The Siemens SENTRON 5SL4120-7CC is a 1-pole miniature circuit breaker with C-curve tripping, rated 20 A at 30 °C and 400 V AC.
Temperature derating and real-world current
At 40 °C the breaker must be derated to 18.48 A; at 50 °C to 16.82 A; at 55 °C to 15.92 A. For a cold-storage or freezer panel where ambient stays near -40 °C, the breaker runs cold and stays cold — no derating penalty, and the C-curve magnetic trip remains crisp.
Mounting position is unrestricted. The sealable design allows lockout-tagout compliance. Halogen-free and silicon-free construction meets clean-room and food-processing material restrictions.