Precision ST-168 - Lumatrol ST-Series Wire-In Photo Control, 277 Volt, 2000 Watt Weatherproof Lexan housing Photocell: 1/2" cadmium sulfide light sensitive element. Turn-on: 1 to 3 foot-candles; Turn-on/off Ratio: 1:3 Time Delay: Minimum 15 seconds. Switch Type: Single-pole, single-throw. Contact position at night normally closed