S
streaker99
Or when the door or window was closed but was seen by the system as being open due to a defective sensor which, being defective, would not detect the door or window being opened by an intruder.
Even YaleGuy3 recognised this as a weakness of the system he promoted.
But a defective sensor shows up as a fault on the system.
If the sensor is no longer communicating with the panel a fault condition occurs and the orange fault light comes on , you get a warning beep every thirty seconds and a message on the LCD screen warning that the 'lounge' 'kitchen' 'front window' or whatever you have named your device has dropped from the system.
The system has adequate safeguards to protect a domestic property.
Not only that but you would always do a risk assesment based on protecting the property in the circumstance that door or window sensors had not activated due to the fact they can be circumnavigated by smasshing the window or breaking through the door without opening it and movement sensors would be in sufficient number and placement to allow for such possibilities.