may be your problem, we have some tips to help you avoid LED failure in recessed lights.