Be trigger happy with your outdoor security light system.

Passive infrared (PIR) lamps, of the type that may be bought in any DIY store, are now very popular with householders. Mounted on an outside wall, they may be used to improve security or simply to illuminate dark areas when a member of the family passes by.

When the PIR unit is properly installed, the lamp does its job well and rarely causes problems. However, when it is not properly set up it may be activated by animals such as dogs and cats passing by, or tree branches and other objects moving in the wind.

This self-contained battery-operated unit will automatically monitor a PIR lamp over a period of several hours overnight. A LED (light-emitting diode) display registers the number of times it has been triggered. By adjusting the aim and sensitivity control on the lamp, re-siting and cutting away foliage as necessary, any improvement can be easily monitored. Multiple causes of false triggering may then be eliminated one by one over a period of a few days.