Do It Yourself Burglar Busters

Just a few years ago, safeguarding your home with an alarm system meant calling in a professional installer--and paying $2,000 or more. Now, using wireless components from Schlage Lock, Black & Decker, American Telephone & Telegraph, or others, a handy homeowner armed with a screwdriver can build an effective security system for about a third of the cost.

Wireless systems use battery-powered sensors that send radio signals to a control box. When an intruder opens a door or window or steps into a protected area, the sensor triggers a loud, high-pitched alarm that sounds in the house. More complex systems can also set off outdoor sirens, flash lights on and off, and send emergency calls over the phone line.

BODY HEAT. A typical system for a three-bedroom house might require at least a half-dozen sensors on first-floor doors and windows, plus several ultrasonic or infrared area detectors that react when movement or body heat disrupts an invisible beam inside the house. Wireless alarms are popular among apartment dwellers who can't drill the holes required for a wired system. They're also good for homeowners who plan to move and want to bring the components along.

Some security professionals say wireless components are more prone to false alarms than wired systems. That produces "an effect like the boy who cried wolf," says Al Colombo, who owned an alarm company in Canton, Ohio, and is now an editor at Security Distributing and Marketing. But he notes that more false alarms result from faulty installation and poor maintenance than equipment problems. So it's important to pinpoint the best sites for the sensors and check for weak batteries at least monthly.

A $6 Radio Shack paperback, Installing Home and Auto Security Systems, covers alarm basics in nontechnical language. Whether you do it yourself or call in a pro, installing a system usually earns a reduction of 5% to 15% in premiums for homeowner's insurance.

Schlage Lock was one of the first marketers to aim for the do-it-yourself crowd. Its $420 Keepsafer Plus kit has three door or window sensors. You can buy additional sensors ($34 each), sirens ($66), and a device that phones a taped message to an emergency number ($109). Black & Decker's Deluxe Home Protector kit ($250), with six sensors, sets off both a siren and a flashing lamp.

MORE JUICE. Ademco, Code-Alarm, and other longtime suppliers to the security industry also sell wireless units to do-it-yourselfers through burglar-alarm dealers. Code-Alarm's System 2000, with just two sensors, retails for $299, for example, and an auxiliary outdoor siren is $90. Professional equipment costs more because it has stronger transmitters that can cover a large home and circuitry to prevent false alarms caused by, say, radio signals from a cordless phone.

An alarm can also be linked to a central monitoring station for about $20 a month. Systems offered by Black & Decker and several others feature add-on devices (about $100) that you plug into a phone jack. When the alarm is triggered, a digital code number flashes on a computer screen and a watchful clerk phones whatever number you designate--police or fire department, neighbors or office.

Some systems let you avoid a monitoring charge by using an automatic dialer that can phone the police directly and play a taped message. But first check whether police in your area will respond to the call. Wary of pranks, "some municipalities have banned tape dialers," says Richard Bisnoff of Alarmingly Safe & Sound in Queens, N. Y., which runs a monitoring station.

Expect an occasional false alarm, especially until you make adjustments for unforeseen occurrences. For example, a dog or cat can trigger a motion detector that's aimed too low. Moving it slightly higher is a small step to take for protection.

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