The Siemens 5SL4204-8 is a SENTRON miniature circuit breaker with a D tripping characteristic, rated 4 A at 400 V AC. Its 10 kA breaking capacity is certified under both EN 60898 and IEC 60947-2, so it covers residential and industrial fault-current requirements without needing a separate SCCR check for most panelboards. The 2-pole, 2-module-width (36 mm) body snaps onto a DIN rail in any mounting position, and the IP20 rating applies only with conductors connected — finger-safe in a closed enclosure, not for wet locations.
D-curve and thermal derating
The 4 A rating holds at 30 °C ambient; at 40 °C it derates to 3.79 A, at 45 °C to 3.68 A, and at 55 °C to 3.45 A.
Panel integration
Width is 36 mm (2 modular units), depth 76 mm, installation depth 70 mm. The sealable design allows the panel builder to lock the toggle position after commissioning — useful for preventing unauthorized switching on critical circuits. Power loss per pole is 1.1 W at rated current in hot operating state; for a 2-pole breaker that's 2.2 W total, negligible for thermal budgeting in a standard enclosure.