I found this little article,
Electronic high-frequency ballasts increase lamp-ballast efficacy, leading to increased energy efficiency and lower operating costs. Electronic ballasts operate lamps using electronic switching power supply circuits. Electronic ballasts take incoming 60 Hz power (120 or 277 volts) and convert it to high-frequency AC (usually 20 to 40 kHz). Electronic ballasts are more efficient than magnetic ballasts in converting input power to the proper lamp power, and their operating of fluorescent lamps at higher frequencies reduces end losses, resulting in an overall lamp-ballast system efficacy increase of 15% to 20%.
Electronic ballasts have a number of other advantages over magnetic ballasts. Electronic ballasts are readily available that operate three or four lamps, allowing the use of a single ballast in 3-lamp and 4-lamp luminaires. This reduces both installation and field wiring labor costs, and may negate the necessity of tandem luminaire wiring as required by the 1992 Energy Efficiency Standards for Residential and Nonresidential Buildings (Title 24). Electronic ballasts are designed to operate lamps in either series or parallel mode. The advantage of the parallel mode of operation is that a single lamp failure will not affect the operation of the remaining lamps controlled by the same ballast. However, ballast losses will increase slightly in the parallel mode. Other advantages of the electronic ballast include reduced weight, quieter operation, and reduced lamp flicker. Electronic ballasts are directly interchangeable with magnetic ballasts, and they are available to operate most full-size and compact fluorescent lamps.
