The Siemens SENTRON 5SY8408-7 is a 4-pole miniature circuit breaker (MCB) with a C-tripping characteristic rated at 8 A AC, designed for 50/60 Hz supply voltages.
For UL 1077 / CSA C22.2 No.235 supplementary protection, it is rated 5 kA. This 40 kA IEC rating provides generous fault-current headroom for most commercial and industrial panelboards, supporting selective coordination with upstream devices without requiring a current-limiting upstream breaker in many installations.
Thermal derating and environmental range
The 8 A rating holds at 45 °C ambient. At 50 °C it derates to 7.75 A, and at 55 °C to 7.5 A. The operating temperature range spans -40 °C to 75 °C, with humidity limits of 95% up to 55 °C, 55% up to 70 °C, and 35% at 75 °C. Vibration resistance per IEC 60068-2-6 is ±1 mm at 5–25 Hz and 50 m/s² at 25–150 Hz.
Material compliance
Halogen-free and silicon-free construction. No neutral conductor switching function on this 4P unit — it switches all four poles as live conductors.