The 5SM3344-0LB: It snaps onto a DIN rail (REG profile) and occupies 4 width units (72 mm at 18 mm/module). Mounting position is unrestricted — top or bottom feed works. The IP20 rating applies once conductors are connected inside a distribution board; this is normal for panel-mount protective devices, not for exposed outdoor installation.
Thermal limits and operating envelope
Ambient operating range is -5 °C to +45 °C. If the panel sits in an unconditioned space that sees summer peaks above 45 °C, you need to derate or move the RCCB to a cooler zone — the thermal curve is not published here, but the 45 °C ceiling is the hard limit for continuous rated current.