Because Dimmable CFLs need a certain amount of energy to initially light up, you should always start with the dimmer switch at it’s highest setting before turning on the light. Once it’s lit, you can then adjust the setting to the proper lighting level. It is recommended that you use standard rotary or slider dimmer switches with Dimmable Compact Fluorescent Light Bulbs. Switches that start dim and ramp up to full brightness won’t work as well. Also, make sure the switch is off before installing a Dimmable CFL.