What the ratings mean on the line
The 125 A continuous rating (Iu) means this disconnect will carry full motor or resistive load current without derating up to 40 °C ambient — above that, you'll need to consult the thermal derating curve in the 3VA manual. The 800 V rated insulation voltage (Ui) tells you the internal clearances and creepage are sized for 690 V AC systems, so it's comfortable in 400 V or 480 V distribution panels. It ships with front terminals for busbar connection, so it lands directly on a busbar stack in the panel — no lug kits needed. The IP40 front protection means it's protected against tools and small wires touching live parts from the front, but it's not sealed against dust ingress; mount it inside a panel with a door. The 70 mm depth and 101.6 mm width fit the standard SENTRON 4-pole footprint, so it swaps into an existing 3VA cutout without re-drilling the mounting plate.