How to Prewire an Alarm System

Walk through the house and determine the locations of all the sensors that are being installed. Mount electrical boxes in the locations where surface-mount sensors such as motion detectors and glass-break detectors are going. Mount an electrical box in the keypad mounting location. Attach the electrical boxes to the wall studs or ceiling joists by holding the box against the wood and driving the attached nails through the box with a hammer. Drill holes in window and door frames for flush-mount sensors.

Starting at the alarm panel, drill holes through the studs, joists, floors and ceilings to create a path for the alarm wires. Run the appropriately-sized wires, one at a time, from the alarm panel to the sensors. Mark both ends of the wires to make final installation easier. Ensure that the wire runs do not use existing plumbing, HVAC or electrical holes as those installers may damage the alarm wires during their final installations.

Feed the ends of the wires into the electrical boxes and holes, leaving 12 inches of slack in the boxes or tied in a loose loop hanging out of the holes. Starting at the sensor end, staple the wires to the wooden studs and joists, pushing the slack back to the alarm panel. Bundle the wires together, where possible, using wire ties to create trunk lines. Place nail plates on the studs and joists where the alarm-wire holes are to prevent drywall screws from damaging the wires.

Fill any holes that were drilled between floors or rooms with fireproofing caulk.

Bundle the wires at the alarm panel with wire ties and secure them in a location that will protect them from damage during construction.