Panel fit and mounting — no shop, no crane
The 3RH2253-1BB40: Mounts on 35 mm DIN rail via screw or snap-on. Width 45 mm, depth 117 mm, height 57.5 mm. Air gaps needed: 10 mm upward, downward, and forward (-), 6 mm sideways — that's the arc clearance. Mounting position is flexible: rotate 180° on a vertical surface or tilt ±22.5° forward/back. So you can wedge it into a crowded panel as long as you leave those gaps. Can you fix it where it sits? Yeah — easy access to the screw terminals, no special tools.