Spec recap for the panel builder
The Siemens 5SL4550-6 is a SENTRON miniature circuit breaker (MCB) with a 1P+N pole design — it switches the line and protects the neutral, but does not break the neutral on overcurrent. Rated 50 A at 30 °C with a B tripping characteristic, it clears faults up to 10 kA per EN 60898 and IEC 60947-2. That 10 kA SCCR at 230 V AC means it safely interrupts a short-circuit up to that level without upstream damage — standard for residential and light commercial distribution boards.
Thermal derating and real-world current
The 50 A rating holds at 30 °C ambient. At 40 °C it derates to 46.19 A, at 45 °C to 44 A, and at 55 °C to 39.81 A. If your enclosure runs warm — typical for a crowded consumer unit — size the upstream protection for the derated figure, not the label. The 4 W power loss per pole at rated current adds up in a multi-way board; keep ventilation slots clear.
Mounting and integration
Snap-on DIN rail mount, 2 modular width units (36 mm wide). Depth is 76 mm, with an installation depth of 70 mm behind the panel face.
Environmental and compliance notes
Halogen-free and silicon-free construction — important for installations where outgassing during a fault could damage nearby electronics or where silicone contamination affects contactors and relays. Operating temperature range is -40 °C to 75 °C, covering outdoor enclosures in cold climates. Pollution degree 2 and overvoltage category III, which is the standard for fixed-installation distribution boards.