Introduction Ceiling-mounted PIR sensors are common in offices and commercial spaces. However, they often have a dead zone directly below the sensor – you can stand right under it and not be detected. Why the Dead Zone Exists The Fresnel…

Introduction Power surges, lightning strikes, or accidental application of high voltage can damage PIR sensors. This guide helps you assess the damage and possibly recover the sensor. Symptoms of Surge Damage Sensor completely dead (no output, no LED if present)…

Introduction High-power radio transmitters like ham radio rigs (100W+) or CB radios can cause PIR sensors to false-trigger. The strong RF field can be rectified by the sensor’s electronics, creating false signals. How RF Interference Happens The high-gain amplifiers in…

Introduction High humidity environments like bathrooms, greenhouses, and tropical locations can cause PIR sensors to malfunction. Moisture in the air and on the lens interferes with infrared transmission. How Humidity Affects PIR Sensors Water Vapor Absorption Water vapor absorbs infrared…

Introduction If you live close to neighbors, their security lights can cause your PIR sensors to false-trigger. The lights themselves emit IR, and they also illuminate areas that your sensor sees. How Neighbor’s Lights Cause False Triggers Direct IR from…

Introduction Large televisions, particularly older plasma screens, can emit significant infrared radiation and electrical noise that interferes with PIR sensors. How Displays Cause Interference Plasma TVs (Worst Offenders) Plasma displays generate significant heat and emit IR. The picture content changes…

Introduction High humidity environments like bathrooms, greenhouses, and tropical locations can cause PIR sensors to malfunction. Moisture in the air and on the lens interferes with infrared transmission. How Humidity Affects PIR Sensors Water Vapor Absorption Water vapor absorbs infrared…

Introduction Hot water pipes running behind walls or ceilings can cause PIR sensors to false-trigger. When hot water flows, the pipe warms up, creating a moving heat source. Why Water Pipes Cause False Triggers When someone turns on a hot…

Introduction In cold climates, people wear heavy clothing that insulates body heat. This can reduce the infrared signal reaching the PIR sensor, making detection difficult. Why Heavy Clothing Affects Detection PIR sensors detect the infrared radiation emitted by a person’s…

Introduction Sometimes you want to hide a PIR sensor behind a plastic cover for aesthetics or protection. But many plastics block infrared, rendering the sensor useless. Why Most Plastics Block IR Common plastics like acrylic (Plexiglas), polycarbonate (Lexan), and ABS…