What Alarm Sensors Do I Need?
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A typical home alarm uses PIR motion sensors to cover rooms and door/window contacts on your entry points, plus optional extras like glass-break, smoke, carbon monoxide, water-leak and panic buttons. Start with the ways in and the main rooms, then add detectors where you want extra cover.
The core sensors
| Sensor | What it does |
|---|---|
| PIR motion detector | Detects movement in a room - your main coverage |
| Door/window contact | Triggers the instant a protected door or window opens |
| Glass-break detector | Hears the sound of breaking glass |
| Panic button | Raises the alarm manually in an emergency |
| Smoke / CO / water-leak | Optional safety detectors for fire, gas and leaks |
How many?
As a rough start: a contact on each external door, PIRs covering your main downstairs rooms and the landing, and a panic button by the bed or front door. A typical 3-bed home is well covered by a handful of PIRs and contacts; add more for outbuildings or extra rooms.
Pets at home?
Use pet-immune PIR sensors so cats and dogs don't set off false alarms. Pet-friendly alarm sensors.
Build your own with the right mix - add sensors to a custom AX PRO kit.
Frequently asked questions
What sensors does a home alarm need?
At minimum, door/window contacts on entry points and PIR motion sensors for your main rooms. Optional extras include glass-break, smoke, carbon monoxide, water-leak and panic devices.
How many alarm sensors do I need?
A typical 3-bed home is well covered by a contact on each external door plus a few PIRs for the main rooms and landing. Add more for outbuildings or extra coverage.
What is a PIR sensor?
A PIR (passive infrared) sensor detects body heat moving across a room. It's the main motion detector in most alarm systems, with pet-immune versions available.