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Alarm System Design

A security system design can be separated into five different levels. These levels are:

Perimeter , which is protecting all perimeter openings to the premises. This is done through inexpensive magnetic contacts for doors and windows. Occasionally photo electric beam detectors are used as well around a perimeter.

Perimeter Backup which generally refers to backing up openings that have glass. Devices for perimeter backup include glassbreak sensors and glass mount shock sensors.

Interior protection is to provide a third and final layer of intrusion protection. Devices for Interior protection are motion sensors, floor flex sensors (pressure sensitive sensors) and photo electric beams.

Life Safety protection is the fourth level of protection and most often overlooked. This pertains to detection devices for smoke, carbon monoxide, and gas. I can't stress enough the value in using professional grade life safety devices that will interface with your security system. They are generally of higher quality than those commonly found at the local department store, and more importantly are supervised by the security system. Since they are powered by the system (hardwired types) they will never require batteries and since the security system has a backup battery, they will continue to work if / when you lose power such as during a thunderstorm. Of course last but not least, they can alert you (by pager), or the proper authorities through a central station to get help immediately. If your home or business catches fire while no one is there, no one may call the fire department until they see flames shooting out of the roof, too late to do any good, with alarm interfaced smoke detectors help could be on the way at the first sign of smoke.

Environmental / Asset Protection is the final type of protection. Less common than the others, it can be a godsend to have if you live in a cold climate and the pilot on your furnace has ever gone out while you're on vacation. Environmental devices include high and low temperature sensors, sump pump float sensors, water sensors, and humidity sensors. Again, these devices can report through the security system via pager or to a central station for response.

When designing a security system for your home or business you should first set out your objectives and what level of protection you want and may expand to at a later date. Will you want now or later advanced system features such as home automation control? The ideal design will include at least the first four levels of protection, however if your budget won't allow it for now, think of what trade offs you are willing to take. Are you only concerned about protection of assets while you're away? If so, maybe a partial perimeter (doors only) and several interior devices will suffice. Are you primarily concerned for your personal protection while you're home at night? If so, then you'll definitely want a full perimeter system and perhaps some perimeter backup devices, as interior devices are *usually* not armed while you're in the premises.

There are also a few case by case considerations when designing a system layout. Since any good system design will include interior protection devices, if you have any pets in your premises you will have to plan accordingly. It is not always the case that if you have pets you will have to sacrifice some level of protection, you simply have to plan.

If your pets will not be in the premises while the security system is armed there is no problem. If the pet('s) will be you will have to consider Pet Immune motion sensors. These sensors will generally regard anything under 85 pounds as a pet and as such not cause an alarm. These motion sensors are a bit more expensive, however they're a must if you want interior protection and have pets. These detectors do have to be mounted in an area where the pets can come no closer than about six feet to the sensor. Since the sensors are generally mounted at a height of between 6 and 7 feet this usually isn't a problem, however keep in mind that your pet may get on furniture below or just in front of a detector bringing it closer to the sensor.

Other alternatives to protecting an interior with pets is: confine the pets to one room or area of the premises where there is no motion sensors, or for pets under 60 pounds use floor stress sensors. Floor stress sensors can be tuned for sensitivity thus letting your pet roam free while still being able sense a human.

Next, figure how many protection points, i.e. individual doors, windows, motion sensors, ect. you have total in your design. Now be sure to add to that total how many additional devices you may wish to add to the system later. Now choose a system that is capable of handling at least your total number of protection points / zones and has the features you're interested in. Note: Ideally you should put one protection point per zone, however if you are just above the maximum zones for one of the systems, or you want to save a little money, you can "loop" zones, that is putting two or more like devices on a single zone. Looped zones will however have to have the same attributes such as entry delay time if it is a door.

When designing a system you also have to keep in mind how much current your powered protection devices require. Door and window contacts do not require power, however motion sensors, glassbreak sensors, and most other devices do. The security panel is only capable of handling so much before you have to add an additional power supply, and how much it can handle varies among brands of systems. Usually for a typical home this isn't a concern, but for large installations with many powered devices you will likely have to get an additional power supply. The power capabilities of a given panel is listed on the spec sheets on our site and the current draw of powered devices are also listed on their respective spec sheets. If you have a question regarding this however, feel free to contact us.

That's the basics for now, this page is a work in progress and we will be adding to it periodically, so if you have any suggestions please contact us with your suggestions.


Protech Systems
division of Secure Systems Plus, LLC
P.O. Box 2523
Columbus, IN 47202

Toll Free: 1-888-811-0727
Fax: 812-392-9994

Selling Home Alarms / home alarm systems direct to do it yourselfers since 1997! Call the Home Alarm Pro's today!