contained in a fire-resistant ABS plastic housing and shall be
ceiling or wall mounted, as indicated. Sensor shall provide
coverage of large glass areas up to 10 675 mm 35 feet wide.
Sensor housing shall be tamper resistant and designed for screw
mounting.] Sensor shall not initiate alarm in response to seismic
vibrations or other ambient stimuli.
(3) Screening: Construct security screens from a maximum of 26
AWG insulated hard-drawn copper. Connect screens to an alarm
circuitry by means of flexible armored cords. Security screen
circuitry shall provide end-of-line resistors in series or
equivalent methods ensuring alarm activation if short-circuiting
of the screen is attempted. [If screen corners are not installed
as a breakwire sensor (wire traps), provide tamper switches.
Provide tamper switches in frames as required with not less than
one switch on each side if dimensions are 610 mm 2 feet square or
less, and two switches if dimensions exceed 610 mm 2 feet square.
Tamper switches shall be corrosion resistant, spring operated, and
shall initiate an alarm with a movement of 50 mm 2 inches or less
and before access to the switch is possible. Electrical
characteristics of the switch shall match alarm system
requirements.]
c.
Object protection
(1) Capacitance proximity sensor: Sensor shall consist of two
solid-state synchronous oscillators, a reference oscillator, and a
detecting oscillator. The detecting oscillator shall be
electrically connected to the sensing wire (antenna) circuitry,
such that the capacitance of the antenna circuitry determines the
frequency and phase of oscillation. If an intruder approaches the
protected objects, the oscillator shall detune with respect to the
reference oscillator, initiating an alarm. The system shall
provide means of indicating an alarm condition at the protected
objects during installation and calibration. Provide the
indicator with a disabling device within a tamperproof enclosure.
The number of objects protected by a single capacitance detector
shall not exceed the unit's maximum capacitance at the desired
sensitivity. Protected objects shall be insulated from ground by
insulating pads which shall have a dielectric constant such as
glass or thermoplastic materials. [If screen grids or radiators
are employed as antennas, insulate from ground. Wires used for
grids shall be larger than No. 14 AWG, 30 percent copper-clad
steel covered with a minimum of 0.397 mm 1/32 inch vinyl coating.
Space grid elements at 150 mm 6 inches maximum, and construct in
a symmetrical manner.] Provide sensor with sensitivity controls
inaccessible to operating personnel. Sensor shall be insensitive
to human body movements in excess of 915 mm 36 inches from the
antenna circuit. Sensor sensitivity to alarm-producing stimuli
shall be readily adjustable from contact to 915 mm 36 inches with
a heavily gloved hand. Sensor shall not initiate nuisance alarms
in response to normal ambient conditions. [Provide sensors with
tamper switches. Interconnecting lines and tamper switches shall
remain under constant supervision, even when the system is set for
authorized access.] Sensor shall not reset upon restoration of
SECURE mode if the antennas were altered during authorized entry
to disable detection capability.
d.
Floor, wall, and ceiling protection
SECTION 13702N
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