70 Watt M89 120/277 Volt F-Can Metal Halide BallastHigh Intensity Discharge (HID) lamps require a ballast to apply starting voltage to the lamp and establish current flow an arc between the lamp electrodes. Without a ballast, the arc will extinguish or draw increasing current until some circuit element burns up. Ballasts provide system stability by limiting the current that can be drawn. Replacement F Can ballasts are used primarily for indoor downlighting applications where quiet operation is