How to Install a Prewired Alarm System

by Robert Vaux

Prewired alarm systems are actually fairly easy to install. The hard part is already done: the wires and connections are in place in your walls, and in many cases terminate at a plate or opening tailor-made for the system. That eliminates the need for a professional to muck about with your wiring (though you can still use one if you wish). Otherwise, installing a new alarm system is simply a matter of examining your existing wiring, and determining which components still need to be added.

Check the spot where your control panel goes. If you're lucky, a control panel may be in place already. Otherwise, there will likely be a small opening in the wall with a series of wires protruding from it. Note which wires are which---each one travels to a separate portion of the house and you'll need to connect them to the control box properly when the time comes. They'll often be color-coded to help you, though the precise color depends on the kind of system you have. You should also note the gauge of the wire and ensure that it is compatible with whatever system you intend to use.

Find the spot for the siren and the spots for any motion detectors in the home. They will likely be high up on the walls, with wires protruding nearby and/or a mounting frame in place. As with the control panel, you should note how many wires are involved and what color they are.

Check the ceilings for wires for any flashing lights, smoke detectors, or CO2 detectors in the system.

Examine each of the doors and windows on the ground floor of your house for contact points. These are small circular impressions about the size of a dime or perhaps a little smaller. They appear in the jam of the door or window, with a corresponding spot on the door or window itself. When the door or window is closed, the two contact points should come into contact. (That keeps the alarm from going off. When the system is activated and an intruder opens the door or window, the contact points separate and the alarm goes off.) Any door or windows which don't have these contact points are not connected to the system and will need to have wires run to the control box before they are covered.

Mount each component in the system to the wiring, one by one. Start with the mounting plates for the control panel, alarms, smoke detectors and motion detectors; they can usually just be screwed into the wall with a screwdriver. Then fit each wire in its appropriate housing on the component, and tighten the wires into place with a screwdriver. Consult the instruction manual for your particular system to see which wire goes there. (Generally speaking, red wires match the positive (+) current, while black wires match the negative (-) current.) Once the wires are connected, fit each component into its housing, and turn them on one by one. Test each component to make sure it operates correctly. If you have a security monitoring service, they may have additional steps to follow before their system goes online.


  • check All alarm systems require regular checks to ensure they're operating at peak capacity. Test each component in your system once a month and replace any piece which may have worn out.

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