A Hybrid system can be used either way and often is configured to use a combination of the two. Alarm systems are protected against sabotage. An attempt to sabotage any part of the system will in itself cause the alarm to go into an alarm state. One method of sabotaging an alarm system is to spray a detector with varnish. This form of sabotage is prevented by using detectors with so called, anti-masking protection.
All alarm systems have their own power supply, either centrally or within the individual components.
Changes caused by moving furniture, window displays, the taking down of, or building of walls and screens, will almost certainly affect the coverage area of the detectors, and the relocation of these detectors should be considered with each and every change to the surrounding area . All alarm systems should be tested regularly, preferably once a month, after a storm, break in the the electrical supply to the building, or after any activity that has caused the alarm to go into an alarm state. At the same time the telephone lines should be checked to see that they are in working order. This to confirm the integrity of the communications between the alarm system and the monitoring station if one is used. The Security Site home page Detectors.