Temperature derating — what 63 A means at panel ambient
The 63 A rating is at 35 °C ambient. At 40 °C it derates to 60.04 A, at 45 °C to 58.46 A, at 50 °C to 56.89 A, at 55 °C to 55.25 A, and at 60 °C to 53.55 A. If your panel runs warm — say 50 °C inside a sealed enclosure — you're effectively limited to 56.89 A continuous. Plan your load accordingly; don't size the breaker at 63 A and expect it to carry that in a hot cabinet. The quick assembly system means it snaps onto the DIN rail and can be ganged with busbars without tools — a time-saver when populating a multi-way distribution board.