The Siemens 5SP3835-2 is a SENTRON main miniature circuit breaker — 3-pole, rated 35 A at 400 V AC, with a 25 kA breaking capacity per EN 60898.
Rated current is 35 A at 30 °C, but it derates linearly: 33.25 A at 40 °C, 32.375 A at 45 °C, 31.5 A at 50 °C, and 30.625 A at 55 °C. If your panel ambient runs 40 °C, you're effectively limited to 33 A continuous — plan your load accordingly. Insulation voltage is 690 V, surge voltage resistance 6 kV, overvoltage category IV, pollution degree 3 — that's the utility-side rating, meaning it's rated for the harsh environment right after the meter, not just clean indoor distribution. The 4.5 modular width units (about 81 mm) are wider than a standard 1 MW MCB; that's because the E-curve mechanism and the 25 kA arc chamber need the space. It's sealable (locking slide, wire seal, cable ties) — important for utility or metering applications where tamper evidence is required.
Fastens via busbar — designed for the SENTRON busbar system. Infeed at the box terminal; outgoing feeder uses spring-loaded terminals. Conductor cross-section: solid or stranded 2.5 mm² minimum, 50 mm² maximum.