Prevent unauthorized use—these switches require coded magnets (sold separately) to actuate, and cannot be bypassed using ordinary magnets. They actuate when a magnet comes within sensing distance, and reset when the magnet moves away. Mount the switch in a stationary position, such as a door frame, and mount the magnet to a movable object, such as the door. They’re often used to detect when a door or window opens, and can be used with movable machine guards. All are rated IP67 for protection from temporary submersion.

Safety relays are required in safety applications with switches that control two or three circuits.

Coded Magnets—Coded magnets include tamper-resistant one-way screws for mounting. To remove screws, see one-way bits and drivers.