A ceiling fan light kit is designed to provide light from a ceiling fan and can either be attached to the ceiling fan prior to the time of retail sale or sold separately for subsequent attachment to the fan.
Building upon standards enacted by Maryland and considered by states, the Energy Policy Act of 2005 required that ceiling fan light kits (CFLKs) contain compact fluorescent lamps (CFLs) or equivalent efficient light bulbs in the package to fill all medium-base screw-in sockets (medium bases are those used on the most common light bulbs). For ceiling fan light kits with non medium-bases, the provision limited lighting power use to 190 Watts. Specifically, the requirement was that light kits not be capable of using more than 190 W, meaning that some type of shutoff must be employed to turn the lights off if more than 190 W are used. The provision also required that ceiling fans be controlled separately from lights, have more than one speed, and have a switch to reverse action of the fan blades (to match differing air circulation requirements for the heating and cooling seasons).
In January 2016, the Department of Energy updated the standards for ceiling fan light kits. As of January 2019, all CFLKs less than 120 lumens must have a minimum efficacy of 50 lumens per watt. All CFLKs equal to or greater than 120 lumens must meet the requirements of the following formula: 74.0 - 29.42 x 0.9983 lumens.
The DOE website has information for manufacturers and consumers about qualifying products, including a Frequently Asked Questions document.