Professional Resources


What is an LED?

An LED is a semiconductor device that produces light when an electric current flows through it. LEDs, which are manufactured in a variety of color temperatures, are grouped onto an LED array (also called an LED module or LED light engine). The LED light engine determines the light quality, while the dimmer and the LED driver (which controls the LED) determine the dimming performance. Please note, though, that while the driver and dimmer work in conjunction together, the dimmer will function only as well as the driver will allow. Ultimately, the driver is responsible for the best possible dimming performance.

LED Bulbs vs LED Fixtures

LED Bulbs
LED bulbs are designed to replace incandescent or screw-in CFL bulbs, as well as candelabra or low-voltage MR16 bulbs. LED bulbs have a driver inside of their base. This driver is what determines if the bulb is dimmable, what dimmers can be used with the bulbs, and the bulb’s overall dimming performance.

To find LEDs compatible with Lutron dimmers, please visit our LED Compatibility Tool.

LED Fixtures
LED fixtures come in a variety of different forms, from cove lights and downlights to pendants and troffers. The driver will either be mounted within the fixture housing or be a separate component mounted remotely from the LED source. You can usually choose from multiple driver options, depending on whether you need a dimmable or a non-dimmable fixture and depending on what type of dimmer you want to use with the LED fixture.

To find a fixture available with Lutron Hi-Performance LED drivers, please visit our High-Performance Fixture List.

Using the Proper Dimmer

As we mentioned above, the driver used in the fixture or the bulb will determine what type of dimmer to use. Almost all screw-in bulbs will require a forward or reverse phase control, however, LED fixtures can require any of the following (depending on the fixture) :

Forward Phase – Also known as “leading-edge” or “triac” dimmers. This is the most common type of control specified for a screw-in LED bulb. Forward phase will include standard dimmers rated for incandescent/halogen or magnetic low-voltage bulbs, as well as Lutron’s line of C•L dimmers.

Reverse Phase – Also known as “trailing edge” dimmers. Reverse phase dimmers include all electronic low-voltage dimmers or controls with phase-adaptive technology. These dimmers will always require a neutral connection.

3-wire – Typically used with Lutron 3-wire LED drivers. Due to the third line-voltage wire to carry the dimming signal, it is much less prone to noise, delivering a precise, smooth dimming signal. It can also generally handle more LED fixtures on a control than 2-wire drivers.

0-10V – An IEC standard exists (though not always followed) for 0-10V which helps compatibility between the driver and the control. These drivers require low voltage for dimming and line voltage for switching. Lutron has a variety of 0-10V dimmers available to meet those requirements. To learn more about 0-10V as well as check out a list of compatible controls, check out our Application Note.

EcoSystem – Allows digital addressing of individual fixtures and provides status feedback, making it easy to digitally assign sensors, time clocks and other controls to one or many fixtures without additional wiring.

DMX 512 – Typically used in theatrical applications, DMX remains popular with RGB LED applications where multiple channels are necessary for individual color control. For more information, please view our DMX webinar.

LED Dimming Wattage Limitations

Dimmers that are rated for CFLs or LEDs will typically have two ratings, one for incandescent or halogen bulbs and one for CFLs or LEDs. A standard Lutron C·L dimmer, for example, can handle 600W of incandescent lighting or a maximum of 150W of LED lighting. This is because CFL and LED bulbs add much more stress on a dimming control than an incandescent light bulb. However, 150W of LED lighting will typically give you more light output on average than 600W of incandescent lighting. Also, the minimum amount of bulbs you can place on a dimming control will vary from bulb to bulb, depending on the design.

To learn more about the minimum and maximum loading of LED bulbs, please check out our Application Note.

Lutron’s LED Testing Program

Controlling LEDs isn’t as simple as controlling an incandescent bulb. While all incandescent bulbs dim smoothly and down to a 0.1% light level, not all LEDs are dimmable. And the ones that are dimmable will vary greatly in performance from one to the next.
That’s why Lutron works with LED manufacturers to help determine the best dimmer/bulb combinations. We test new bulbs every day, monitoring and noting dimming performance (range, smoothness, shimmer, buzzing, etc.), as well as the electrical characteristics of the bulb to make sure it is compatible with the dimmers being tested.
If the bulb meets our standards, we will post the model number on our LED Compatibility Tool, and more specific details from the testing can be found on the report card posted on our LED Report Card Tool.
This is the most reliable way to ensure your LED product will perform acceptably when used with a dimmer.
If you are a fixture manufacturer who would like to apply for Lutron's testing program, please contact

To Learn more...

Controlling LEDsExplore all aspects of LED control, from the basics of LED function through the steps necessary to select the best light source and dimming options.

Challenges of Dimming LED loads on ELV and MLV TransformersThis paper will explain the technical difficulties with dimming low-voltage LED lamps on magnetic and electronic transformers, and provide some design tips to improve the situation and avoid problems.

LED Frequently Asked Questions