An electronic circuit breaker includes controllable mechanical contacts adapted to connect a primary power source to at least one load; and control circuitry for monitoring the flow of power from the primary power source to the load, detecting fault conditions and automatically opening the contacts in response to the detection of a fault condition. A primary power source supplies power to the control circuitry when the contacts are closed, and an auxiliary power source supplies power to the control circuitry when the contacts are open, whether by a trip or by manual opening.