Siemens 5SY4203-8 Molded Case Circuit Breaker

Siemens 5SY4203-8 is a 2-pole molded case circuit breaker rated for 400 V AC, with a nominal current of 3 A and a short-circuit breaking capacity of 10 kA, delivering reliable overload and fault interruption for small distribution circuits. It adopts a Type D tripping curve, which can accommodate short, higher-impedance faults without nuisance tripping on light overload, while still clearing severe faults quickly; this combination suits reserve circuits, lighting, and control circuits in 230/400 VAC systems. The device has a stated mounting footprint of D=70 mm (70 mm width/depth depending on orientation as specified in the datasheet), and it accepts conductor cross-sections from 0.75 to 35 mm2, enabling flexible wiring options for compact installations. As part of Siemens' SENTRON 5SY family, the 5SY4203-8 is a 2-pole device designed for 400 V systems, with a 10 kA short‑circuit rating for robust fault handling. This model is widely cataloged under 5SY4203-8 by Siemens distributors and resellers, reflecting its role as a standard, low-current protection option within European-style electrical installations.