EQUIPMENT: T1200-C
PUBLICATION: MARINEC-P-A
ISSUE No. & DATE: 3 02/14
© 2014 Thorn Security Ltd PAGE 53 of 67
Registered Company: Thorn Security Ltd. Registered Office: Dunhams Lane Letchworth Garden City Hertfordshire SG6 1BE
19.8 Electrical Design of Detection
Zones
To allow the panel to correctly monitor for fault
conditions, the wiring for each zone must be
installed as a continuous pair with no spurs or tees
and be terminated with a 10k 0.25W end-of-line
resistor. Correct polarity must be strictly observed
throughout.
19.8.1 Maximum Number of Devices on
a Zone
The maximum number of devices supported by a
zone depends on the quiescent current drawn by
each device. The quiescent current will be listed on
the device data sheet provided by the Manufacturer
of the device.
The maximum quiescent current available to the
devices on a zone is 1.2mA. Exceeding this value
will prevent the panel from correctly monitoring for
open circuit fault conditions.
Note: BSEN 54-2 recommends the maximum
number of devices per zone is 32 (including
MCPs) and requires that the maximum number
of devices connected to a panel is limited to 512
(a single microcontroller failure should not
result in more than 512 devices being lost).
19.8.2 Intrinsically Safe Zones
Warning: I.S. zone wiring and equipment
installation must comply with the installation
guidelines provided with the I.S. fire detection
equipment and the I.S. barrier. [See section 17.6
above].
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