Siemens 5SL7440-8RC MCB, 415V 4-pole 10kA D 40

The Siemens 5SL7440-8RC is a 4-pole miniature circuit breaker rated 415 V, 10 kA breaking capacity, with a D-curve trip characteristic set at 40 A. The D-curve means it tolerates the high inrush currents typical of motor and transformer loads, tripping between 10× and 20× rated current for short-circuit protection. The 10 kA interrupting rating at 415 V is the fault current it can safely clear without welding contacts or cascading failure upstream — a key selectivity figure when coordinating with a downstream panel feeder.