Door Contacts – Wireless October 28th, 2009
You will definitely want door contacts included in your home security system. Most burglar alarm kits automatically include them.
There are two main kinds of door contacts, “hard-wired” and “wireless”. In this article we will deal with the wireless.
There are two advantages to wireless door contacts:
1. They are very easy to install, in most cases.
2. They can be place on virtually any door, even those which cannot be accessed for hard-wired contacts.
Examples of places where a hard-wired contact cannot be installed would be in a home with a cement slab on the main floor, or a bi-level home with a cement slab, since the installer can’t get under the floor to drill into the door casing from below.
In any case, wireless contacts of the disadvantage of requiring individual batteries, although they can be expected to last for two or three years or more.
The wireless contact typically consists of two pieces, one attached to the door itself, and one attached to the frame of the door. Most are rectangular box-shaped pieces, but some are recessed into the door and door frame, similarly to a hard-wired contact.
The two pieces are placed directly facing each other, but not touching. They are “connected” by waves traveling through the small air space between them. In this way, when the door is opened, the “connection” between them is broken, and the alarm is set off.
Simple, even primitive as modern technology goes, but very effective, and crucial to your home security system, because doors are the most popular entry point for burglars.
