What it is and what it does
The Siemens SENTRON 5SL6440-7BB is a 4-pole miniature circuit breaker (MCB) with a C tripping characteristic, rated 40 A at 400 V AC. It provides overcurrent and short-circuit protection for final circuits in residential and infrastructure builds, with a breaking capacity of 6 kA per both EN 60898 and IEC 60947-2. The C-curve means it trips between 5 and 10 times rated current — suited for circuits with moderate inrush, like lighting banks, small motor loads, or general socket outlets. The 4-pole design switches all three phases plus neutral, common for three-phase distribution boards in European-style panels.
Panel fit and integration
Occupies 4 modular width units (72 mm wide) on a DIN rail, with a depth of 76 mm and height of 90 mm. Mounts in any position — no derating needed for orientation. Installation depth is 70 mm behind the panel surface, so it clears shallow enclosures. IP20 with connected conductors; suitable for clean, dry indoor environments. Sealable design allows locking in the OFF position for lockout/tagout. Accepts supplementary devices (auxiliary switches, shunt trips, undervoltage releases) for remote status or emergency-off integration.
Environmental and compliance
Halogen-free and silicon-free construction, rated for ambient temperatures from -40 °C to 75 °C. Overvoltage category III, pollution degree 2 — standard for fixed-installation distribution boards. Power loss is 3 W per pole at rated current in hot operating state.