How to Wire an Alarm Sensor

Open the window. Screw an alarm sensor to the bottom of the window with wood screws using a Phillips screwdriver. Place a sensor receiving plate on the windowsill, beneath the sensor plate. Screw the sensor receiver plate into the window sill with wood screws using a Phillips screwdriver.

Slit 2 inches in between the electric cable at the end of the electric cable spool with a utility knife. Pull the two electric wires at the end apart from each other. Strip 1/2 inch of insulation off the ends of each wire with a wire strippers.

Loosen the two screws on the side of the sensor receiving plate with a Phillips jeweler's screwdriver. Wind the exposed ends of the two wires around the two screws--one wire wound around one screw each. Tighten the screws.

Run the electric cable down the side of the wall and along the baseboard until you come to the control panel of the alarm system that is already installed in the home--typically the control panel will be in an out-of-the-way location such as a closet. Enter the password on the control panel's keyboard to disarm the alarm system

Cut the electric cable off the electric cable spool with the blade of the utility knife. Separate the two wires from the end of the electric cable and strip them in the same manner as you did on their other end.

Remove the screws from the side of the control panel with a Phillips screwdriver. Open the cover. Loosen a pair of input screws on the "Input" section inside of the control panel with a Phillips jeweler's screwdriver.

Wire the pairs of wires to the input screws. Tighten the screws. Close the cover and reattach the screws. Rearm the control panel. Press the "Menu" button and navigate to the "Settings" menu--the exact name varying depending on the make of the alarm system.

Follow the directions provided with the alarm security system kit to configure the control panel to accept the presence of the alarm sensor you have installed. Return the control panel to its normal setting.