For replacement lighting, HID lighting is the most efficient way to provide a light source to plants throughout the various stages of the growing process. However, with HID lighting comes the need for a heavy electrical load to ignite and run the HID lamps. Traditional domestic timers cannot be used to switch HID lights, as they cannot handle the high electrical loads needed. Domestic timers will become damaged, or even become a electrical hazard. The first sign of this will usually be the contacts in the timer welding together stopping the lighting switching off. The primary function of a contactor is to ‘switch’ high electrical loads between the power source and the HID lighting.By diverting electrical loads from the timer through a contactor or relay, the HID lighting cycle can be managed effectively and safely.