What it is and what the ratings mean for fit
The Siemens 5SU1656-0KK06 is a SENTRON RCBO — a combined residual-current and overcurrent protective device — in a 2-pole 1P+N configuration. It switches the line conductor only, with the neutral passing through the residual-current transformer but not switched. The B-curve tripping characteristic means the magnetic trip activates at 3 to 5 times rated current, suited for resistive and general-purpose loads where inrush is moderate. The AC residual-current type detects sinusoidal AC fault currents only; if the installation has pulsed DC or smooth DC fault potential (variable-speed drives, UPS, LED lighting), an A or F type would be required instead. Rated 6 A at 30 °C with a clear thermal derating curve: 5.7 A at 40 °C, 5.4 A at 50 °C, 5.1 A at 60 °C, and 4.62 A at 70 °C. For a panel running at 50 °C ambient, the usable current is 5.4 A — not 6 A. The breaking capacity is 6 kA per EN 60898 (the standard for household and similar installations) and 25 kA per IEC 60947-2 (the industrial standard). The higher 25 kA figure applies when the device is certified under the industrial standard, giving headroom for high-fault locations like substation secondaries. Rated voltage is 230/240 V AC at 50 Hz. The device occupies 2 modular-width units (36 mm) on a DIN rail, with an installation depth of 70 mm and overall depth of 77 mm. Mounting position is any orientation. Supply can enter from top or bottom — no mandated orientation. The IP20 rating applies only when the distribution board is installed with connected conductors; the device itself is not sealed against dust ingress without the enclosure.
Sourcing and lifecycle
The device is halogen-free and silicon-free, which matters for outgassing-sensitive environments like clean rooms, medical equipment, or sealed enclosures where silicone vapors can contaminate contacts or optics. The degree of pollution is 2 (non-conductive pollution that becomes conductive only when condensation occurs), typical for standard indoor distribution boards.
Panel integration notes
Mounts on a standard 35 mm DIN rail. Two modular-width units (36 mm) means it occupies the same slot pitch as two single-pole MCBs. The test button requires a minimum 100 V to operate the test circuit — verify the phase-to-neutral voltage exceeds this before relying on the built-in test function during commissioning. The residual current sensitivity is 30 mA (standard for personal protection against direct contact). The product designation per IEC 81346-2 is F (protective device). Overvoltage category III applies — suitable for fixed installations downstream of the main distribution board, not for equipment-level (Cat II) or utility-metering (Cat IV) locations.