What this MCB does and where it fits
The Siemens SENTRON 5SJ4105-8HG40 is a 1-pole miniature circuit breaker with a D tripping characteristic, rated 0.5 A at AC and 10 kA breaking capacity per EN 60898. The 70 mm installation depth matches the common SENTRON 5SJ4 footprint, so it retrofits into existing distribution boards without re-spacing the busbar.
The 0.5 A rating holds at 30 °C and 40 °C ambient, but above that you need to derate: 0.48 A at 45 °C, 0.46 A at 50 °C, 0.44 A at 55 °C, and 0.42 A at 60 °C. The terminal torque spec is 3.5 Nm for Cu conductors rated 60/75 °C, which is a standard value for this class.
Environmental and compliance fit
Halogen-free and silicon-free construction, which matters for panels in clean-room or semiconductor-adjacent environments where outgassing can contaminate optics or contacts. The IP20 rating on the body (IP40 in the handle area) is typical for enclosed distribution boards — no washdown rating, so keep it behind a panel door in wet areas.