A ballast (20) for powering one or more gas discharge lamps (70,72,74,76) comprises an inverter (200), an output circuit (300), and an arc protection circuit (400). Arc protection circuit (400) monitors an electrical signal within the output circuit (300). When an arcing condition occurs at the ballast output connections (302,304,306,308,310), the electrical signal includes a high frequency component having a fundamental frequency that is much greater than the normal operating frequency of the inverter (200). In response to the high frequency component exceeding a predetermined threshold, arc protection circuit (400) disables the inverter (200) for a predetermined shutdown period. Arc protection circuit (400) also provides a restart function for periodically attempting to ignite and operate the lamps. Arc protection circuit (400) is preferably realized using a microcontroller integrated circuit (440) with associated discrete circuitry, and is especially well-suited for use in ballasts for powering multiple lamps via a current-fed self-oscillating inverter and an isolated parallel resonant output circuit.