Alarm components

An alarm system, regardless of whether it is wireless or hard wired, has the same basic set up.

The control panel

The control panel is the electronic heart of a security system. All components of the alarm are connected (either wirelessly or by cables) to the control panel and it is the control panel that interprets the signals received from the sensors and other devices.

The alarm must be armed for the control panel to be able to receive signals in the event of an alarm activation. If the alarm is disarmed the building is not protected.

The control panel will still receive signals such as low battery warning from a sensor, tamper alerts or low battery warnings even with the system is not armed.

If the alarm is monitored the control panel will automatically send signals to the monitoring company when the alarm is armed. If the system is self monitored the control panel will automatically send a text via an in-built cellular modem in the event of an activation.


All alarms will include one or more sensors which detect possible intrusion. Different sensors are designed to be activated in different ways including when they detect heat, body movement or air movement (shock waves) or the beams that they emit are interrupted. These include:

  • PIR sensors (pictured) detect body heat and movement and are the most common type of alarm sensor. They are used in internal rooms or areas of the building.
  • Door and window switches monitor the perimeter of the building by giving instant notification if someone tries to enter.
  • Smoke detectors are active even when the alarm is not armed and can be a valuable addition to a security system.

Basic alarms will have an in-built sensor but the majority of alarm models include a number of sensors with the option to add extra sensors for additional rooms or areas.


Many, but not all alarms include a siren which will make noise in the event of an alarm trigger to help draw attention to a possible intrusion.

These can be mounted on the outside of a building to help attract attention, or inside to help repel intruders (like the small flush mounted high pitched piezo siren pictured).

Some alarm models include an in-built piezo or high pitched siren inside the control panel.