How Do Intruder Alarm Systems Work?

Sep 14, 2022

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Crime is a serious problem in the UK and across the world. If you’re living in the UK, or you’re planning on visiting. You might be worried about your safety. Unfortunately, crime happens everywhere and that includes your home. It is important to be aware of the different types of crimes that can occur in your home so that you can take steps to prevent them from happening or make them less likely to happen again if they do occur.

The good news is that overall crime rates are dropping, but some types of crime are on the rise and others are still very common.

In this article, we look at how you can reduce the risk of your home or business premises being burgled or damaged by crime. We also cover steps that you might take to protect public buildings such as schools and community centres in your local area.

What Is Burglary?

Burglary is when someone enters your house or business without permission and steals valuable items.

Burglars usually target the homes of people who are away from their property. In addition, they can also target commercial premises such as shops and restaurants.

The law says that burglary is defined as: “entering any building or part of a building as a trespasser with intent to steal anything in the building”. If someone steals something whilst on their way out of the building they would still be committing burglary even if they didn’t physically enter into the property with the intent to steal something inside it.

People commit burglary for many reasons, money is often a motive. However, some burglars may be motivated by other factors or they may also be repeat offenders. The consequences of burglary can include damage to the property including windows being broken as well as people being hurt if there’s an altercation between the burglar and another resident who lives at the property.

burglary break in

The Solution: What Is An Intruder Alarm System?

An intruder alarm is a device that makes a loud siren when it detects motion or sound when you’re not in the building. These alarms are also known as burglar alarms and are suitable for domestic, commercial and retail properties.

The Benefits Of An Intruder Alarm

Intruder alarm systems are a great way to secure your home or business without having to spend a lot of money on additional security measures. The core benefit of an intruder alarm system is sounding an alert when an unwanted presence is on your property.

Intruder alarm systems are designed solely to improve domestic and commercial security. Whilst the owner is absent from the premises, intruder alarms will sound when sensors detect unwanted movement. Upon to owner’s return, burglar alarms can then be disarmed with a unique four-digit code.

OHEAP logo intruder alarm

Intruder Alarms Protect Contents

Your security system also protects your contents from theft. If a burglar breaks in and attempts to steal your belongings, they will be greeted with an alarm that alerts you to the problem. This gives you the opportunity to call the police and hopefully catch them before they can escape with your possessions.

Intruder Alarms Reduce Insurance Premiums

An intruder alarm can reduce your insurance premium. This is because having an alarm installed reduces the risk of burglary, which in turn reduces liability and risk. You may also be able to secure discounts on insurance policies if you have a monitored intruder alarm installed.

Intruder Alarms Protect People

Alarms can alert you to a break-in and provide a warning that someone is in your home. This allows you to protect yourself and others by getting out of danger.

Intruder Alarms Deters Crime

One of the best benefits of an intruder alarm is that it will deter crime. If you have an intruder alarm installed in your home, it will make your home less vulnerable to burglary or theft. A visible burglar alarm system is far more likely to deter someone from committing a crime than those who have no system at all.

Intruder Alarm Components

Intruder alarm systems are a combination of detection and deterrent components. Components are connected via a control panel and are designed to deter and detect intruders. For example, the main components include sensors, sounders and external communications devices.

Sensors should be located around property entry points to instantly alert and sound. Loud alarm sirens are often enough to deter a burglar from staying too long on the property.

Overall, considering these systems are typically inexpensive, it’s the perfect way to protect your premises.

The Intruder Alarm Siren

These sirens are vital when alerting neighbours to the break-in and draws attention to the burglar.

It can be used to alert people of a threat, scare off intruders or simply notify people of a possible threat. For example, if you hear someone trying to break into your building after activating your security system, an alarm will notify everyone in the area of a possible threat.

An intruder alarm siren will automatically alert law enforcement and emergency services when it detects an intruder, so you don’t have to do anything but stay safe.

intruder alarm

Intruder Alarm Siren Volume

The core benefit of a good outdoor siren is that you can hear the warning from a distance. External sirens sound 85dB at a minimum, similar to that of a busy road. Many burglar alarm sirens sound 120dB which is similar to a police siren.

The alarm sounds and lights flash as soon as there is movement near one of its sensors (such as door/window sensors). If there are no threats detected by the system, it will go back into standby mode within 15 seconds after sounding its initial warning tone and flashing its lights.

Intruder Alarm Siren Installation

When installing your siren, focus firstly on visibility to passersby. Secondly, ensure the siren is out of reach from intruders and vandals. Most sirens will come with an integral spirit level to ensure your siren is level. Drill the holes necessary to mount the base plate. Once the base plate is mounted, the siren should simply clip/slide on.

  • A ladder.
  • A drill.
  • A crosshead screwdriver.
  • Spare wall plugs.

An external burglar alarm siren, pictured below, is a siren that must be located on the outside of the premises for maximum effect.

The Intruder Alarm Sensors

PIR sensors work by detecting infrared light. This infrared light is given off by a moving object or person that emits heat. Door and window sensors are used to detect when a door or window is opened. These can be connected to the control panel or a keypad, and can also be used with other sensors to trigger an alarm. Typically they are powered by batteries.

Intruder Alarm Sensors Installation

Intruder alarm sensors, pictured below, need to be attached to the wall. The position of the sensors should be placed approximately 7 feet from the floor and at least 2cm from the ceiling. Mark on the wall where you want the sensor to go and then use either screws or sticky strips.

Where To Start With Burglar Alarm Sensors

After you’ve decided which burglar alarm sensors are right for your home, you can move on to setting them up and testing them. We suggest starting with the control panel and then adding additional devices as needed.

Once everything is set up and tested, you will be able to rest easy knowing that if something happens in your home while you’re away, an alert will immediately be sent to the police department or security company where you have an active monitoring plan.

intruder alarm sensor

The Intruder Alarm Control Panels

The heart and brain of the intruder alarm system. A central control panel can be self-installed if the DIY installer is confident enough to do so. You will typically find a keypad and LCD screen for alarm activation, detection and fault codes.

The keypad is a control panel that allows you to arm and disarm your alarm system. It’s the most common type of control panel and it’s easy to install. Also, you’ll be able to set up your burglary alarm in no time. The keypad should be installed in a central location so that it can easily be accessed by everyone who lives in the home or business.

Keypads are often used with other sensors like motion detectors, glass break detectors and door/window contacts. A burglar intruder will trigger these alarms when they enter your home or business premises without permission.

The Cost Of UK Burglar Alarms

In the UK, typical burglar alarms cost in the region of £125 – £750. The cost however isn’t necessarily important. The reason we say this is because intruder alarms will drastically reduce your home insurance costs.

burglar alarm keypad

The 4 Key Reasons for False Alarms

If you have an intruder alarm, it’s likely that you’ll get a false alarm at some point. It’s not surprising, as they’re designed to let you know if there are intruders in your home. But what causes these false alarms? Here are some common reasons why your system might go off when nothing is actually happening.

To prevent false alarms, it’s crucial to have a good security system installed in your home. If a professional is installing your system or if you’re installing it yourself, make sure they know how to properly set up the alarm and teach your staff how to use it.

1) Sensors Not Recognising Pets

The sensors used with intruder alarms do not recognise pets. If you have a pet, you will need to adjust the settings of your alarm so that it does not respond to your pet’s movements.

You should also be careful where you place the sensors; they should not be placed too close to the floor or any other low area where a pet may pass through them. Security companies can help with adjusting this setting if you are having problems with false alarms.

2) Low Battery

If you’re getting a lot of false alarms, it might be time to replace the batteries. A security system that uses batteries may require you to replace them more often than you realise. This is because security systems use a lot of power and the batteries can drain easily. Following the replacement of your batteries, remember to check all sensors.

3) Poor Installation of The Alarm or Sensor

The most common reason for false alarms is poor installation. The security system may have been installed improperly, or it could be malfunctioning because of poor wiring. If you have a wired system and get false alarms, check for loose wires and broken connections.

4) Insects

Insects are one of the most common culprits for false alarms. They can set off an alarm, especially if they are in the motion sensor. Insects can also set off the alarm if they land on a sensor and move out of it.

Spiders are a common problem with burglar alarms, especially during the summer months. The heat emitted by burglar alarm sensors attracts spiders and they will often climb onto the sensors in search of a warm spot. This can cause problems in that the spider’s body may act as a physical obstruction to the sensor, preventing it from detecting movement and activating your alarm.

Insects can affect burglar alarms in many ways. They can damage sensors, they can damage wiring and they can cause false alarms to go off.

Crime Statistics

In 2022 there were 192,060 home burglaries reported in England and Wales. This worked out as a burglary every 164 seconds. Intruder alarm systems ensure your property is safe.

As a property owner, you have a responsibility to protect your property and employees from criminal activity. “The 2021 Commercial Victimisation Survey (CVS) estimated that 38% of business premises (151,000 premises) in the Wholesale and retail sector in England and Wales had been a victim of crime between April 2020 and March 2021, which was similar to the 2018 prevalence rate (40%), though lower than the 2012 prevalence rate (53%)” (

Crime is a serious problem that affects many property owners. The most common types of crime that affect property owners include burglary, theft and arson.


It is important to note that intruder alarm systems do not replace the need for good security. It is still important to have a lock on your front door and make sure that you have some form of identification with you at all times. The best way to protect yourself from intruders is by keeping your home well lit, making sure it looks occupied during the day and not leaving valuables in plain sight inside or outside the house.

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