A line-side circuit interrupter protection system monitors the current flowing in a circuit in order to determine whether any current is flowing outside of the circuit upstream of the point at which a power supply is connected to a plurality of circuits. The system is located between the power supply and the main circuit panel, which is advantageous in certain applications in which an auxiliary power supply is used when a utility power supply is unavailable. In the event that the system detects current flowing outside of the circuit, the circuit will be broken to eliminate any potentially unsafe conditions.