RepRap Prusa i3 - Using the Z Sensor; Z Sensor Functionality and Safety; Sensor Positioning

Prusa i3 – Build Manual
4. Ramps Mounting
Now is a good time to mount the Ramps board while access to the frame is easy before the X-axis goes on.
Unplug the power connector from the Ramps board (parts picture), it will be wired up later to the power supply
& always on fans.
4.1 Ramps mount
Clip the Ramps mount to the rear left of the frame and slot in the clamp bolt (but not tighten) , Fig 4.1a
Fig 4.1a:
Version: 1.3 Page: 18