FIGURE 14.56, are
suitable.
Intruder alarm sounders
Alarm sounders give audible warning possible criminal act.56
Intruder alarm sounder.
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. intruder gains access one
room cannot move from without triggering the alarm. Bells or
sirens enclosed waterproof enclosure, such shown Fig.Electrical installations and wiring systems
337
PROXIMITY SWITCHES
These are designed for the discreet protection doors and windows. 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.8 and high. The
outside sounder should displayed prominently since the installation of
give space protection. 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. Space protection does have the disadvantage of
being triggered domestic pets but simpler and, therefore, cheaper
to install. 14. 14.
FIGURE 14. They
are made from moulded plastic and are about the size chewing-gum
packet, shown Fig.55
PIR intruder alarm detector.54
Proximity switches for perimeter protection.
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. 14. The PIR shown Fig. Perimeter protection involves much more extensive and, there-
fore, expensive installation, but easier live with.
FIGURE 14.
PIR DETECTORS
These are activated moving body which warmer than the surround-
ings.55 has range 12m and detection zone
of 110° when mounted between 1.54.
