14. The PIR shown Fig.
PIR DETECTORS
These are activated moving body which warmer than the surround-
ings.8 and high. Space protection does have the disadvantage of
being triggered domestic pets but simpler and, therefore, cheaper
to install. Bells or
sirens enclosed waterproof enclosure, such shown Fig.56
Intruder alarm sounder. intruder gains access one
room cannot move from without triggering the alarm. One moulding contains reed switch, the
other magnet, and when they are placed close together the magnet main-
tains the contacts the reed switch either open closed position.56, are
suitable. 14. Perimeter protection involves much more extensive and, there-
fore, expensive installation, but easier live with.
Intruder alarm sounders
Alarm sounders give audible warning possible criminal act.
.55 has range 12m and detection zone
of 110° when mounted between 1. They
are made from moulded plastic and are about the size chewing-gum
packet, shown Fig.
Opening the door window separates the two mouldings and the switch
is activated, triggering the alarm.
Trap protection places alarm sensors internal doors and pressure pad
switches under carpets through routes between, for example, the main
living area and the master bedroom.
FIGURE 14.
FIGURE 14.
FIGURE 14.
Definition
Trap protection places alarm sensors
on internal doors and pressure pad
switches under carpets through
routes between, for example, the
main living area and the master
bedroom. usual connect two sounders intruder alarm installa-
tion, one inside make the intruder apprehensive and anxious, hopefully
encouraging rapid departure from the premises, and one outside.55
PIR intruder alarm detector.Electrical installations and wiring systems
337
PROXIMITY SWITCHES
These are designed for the discreet protection doors and windows. The
outside sounder should displayed prominently since the installation of
give space protection. 14.54
Proximity switches for perimeter protection.54
