Rated 277 VAC and 125 VDC, with an interrupting capacity of 6 kA AC and 10 kA DC.
The 63 A rating means this breaker handles branch circuits up to that continuous current — sized for a heavy lighting panel or a moderate motor feeder. Trip curve B (3–5× In instantaneous trip) is the standard for resistive loads and general-purpose distribution where you want fast clearing on short circuits but tolerance for inrush from small transformers or capacitor banks. The 6 kA interrupting rating at 277 VAC is adequate for most commercial panelboards with available fault current under that threshold; the 10 kA DC rating covers battery-bank or UPS output circuits.
Panel integration
The 3-pole body occupies three modular 17.5 mm widths — standard for a 3P MCB in a distribution board.