What it is and what it does
The Siemens 5SL6450-7 is a SENTRON 4-pole miniature circuit breaker with a C tripping characteristic, rated 50 A at 30 °C on a 400 V AC system. It's built for residential and infrastructure branch-circuit protection — think distribution boards in apartment blocks, light commercial, or utility rooms where you need a clean 6 kA interrupting rating per EN 60898 and IEC 60947-2. The C-curve means it holds through mild inrush — motorized loads like small pumps, fans, or compressors — and trips fast on a hard short. At 50 A it's sized for a 25–30 kW resistive load or a 15–18 kW motor group on a 400 V three-phase feed.
Ratings that matter for fit
The 50 A rating is at 30 °C ambient. At 40 °C it derates to 46.97 A; at 55 °C it's 42.01 A. If your panel runs hot — and most do, especially in summer — size the upstream protection for the derated value, not the label number. Breaking capacity is 6 kA at 400 V AC under both EN 60898 and IEC 60947-2. That's standard for residential and light commercial service-entrance gear. If your available fault current is higher, you'll need a current-limiting upstream device or a higher-rated breaker. Four poles, 4 modular width units (72 mm), neutral not switched. Mounts in any position. IP20 with conductors connected — fine inside a closed panel, not for wet locations.
Panel fit
Snaps onto standard 35 mm DIN rail. Depth is 76 mm (70 mm behind panel face), width 72 mm (4 modules), height 90 mm. Sealable with a lead seal or lockable cover — useful for utility-metering applications where tamper evidence is required. Halogen-free and silicon-free construction — no corrosive off-gassing in a fire, which matters for ventilation-duct or clean-room adjacent panels.