The Siemens 5SP3735-2XX03 is a SENTRON 5SP3 main miniature circuit breaker (MCB), also designated a main circuit breaker (SHU) for residential and infrastructure metering panels. It is a 1-pole device rated 35 A at 230/400 V AC, 50 Hz, with a tripping characteristic E — a curve designed for selective coordination with downstream MCBs in distribution boards, offering a delayed thermal-magnetic response that reduces nuisance tripping on transformer inrush or motor starting loads. Overvoltage category IV confirms it is rated for the utility-side interface, not just downstream distribution. Wire acceptance is generous: solid and stranded conductors from 2.5 mm² up to 50 mm², which covers meter tails and main feeder cables. The box terminal infeed and spring-loaded outgoing terminal simplify panel wiring — no special lugs needed for the larger cross-sections.
Mounts on a 40-mm busbar system per DIN 43870 Part 2. Occupies 1.5 width units. Depth is 76.3 mm. Suitable for indoor panel environments only. The switch position indicator shows OFF = green, ON = red, a quick visual for commissioning or fault-finding.
Shock resistance is 30 g for at least 3 impacts at 11 ms duration; vibration resistance per IEC 60068-2-6 at 2 g over 5 to 150 Hz. Mechanical service life is 20 000 switching cycles typical.