(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
the 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 the
discriminator on the job to the precise needs of the application.
Connect sensors to an electronic control unit by means of wiring
or fiber optics cable run in [rigid steel conduit] [EMT]. Sensor
sensitivity shall be individually adjustable unless sensor is
designed to accommodate vibration ranges of the specific surface
type on which it will be mounted. Sensitivity adjustments shall
not be accessible without removing the cover on the sensor.
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 the rear of the
enclosure. When correctly arranged, installed, and connected into
an electrically supervised detector circuit, the cutting,
breaking, or grounding of gridwire shall initiate an alarm.
Install gridwire in a pattern of 100 mm 4 inches on center over a
wall, door, or ceiling area generally not exceeding 1220 by 2440
mm 4 by 8 feet in dimensions, for each terminal strip. Cover the
grid pattern by a cosmetic material such as paneling. Hard-drawn
gridwire used in fabricating security sensors shall not exceed
17.8 N 4 pounds tensile strength and shall be capable of carrying
a current of 60 milliamperes at 60 volts with a temperature rise
of not more than one degree C 2 degrees F. Wire shall not be
larger than 26 AWG.
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NOTE: Utility inlet openings are protected in a
variety of methods, the correct one being dependent
on two variables: the nature of the intrusion
threat (e.g., physical penetration, electrical,
electro-optical) and the characteristics of the
utility inlet opening (e.g., discharge water from a
nuclear plant, office air duct, electric conduit).
Subsequent to such analysis, almost any of the
intrusion detection sensors described herein could
provide the necessary protection. Normally a
breakwire trap sensor is used for this application.
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(3) Protection of utility inlet openings: Provide protection by
a sensor of the [breakwire] [wire trap] type consisting of up to
SECTION 13702N
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