They consume eight to 10 watts when operating with the lamp in the circuit. The ballast will consume about four watts when the lamps are removed although the ballast is still energized.
Electronic ballasts start and regulate fluorescent lamps with the use of electronic components.
Longer lamp life Fluorescent lamps are more efficient at higher frequencies. Therefore, 40-watt T12 lamps operate at 34 watts when operated on an electronic ballast. At these lower wattages, the lamps provide light output close to rated lumens at 60Hz. This ballast contains an electronic switch that cuts off the power to the cathode after the lamps have started to light. Generally, these ballasts have a life expectancy of 25 years.