Using dimmer switches 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 outfitted dimmable ceiling lights in your home with LED bulbs only to have the bulbs heave erratically or burn out, there’s likely a very simple reason with a very simple solution.
You Bought Non-Dimmable Bulbs
Traditional incandescent bulbs had no “dimmable” or “non-dimmable” options to worry about. Regardless of the type of bulb 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 led to the incandescent filament in the bulb glowing less brightly until it was dimmed down to barely a candle’s worth of light.
With LED bulbs, however, the bulb doesn’t contain a filament but a light-emitting diode—a type of specialty circuit. This is also why LED bulbs don’t burn out the same way as traditional bulbs. Adjusting the brightness of an LED is a more complex operation than simply cranking the raw power up or down.
Because of that, you need an LED bulb designed specifically 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 in a dimmable circuit, you can expect negative outcomes, including flickering, failure to dim, and premature bulb failure.
If you find yourself in a situation where the non-dimmable bulbs you purchased kinda-sorta work in your dimmable fixtures (such as they turn on if you turn the dimmer up all the way but otherwise don’t dim), we recommend swapping them out and putting the bulbs in non-dimmable fixtures. Even though the bulbs work when you adjust the brightness of the dimmer to 100%, at everything below 100%, you’re stress-testing the bulb’s internal circuits.
Dimmer switches work by pulsing the electricity sent to the bulb, and if the LED bulb is not designed for that, it’s like you’re forcing the bulb to experience tens of thousands of mini “brownouts.” It’s no wonder non-dimmable bulbs fail quickly when used with a dimmer switch.
You Have 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 kind of dimmer switch you have matters.
We’ll skip the deep dive into electrical theory, but there are a few key details you need to know to understand why your dimmer switches seem to keep eating your LED bulbs.
First, the electricity delivered to your home is alternating current (AC) and derives its name from the fact that the electric current reverses direction and magnitude continuously 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 valley, and those peaks and valleys roll by multiple times a second.
Second, there are different types of dimmer switches. The older dimmer switches (common in homes built throughout the 20th century and even into the early 21st century) are called leading-edge dimmers. They are called such because they cut the power on the leading edge of the electrical “wave.”
Newer dimmers are called trailing-edge dimmers because they cut the power on the opposite side of the wave. The only reason this matters at all is that LED manufacturers build their dimmable LEDs with the premise that you will be using modern trailing-edge dimmers. (As an aside, some manufacturers include a manual toggle switch on the body of the dimmer so you can select which kind of dimming function you want, leading or trailing.)
Using an older dimmer switch with dimmable LED bulbs can work fine, but it can also lead to issues with flickering and improper dimming. We recommend using a high-quality option like the Lutron Diva dimmer. It’s not worth using a cheap dimmer switch 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 a reputable and established company like Lutron, you’ll also enjoy additional support, like the company’s extensive and detailed LED bulb compatibility database. Here’s the list for the Lutron Diva dimmer.
There’s another issue with older dimmer switches to consider. Because older dimmer switches were designed for incandescent bulbs, the switches assume there is a relatively high load on the circuit.
If you have 10 40W bulbs in an array of recessed ceiling lights, you have a 400W maximum load and a 40W load when dimmed back to 10% brightness. Equivalent LED bulbs, however, only use around 6W each. So under 100% load, the circuit only uses 60W. Under 10% load, it only uses around 6W. If the older dimmer (designed for incandescent lights) expects a higher minimum load, there may be erratic outcomes like flickering,
Finally, there’s one more issue to consider if you’re experiencing frequent LED bulb failure in your ceiling fixtures. This doesn’t have to do with the dimmer switch, but if you’re here searching for a solution we want to cover the bases.
LED bulbs packed into recessed can light fixtures often “burn out” prematurely because of excess heat. If you suspect that might be your problem, we have some tips to help you avoid LED failures in recessed lights.