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Table 7-2.—Controller Troubleshooting Tips—Continued | Up
Construction Electrician Intermediate - Electricity handbook for electricians | Next
National Electrical Code Requirements for Security/Fire-Alarm Ssytems |
CHAPTER 8
ALARM SYSTEMS
INTRODUCTION
Many buildings and complexes being constructed
today are equipped with some type of intrusion
detection and fire-alarm systems. You, as a
Construction Electrician, will be challenged to install,
troubleshoot, and maintain these systems. Numerous
detection and fire-alarm systems are in existence
today. In this chapter, we will discuss the function and
operation of a typical detection system and various
fire-alarm systems. When you are in charge of the
installation or maintenance of either a detection or a
fire-alarm system, you should acquire reference
material, such as manufacturer’s literature. If such
material is unattainable, refer to Maintenance of Fire
Protection Systems, NAVFAC MO-117, that provides
an excellent description of several fire-alarm systems.
Commercial Intrusion Detection Systems (IDS),
Design Manual 13.02, provides descriptions ofvarious
intrusion detection systems.
The purpose of any alarm system is either to
protect life or property or to detect an intrusion. Alarm
systems are set up to (1) give early warning so
occupants may evacuate the building and (2) notify the
fire department and/or security so they can react as
soon as possible.
This chapter will increase your knowledge about
security/fire-alarm system installation techniques,
operations, and maintenance.
INSTALLATION TECHNIQUES
Before the installation of a security/fire-alarm
system is started, a sketch of the building should be
prepared or the original blueprints should be obtained.
This sketch should be drawn to scale and should show
the location of all windows and doors, chases, closets,
and so forth. A simple riser diagram showing the
various components, such as smoke and heat sensors,
control panel, and alarm signals, should also appear on
the sketch. When this is completed, the installer can
begin the design of the security/fire-alarm system. As a
Seabee, it is important to check all supporting
documents in the manufacturer’s manual before
installing a system. If you encounter a problem,
contact the NAVFAC alarm systems coordinator.
TYPES OF FIRE-ALARM SYSTEMS
Building alarm systems may be local or local with
base alarm system connections. They may be coded or
noncoded and may operate either on line-voltage or
low-voltage electric power. Their characteristics are
described in the following paragraphs.
Coded Alarm Systems
A coded alarm system has audible or visual alarm
signals with distinctive pulsing or coding to alert
occupants to a fire condition and the location or type of
device that originated the alarm. Coding the audible
appliances may help personnel to distinguish the fire-
alarm signal from other audible signals. Clear and
early recognition of the signal should encourage a
more orderly and disciplined evacuation of the
building. A common characteristic of coded alarm
systems, especially of selective coded and multiplex
coded systems, is that the coded alarm identification
provided by the audible alarm signals is not repeated
continuously. Normally, after four complete
repetitions of the coded signal, the coding process
ends.
Noncoded Alarm Systems
A noncoded alarm system has one or more alarm-
indicating appliances to alert the building occupants of
a fire but does not tell the location or the type of device
that has been activated (manual alarm or automatic
protection equipment). The audible or visual alarm
appliances operate continuously until they are turned
off, until a predetermined time has passed, or until the
system is restored to normal. The location or type of
device originating the alarm condition can be
determined by using an annunciator system. An
annunciator is a visual-indicating device.
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