The Siemens SENTRON 5SP3750-2KK03 is a 1-pole main miniature circuit breaker (MCB) from the 5SP3 series, rated 50 A with an E tripping characteristic. It's designed for residential and infrastructure metering panels, mounting on a 40-mm busbar system per DIN 43870 Part 2. Rated breaking capacity is 25 kA at 230 V AC per EN 60898, and 25 kA per the circuit-breaker standard — enough to handle high-fault utility feeds common in meter mains positions. Overvoltage category IV and surge voltage resistance of 6 kV confirm it's built for the primary supply side, not downstream subpanels. The E curve (tripping characteristic class E) means magnetic trip thresholds are higher than a standard B or C curve, intended to ride through inrush from transformers or long cable runs without nuisance tripping — typical for main incoming breakers in European meter cabinets.
Mounting and wiring
Mounts directly on a 40-mm busbar system compliant with DIN 43870 Part 2 — the standard meter-panel rail. No DIN-rail adapter needed; it clips onto the busbar with integral spring contacts for the line side. Occupies 1.5 width units in the cabinet grid. Terminals accept solid or stranded conductors from 2.5 mm² up to 50 mm². That's a wide range — fine for a 50 A feed on 10 mm² or 16 mm², but also big enough for parallel runs or a heavier main tail. Outgoing feeder uses spring-loaded terminals, so no screw tightening on the load side. Infeed at the box terminal (top) is stipulated by the installation position in the lower section of the meter panel. IP40 with conductors connected — protects against solid objects >1 mm but not water ingress. Not for outdoor or washdown locations; keep it inside the sealed meter enclosure.
Environmental and mechanical limits
Ambient temperature range -25 to +55 °C, storage from -40 to +70 °C. Shock rated at 30 g (3 impacts, 11 ms duration); vibration 2 g per IEC 60068-2-6 (20 cycles, 5–150 Hz). That covers typical utility cabinet vibration from transformer hum or nearby switching gear. Sealable with a locking slide, wire seal, cable ties, or Antilux — common requirement for utility meter locks to prevent tampering. Switch position indicator shows OFF = green, ON = red.
Lifecycle and compliance
Designed per EN 60898 (breaking capacity 25 kA) and carries overvoltage category IV. Insulation voltage rated 690 V. The product designation follows DIN EN 61346-2 and DIN EN 81346-2 (function code F).