One-pole miniature circuit breakers are used in a single circuit to interrupt currents in the event of an overload. They're UL489 listed for use as branch circuit protection or as supplementary protection from damage caused by short circuits. These circuit breakers follow trip curves to determine when they will interrupt the current. If the current exceeds a device's rating up to a certain factor, the circuit breaker will have a delayed trip to prevent nuisance tripping. If the current exceeds the device's rating at or above that factor, it will immediately trip. They're mounted on standard 35mm DIN rail in low-voltage electrical applications such as panelboards, control panels, and motor control centers.