The Siemens 5SL6550-7BB is a SENTRON 5SL6 miniature circuit breaker — 2-pole 1P+N configuration, C-curve trip characteristic, rated 50 A at 230 V AC with a 6 kA breaking capacity certified to both EN 60898 and IEC 60947-2. At 50 A this is a high-current single-pole-plus-neutral breaker for the Italian market variant (the -7BB suffix). The neutral pole is switched — the breaker opens both line and neutral when it trips, which matters for installations that require full isolation on a single module width. If your panel's SCCR is higher, you'd step up to the 5SY series or a higher-rated SENTRON variant.
Thermal derating — the number that actually governs the load
At 40 °C it derates to 46.19 A, at 45 °C to 44 A, and at 55 °C to 39.81 A. That's a 20 % drop from the nameplate at the top of the operating range. The C-curve's magnetic trip threshold (5–10× In) means a 50 A unit holds through 250–500 A inrush before instant tripping — fine for lighting banks, distribution subfeeds, and small transformer primaries. For a motor circuit with locked-rotor inrush above 500 A, you'd want a D-curve or a motor-protective breaker instead.
Panel fit and installation notes
Depth behind the panel face is 70 mm installation depth; overall depth including the front profile is 76 mm. Terminals accept solid and stranded copper up to 25 mm² (the 5SL6563-7BB peer confirms the range). Halogen-free and silicon-free construction — no outgassing concerns in clean environments or sealed enclosures. Sealable per the spec, which matters for utility-metering applications where tamper evidence is required. Ambient storage range -40 to +75 °C covers warehouse and transport extremes.