Loop cable
See the part on Cables
NOTE: Multi-core cables carrying more than one circuit should never be
used.
Cable separation
Where the outgoing and return cables of a loop which covers more than the
equivalent of one zone must not run together, for example, either close to
the Control Panel or in a service duct. There should be as much physical
separation as possible between the cables and the mechanical protection of
the cable should be to a particularly high standard. This is to minimise the
risk of accidental damage to both cables. There should be separation from
the mains supply cable.
Loop Coverage
A loop circuit must not cover more than 10,000m
2
of floor area of a
protected site.
Spur circuits
Where appropriate, a spur circuit may be used in order to save cable and,
therefore, installation cost. A device (outstation) has terminals for cable
connections. The 2-way type allows straight in-out connection, while the
3-way has an added common line connection, that is in-out-comm line.
The spur circuit must always be taken from the line com terminals.
NOTE: 3-way devices are only available as sounders, interfaces and
repeats. If it is not appropriate to use these devices in the required
location a ‘T’ breaker should be used.
NOTE: Spurs should not cover more than the equivalent of one zone as
defined in BS 5839 : Part 1 : 1988.
NOTE: The common line to accept spurs may be left unconnected, if
using the device for 2-way connection.
Lightning protection
CAUTION: Lightning protection must be used if a loop cable is routed on
exterior wall of a building.
Loop cable
Loop Circuit Connections
Senator II Installation Manual
5-2
78910-03NM Issue 2_10/96