How does a home security system work?

A home security system is made up of a central processing unit called an alarm control panel, a controller called an alarm keypad, various types of detection devices, and notification devices which are normally alarm sirens or strobes. The alarm control panel needs power from an AC or DC transformer and usually has a backup battery supply in case of a power outage. The keypad used to arm or disarm the system is wired to the alarm control panel or, if it is a self contained or all-in-one security system, the keypad is built right into the alarm control panel. When the home security system is armed, the detection devices are active and ready to activate an alarm. When the security system is disarmed, no alarm can be activated. Once an alarm is activated, the notification devices sound loud noises or flash bright lights to scare away intruders and alert people to the intrusion.

A home security system can act as a local system which merely activates the notification devices when an alarm is activated or it can be monitored by a central station. With a monitored home security system, the alarm activation is sent to a central station via telephone, internet or cellular signal so that a live operator can respond to the alarm signal and contact the homeowner and/or local authorities.