SCCR and interrupting capacity
For a panel builder coordinating with upstream fuses or a main breaker, that 100 kA figure at 400 V means you can typically skip a current-limiting fuse ahead of this device in a 100 kA SCCR-rated panel, as long as the feeder can deliver that. The gL/gG fuse backup ratings (50 A at 400 V, 40 A at 500/690 V) give you a coordination path if the available fault current exceeds the breaker's standalone rating.
Spring-loaded terminals on the main circuit accept 2× (0.5 to 2.5 mm²) solid or stranded. Strip length for the spring cage is not specified here, but typical Siemens spring terminals on this class need about 8–10 mm. Clearances: 50 mm above and below, 30 mm to the side, 0 mm front and back — meaning you can stack adjacent devices tight side-to-side, but leave breathing room top and bottom for arc venting.