The Siemens SENTRON 5SY8603-8 is a 4-pole miniature circuit breaker (3P+N) with a D tripping characteristic, rated 50 kA at 400 V AC per IEC 60947-2 and 5 kA per UL 1077. It also carries a 15 kA DC interrupting rating at 60 V (max 72 V) per IEC 60947-2. The combined terminal at both top and bottom accepts the neutral conductor switching — the N pole is switched, not just solid-linked, which matters for full isolation on a 3P+N supply.
Environmental and compliance fit
Rated for ambient temperatures from -40 °C to 75 °C, with derating above 55 °C per the humidity curve (max 95% RH at 55 °C, tapering to 35% at 75 °C). That covers unheated warehouse storage and hot panel interiors alike. Vibration resistance per IEC 60068-2-6 (±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz) means it holds up on a machine frame or near a reciprocating compressor.
Mechanical endurance and panel integration
Rated for 10 000 mechanical operating cycles typical — that's the handle mechanism life, not the electrical endurance under fault. For a panel that sees daily switching of a motor feeder, that's a solid service life before the mechanism needs attention.