Beginning with this post, with the help of Lutron Technical Documentation and Support, we will begin to discuss some of the most common questions we hear with regard to Light Emitting Diode (LED) and Compact Fluorescent Light (CFL) bulbs - dimmability. You can effectively dim LED and CFL bulbs, but you need to be armed with the right information. We’ve answered a few of the most commonly-asked questions about dimming different types of bulbs here.
Let's start with the Federal legislation that has gotten us to this point. The Energy Independence and Security Act of 2007 (which addressed energy consumption including heating, cooling, electrical and more) set a new, energy efficient standard for light bulbs. For our discussion, basically put, light bulbs must meet or exceed a minimum energy efficiency requirement - if it is consuming (X) amount of energy it must produce a minimum of (Y) amount of light output (you will see this stated as the efficacy of a bulb or lumens per watt). Incandescent bulbs are much less efficient than most other types of electric lighting. Incandescent light bulbs convert approximately 5% of the energy they use into visible light, with the remaining 95% of energy being converted into heat (remember the Easy Bake oven?). The luminous efficacy of a typical incandescent light bulb is approximately 16 lumens per watt (lm/w), compared to approximately 60 lm/w of a compact fluorescent light bulb. The law took a phased approach, starting in January 2012, and was completely implemented by January 2014. So, under this law the 40, 60, 75 and 100 watt incandescent bulbs that we grew up with can no longer be manufactured.
New screw-based light bulbs will use fewer watts, consuming less energy (X) to achieve the same level of light output (Y). Common household light bulbs that traditionally used 40, 60, 75 and 100 watts will now use significantly less energy. Screw-in LED bulbs and CFL are great, energy-saving alternatives. LEDs and CFLs that are designed and constructed for dimming applications can be effectively dimmed. Dimming these bulbs saves even more energy and gives you the same kind of flexibility and control you expect from your incandescent bulbs. The bulbs will deliver excellent dimming performance when paired with a compatible dimmer, but there are some challenges.
Are all CFL or LED bulbs dimmable?
No, not ALL standard CFL or LED screw-in replacement bulbs are dimmable. If you want to dim a standard CFL or LED screw-in bulb, you must use a light bulb that was designed for dimming. You can find out if a bulb is dimmable on the bulb’s package and/or on the bulb itself. Bulbs that can’t be used on a dimmer switch will have the caution statement "not for use with dimmers" marked directly on the bulb. Possibly the easiest way to know that you have placed a NON-dimmable CFL or LED on a circuit with a dimmer switch is that, once you turn the switch on, the bulb will begin to flicker or will not turn on at all. Remove those bulbs right away. Leaving them in that circuit will compromise the electronics in the ballast or driver. You will have potentially damaged the bulb and you will have voided any manufacturer’s warranty.
What is a "standard" or "conventional" dimmer?
A standard or conventional dimmer is a dimmer switch that is rated for use with incandescent light
bulbs. In some cases, an LED manufacturer may recommend a standard or conventional dimmer be used with their product. However, Lutron doesn’t recommend using standard or conventional dimmers with LEDs. Lutron’s LED Control Center of Excellence tests fixtures and bulbs and reports exactly which controls to use with those fixtures and bulbs. The LED Control Center of Excellence doesn’t test standard dimmers with LEDs because standard dimmer switches aren’t UL Listed to work with LEDs.
Can I use dimmable CFLs and LEDs with the standard incandescent dimmer that I currently have?
It depends on the dimmer. Some dimmable LEDs may work fine with a standard incandescent dimmer. However, standard incandescent dimmer switches are not UL Listed to work with LEDs, so Lutron does not test them or recommend you use them. To ensure compatibility, Lutron strongly suggests using their line of C•L® dimmers, which include features to help maximize the dimming performance. Many bulbs on the market dim to low light levels and some bulbs can dim lower than others. To help maximize your home or office dimming experience, Lutron C•L® dimmers are equipped with an adjustable low-end trim. Adjusting the low-end trim will help you set the bottom of the dimming range for the type of bulb you’re using. Dimming range will depend on both the bulb and the control. Many LED bulbs are not capable of being dimmed below a 10% measured light level, regardless of the control used.
Green Electrical Supply stocks a wide variety of Lutron C•L® dimmers. At the bottom of most individual product pages, you will find a brief video produced by Lutron that will show you just how easy it is to set the dimming range on their C•L® dimming switches. Take some time to see our selection of Lutron C•L® dimming controls and stay tuned – more LED and CFL dimming questions to be answered in posts to come.
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