What it is and what it does
The Siemens 5SV4642-0KL is a 4-pole residual current circuit breaker (RCCB) from the SENTRON 5SV4 series, designed to protect against earth faults in AC circuits. It is rated 25 A at 230/400 V AC, 50 Hz, with a 30 mA trip sensitivity and instantaneous response — meaning it clears a ground fault as soon as leakage exceeds that threshold, no intentional delay.
Key ratings and what they mean for fit
The 25 A rating holds flat from 40 °C to 60 °C — no derating needed in a warm panel up to that point. At 65 °C it drops to 23.3 A, and at 70 °C to 17.62 A. The 10 kA short-circuit current rating (SCCR) means it can safely interrupt a fault up to that level without welding its contacts or cascading upstream. Overvoltage category III qualifies it for fixed-installation distribution boards, not just downstream equipment. The I²t value of 58 000 A²·s is the let-through energy the device can withstand — useful for coordination with an upstream MCB or fuse. The AC fault-current type means it detects sinusoidal AC leakage only; if your load has pulsed DC or smoothed DC leakage (VFDs, battery chargers, LED drivers), you need an A or B type instead.
Mounting and panel integration
Snaps onto a DIN rail (REG mounting), occupies 4 width units (72 mm), and accepts supply from top or bottom. The 70 mm installation depth fits standard 100 mm deep enclosures. Mounting position is unrestricted — any orientation works. The N-left variation means the neutral pole is on the left side when viewed from the front, which matters for busbar alignment in a multi-device row. IP20 protection applies only when installed in a distribution board with connected conductors — the device itself is not sealed for wet or dusty environments.