What it is and what the ratings mean
The Siemens SENTRON 5SL4440-7 is a 4-pole miniature circuit breaker (MCB) with C-curve tripping characteristic, rated 40 A at 400 V AC. Its 10 kA breaking capacity is certified to both EN 60898 and IEC 60947-2 — the EN standard covers residential and commercial distribution, while the IEC standard covers industrial panel applications. That dual rating means the same part meets the SCCR requirement for most sub-distribution boards and final-load circuits without needing a separate upstream current-limiting device. The C-curve (5–10× In magnetic trip) handles moderate inrush from lighting banks, small motors, and transformer-coupled loads without nuisance tripping. The 4-pole design switches all three phases plus neutral, so it is suited for three-phase final circuits where the neutral must be disconnected for isolation — common in European-style TN-S or TT distribution boards. Multi-phase operation is rated at 440 V AC maximum, giving headroom above the nominal 400 V for voltage swell conditions.
Mounting and integration
Snaps onto standard DIN rail (EN 60715). Four modular width units (72 mm wide) occupy four 18 mm slots in the distribution board. Depth of 76 mm and installation depth of 70 mm leave clearance behind the DIN rail for wiring — standard 35 mm deep enclosures with 10 mm back clearance work. Mounting position is unrestricted, so the breaker can be installed horizontally or upside-down without derating the thermal-magnetic trip. IP20 with connected conductors — finger-safe from the front once wired, but not rated for washdown. Suitable for indoor panel use in residential buildings and infrastructure (schools, offices, light commercial). Pollution degree 2 and overvoltage category III cover fixed-installation environments.
Power loss and supplementary devices
Per-pole power loss at rated current in hot operating state is 3.3 W, so the total 4-pole dissipation is 13.2 W at full load. That heat must be considered when packing multiple breakers in a sealed enclosure — derate or ventilate above 40 °C ambient. The breaker accepts installable supplementary devices (auxiliary contacts, shunt trips, undervoltage releases) on the left side, per the SENTRON accessory range.