oscillator shall detune with respect to the reference oscillator,
initiating an alarm. System shall provide means of indicating an
alarm condition at protected objects during installation and
calibration. Provide 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, they shall be
insulated from ground. Wires used for grid shall be larger than
No. 14 AWG, 30 percent copper-clad steel covered with a minimum of
0.794 mm 1/32-inchvinyl coating. Space grid elements at 150 mm 6
inchesmaximum, 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.
Constantly supervise interconnecting lines and tamper switches
even when system is set for authorized access.] Sensor shall not
during authorized entry to disable detection capability.
c.
Floor, wall, and ceiling protection
(1) Vibration sensors: Sensors shall sense and selectively
amplify signals generated by forced penetration of a protective
structure. Sensors shall initiate alarms upon detecting drilling,
cutting, or blasting through walls, or other methods of forced
entry through a structure. Mount vibration sensors directly
contacting the surface to be protected. Sensors shall be designed
to give peak response to structurally conveyed vibrations
associated with forcible attack on the protected surface. Provide
at least one sensor on each monolithic slab or wall section, even
though spacing closer than that required for midrange sensitivity
may result. House sensors in protective mountings and fasten to
surface with concealed mounting screws or an epoxy. [Provide
sensors with tamper switches.] Removal of a sensor from the
surface shall initiate an alarm. An adjustable alarm
discriminator shall function to prevent incidental vibrations
which may occur from triggering the alarm circuit. Adjust
discriminator on the job to precise needs of application. Connect
sensors to an electronic control unit by means of wiring or fiber
optics cable run in [rigid steel conduit] [electrical metallic
tubing (EMT)]. Sensor sensitivity shall be individually
adjustable unless sensor is designed to accommodate vibration
ranges of specific surface type on which it will be mounted.
Sensitivity adjustments shall not be accessible without removing
the sensor cover. Sensor shall not be responsive to airborne
sound.
(2) Gridwire sensors: Provide strands of hard-drawn copper wire
stapled to a wall, door, or ceiling and attached to a terminal
strip enclosure. Enclosure shall be tamper switch-protected both
on the cover and with a pry-off tamper switch on rear of
enclosure. When correctly arranged, installed, and connected into
SECTION 13703N
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