The Siemens SENTRON 5SJ6440-7 is a 4-pole miniature circuit breaker from the 5SJ6 series, rated 40 A at 400 V AC with a C tripping characteristic.
The 6 kA breaking capacity is the standard domestic and light-commercial rating — adequate for most sub-distribution boards where the upstream transformer impedance limits fault current. The DC rating maxes at 60 V, which limits its use in DC circuits to low-voltage control or battery applications.
Installation and environment
The 4-pole design occupies 4 width units — 72 mm of rail space at the standard 18 mm per module. IP20 protection with connected conductors — finger-safe when wired, but not protected against moisture ingress; install inside a panel with a minimum IP54 enclosure if in a damp environment. Ambient temperature range is -20 to +45 °C, with periodic excursions to +55 °C at up to 95% humidity. Storage range is -40 to +75 °C.