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Number of Outdoor Receivers
To estimate the number of Receivers, assume a maximum Receiver spacing of 90 m (300 ft.) between
Receivers, in both directions, for Receivers that are not within 30 m (100 ft.) of a building with inside coverage.
Receivers within 30 m (100 ft.) of a building should be spaced at the spacing of Receivers in the building
(spacing the outside Receivers at a somewhat larger spacing is acceptable in most cases).
An outside area directly between two buildings with inside protection will need no additional Receivers if the
buildings are 90 m (300 ft.) or less apart. If the buildings are more than 90 m (300 ft.) apart the outside Receivers
should be placed evenly spaced between the buildings. Make sure the standard 90 m (300 ft.) spacing is not
exceeded. For spacing outside adjacent to a covered building, start the 90 m (300 ft.) spacing at the building
wall.
Allowance for Special Coverage Requirements
For purposes of the bid, the number of Receivers estimated above should be raised by 5% to allow for special
coverage considerations and RF problem areas.
Number of Transponders
Assume one Transponder per building for indoor installations. If wiring can be run from other buildings or from
outdoor Receivers, they may be connected to one Transponder but never exceed the total number of 64 devices
(Receivers and Alert Units) per Transponder. All outside wiring must be under ground or in metal conduit.
Number of Receiver and Alert Units Per Multiplex Bus
Although each bus can handle 8 Receivers and Alert Units it is a good idea to leave some addresses available
on each bus to allow for future expansion.
Multiplex Bus Wire
The multiplex bus should be wired with 4 conductor 18 gauge (1.2 mm) wire. The wire should not be paired or
shielded. In the United States this is the same as fire system wire, except it should not be red.
Number of Alert Units
The number of Alert Units will be determined by each system's requirements. In general, enough Alert Units
should be installed to be heard and seen from all outdoor locations of protection. Remember that even in a silent
system, Alert Units can be used outside to provide test feedback. Horn/Strobe units should be mounted in
predictable locations to make them easy to identify by subscribers. Alert Units are not required indoors because
the indoor Receiver provides alarm and test feedback. Each Transponder will drive one siren and one strobe if
they are less than 15 m (50 ft.) from the Transponder.
It is a good idea for each protected parking lot to have a siren/strobe near it.
Security Escort Training
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