Protecting Steel Doors with Threshold Contacts
For steel doors with aluminum thresholds, it is sometimes convenient to mount the magnet in the bottom of the door and the switch in the hollow space beneath the threshold.
Note: Because of the distance between the magnet and switch, a Sentrol wide gap switch should be used.
Use a Sentrol steel door magnet combined with an Interlogix wide gap switch.
Remove door from hinges. Drill 1" (2.54 cm) diameter hole in bottom of door about 2" (5 cm) from front edge of door. Glue with RTV or epoxy and snap-fit magnet into hole.
Attach switch on inside of threshold with RTV mounting compound. Position it so it will be directly beneath and perpendicular to magnet with end centered beneath it when threshold is replaced.
Replace threshold and door.
Test for correct operation with ohmmeter while opening and closing door.
Connect switch to alarm loop.