The Siemens 5SL4425-7 is a SENTRON miniature circuit breaker, 4-pole with C-curve trip characteristic, rated 25 A at 400 V AC. It breaks 10 kA under both EN 60898 and IEC 60947-2, which covers the fault-current headroom for most residential and light commercial distribution boards. The 4-pole design (4P) means it switches all three phases plus neutral — common for three-phase sub-distribution where you want the neutral isolated on fault.
What the ratings mean for fit
The 25 A rating holds at 30 °C ambient; at 40 °C it derates to 23.68 A, at 45 °C to 23 A, and at 55 °C to 21.54 A. If your panel runs warm — say, tightly packed with other breakers — the effective continuous current is lower than the label. The C-curve trips magnetically between 5× and 10× In, so it handles motor inrush and transformer energization without nuisance trips, but still clears fast on a hard short. Mechanical life is 10 000 switching cycles typical, which is fine for a distribution breaker that sees infrequent operation; not a switching duty device. Breaking capacity of 10 kA per EN 60898 and IEC 60947-2 at 400 V AC means this breaker can safely interrupt a fault up to 10 kA without welding contacts or venting plasma. That covers the prospective short-circuit current of most final sub-circuits in a building installation. The overvoltage category is III (distribution level), pollution degree 2 (normal factory/office environment).
Where it goes
Rated for residential buildings and infrastructure per the manufacturer's suitability listing. The 4-module width (72 mm) snaps onto standard DIN rail; mounting position is any, so it can go sideways or upside-down in tight enclosures. Depth is 76 mm, installation depth 70 mm — check your enclosure depth before committing. IP20 with connected conductors, so it's for indoor panel use only, not washdown or outdoor.