Burglar & Intruder Alarms-Protecting Home & Family-Business Access Control

Not too long ago our burglar alarm was a dog and very good neighbours. Today we have very sophisticated systems that few occupiers really understand.

No matter whether your intruder alarm is a basic DIY system, wireless burglar alarm or complex state-of-the-art integrated access control and security system, the principle is very much the same.

Let's take a look at how Circuit Alarms, Basic Motion Detectors, and more Advanced Motion Sensors work.

Circuit alarms come in two types: closed circuit and open circuit.

The concept is identical: electricity travels through the circuit protecting a door or window. With an open circuit, the current is not completed until the door or window is open, this triggers the alarm. The downside to this intruder alarm system is that all the burglar needs to do is cut the wires; this prevents the circuit from being completed.

Whereas a closed circuit intruder alarm, the current is broken when the door or window is opened, thus triggering the alarm.

All intruder alarms have a control panel and vary in complexity. They either have a keypad or traditional key to arm and disarm the burglar alarm. It is likely to have 'zones'; each zone represents a protected area. When the intruder alarm is activated, the control panel will sound internally as well as repeater sounding much louder through an external box, which may also flash. The control panel and external box will keep sounding until it is reset with a predetermined code or key.

The control panel should be sited in a place where the burglar cannot easily find and interfere with it.

Closed circuit burglar alarms are generally used as perimeter protection but be mindful that although the circuit goes around the door or window frame, if a panel is remove from the door, a window is removed without breaking the circuit, the intruder alarm will not be activated.

A motion detector offers an excellent back up. You may see these called PIR detectors and are located high up in corners, flashing each time they detect motion, even when the burglar alarm is off.

You can surround your home with a closed circuit alarm system that will sound the alarm when an intruder breaks the circuit. But once the criminal is inside, you need a whole different approach to how burglar alarms work. Motion detectors can assist in opening automatic doors and gate by detecting people approach. They can switch lights on too.

More advanced are passive infrared (PIR) motion sensors that see the heat given off by a person's body. The PIR measures the average room temperature and triggers the alarm when the energy rises rapidly, particularly when a human, whose average body temperature is 98.6 degrees, enters a room with an average of say 80-degrees

Don't worry about setting the alarm off when you enter a room, generally there is delay of a few seconds enabling you to reach the control box and disengage the alarm before setting it off.

If you have pets, don't forget to inform your security consult so that special PIR units can be sited in such a way that allows pets to roam without activating the system. . There are more advanced motion sensors, photo-sensor motion detectors for example. A beam of light is shone across an area in your property. When someone walks through the beam, it is broken and the sensor triggers the alarm.

A good intruder alarm system would combine both circuit and motion sensor alarms, thus providing you with two lines of protection against burglars

Digby Farquart is a UK security consultant and crime prevention advisor He writes articles for top sites such as UK Security Directory and Crime Prevention