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 3.4.3.2 Nuisance Alarm Rate (NAR). Sensor subsystems should be designed
and installed to generate the absolute minimum number of nuisance and false
alarms per unit of time. False alarms are differentiated from nuisance
alarms in that the former are caused by nonintrusion phenomena inherent to
the system, such as a malfunction, while the latter are valid alarms
generated by phenomena not within desired detection parameters. These
include animals, wind, etc. Nuisance and false alarms are terms often
mistakenly used interchangeably. Because nuisance alarms cannot be
completely controlled in the typical installation, there is a growing
technique of assessing alarm annunciations through closed-circuit television
cameras covering the sensor field This permits automatic assessment of a
sensor zone on alarm and minimizes the need to deploy response forces if
nuisance generated. Carefully designed sensor subsystems, even in the most
hostile environments, can substantially minimize nuisance and false alarms
to acceptable limits.
3.4.4 Design for Cost-Effectiveness. The requirement to maximize system
detection probability and protection-in-depth does not mandate the
saturation of protected areas with sensors, cameras, or other devices.
Equally, once a decision has been made that the criticality versus threat
circumstances require protection, "doing it cheaply" is just as inefficient
and ineffective. Cost-effectively, one can utilize the appropriate mix of
barrier, electronic, and procedural options keyed to the unique requirements
of the site. Recent developments, as well as those now in research and
development, are bringing the cost of electronic systems down in both
equipment and installation. A comprehensive application of the design
process will have the most immediate impact in both short term and life
cycle costs of security systems.
3.4.5 Flexibility and Expansion. One of the most cost-effective measures
to be taken is to build the security system for flexibility and future
enhancement. It ordinarily follows that once properly installed and
operational, the in-place system is periodically expanded to accommodate
new alarm points, increased electronic access controls, expanded CCTV
coverage, etc. Most modern alarm and video control systems are modularly
expandable and permit future growth both on- and off-site. Designs should
anticipate such expansion and not limit control elements, conduit, and
other system components to the specific requirements of the immediate
installation.
3.4.6 Build the Detection Subsystem for Point-for-Point Annunciation.
Unless specified, contract installers may often daisy chain alarm devices to
simplify the job and reduce their cost. This results in the annunciation of
any number of devices at the reporting unit without giving the operator the
benefit of knowing which device in the area is causing the alarm. Each
alarm point should be wired separately back to the control unit on a
dedicated zone for reporting to the control console. This technique also
substantially eases troubleshooting by maintenance personnel and reduces
downtime, repair time, and cost.
3.4.7 Build the System for Ease of Operation and Maintenance. Keep the
system as simple as possible and carefully consider the interface of man and
machine throughout its control function applications. In particular, at the
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