The Davin Eco 4 way Contactor / timer will run up to 4 x 600w lights. This unit is unique in design compared to others as it has a separate socket to run a heater or fan. The heater socket is engaged when the timer cuts the lights out. This is especially useful for when the lights are cut off and the cooler nights require a heater. Or in contrast if the lights are on in the night this socket can be used to engage a fan for the warmer days.