Alarm Keypads and Key-Operated Switches

Alarm keypads, key-operated switches, and similar devices are used to turn the alarm system on and off.

Some alarm sensors are always on and should never be off. For example, glass-breakage sensors should always send an alarm when glass is broken. Likewise, sensors for emergency exit doors (never used for anything but emergency exits) should always be monitored.

Each authorized employee should have his or her own unique code to activate and deactivate the alarm system. Each code entry should generate a log entry at the monitoring point. The log entry should include the date and time of the activity, a description of the activity (typically a normal door opening or a normal door closing), and the individual’s identification code. Individually assigned codes help establish accountability and are a valuable investigative tool.

The alarm keypad can serve as a duress sensor. Often, an employee forced to deactivate the alarm system might enter his or her authorized access code with the digits reversed. For example, if the employee’s code was 2-3-5-9, the employee would enter 9-5-3-2 under duress. That would deactivate the alarm system, satisfying the attacker, while it covertly sent a “duress opening” signal to the monitoring location. A duress feature on alarm keypads is a very desirable feature.

If need dictates, a system can include more than one alarm keypad.

The alarm keypad should never be located where the public has visual or physical access. Being able to observe the alarm keypad and its operation may enable an attacker to compromise it. The keypad should be near the employee entrance. The employee entrance must never be the public entry door.

The sensor on the employee entrance, probably a magnetic switch or plunger switch, should be on an alarm processor circuit typically known as the entrance/exit delay circuit. This circuit does not generate an alarm immediately when the associated sensor is activated upon entry. Instead, time is allowed for an authorized code to be entered in the keypad. If an authorized code is not entered, or if it is not entered in the time allowed (typically 20 to 30 seconds), an alarm is generated.

The alarm keypad also may contain a noisemaker or siren that sounds during an alarm condition.

Alarm keypads sometimes have light-emitting diodes to indicate the alarm system’s status. The diodes may identify the zone containing a sensor that has detected something. Modern keypads are usually alphanumeric displays that identify the system’s status, the system’s power status, and the zone (sensor) status.