The Siemens SENTRON 5SL4108-6 is a 1-pole miniature circuit breaker with a B tripping characteristic, rated 8 A at 30 °C and 400 V AC, with a 10 kA breaking capacity per EN 60898 and IEC 60947-2.
Thermal derating and ambient limits
At 40 °C it derates to 7.39 A, at 45 °C to 7.04 A, and at 55 °C to 6.37 A. If the panel runs hot — near a drive or transformer — size the breaker for the actual load at the expected ambient, not the 30 °C nameplate. The breaker itself is rated for -40 to 75 °C storage and operation, so it handles cold warehouses or rooftop enclosures.
The B-curve trips at 3-5× In, so it's a good fit for resistive and lighting loads — not for motor starting, where a C or D curve would avoid nuisance trips.
Physical fit and accessories
Width is 18 mm — one modular unit — so it occupies a single slot on the DIN rail. The breaker accepts supplementary devices (shunt trip, auxiliary contacts, alarm switch) on the side, per the product extension feature. Sealable terminals (yes) let the panel builder lock the cover after commissioning. Rated IP20 with conductors connected, pollution degree 2, overvoltage category III — standard for enclosed distribution boards.
Current production — no phase-out or last-time-buy notice on record. The 5SL4108-6 is an active catalog item in the SENTRON family.