XFP 16 ZONE ANALOGUE ADDRESSABLE FIRE ALARM PANEL
XFP ENGINEERING MANUAL • Approved Document No. DFU1200510 Rev 3 • Page 8 of 36
Analogue addressable loop wiring
Fig. 4 below shows a typical analogue addressable loop complete with loop isolators, detectors, loop-
powered sounders, modules and monitors. The descriptions and availability of the devices shown may
not be applicable to all manufacturers’ protocols – check with your supplier for further details. Also this
example arrangement of devices may not be permitted by design and installation regulations in certain
countries. The loop should be connected to the relevant 5mm connector block on the panel’s Main
Control PCB and its screens terminated at the panel’s base earth distribution post as shown on page 9.
Fig. 4 : A typical analogue addressable loop
Design issues - reducing faults and their consequences
To ensure a reliable system, it should be designed and maintained to local design and installation
regulations. The XFP has loop isolators included in the panel, and loop isolators should be included in
the loop wiring. A single short circuit fault will now only disable devices in the section of wiring
between isolators. Local design and installation regulations will dictate how many devices or zones may
be lost in the case of this type of fault. In the case of a single open circuit no devices will lost, since
communication is from both ends of the loop, but a loop integrity fault will be shown.
Note that a critical design issue with any analogue fire system is the combined effect of loop resistance,
loop capacitance and the current demand of items connected to the loop.
Factors that influence this include loop length, cable diameter, cable type, the number of isolators used
and the number and type of devices between isolators. There are no hard and fast rules regarding these
factors as every situation is unique. However, if the following conservative advice is followed, the loop
WILL almost certainly work.
• Absolute maximum loop length = 1km, with either 1mm
2
or 1.5mm
2
cables.
• No more than 20 addressable devices between loop isolators of which no more than 6 are loop sounders.
• If loop sounders are used, use 1.5mm
2
cable and do not fit more that 32 loop sounders per loop in total.
• If more than 10 loop sounders are used per loop then the maximum loop length per loop should be no
greater than 750m.
The above
SHOULD NOT
be considered the maximum operating conditions for the panel as many other
permutations are possible. Any limitations are a consequence of device manufacturers’ protocol, coupled
with the cable’s characteristics. The panel’s loop driver is easily capable of driving lightly loaded loops up to
4 km long without a problem. However, devices connected at the end of 4 km may not be able to read the
data if corrupted by the cable. Always refer to the instructions supplied with each device prior to installation.
