The 5SM3646-0LB: It is an instantaneous (non-delayed) type, meaning it trips without intentional time delay on a residual fault. That makes it unsuitable for selective coordination with downstream RCDs unless the downstream devices are short-time-delayed or have a lower threshold. The 1 kA surge current resistance (8/20 µs waveform) is standard for this class — it will survive typical lightning-induced transients on a building supply without nuisance tripping or damage.
Snaps onto DIN rail (REG profile), occupies 4 width units (about 72 mm at 18 mm per unit). Installation depth is 70 mm, which fits standard distribution board enclosures. Mounting position is unrestricted — vertical, horizontal, or inverted all work. IP20 protection applies once installed with conductors connected — so it is rated for indoor, dry-location use inside a distribution board.
Environmental limits and service life
Rated for ambient temperatures from -5 °C to 45 °C during operation. The 45 °C maximum operating limit means the breaker is fine in a ventilated panel in most climates, but if the enclosure is in direct sun or next to heat sources, you need to check internal temperature rise. The finger and back-of-hand safe protection (per IPXXB) means the terminals are shielded against accidental contact during wiring — a standard safety feature on modern DIN-rail devices.