The Siemens 5SP3840-2XX32 is a SENTRON main miniature circuit breaker (SHU) — three poles, 40 A rated current, E tripping characteristic, and a 25 kA breaking capacity certified to EN 60898. It's designed for residential and infrastructure metering panels, mounting on a 40 mm busbar system per DIN 43870 Part 2. The E-curve (class E) means it's tailored for transformer and power-supply protection — higher inrush tolerance than a B or C curve, common in main distribution board applications.
Solid and stranded conductors from 2.5 mm² up to 50 mm² are accepted at the box terminal — that's a wide range covering everything from a 2.5 mm² control circuit to a 50 mm² incoming feeder. The outgoing side uses spring-loaded terminals, so no screw torque to chase on the load side. Sealable with a locking slide, wire seal, cable ties, or Antilux — common for utility-metering applications where tamper evidence is required. The switch position indicator shows OFF = green, ON = red for quick visual status at the panel door.
Protection class IP40 with conductors connected — fine for dry indoor enclosures but not washdown areas. Shock resistance rated at 30 g for at least 3 impacts (11 ms duration), and vibration resistance per IEC 60068-2-6 at 2 g over 20 frequency cycles from 5 to 150 Hz. Mechanical service life is 20 000 switching cycles typical — solid for a main breaker that sees infrequent operation.