What it is and what it does
The Siemens 5SL3302-7 is a SENTRON miniature circuit breaker (MCB) — a 3-pole, C-curve device rated 2 A at 400 V AC. It protects branch circuits against overload and short-circuit in residential and light commercial distribution boards, per its stated suitability for residential buildings and infrastructure. The C-curve characteristic means it trips instantaneously at 5 to 10 times rated current — a good fit for moderate inrush loads like small motors or lighting banks, but not for high-inrush transformers or switching power supplies (those want a D-curve). Breaking capacity: 4.5 kA per EN 60898 (the domestic standard) and 5 kA per IEC 60947-2 (the industrial standard). At 400 V AC, that covers most residential and light commercial fault levels in Europe and Asia. If your site has a prospective short-circuit current above 5 kA, step up to the 5SL6 series.
Thermal derating — the real-world current
The 2 A rating holds at 30 °C ambient. At 40 °C it derates to 1.9 A; at 55 °C it drops to 1.75 A. If the breaker sits in a crowded enclosure with other heat sources, use the 40 °C or 55 °C column for your load calculation — the 30 °C number is the catalogue ideal, not the panel reality.
Panel integration notes
Three modular width units (54 mm total) on a standard DIN rail. Depth is 76 mm, installation depth 70 mm. Mounting position: any. IP20 with connected conductors — suitable for enclosed distribution boards, not for wet or dusty environments. Sealable (tamper-evident cover available). Halogen-free and silicon-free construction, so it won't outgas corrosive compounds in sealed enclosures.