Sizing and coordination
The 4 A D-curve is sized for small motor or solenoid circuits where the starting surge exceeds 10× rated current for a few cycles. At 400 V AC the breaker clears faults up to 30 kA (IEC 60947-2), giving headroom for selective coordination downstream of a larger feeder MCB or MCCB. The 6 kA EN 60898 rating is the standard domestic/commercial limit; the higher IEC figure is what matters in industrial switchgear.
Snap-on 18 mm width (1 MW) mounts on standard DIN rail. Accepts solid or stranded conductors from 0.75 up to 35 mm² — big enough for the load side of a 4 A breaker, which is unusual; typically a 4 A MCB only needs 1.5–2.5 mm², but the 35 mm² terminal capacity lets you use it as a tap-off point for larger incoming feeders. Combined top and bottom terminals simplify daisy-chaining in a distribution board.