Dimmable LED Light Bulbs: Switch Them On!

by mbryce2012 on September 11, 2012

An incredible amount of technology goes into creating the lighting spectrum given off by dimmable LED light bulbs, which is part of the reason they are taking so long to catch on despite their energy saving capacity.

How Light Bulbs Dim

The incandescent light bulb is a simple being: Increase the voltage, increase the light. Decrease the voltage, dim the light. However, the LED (light-emitting diode) light bulb is a much more complicated species.

There are two ways to dim a LED lamp: Pulse-width modulation, and analog dimming.

The pulse-width modulation (PWM) LED uses an on-off cycle to cause a dimming effect. So if you want your light to dim to 25% brightness, the little LED lights would pulse “on” during ¼ of the cycle. So, why doesn’t it look like the light is pulsing?

PWM Dimmable LEDs rely on our eye’s ability to average the light signals being emitted. We don’t see flickering because the LED cycle is in the hundred-thousands of a second. It’s too quick for us to see pulsing. We just process the 25% cycle as less light- a dimming effect.

Analog dimming works by controlling the current feed to the LEDs, reducing the current via the driver electronics to dim the bulb. While this is easily implemented, the LED performance is compromised for two reasons: The bulb is less efficient at dropped currents, and the consistency of the light color is not high quality.(1)


Dim Switch Technology

The biggest problem faced by dimmable LED technology is that it often doesn’t work with the existing wiring currently used to dim incandescent lights. Some of the problems you may experience are:(2)

Lights “dropping out” as you dim them. Meaning at some point, they just shut off as you turn the dim switch down.

  • Flickering
  • The bulb simply not working at all.
  • The lights shutting off randomly

These problems occur because the dimmers are wired to handle much higher voltages than required for the LEDs (about 600 Watts vs. 60 watts or less).

Shopping for Bulbs and Switches

The bottom line is that if you are planning to install dimmable LED lights in your home, do your research first. Lutron makes a dim switch rated for CFL/LED technology, and so does LEDWholesalers. Check your bulb against the switch manufacturer’s directory to make sure the dimmer switch you choose works well with your particular LED bulb.

See the Lutron video below for a detailed explanation of LED lighting and dim switches.

Lutron Dimmable LED Lighting Video Link

Also remember that not all LEDs are created equal. Check consumer reviews and talk to the sales associates before making a purchase. Are you looking for a pure white light, or more of a soft yellow? Do you want bright light to illuminate a garage or kitchen, or dimmer light for a living room or bedroom?

Ask yourself those questions, find the appropriate wattage (LEDs might vary even within the wattage-equivilent) and brand, then look for your dimmer switch.

When done properly, a LED bulb can save you up to $300 in energy costs over the course of it’s durable life… and provide you with light quality equal to that of an incandescent lamp.



  1. http://www.aegps.com/fileadmin/user_upload/MEDIA_PDFs_JPEGs/News/AEG_PS_in_the_Media/2011-06_LEDsmagazine.pdf
  2. http://www.homeconstructionimprovement.com/using-dimmer-switches-with-led-lights/


Leave a Comment

Previous post:

Next post: