PIR Motion Sensors Explained: Coverage, Pet-Immunity & Placement

How does a PIR motion sensor work?

A PIR sensor measures the infrared radiation given off by warm bodies. When a person moves across the sensor's zones, the rapid change in heat pattern triggers an alert. Because it reacts to change rather than emitting a signal, it is energy-efficient and runs for years on battery.

What does pet-immune (pet-friendly) detection mean?

Pet-immune detection tunes the sensor to ignore the smaller heat-and-mass signature of household pets while still detecting a human intruder. This lets you arm the system at night or when out without your dog or cat causing false alarms.

Where should you place a motion sensor?

Mount PIR sensors in corners of rooms that an intruder must cross — hallways, staircases and living rooms — typically 2–2.2 m high and angled across the room rather than straight at a door.

Avoid pointing sensors directly at windows, heaters or air-conditioner vents, which can cause false triggers.

• Best spots: entry hallways, stair landings, main living areas.
• Outdoor zones: use the solar outdoor PIR alarm for gardens, farmhouses and parking areas.
• Coverage: 110° angle with sensitivity adjustable up to level 5.