An energy saving lighting control system for operating fluorescent light fixtures is provided with means for controlling the light level according to the light required for the task being done in the area. Ambient light available from sources outside of the controlled area such as daylight can be harvested to reduce the amount of artificial lighting required. A method of providing sensor inputs to detect occupancy in the controlled area provides control signals to the lighting control system which are used to reduce the light level or turn light fixtures off at times when the area is not occupied. A method of providing a central control of the operation of the lighting system can provide time-of-day scheduling, can provide minimum and maximum lighting levels, and can provide calibration and set-points for response times to various sensor inputs. In order to minimize the installation cost of the lighting control system, the system is provided with components that can be controlled using signals carried along the power conductors that provide primary operative power to the lighting fixtures. Special circuitry in the ballasts for fluorescent lamps provides a starting sequence and operating conditions that maximize the life of the lamps which therefore minimizes maintenance costs.