According to aspects of the disclosure, an uninterruptible power supply is provided comprising an input configured to be coupled to, and receive input power from, a circuit breaker, an output configured to be coupled to, and provide output power to, at least one load, an energy-storage-device interface configured to be coupled to, and receive back-up power from, an energy-storage device, and at least one controller configured to determine whether a current through the circuit breaker meets at least one over-current criterion, and control, responsive to determining that the current through the circuit breaker meets the at least one over-current criterion, the uninterruptible power supply to provide the output power to the load, the output power being derived from the input power and the back-up power.