The schematic below shows how the MeltSwitch is typically installed.  The melt flowing over the ejector pin pushes the ejector, which then pushes the transfer pin and closes the switch.  The ejector pin should extend above the molding surface at least 0.006 inches if the ejector pin is required to be flush with the molding surface after the melt flows over it.   There also needs to be sufficient clearance behind the heads of the ejector pin and transfer pin so that they can move forward and back.  The combined length of the ejector pin and the transfer pin is the distance from the molding surface to the front of the clamp plate.  Wire tie-downs should be used to secure the wire so that it won’t be damaged by the ejector plate and the wires can be connected to a 2-pin magnetic connector attached to the mold or machine platen.