The Siemens 5SU9356-7KK16 is a SENTRON RCBO — an RCD-operated circuit breaker combining overcurrent and residual-current protection in a single 2-module-wide (36 mm) package. It's a 1P+N design, meaning it switches and protects the phase conductor only, with the neutral switched but not protected. Rated 16 A at 30 °C with a C-curve tripping characteristic, it's sized for general-purpose branch circuits with moderate inrush — think lighting, socket outlets, or small motor loads in commercial or industrial distribution boards. Breaking capacity is 6 kA per EN 60898 and 10 kA per IEC 60947-2 — the higher figure applies when the device is used as a circuit breaker under the industrial standard, giving you headroom on fault-current capability in a panel with higher prospective short-circuit current. The C-curve (magnetic trip between 5 and 10 times In) handles motor-starting and capacitor-switching inrush without nuisance trips, while still clearing hard faults fast.
Temperature derating and panel placement
The 16 A rating is at 30 °C ambient. At 40 °C it derates to 15.04 A, at 45 °C to 14.56 A, at 50 °C to 13.92 A, and at 55 °C to 12.96 A. If your distribution board runs warm — typical in a crowded DIN-rail enclosure — size the load accordingly. The device is rated for any mounting position and accepts supply from either top or bottom, which simplifies panel wiring. Installation depth is 70 mm; total depth including terminals is 77 mm. Width is 36 mm (2 modular units). The IP20 rating applies with the distribution board installed and conductors connected — standard for enclosed panel use, not for wet or outdoor locations without a higher-rated outer enclosure.