What this RCBO is and what it does
The Siemens 5SU1323-1BB32 is a SENTRON RCBO — a combined residual-current circuit breaker with overcurrent protection — in a 2-pole, Type AC, 30 mA residual-current variant. It is rated 32 A with a C-tripping characteristic, meaning it handles moderate inrush from motor or lighting loads without nuisance tripping, while still clearing overloads and short-circuits. The 30 mA sensitivity catches line-to-ground faults that could be lethal, so it is the standard choice for socket-outlet circuits in residential and light commercial distribution boards.
Breaking capacity and selectivity
This RCBO carries two breaking-capacity ratings: 4.5 kA per EN 60898 (the residential standard) and 15 kA per IEC 60947-2 (the industrial standard). The 4.5 kA figure governs its use in domestic consumer units; the 15 kA rating means it can be installed downstream of a larger upstream device in an industrial sub-distribution board where fault currents are higher. The 4-module width occupies four 18 mm DIN spaces — typical for a 2-pole RCBO with neutral switching.
Installation and wiring constraints
Terminals accept solid or stranded conductors from 1.5 mm² up to 25 mm², with a tightening torque of 2.5 to 3 N·m. The supply can enter from either top or bottom, and the mounting position is unrestricted. The 70 mm installation depth fits standard DIN-rail enclosures. IP20 applies only when the distribution board is installed and conductors are connected — the device itself is not sealed against dust ingress until enclosed.