The Siemens 5SM2623-0 is a 2-pole residual current circuit breaker (RCCB) from the SENTRON family, designed as a plug-in RC unit for the 5SL4 miniature circuit breaker series. It carries a 40 A rated current and a 300 mA tripping fault current, Type AC, for 230 V AC systems. Type AC detection means it responds to sinusoidal AC residual currents — the common choice for general-purpose circuits without pulsed DC or variable-speed drive loads. The 300 mA sensitivity is typical for fire protection or circuits feeding equipment with higher leakage, rather than personnel protection (which usually calls for 30 mA). The 40 A rating is at 40 °C ambient; the part derates to 32 A at 70 °C, so panel builders need to check the thermal curve when packing breakers into a warm enclosure.
Panel fit and mounting
Occupies 2 modular width units (MW) on a DIN rail, with a 70 mm depth that matches the standard 5SL4 breaker footprint. Mounting position is unrestricted — any orientation works. The 70 mm × 70 mm × 90 mm envelope (W×D×H) means it fits the same cutout as the companion MCB. Fastening method is REG (regular DIN-rail clip). Mechanical service life is 10,000 cycles — standard for a protective device that rarely operates.