Recessed door sensors are used in Home security alarm systems to sense opening and closing of doors. In recessed Mount sensors the contact and the magnet are recessed (Hidden) into the door and door frame. A small circular hole must be drilled into the door frame and in a corresponding point on the door to place the sensors.The Working of Recessed mount sensor is same as Surface mount sensor,When the magnet moves away from contact(Switch) the circuit gets opened and alarm raises.
Placing of Recessed Mount sensors are quite a tough job which should be done with lot of care.It involves drilling of door frame and door ,so fix the place where you are going to place the sensor and start the work.
Like surface mount sensor ,recessed type also has two parts one Magnet part and one Reed switch part.
Placing of Reed Switch part of Recessed Mount Sensor.
The Reed switch part is the wired part of sensor where you have 2 Wires or More.This part should be placed at the Door Frame as in the picture above. While drilling make a way to take the wires out which should lead to the alarm panel.
Placing of Magnet Part.
Mark a Point straight from the area where the reed switch part placed in door frame and drill a hole,here the magnet part of the sensor should be placed.
Before connecting it to the alarm panel, check with the multi meter for continuity when door is closed.If tested OK proceed to connecting it to alarm panel.