Siemens Type BQ breakers provide easy lug-in/lug-out connections in Siemens Panelboards. Circuit breakers provide a manual means of energizing and de-energizing a circuit. In addition, circuit breakers provide automatic over current protection of a circuit. A circuit breaker allows a circuit to be reactivated quickly after a short circuit or overload is cleared. Unlike fuses, which must be replaced when they open, a simple flip of the breaker’s operating handle restores the circuit. All circuit breakers perform the following functions: - Sense when an over current occurs - Measure the amount of over current - Act by tripping quickly enough to prevent damage to itself and associated conductors