Figure 8-4.Wire the shunt lock switch to the magnetic
contacts as shown.
the magnet unit is mounted on the door or window
(moving part) itself. The two units should be
positioned so that the magnet is close to and parallel
with the switch when the door or window is closed.
This keeps the shunt lock actuated, but opening the
door or window moves the magnet away and releases
the switch mechanism.
As long as the faces of the switch and magnet are
parallel and in close proximity when the door or
window is closed, they may be oriented side-to-side,
top-to-top, or top-to-side. Mounting spacers may be
used under the units if necessary to improve their
alignment and proximity.
Terminal covers are available for most makes of
door contacts to give the installation a more finished
look and also to protect the terminal connections
The wiring of any alarm system is installed like
any other type of low-voltage signal system; that is,
one must locate the outlets, furnish a power supply.
and finally interconnect the components with the
proper size and type wire.
ALARM SYSTEMS INSTALLED IN
Many changes and advances in developing
complete security/alarm systems for building
operation and protection have taken place in the past
few years. Numerous existing buildings are currently
having security and fire-alarm systems installed either
to replace their obsolete systems or to provide
protection they never had.
The materials used for installing a complete alarm
system in an existing building are essentially the same
as those used in new structures. However, the methods
used to install the equipment and related wiring can
vary tremendously and require a great deal of skill and
ingenuity. Each structure is unique.
When concealed wiring is to be installed in a
finished existing building. the installation must be
planned so that the Least amount of cutting and
patching is necessary. In most cases, this means giving
special consideration to the routing of conductors.
Unlike the wiring of a new building where the installer
would try to conserve as much material as possible, the
amount of material used (within reason) is secondary
in existing buildings. The main objective in
security/fire-equipment installations in existing
buildings is to install the wiring in the least amount of
time with the least amount of cutting and patching of
the existing finishes of the building.
Before any actual work on an existing building is
started, the contractor or the installers should make a
complete survey of the existing conditions in the areas
where the security system will be installed. If the
majority of the work can be done in exposed areas (as
in an unfinished basement or attic), the job will be
relatively simple. On the other hand, if most of the
wiring must be concealed in finished areas, there are
many problems to be solved. The initial survey of the
building should determine the following:
1. The best location for the alarm control panel.
2. The type of construction used for the exterior
and interior walls, ceilings, floors, and so forth.
3. The location of any chases that may be used for
routing the conductors and the location of closets,
especially those located one above the other for possible
use in fishing wires.
4. The material used for wall and ceiling
finishesplaster, drywall, paneling, and so forth.
5. Location of moldings, baseboards, and so forth,
that may be removed to hide conductors.
6. Location of decorations or other parts of the
building structure that cannot be disturbed.
7. Location of any abandoned electrical raceways
that new alarm system wires might be fished into. Do
not overlook similar possibilities. For example, an old
abandoned gas line can be used to fish security-system
wires in an old building.
8. The location of all doors and windows, coal
chutes, and similar access areas to the inside of the
As indicated previously, the most difficult task in
running wires in existing buildings is the installation of
concealed wiring in finished areas with no unfinished
areas or access to them. In cases like these. the work is
usually performed in one of two ways. First by
deliberately cutting the finished work so that the new
wiring can be installed. Of course. these damaged