Breaking capacity and dual-standard certification
The higher IEC 60947-2 figure applies when the breaker is used as a distribution or industrial circuit protector — the 20 kA SCCR gives headroom for fault currents in panelboard feeders without cascading upstream fuses. The 5SY4320-8 carries approvals under both the household-standard (EN 60898-1) and industrial-standard (IEC 60947-2 / UL1077) frameworks, so it can be specified in residential DBs or industrial MCCs without a change order.
Temperature derating and panel integration
At 35 °C ambient the breaker holds the full 20 A rating. The published derating table lets you calculate the real load limit inside a warm enclosure without guessing. Mounting position is any orientation. The quick-assembly system snaps onto the rail and the combined top/bottom terminals accept the busbar or ring-tongue feeder.