What it is and what it does
The Siemens 5SL6325-7BB is a SENTRON miniature circuit breaker (MCB) — a 3-pole unit with a C tripping characteristic, rated 25 A at 400 V AC. It's built for residential and infrastructure branch-circuit protection, with a 6 kA breaking capacity certified to both EN 60898 and IEC 60947-2. That 6 kA rating means it can safely interrupt a fault current up to 6,000 A without welding its contacts or failing catastrophically — enough for most domestic and light commercial distribution boards.
What the ratings mean for fit
The C-curve trips between 5× and 10× rated current — so at 25 A, magnetic trip starts around 125 A and is guaranteed by 250 A. That's the standard choice for general-purpose loads like lighting, socket outlets, and small motor circuits where inrush isn't extreme. The 6 kA SCCR at 400 V AC covers the vast majority of domestic and commercial fault levels; if your upstream transformer can deliver more, you'll need a current-limiting upstream device or a higher-rated breaker. Temperature derating is baked in: at 40 °C ambient the breaker carries 23.68 A continuous, at 45 °C it's 23 A, and at 55 °C it drops to 21.54 A. If your panel runs hot — say, a sealed enclosure in a boiler room — factor that derating into your load calculation. The 3-pole design (3P) switches all three phases together; there's no switched neutral, so it's for TN or IT systems where the neutral is bonded elsewhere.
Mounting and integration
Snaps onto standard 35 mm DIN rail. Width is 54 mm (3 modular units), depth 76 mm, height 90 mm — fits any standard distribution board. Mounting position is unrestricted, so you can lay it sideways or upside-down if the enclosure layout demands it. IP20 with connected conductors, meaning finger-safe once wired, but not protected against dripping water — keep it inside a cabinet.