The U.S. Department of Energy's CALiPER program has released a special report on LED lamps available through the retail marketplace and targeted toward general consumers. While previous reports in the CALiPER retail lamps series have focused on basic performance parameters, such as lumen output, efficacy, and color quality, the new report – CALiPER Retail Lamps Study 3.1 – focuses on the dimming, power quality, and flicker characteristics of a subset of 14 LED A lamps from CALiPER Retails Lamps Study 3, as controlled by four different retail-available dimmers.
 
LED lamps interact with and impact the performance of phase-cut dimmers in ways that incandescent lamps do not. The results clearly demonstrated three key impacts of dimming an LED lighting system with a phase-control device. First, installing a phase-cut dimmer will change the performance of any type of lighting system – even when the dimmer is set to full output. Second, the choice of dimmer can make a difference. Third, the change in performance is less predictable when dimming LED lamps than when dimming incandescent lamps; in some cases there may be almost no change, and in other cases, the change may be dramatic.
 
Among the other observations:

•There were substantial differences in minimum dimmed level between LED lamps, but when averaged across the four dimmers, 11 out of 14 lamps dimmed to 10% or less of their light output when operated by a switch.

•The relative efficacy for all LED products was higher than for the benchmarks at any point in the dimming range.

•Half of the LED lamps produced the same or less flicker when dimmed than the incandescent benchmarks did. A few LED lamps showed flicker performance similar to that of a magnetically ballasted fluorescent lamp, and one showed substantial flicker, even when switched.
 
For more details, see the full report.