What it is and what it does
The Siemens 5SU9356-1KX10 is a 2-pole RCD-operated circuit breaker (RCBO) from the SENTRON family, combining overcurrent protection and residual current detection in a single 36 mm wide, 2-module-width unit. It is rated 10 A with a 30 mA residual trip threshold, Type AC (sensitive to sinusoidal AC fault currents), and a Class C tripping characteristic for moderate inrush loads like small motors or lighting banks. Breaking capacity is 6 kA per EN 60898 for domestic/commercial distribution boards, and 10 kA per IEC 60947-2 for industrial panel applications — the higher figure gives you coordination headroom in a sub-distribution board with a 10 kA prospective fault level. The 30 mA residual sensitivity is the standard for personal protection against direct contact in final circuits (IEC 60364), and the Type AC designation means it detects sinusoidal AC fault currents only — not pulsed DC or smooth DC, so it is suited for circuits without electronic loads that generate DC fault components.
Thermal derating and installation
The 10 A rating holds at 30 °C ambient; above that, derate to 9.4 A at 40 °C, 9.1 A at 45 °C, 8.7 A at 50 °C, and 8.1 A at 55 °C. In a sealed, high-fill panel near other heat sources, use the 40 °C column for realistic continuous load planning. Mounting position is any orientation, and the supply can enter from top or bottom — useful when retrofitting into an existing board with fixed busbar routing. Installation depth is 70 mm, overall depth 77 mm; the IP20 rating applies only when the distribution board is installed and conductors are connected. Rated insulation voltage (Ui) is 264 V, overvoltage category III, pollution degree 2 — standard for fixed-installation final circuits in residential and light commercial panels.
Lifecycle and sourcing
Halogen-free and silicon-free construction supports compliance with low-smoke, zero-halogen material requirements common in rail, marine, and public-building installations. The product is classified per IEC 81346-2 and DIN EN 61346-2 as function F (protection).