There's the suspicious-looking person sitting in a car parked down the street, the frightening tales from the neighbors of window tampering, a creak in the middle of the night--all triggers to make you wonder, "Is our home safe?"
Door and window locks, known as "physical security," are considered by security experts to be the first line of defense against intruders. For most people, they're the only defense. But as technology has advanced, sophisticated alarm systems once available only to businesses and the wealthy have become accessible to a wide range of homeowners.
They range from easy-to-install, simple arrangements of sensors that sound an alarm when a door or window is open to sophisticated systems that include a duress alarm that lets you silently signal the authorities if an intruder is attempting to enter your home.
"Some even have printouts to tell you what area (of the house) has been violated," says Neil Coyne of Ferrell's Electric Supply in Anaheim, which installs and repairs home alarm systems.
Despite their different features, alarm systems basically work the same way.
Magnetic sensors or switches on doors and windows are connected through hard wire or radio signals to a control unit. When a door or window is opened while the sensor is on, electrical contact is either broken or made and the alarm is activated.
Some sensors can pick up the breaking of a window, while others detect smoke and heat and relay the information to a control center that automatically alerts authorities.
Sensors connected by hard-wire systems are more reliable and less expensive but are usually more difficult to install. The wires have to be inconspicuous to prevent them from being a target for tampering, as well as for aesthetic reasons. Wireless systems are easier to install and can be transferred into your new home when you move, but have to be continually checked to make sure they're working properly.
"Some wireless systems automatically check the transmitter and sensor to see if they're operating," says Mike McCoy, police service officer with the Santa Ana Police Department.
"Without that, because the sensor operates off 9-volt batteries, if one of the batteries dies, you won't be protected at that door or window."
"Interior alarms" are designed to sound after an intruder gets inside the home. These sensors use infrared beams, microwaves or ultrasound to detect unexpected heat or motion in a room or hallway. Police say it's better to alarm the house so that you'll know someone is trying to get in before they succeed.
"Chances are high with an interior system that the assailant and the merchandise will be gone when we get there," McCoy says.
The control center, where information sent from the windows and doors is processed, is often placed in a closet or in some other hidden area to keep it from being tampered with by a burglar. A key pad by the front door or the master bedroom lets you arm and disarm the system with a code. Some systems have a remote control that lets you activate the alarm from anywhere in the house.
The alarm sounds a loud horn or bell when it detects an open door or window. An automatic dialer notifies the police or a security service of the break-in. Unfortunately, however, home alarms have a reputation for sounding for no apparent reason.
"False alarms are a real problem for us," McCoy says. "They're caused by sensors that react to various environmental factors other than intruders."
Sgt. Glenn Deveney, community services supervisor for the Fullerton Police Department, says, "We've seen false alarms caused by insects. Spiders might build webs inside the sensing units, which sets them off. They can also be (activated) by dust or animal hair."
A good number of false alarms are caused by systems that haven't been regularly inspected.
"There's no alarm system that's maintenance-free," Deveney says. "If the system you're looking at comes with a maintenance contract, it's a good idea to take it."
Most Orange County cities allow up to four false alarm responses a year before fining the homeowner $50 a call. A state law requires home alarms to have an automatic siren shut-off in case the homeowner is not there to disarm a false alarm.
You can also program your automatic dialer to call a security monitoring company, which will call to see if it's a false alarm. These monitoring services typically charge between $25 and $35 a month.
"The benefit of these services is you know someone will respond," McCoy says. "When no one's home, it's a lot better than to have an alarm go off and hope the neighbors will hear it and call the police."
The system you choose should allow you to tailor it to your needs.
"A lot of people aren't good with key pads. They come home and try to disarm the alarm and end up causing it to go off," Deveney says. "In that case, you need one with a variable delayed alarm that gives you enough time to deactivate it."