A PIR sensor (Passive Infrared sensor) is the tiny eye that spots movement in your alarm system. It doesn’t need a laser or a camera – it simply senses the heat that living bodies give off. When someone walks in front of it, the sensor picks up the change in infrared energy and sends a signal to your alarm or camera.
The sensor is made of two infrared‑sensitive plates placed side by side. In a steady state, both plates see the same temperature and cancel each other out. As soon as a warm body moves across the field, one plate registers a rise while the other stays cool. That difference creates a voltage spike, which the sensor translates into a trigger for your security system.
Because it’s passive, a PIR sensor doesn’t emit any radiation – it only watches. That makes it low‑power, cheap and reliable for indoor and outdoor use. Most home security kits use a detection range of 5‑12 metres and a field of view of 90‑180 degrees, enough to cover hallways, living rooms or driveways.
When picking a PIR sensor, look for three things: range, sensitivity and pet‑immune settings. A larger range means fewer units to cover the same area, but too much range can cause false alarms from passing cars or neighbors. Sensitivity lets you fine‑tune how big a temperature change triggers the alarm – useful if you have a lot of pets. Many UK‑based systems, including Birmingham Security Command Center, offer a “pet‑friendly” mode that ignores animals under 15 kg.
Installation is straightforward. Mount the sensor 2‑3 m high on a wall or ceiling, aiming it slightly downward. Make sure nothing blocks the view – a plant or a picture frame can create blind spots. If you’re covering a doorway, angle the sensor so the top of the door frame is within the detection zone. Test it by walking across the field; most units have an LED that flashes when motion is detected.
Don’t forget to integrate the sensor with your alarm’s control panel or smart hub. A wired connection gives constant power and reliable alerts, while a battery‑powered model offers flexibility for hard‑to‑reach spots. If you choose wireless, pair it with a hub that supports 2.4 GHz Wi‑Fi or Zigbee, and place the hub near your router for a stable signal.
Now that you know how PIR sensors work, you can decide whether they’re right for your home or business. They’re the backbone of most motion‑based alarms, and with the right settings they stay quiet when your dog runs around but scream the moment a stranger approaches. Need help picking the perfect model for Birmingham? Our experts can walk you through the options and set up a system that fits your budget and peace‑of‑mind goals.
Ready to boost your security? Start by surveying the rooms you want to protect, note the layout, and choose a sensor with the right range and pet‑immune features. A quick install, a few adjustments, and you’ll have reliable motion detection watching over your property 24/7.
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