The Siemens 5SU1356-1KK13 is a SENTRON RCBO — a combined overcurrent and residual current device in one 2-module-wide (36 mm) package. It protects a single-phase final circuit: one pole switched and protected (1P+N), neutral switched but not protected. The C-curve trip characteristic means it holds up to 5–10× rated current for short magnetic trips, suited to mixed resistive and moderate inductive loads like small motor or lighting circuits. The 30 mA residual current element catches earth faults at the sensitivity level required for personal protection in most residential and light commercial installations. Rated 13 A at AC (30 °C ambient), the device derates linearly as panel temperature rises — at 40 °C it carries 12.48 A, at 50 °C it carries 11.96 A, and at 70 °C it drops to 10.01 A. This derating curve matters when the RCBO sits in a densely populated enclosure with limited airflow; the 13 A nameplate is only valid at the reference ambient. Breaking capacity is 6 kA per EN 60898, adequate for most final sub-distribution boards with a typical upstream fault level under that threshold. The residual current type is AC — it detects sinusoidal AC earth fault currents only. For circuits with pulsed DC or smooth DC fault components (variable-speed drives, LED drivers, EV chargers), an A or F type RCBO would be required instead. This part is for straightforward AC loads without rectification or switching power supplies in the protected circuit.
Mounting and integration
Snaps onto standard 35 mm DIN rail. The 2 MW (36 mm) width plus 77 mm depth and 70 mm installation depth means it fits standard distribution boards without overhang. Supply can enter from top or bottom — no orientation restriction. Mounting position is any, so it works in horizontal busbar or vertical riser configurations. IP20 applies only when the distribution board is installed and conductors are connected; the RCBO itself is not sealed for wet locations. Operating temperature range is -40 °C to 75 °C, covering cold storage and hot rooftop enclosures. Pollution degree 2 and overvoltage category III are standard for fixed-installation final circuits. Halogen-free and silicon-free construction matters for environments sensitive to outgassing — clean rooms, medical facilities, or sealed enclosures where corrosive byproducts from a fault arc could damage nearby electronics.