Advance 71A8793 is a magnetic ballast designed to operate a high intensity discharge lamp, typically a 1000 watt high pressure sodium lamp. The ballast provides the correct starting and running voltage to the lamp using a constant wattage autotransformer circuit. It accepts standard line voltages such as 120, 208, 240, and 277 volts at 60 Hertz, allowing it to be used in a variety of electrical systems. This type of ballast is commonly used in industrial and commercial lighting applications including warehouses, gymnasiums, parking lots, and street lighting. The unit must be used with the appropriate lamp and ignitor to start and maintain stable lamp operation.