Perhaps the best way to protect overhead door contacts from industrial motorized traffic like forklifts and large trucks is to recess or bury them into the concrete floor, allowing vehicles of this type to safely pass over them totally unaffected.
The G.R.I. 4510 switch series has been designed from the ground up, so to speak, for just such an application. The 4510 series features all stainless steel construction for maximum resistance to corrosion and has a wide working gap for those loose or badly worn overhead doors.
To best visualize the installation process, it is recommended we temporarily mount the magnet to the door. Remember to choose a mounting point that will require a minimum amount of concrete removal.
Place switch on floor, testing the position of the switch to magnet. It is recommended that 1" to 1 1/4" be used as the operational distance. Marking this switch position with a felt tip marker, we can now begin chipping out concrete.
A channel approximately 1/2" to 3/4" deep and 1/2" wide will be sufficient. Place the switch in the opening and retest to confirm adequate gap. Apply concrete patch to contain and cover magnetic door switch and cable. Retest for positive operation by opening and closing the overhead door.