Whether you're securing a flat in Birmingham or fitting out a warehouse in Wolverhampton, having an intruder alarm system in place is one of the most effective ways to deter and detect unauthorised entry.
But how do intruder alarms actually work?
In this guide, we’ll explain the basics from motion sensors to sirens, and even smartphone alerts. We’ll also show you how modern systems like Ajax security alarms are changing the game for homeowners and professional installers across the UK.
🔐 What Is an Intruder Alarm System?
An intruder alarm system is a setup of electronic devices that work together to detect, alert, and respond to unauthorised movement or break-ins.
Depending on your setup, it can:
- Detect movement or vibrations
- Sense doors/windows being opened
- Trigger a loud siren or silent alert
- Notify your phone or a central monitoring station
Intruder alarms come in two main types:
🔹 Wired Systems
- Traditionally hardwired
- More difficult to install (usually for larger or older buildings)
- Very reliable once set up
🔹 Wireless Systems
- Use radio signals to connect sensors and control panels
- Easier and cleaner to install
- Can be managed through smartphone apps
✅ At WME, we recommend Ajax Security Systems, wireless, stylish, and incredibly easy to configure.
⚙️ Key Components of an Intruder Alarm System
1. Control Panel / Hub
This is the brain of the system. It connects to all devices and determines how to respond when a sensor is triggered.
✅ WME Recommends:
Ajax Hub 2 – supports motion cameras, SIM cards, Ethernet, and Wi-Fi for total control
2. Motion Detectors
Use PIR (Passive Infrared) sensors to detect body heat and movement in a room. Some models include pet immunity to avoid false alarms from cats or dogs.
✅ WME Recommends:
- Ajax MotionProtect – detects humans, ignores pets up to 20kg
-
Ajax MotionCam – includes a built-in camera to verify alarms instantly
3. Door & Window Sensors
Detect when doors or windows are opened. These are vital entry points and often the first part of the system to respond.
✅ WME Recommends:
Ajax DoorProtect – slim and easy to install on any frame
4. Sirens (Indoor & Outdoor)
Once triggered, sirens create a loud noise to scare off intruders and alert people nearby. Some systems also have flashing lights.
✅ WME Recommends:
- Ajax StreetSiren – 113dB volume, weatherproof, tamper-proof
-
Ajax HomeSiren – indoor use, stylish and compact
5. Remote Access & Smart Features
Modern intruder alarms can be armed/disarmed remotely, send push notifications, and even alert multiple users.
✅ Ajax systems work with:
- Ajax mobile app for iOS and Android
- Google Assistant, Alexa & Apple Shortcuts
- Optional SIM + Wi-Fi dual backup
📶 How the Ajax Intruder Alarm Works – A Simple Example
Let’s say it’s 1am and someone opens a side window in your home:
- The Ajax DoorProtect sensor picks up the breach
- The Ajax Hub sends a signal to the siren
- The StreetSiren outside begins blaring
- You get an instant alert on your phone
- If you’ve enabled visual verification, the MotionCam sends a photo of what triggered the alarm
You can then view the footage, contact emergency services, or disarm the alarm from your phone if it’s a false alarm.
🔧 Benefits of Modern Wireless Intruder Alarms
🚫 No messy wiring
📲 Real-time mobile alerts
🔋 Long battery life (up to 5–7 years)
🛠 Easy DIY or professional installation
🔄 Expandable – add smoke detectors, leak sensors, keypads, remotes and more
Looking for a complete kit? Check out our Ajax Wireless Starter Kits, ideal for homes or small businesses.
🏡 Who Should Use an Intruder Alarm?
Intruder alarms are useful for:
- Homeowners who want peace of mind
- Landlords protecting empty properties
- Electricians offering smart home upgrades
- Small businesses storing tools, stock, or equipment
- Retail premises looking for motion-triggered alerts after hours
❓ FAQs
Q: Can I install an intruder alarm myself?
Yes, many systems like Ajax are designed for quick DIY install. No wires, no drilling needed.
Q: Will it work during a power cut?
Yes, Ajax systems come with built-in battery backup and optional SIM connectivity.
Q: Is the alarm loud enough to scare intruders?
Absolutely. Outdoor sirens reach up to 113 decibels, similar to a rock concert.
Q: Can I add cameras to an Ajax alarm system?
Yes, Ajax MotionCam and MotionCam Outdoor come with built-in photo verification.
Intruder alarms work by detecting suspicious activity and instantly alerting you or triggering a loud response to scare off potential threats. And thanks to wireless systems like Ajax, protecting your home or business has never been easier, smarter, or more reliable.
Whether you're a DIY homeowner or a professional installer, WME has the full Ajax range ready to go, including hubs, detectors, sirens, remotes, and starter kits.
🔐 Secure your home the smart way – browse Ajax Security Systems now