40 A RCBO with type F residual current detection
The Siemens 5SU1354-4KK40 is a 1P+N RCBO from the SENTRON Super resistant K series, rated 40 A at 30 °C with a 30 mA type F residual current trip threshold and C tripping characteristic. The type F detection handles mixed-frequency residual currents from variable-speed drives, washing machine inverters, and similar loads where type A would nuisance-trip on the high-frequency content. The 2-module-width (36 mm) body fits standard DIN-rail enclosures with a 77 mm depth — check the enclosure depth before specifying, as some shallow consumer units leave less than 80 mm behind the rail.
Temperature derating and environmental limits
Rated current is 40 A at 30 °C ambient, derating to 37.6 A at 40 °C, 36.4 A at 45 °C, 34.8 A at 50 °C, 32.4 A at 55 °C and 60 °C, and 30.8 A at 65 °C, down to 29.2 A at 70 °C. In a 40 °C panel — typical for a sealed outdoor enclosure in summer — the continuous load limit drops to 37.6 A, so a 40 A circuit feeding a continuous EV charger needs a higher-rated device or active ventilation.