What this RCBO is and what it does
The Siemens SENTRON 5SU1354-1LB16 is a combined residual-current circuit breaker with overcurrent protection (RCBO) in a 1P+N configuration — one protected pole plus a switched neutral. It occupies 2 modular width units (36 mm) on a DIN rail and is rated 16 A at 30 °C with a C tripping characteristic, meaning it handles moderate inrush from motor starters or lighting ballasts without nuisance trips. The short-time delayed G characteristic (super resistant K variant) tolerates brief leakage pulses from electronics or surge suppressors, so it won't drop out on equipment with normal leakage.
Breaking capacity and standards
Rated 10 kA per EN 60898 for residential and light commercial distribution boards, and 20 kA per IEC 60947-2 for industrial panel duty. The higher industrial rating means this RCBO can be used downstream of a transformer or large feeder without needing a current-limiting upstream device in most installations. Overvoltage category III and pollution degree 2 cover fixed-installation environments inside a distribution board.
Thermal derating — what the numbers mean for panel design
The 16 A rating holds only at 30 °C ambient. In a crowded enclosure at 40 °C the continuous current drops to 15.2 A; at 50 °C it's 14.4 A; at 60 °C it's 13.6 A; at 70 °C it's 12.32 A. If you are populating adjacent slots in a high-density board, size the upstream protection for the derated value at your expected internal temperature, not the 30 °C headline. Mounting position is unrestricted, so vertical or horizontal DIN-rail orientation does not affect the derating curve.