There is provide a method of installing a security alarm system in a building having one of a doorbell chime, a smoke detector, a carbon monoxide detector and a thermostat in an existing location. The method includes disconnecting the one of the doorbell chime, the smoke detector, the carbon monoxide detector and the thermostat from existing wiring thereof. The method includes removing from the existing location the one of the doorbell chime, the smoke detector, the carbon monoxide detector and the thermostat. The method includes installing in the existing location a security control panel. The method includes connecting the existing wiring to the security control panel so as to receive power therefrom.