Breaking capacity

Breaking capacity is the rated prospective fault current that a protective device, such as a fuse, MCB (miniature circuit breaker), RCBO (residual current breaker with overcurrent protection) or other circuit breaker, can interrupt under stated conditions. It is normally shown in kA (kiloamperes) on electrical certificates, consumer-unit schedules and product data. IET model BS 7671 forms record prospective fault current at the supply and breaking capacity for protective devices, while circuit-breaker guidance describes the short-circuit breaking rating as the highest prospective current a circuit breaker can break without damage. In home energy work, the term may appear around solar inverter circuits, battery inverter circuits, EV charger circuits and heat pump electrical supplies because those circuits rely on protective devices matched to possible fault current.