A common problem with a dimmer switch that does not dim the lights is that the user has switched from incandescent lights to compact fluorescent or other types of energy saving lamps. Older dimmer styles are not compatible with the newer lamps and often do not work at all. If dimming the lights is important, EnergyStar recommends switching to a compact fluorescent dimmer switch and dimmable CFLs.
With these older dimmer switches, known as legacy dimmers, full current illuminates the bulb to full brightness. Reducing the current reduces the brightness of the light. Using an incandescent lamp allows the light to operate from zero percent current to 100 percent current. However, the circuitry for most CFL and LED lamps requires full current to operate. Dimming these lights requires pulsing the power so the light flashes at a faster rate, one that the brain does not detect, in order to produce less light, according to LEDs Magazine.
Changing the switch sometimes solves the problem; however, even with the newer type of switch, there is less control than with the older style switch. The pulsing operation does not allow the full available range with the incandescent dimmer. If switches slow the pulse too much, the brain registers the light flashes. If the light remains too bright with the dimmer, consumers should consider switching to other CFL and LED lamps that provide a warmer color to achieve the desired lighting levels.