The Siemens SENTRON 5SL4640-7 is a 4-module-width (72 mm) miniature circuit breaker with a 3P+N pole configuration, rated 400 V AC and 10 kA breaking capacity per both EN 60898 and IEC 60947-2. The C-curve tripping characteristic means it handles moderate inrush from motor or lighting loads without nuisance tripping — the magnetic trip operates at 5 to 10 times rated current, so a 40 A unit holds through a 200–400 A surge for a few milliseconds. This is the go-to for residential and infrastructure distribution boards where you need a switched neutral in a single housing.
Sizing and panel fit
At 72 mm wide (4 MW), it occupies four 18 mm DIN-rail positions — standard for a 3P+N breaker at this current. Depth of 76 mm and installation depth of 70 mm leave clearance behind a standard 80 mm deep enclosure gland plate. Mounting position is unrestricted, so it can go sideways in a tight sub-panel without derating the thermal trip. Power loss per pole is 3.3 W at rated current; four poles sum to 13.2 W heat dissipation inside the enclosure — factor that into your thermal budget if the panel is sealed.