Intruder alarms, terminology and information

Intruder alarm

Intruder alarms detect attempted intrusion or unauthorised entry into a building, room, site or secure installation and trigger a response. Well-fitted and maintained intruder alarms can make organisations and individuals less likely to become victims of burglary, vandalism and other forms of attack.

There are many different types of intruder alarms, with selection depending on personal preference, location, building size, level of protection required, monitoring, method of response and so on.

Intruder alarms can be wired or wireless. Generally wireless alarms are easier to install. Installing wired alarms can be disruptive and even domestic installations will generally need to be fitted by a professional.

Intruder alarms can be ‘bells only’, ‘speech-dialler’ or monitored alarms.

Bells-only alarms, also known as ‘audible alarms’ make a loud noise when they are triggered. This is intended to alert nearby people to a potential intruder and to scare off the intruder. Unlike monitored or speech dialler alarms, there is no guarantee that any form of assistance will come.

A speech dialler or ‘text alert’ system will call or text nominated phone numbers. Contacted ‘keyholders’ may then take action, either investigating themselves, or notifying another respondent. They then may be able to remotely access CCTV cameras or microphones within the premises to monitor the situation and determine what sort of response is required.

Alarms may be monitored commercially, sometimes as part of a wider contract for installation and maintenance. The alarm connects to an alarm receiving centre (ARC) when triggered. The receiving centre will generally first ring the building and ask any respondents for their password identification. If this is incorrect or if there is no answer, they may inform the nominated keyholder(s) or respond themselves, or may notify the police.

Because of the number of false alarms, the police will only respond to alarms with a police unique reference number (URN).  The police accept 3 types of new installation:

Sequential: The first alarm notifies a keyholder. A second, different alarm in a designated period will notify the police.
Audio: The alarm activates microphones allowing the alarm receiving centre to listen for any criminal activity.
Visual: The alarm activates CCTV cameras allowing the alarm receiving centre to look for any criminal activity.

Response may be withdrawn following three false calls in 12 months and will only be restored if the system complies with the police policy on reinstatement.

To avoid noise nuisance alarms should cut out after 20 minutes. Failure to do so can result in prosecution.

  • masterblaster1
  • 7_1751
  • 7_2320
  • premier_elite_odyssey_2
  • 7_20
  • 7_2499
  • 7_283
  • 7_767
  • fmk_polishedchrome
  • 7_3805

What components are there?

Before you can even start the planning phase of your alarm system, you need to understand what components you may need to use. Alarm components can be broken up into several categories:

Input Devices: These are the sensors that will activate the alarm when someone breaks into your home. Examples include door and window sensors, motion detectors, and glass break sensors.

24 hour Input Devices: These are special types of sensors that activate the alarm whether it is turned on or off (24 hours a day). These include fire/smoke sensors and water leak sensors.

Output Devices: Example output devices include horns/sirens and strobe lights. These tell you and your neighbors that the alarm has been activated and scare off intruders.

Alarm Panel: The alarm panel is the brains of the alarm system. This consists of the circuit board, power supply and battery to provide power, your phone line connection, and the a metal box to secure it all.

Keypads: These are used to activate/deactivate the alarm, determine what zone has tripped the alarm, perform programming and diagnostics activities.

Types of Sensors / Input Devices

Door Sensor
Door sensors will trigger the alarm when the door is opened. These should be installed at every exterior door including the door to the garage. These sensors can also be used as a door chime which makes a quick beep when a door is opened and the alarm is not active. Installing the round plug style sensors can void the warranty on your door and your builder may not let you install them until you have purchased the home. You could use window style sensors on a door (although they will not be hidden) or you could pre-wire the sensor and drill the hole in the door later after you move in.

Window Sensor
Window sensors will trigger the alarm when the window is opened. Having a separate channel for each window will quickly use up all the available channels on your alarm panel (this is covered in the Alarm Planning guide). Unlike door sensors, these sensors are visible on the window. There are types of window sensors that are hidden, but drilling into a window to hide a magnet is usually a very bad idea. You will probably break the seal on your window and any drilling in the window will void the warranty. Your best bet is to use 2-way tape to attach the sensor to the window so that no drilling is required. Sometimes you may want to activate the alarm at night even though a bedroom window is open. This can be done, but obviously that window is not protected by the alarm. Using motion detectors may be a better option.

Motion Detector
Motion detectors will trigger the alarm when they detect motion in their area of coverage. Typically these are not installed on the second floor. You don’t want the alarm going off when someone goes to the bathroom in the middle of the night. Motion detector usually have 90 degree area of coverage, so installing them in the corner of the room works best. Motion detectors should be installed in every major room of the home and if necessary they should also protect the alarm panel (in the basement or a utility closet). I prefer to install the motion detectors near the 4 exterior corners of the first floor so that they also cover the hallways. In an existing home you may choose to install them on an interior wall so that you don’t have to deal with insulation when running the wires. Some motion detectors will detect small pets and set off the alarm, while others are designed ignore pets up to 40 or even 80 pounds. Be sure to review the specifications of the sensor before purchasing. Note: Usually motion detectors are referred to as PIR (Passive InfraRed) sensors. Some sensors utilize both PIR and microwave sensors for increased reliability.

Glass Break Sensor
A glass break sensor will trigger the alarm when it detects the noise or vibration of glass breaking. The model on the left is attached directly to the window and can only determine if that window is broken. These are usually used by businesses on large plate glass windows. The model on the right can detect any glass breaking within a given distance and are usually mounted toward the center of the home or near an area with a lot of windows. In the example floor plan above, the glass break sensor is facing the rear exit glass door. Dropping a glass or loud noises can sometimes trip a glass break sensor and set off the alarm. The quality and sensitivity setting of the alarm control this behavior.

Vibration/Shock Sensor
shock sensors, also known as vibration or inertia sensors, are a very useful detector in alarm systems. they are designed to detect forced entry through windows, doors and walls/ceilings/roofs. For example, when fitted to say a large 2 metre wide window frame the detector will detect any attempted entry using force. Because they are perimeter detectors they can be armed while the premises are occupied.

Smoke Sensor: 24 hour
If you are building a new home then the builder will already be installing smoke detectors, but if you are paying for alarm monitoring you may want to connect these smoke detectors to the alarm system. In a new home by code the builder will place one smoke detector on every floor and in every sleeping room. These should be combination smoke/carbon monoxide detectors. Ideally they will be networked and hard wired for power with battery backup.

Sirens / Output Devices

Horn/Siren
The siren makes the noise when the alarm is activated. The horn on the left is intended to be hidden (perhaps in the basement) or mounted outside the home to alert neighbors. The siren on the right should be mounted near the center of the first floor. Although a horn/siren is optional, it is strongly recommended since it will do the most to scare away a burglar.

Strobe Light
Mounting a strobe light outside the home is another way to alert neighbors that your alarm has been activated. Strobe lights can also be used inside the home for the hearing impaired.

Other Alarm Components

Keypad
Keypads are used to activate and deactivate the alarm. They can also be used to indicate which sensors (zones) are currently active. More advanced keypads can report a history of past alarms and perform programming functions. A keypad should be located near the entrance/exit of your home that you are most likely to use so you can activate the alarm as you leave. You can also install a second keypad in the master bedroom to activate the alarm system at night.

Main Panel
The main panel is the “brain” of the alarm system. The circuit boards are placed in a locked metal box that also contains a battery backup. All wires for the alarm system will run to this panel. The panel should be located in the basement (if available) otherwise it should be placed in a utility closet.