Timers, Relays & Contactors
Because of the high wattage used with grow lighting a contactor or relay is needed to switch lights on and off - when used with a normal timer the high wattage can melt the normal timer contacts together leaving your grow light stuck in the on position risking flowering plants reverting back to grow because of the constant light on hours.
Hytec Hydroponics sell many different types of relays and contactors some with inbuilt timers to control your grow lighting hours without any risk of over powering any weak normal house hold timers and risking electrical fires.