Magnetic Detection

Most intrusion detection systems in use today utilize some form of electrical circuit running through wires, mechanisms, metalized tape or foil. If any part of the electric circuit running through two pieces of metal in the door locks or window lock mechanisms, or if a strip of metallic tape on the window glass is broken, it trips an alarm.

Circuits work well when an intruder attempts entry as one would expect, by opening a door or window. Burglars however, know how to use crowbars and other burglary tools to get through doors without disrupting these electrical circuits. In warm climate regions, houses may have thin walls, and entry can be gained by cutting through a wall. Tape or wire mesh in the wall would have to be torn or cut through to gain entry, thus tripping the security alarms.

Limitations occur in a circuit system because the gap or break can be bridged when the burglar breaks the tape or magnetic connection with a long wire or piece of metalized tape, prying open a door or window frame without setting off the alarm.

Magnetic Contact Circuits

Electromagnetic systems are often used on doors to apartment buildings and secure areas in government offices. They use a magnet in one sealed enclosure and a switch in another sealed enclosure and when the magnetic contact is broken, the alarm signal sounds.

In order to open a door protected with a magnetic door latch, a button has to be pushed by an attendant to allow the door to be opened by the visitor. The button merely moves the door mechanism to the open position. When the electrical switch is turned off (button is released), the mechanism closes again. These systems are used in place of key/lock systems and they ensure a human being is controlling access. Some electromagetic lock systems can withstand well over a ton of force making them difficult to break through.

Electric circuit based security systems will protect the perimeter of a house, but will not be effective if someone is already inside your home. If you have valuables such as jewelry, art or collections in your home, you would be wise to consider motion detection systems. Follow this link to learn about magnetic contact sensors.

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