Derating and integration
Rated 4 A at 35 °C ambient, but the published derating curve drops it to 3.22 A at 60 °C — a 20% reduction. In a crowded DIN-rail enclosure with multiple breakers side by side, the internal temperature often exceeds 50 °C, so size the load circuit against the derated figure, not the 35 °C nameplate. The 2-module-width (36 mm) body snaps onto any standard DIN rail; the quick-assembly system lets you gang busbars without individual wiring. IP20 with conductors connected — fine for a dry enclosure, not for washdown zones.
Listed as current production. The 5SY4504-8 carries dual certification: IEC/EN 60898-1 for general-distribution MCB duty and IEC/EN 60947-2 plus UL 1077 for industrial control-panel use. Halogen-free and silicon-free construction. Neutral conductor switching is integrated — the 1P+N design breaks both line and neutral, which some local codes require on final subcircuits.