How do you dim LED lights?

This guide will explain how dimming works; how you can dim our LED lights with either a 120V AC magnetic low voltage dimmer switch or a 12V DC dimmer switch; and which of our LED lights are dimmable and which are not.

The facts about dimming may seems complex at first, but if you understand a few terms, you’ll at least be able to locate the right switches and drivers for your LED light installation. Just as you don’t need to understand the chemistry behind caffeinated coffee, or how coffee is decaffeinated, to order the right cup, you don’t need to be an electrical engineer to find the proper accessories for your LED lights.

A LITTLE THING CALLED PHASE CONTROL

There are four terms to know about dimming LED lights and, conveniently, they go in pairs. The first is “forward phase control”, which is a characteristic of “magnetic low voltage” power sources. The second is “reverse phase control”, and it’s a feature of “electronic low voltage” power. The “phase” in “phase control” just means the shape of the frequency of electricity. When a light is dimmed, it’s being turned on and off rapidly, 120 times per second. That means that, for 50% of a phase cycle, the light is on. “Forward phase control” means it’s on for the first half of the cycle, and “reverse phase control” means it’s on for the second half. That’s it! So if you have a dimmer switch with forward phase control, you need a 12V driver with the same phase.

Another term you’ll need to know is Pulse Width Modulation (PWM). Some dimmers reduce the actual voltage going into the LED fixture, which can damage the LED bulbs. A PWM dimmer instead chops up the steady 12V current, turning it rapidly off and on for different periods of time, depending on how dim the light should be. Our 12V Inline Dimmer Switch is a PWM dimmer, while 120V AC dimmers are not PWM.

USING A 120V AC MAGNETIC LOW VOLTAGE DIMMER SWITCH

If you want to use a 120V magnetic low voltage dimmer switch with your new LED lights, our 12V Dimmable Drivers are made specifically for use with this kind of switch. (Don’t be confused by the phrase “magnetic low voltage switch.” It doesn’t mean that the switch is low voltage, just that it’s compatible with a low voltage driver.) Our dimmable DC drivers are designed for use with high voltage dimmer switches that are rated for magnetic low voltage loads or that are stated to have symmetric forward phase control. These drivers are wired between the switch and the LED fixture.

USING A 12V DC ELECTRONIC LOW VOLTAGE DIMMER

We sell two 12V dimmers that are for use with all of our standard 12V adapters and drivers. These drivers are “electronic low voltage” power sources, so they require a dimmer switch that has reverse phase control. Unlike switches used with our dimmable drivers, the 12V dimmer switches are connected between the driver (or adapter) and the light. These switches are not compatible with any of our dimmable drivers, even though the driver is 12V, because they have opposite phases. Our 12V dimmers are also known as a PWM switch. The Reign dimmer has a wattage limit of 60W and the Inline Dimmer has a wattage limit of 24W.