Five Causes of PIR False Alarms

  1. The first cause of PIR false alarms is low or unstable voltage at the detector. Test to make sure the voltage at each PIR is above 13VDC and stable.
  2. The second cause of false alarms is sudden infrared movement / heat changes in view of the detector. Check behind and inside the PIR for insects and identify objects that can move or rapidly change temperature (e.g. pets, vermin, fax, mailbox, radiator or boiler etc).
  3. The third cause of false alarms is white light momentarily blinding the detector. Always choose PIR’s with genuine white light filters and avoid fitting facing glass with 50% of its operating range.
  4. The fourth cause of false alarms is a direct draught striking the detector. This causes air convection inside the PIR. Make sure cable and screw holes are totally sealed and don’t forget the hole where the cable comes through the cavity wall or ceiling.
  5. The fifth cause of false alarms is RFI/EMI signals. A mobile phone can be used to test susceptability to RFI by placing the aerial against the PIR casing and transmitting. Fit an ACT 1376 stabiliser inside the PIR to eliminate RFI.