Site survey
Page 32
FiberPatrol Site Planning & Installation Guide
Service loops
A 10 m (33 ft.) service loop is recommended for every 300 m (984 ft.) of installed sensor cable.
A 10 m service loop is also recommended on the hinged side of each gate that is protected by
sensor cable. In addition, a 10 m (33 ft.) splice point service loop is required for each section of
sensor cable at all splice locations. A 10 m service loop is typically comprised of 5 loops of cable
with a 60 cm (2 ft.) diameter. Service loops should be securely attached to the lower section of the
fence beside a fence post. Attach service loops directly to the fence fabric using one cable tie at
each 45º point of the loop (8 cable ties).
Isolation loops (optional)
Isolation loops can be used at the start point of detecting cable, on both sides of gates that will be
setup as independent zones, at cable bypasses and at zone boundaries. Isolation loops use
approximately 13 m (43 ft.) of sensor cable coiled into 60 cm (2 ft.) diameter loops (7 loops) to
provide a distinct zone demarcation point. Isolation loops can be buried in cable vaults, which will
provide the greatest level of isolation between two zones. However, if using a buried vault is
impractical, isolation loops can be attached directly to the fence fabric with 14 in. steel cable ties.
shows a cross section of a fence-mounted isolation loop attachment and
shows the buried vault installation method for isolation loops. Isolation loops are attached to the
fence in the same manner as service loops (see
Figure 36 Service loop
Figure 37 Zone boundary isolation loop (fence-mounted)
service loop 5 loops
10 m (33 ft.)
60 cm
(2 ft.)
of sensor cable
fence wire
7 loops 60 cm (2 ft.) diameter
isolation loop cross section
app. 13 m (43 ft.) of sensor cable
14 in. steel cable tie
