The Siemens 5SJ6140-7 is a 1-pole SENTRON miniature circuit breaker from the 5SJ6 series, rated 40 A with a C tripping characteristic and a 6 kA breaking capacity per EN 60898 and IEC 60947-2. That C-curve means it's built for moderate inrush loads — lighting banks, small motor circuits, control transformers — where the start-up current is a few times the rated value but not the high spike a D-curve handles.
The terminals accept solid or stranded copper from 0.75 mm² up to 25 mm² — that's a wide range, so you can land a 2.5 mm² lighting circuit or a 10 mm² feeder without adapters.
Rated for ambient temperatures from -20 °C to +45 °C, with periodic tolerance up to +55 °C at 95% humidity. Storage range is wider at -40 °C to +75 °C. Vibration resistance tested to 50 m/s² at 25–150 Hz and 60 m/s² at 10–150 Hz per IEC 60068-2-6, so it holds up on machinery with moderate vibration. Mechanical life is 20 000 switching cycles typical.