What the 3200 A rating means for your bus
The ENW22331 is a 3-pole chassis rated 3200 A at 40 °C — that is the continuous current it carries without derating in a typical 40 °C switchroom. At higher ambient temperatures you derate per the EasyPac NW thermal curve; the 40 °C baseline is what you use for the main bus tie or incoming feeder in a low-voltage switchboard. If your site has a high-fault transformer close-coupled, you step up to the H or L breaking capacity variant.
Drawout mounting — what it changes for panel integration
Drawout mounting means the chassis slides into a fixed cradle, so you can rack the breaker out for maintenance or replacement without unbolting busbars. The footprint is 445 mm deep by 400 mm wide by 440 mm high — you need that clearance in front of the cradle for the racking mechanism to travel, plus space above for arc-venting if the switchboard is arc-resistant.