The Siemens 5SU1354-1LB32 is a SENTRON RCBO — a combined residual-current circuit breaker with overcurrent protection in a single 2-module-wide (36 mm) package. Rated 32 A at 230/400 V AC with a 10 kA breaking capacity per EN 60898, it covers the common residential and light-commercial branch circuit where both earth leakage and overload/short-circuit protection are needed in one DIN-rail device. The Type C tripping characteristic (5–10× In magnetic release) suits motor and lighting loads with moderate inrush; the AC fault-current type detects sinusoidal residual currents. Active in the current Siemens lineup, so factory supply is standard — no last-time-buy pressure.
Ratings and what they mean for fit
The 32 A rating at 40 °C ambient (30.4 A derated) is the continuous current the RCBO can carry without tripping on thermal overload — size your downstream load to stay under that curve. The 10 kA breaking capacity per EN 60898 means it can safely interrupt a fault current up to 10,000 A at the rated voltage; that's standard for most final sub-circuits in a TN or TT system, but verify the prospective short-circuit current at the installation point. The Type C curve trips magnetically between 5 and 10 times rated current (160–320 A), so it avoids nuisance trips on capacitor inrush or motor start but clears fast on a hard short.
Mounting and wiring notes
Snaps onto 35 mm DIN rail; occupies 2 width units (36 mm). Wire capacity: solid or stranded 0.75–35 mm² — that's a generous terminal for a 32 A device, allowing easy feed-through of larger supply conductors. Supply can enter from top or bottom. Mounting position any, which simplifies panel layout. Depth 77 mm plus 70 mm installation depth behind the panel surface — check enclosure depth clearance. IP20 with distribution board installed and conductors connected; not for wet or dusty environments without an enclosure.
Thermal derating and ambient limits
Rated current drops with ambient temperature: 32 A at 30 °C, 30.4 A at 40 °C, 28.8 A at 50 °C, down to 24.64 A at 70 °C. If the panel runs hot (e.g., enclosed switchgear or adjacent heat sources), use the 50 °C or 60 °C column for your load calculation. Operating ambient range -25 to +55 °C; storage -40 to +75 °C. Maximum power dissipation 11.4 W — relevant for thermal budgeting in a multi-device enclosure.
Lifecycle and sourcing
Listed as current production — no phase-out or obsolescence notice on record. The 5SU1 design is the standard Siemens RCBO platform for the European and export markets. Sourced through independent distribution; quoted to order against an RFQ. Availability and current pricing confirmed at quote time.