Anubis Systems Technologies

DOOR/WINDOW CONTACTS (PERIMETER PROTECTION DEVICES)

Of the two main groups of devices that comprise a modern alarm system, contact type switches are the simplest by far, and the most powerful.  When properly utilized, they can detect an intrusion into the protected space even before physical entry is gained.  Contacts on certain entry doors also act as "triggers" that enable the system to detect an entry by an actual user and give them the time required to access the control unit and disarm or turn it off.  The most common types of contacts employ a micro switch made of very thin metal reeds that are sealed into a plastic or aluminum housing.  They are either surface mounted or flush mounted into the door or window frame.  Surface mounted contacts are usually secured with double sided tape or screwed onto the door frame.  Wires connected to the switch terminals are in turn terminated into one of the zones of the control unit.  A simple magnet is mounted immediately adjacent to the switch on the door or window itself.  When the two units (magnet and switch) are in close proximity, the control unit recognizes this as a "normal" condition.  When you open the door/window, the reed switch is activated and the alarm system interprets this as a "break" in the wire which in turn triggers the zone to which the switch is terminated.

Most alarm systems are capable of recognizing when a switch is "tampered" with, and it is up to you as the concerned customer to ensure that this feature is activated.  In most instances, most alarm companies will install "low security" normally closed switches and in the case of a flush mounted installation, this provides excellent protection.  Surface mounted switches, however, are far more accessible to a knowledgeable burglar or thief, and in some applications a higher security switch may be the more prudent choice.   Your professional security consultant should present these options to you, the customer, during the course of his normal walk around inspection of your premise.  In most instances the difference in cost between the lower and the higher security switches is not even worth mentioning.

Some alarm systems require even higher security contacts.  These employ a reed switch with three terminals.  When an "alarm" condition is achieved (by the opening of a door or window), one "side" of the terminals will "open", and the other will "short".  The combination or a single action (an opening or closing terminal) will result in a faulted or tripped zone.  Still other types of contacts employ a "biassed" magnet/switch combination.  When an intruder attempts to bypass the magnet on the door or window with another magnet, the switch will immediately open and display an alarm condition. The simplest contact switch device is one that is rarely utilized today, althought there are still legitimate applications that do crop up from time to time. This device employs a spring loaded microswitch, which looks very similar to the switches used in your car to turn on the interior lights when you open your door.

For more information you can email us or telephone (778) 863-7147.