Door Contacts – Hard Wired October 28th, 2009
Virtually all home security systems will have contacts on the doors, so that when the door is opened, the alarm will be set off.
Door contacts come in a variety of styles, but the two main categories are “hard-wired” and “wireless”.
The hard-wired door contacts are the most popular, and have two advantages over the wireless:
1. They are less expensive.
2. They don’t require individual batteries.
The hard-wired contacts consist of two separate components. The first is the contact which is embedded into the door casing. It is recessed into the door casing, so that it is almost invisible. But it is connected by a wire to the security system.
Normally, a hole is drilled into the casing from under the house, either from a crawl space, or some basements. It may sometimes be drilled in from an attic into the top part of the door casing.
In any case, directly across from the contact embedded in that door casing, is a matching magnet embedded into the door itself. It lines up face-to-face with the wired component embedded in the casing.
When the door is opened, the magnetic “connection” between the two components is broken, setting off the alarm.
Sometimes with some floor plans, there is no way to get under the floor of a home or an attic. Then hard-wired door contacts can’t be installed.
For example, a bi-level home with a cement slab on the lower level will usually require wireless contacts, because you can’t get under the cement, obviously, and there is no attic that is close to the door frames.
Another example is when there is a finished basement under the home, with no “drop ceiling” to get into, so there is no way to get to the doors on the main floor, without destroying the finished ceiling of the basement. And so wireless contacts must be used.
Needless to say, door contacts are one of the most important parts of your security system, since it is the most popular way that a burglar enters a home.
