The Siemens 5SU9356-7KP16 is a SENTRON 5SU9-series RCBO — an RCD-operated circuit breaker combining overcurrent and residual-current protection in a single 36 mm-wide, 2-module housing. It's rated 16 A with a Type C tripping characteristic and Type A fault-current sensitivity, making it a go-to choice for final circuits in commercial and residential distribution boards where both short-circuit and earth-fault protection are needed on a single DIN-rail footprint.
Ratings and what they mean on the board
The 16 A rating at 30 °C is the headline number, but the derating curve tells the real story for a warm enclosure: at 40 °C it's 15.04 A, at 45 °C it's 14.56 A, and at 55 °C it drops to 12.96 A. If your panel ambient runs hot, size the upstream protection accordingly — the RCBO itself will trip on overload before the cable, but you lose headroom fast above 40 °C. Breaking capacity is 6 kA per EN 60898 and 10 kA per IEC 60947-2. The EN figure governs domestic and light commercial boards; the IEC figure applies when the device is specified per the industrial standard. Either way, it's rated for the fault levels typical of a sub-distribution board fed from a transformer of up to about 630 kVA. The energy limiting class of 3 means it lets through less let-through energy (I²t) than class 1 or 2 devices — helpful for downstream cable protection. Type A residual-current detection covers sinusoidal AC faults plus pulsating DC faults up to 6 mA smooth DC — the standard for circuits with electronics, rectifiers, or single-phase drives. The instantaneous design (no intentional delay) trips within 40 ms at rated residual current, which is the norm for socket-outlet circuits where personnel protection is the goal.
Mounting and wiring
Snaps onto a 35 mm DIN rail, occupies 2 width units (36 mm), and the installation depth behind the panel is 70 mm. Supply can enter from either top or bottom — no mandatory orientation. The terminals accept solid or stranded conductors from 0.75 mm² up to 35 mm², which covers everything from 1.5 mm² lighting circuits to 10 mm² submains. Touch protection is built in (fingertip-safe terminals per the standard). Mounting position is any — horizontal, vertical, flat — no derating required for orientation. The ambient operating range is -25 to +45 °C; storage range is -40 to +75 °C. The device is halogen-free and silicon-free, which matters for panels in clean-room or semiconductor-adjacent environments where outgassing is a concern.