What this RCBO is and where it fits
The Siemens 5SU1654-1KK32 is a 2-pole (1P+N) residual current circuit breaker with overcurrent protection — an RCBO from the SENTRON 5SU1 series. It combines a C-curve MCB (32 A rated, 10 kA breaking capacity per EN 60898) with an AC-type residual current module in one 36 mm-wide, 2-module housing. That means a single device protects a final circuit against both overload/short-circuit and earth leakage, saving a DIN-rail position versus separate MCB + RCCD.
Key ratings — what they mean for your panel
Rated 32 A at 30 °C ambient, with a derating curve published down to 24.64 A at 70 °C. If your enclosure runs hot (say 50 °C), plan for 28.8 A continuous — the 32 A label only holds at 30 °C. The C-curve (magnetic trip at 5–10× In) suits moderate inrush loads like small motor starters or lighting banks; for purely resistive loads a B-curve would trip faster, but C is the standard choice for mixed general-purpose circuits. Breaking capacity is 10 kA per EN 60898 — adequate for most commercial and light-industrial distribution boards fed by a transformer of typical impedance. If your fault level at the panel exceeds 10 kA, you need an upstream current-limiting device or a higher-rated breaker. The residual current module detects AC-type earth leakage only. If your load generates pulsed DC fault currents (variable-speed drives, LED drivers, UPS equipment), specify an A- or F-type RCBO instead — the 5SU1 AC type will not trip on smooth DC or mixed-frequency waveforms.
Mounting and wiring constraints
Snaps onto standard 35 mm DIN rail, any mounting position. Width is 36 mm (2 module units). Accepts solid or stranded conductors from 0.75 mm² up to 35 mm² — covers everything from 1.5 mm² lighting circuits to 10 mm² sub-mains. Supply can enter from top or bottom, which simplifies busbar routing in dense panels. Installation depth is 70 mm (device body 77 mm overall). IP20 rating applies only when the distribution board is installed and conductors are connected — the terminals are finger-safe but the device is not sealed against dust ingress. Ambient operating range is -25 to +55 °C; storage from -40 to +75 °C. Power loss at rated current is 11.4 W maximum. In a multi-device enclosure, sum the losses and check the cabinet's thermal dissipation — 12 RCBOs at full load would dump nearly 140 W inside the panel.