The Siemens 5SU1354-1RC40 is a SENTRON RCBO (residual current circuit breaker with overcurrent protection) rated 40 A with a 30 mA residual current trip of Type AC and a C tripping characteristic. This 2-pole, 1P+N device occupies 2 modular width units (36 mm) on a DIN rail and is designed for 50 Hz AC systems. It carries a 10 kA rated short-circuit capacity per EN 60898 and a 15 kA rating per IEC 60947-2, making it suitable for residential and light commercial distribution boards where both overcurrent and earth-fault protection are needed in a single unit.
What the ratings mean for fit
The 40 A rated current and C characteristic mean this RCBO is intended for circuits with moderate inrush currents — common for lighting banks, small motor loads, and general-purpose socket outlets. The C-curve trips at 5 to 10 times rated current, so it holds through the startup surge of a refrigerator compressor or a bank of fluorescent ballasts without nuisance tripping. The 30 mA residual-current sensitivity with Type AC detection means it responds to sinusoidal AC fault currents only — the standard choice for basic shock protection in residential and commercial circuits. It does not detect pulsating DC or smooth DC fault currents, so for circuits with variable-speed drives, UPS systems, or EV chargers, a Type A or Type F RCBO would be required. Breaking capacity: 10 kA per EN 60898 and 15 kA per IEC 60947-2. The EN 60898 rating governs its use in domestic-type installations; the higher IEC 60947-2 rating applies when installed in industrial distribution boards with higher prospective fault currents. Either way, it safely interrupts faults up to those levels without cascading upstream.
Mounting and integration
Snap-on DIN-rail mount, 2 MW (36 mm wide), 70 mm deep, 90 mm tall. The power supply can enter from either top or bottom, and the device can be mounted in any orientation. IP20 rating applies once the distribution board is installed with conductors connected — this is a panel-internal device, not for outdoor or washdown locations. Overvoltage category III and pollution degree 2 confirm it is rated for fixed-installation use downstream of the main distribution board, not for direct utility connection. Operating temperature range -40 °C to 75 °C covers most indoor and sheltered outdoor enclosures.