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Loop Loading
Loop length and quantities for Standard mode with non VAD devices
Use either Table 2 or Table 3 to determine the maximum number of devices on a loop and loop cable length possible for lumped
alarm load. The examples 1 and 2 below show how to use the tables to determine loading and loop cable length.
Table 2 Lumped load using 1.5mm² loop cable
Assuming S-Quad with older sounder including strobe and S-Cube Mark 1/2 devices, ie non compliant Part 23 devices.
A
Loop cable length in Km including spurs using 1.5mm² cable
Total
Alarm
0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0
Current
225 mA
250 mA
275 mA
300 mA
325 mA
350 mA
375 mA
400 mA
170 140 110 70
Table 3 Lumped load using 2.5mm² loop cable
Assuming S-Quad with sounder including strobe and S-Cube Mk 1/2 devices, ie non compliant Part 23 devices.
A
Loop cable length in Km including spurs using 2.5mm² cable
Total
Alarm
0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5
Current
200 mA
275 mA
300 mA
325 mA
350 mA
375 mA
400 mA
Example 1
Devices allowed on a known loop cable length for Lumped alarm load
If the loop cable length is known then you can determine the maximum number of devices that can be connected to a loop where
there is lumped alarm devices.
a. First calculate the total alarm current value
b. Use the calculated total alarm current
of devices
that can be connected to the loop.
C
For example if the total alarm current
you for lumped alarm devices the maximum number of devices allowed on the loop must be limited to
Example 2
Loop cable length allowed for known Lumped alarm device load
If the number of devices on a loop is known then you can determine the maximum cable length that can be used on the loop circuit.
a. First calculate the total alarm current value
b. Use the total alarm current
maximum length of loop cable allowed
For example if the total alarm current
maximum loop cable length
2.5mm² loop cable is used then the cable length can be up to 2.5Km.
4188-1075 issue 3_Part 2_08/14
190 150 130 100 70
170 130 100 70
180 150 120 90
170 140 110 70
n/a n/a n/a n/a n/a
160 130 100 70
n/a n/a n/a n/a n/a n/a
n/a n/a n/a n/a n/a n/a n/a
190 170 150 120 100 80 60 n/a n/a
190 170 150 130 110 90 70 n/a n/a n/a n/a
, use Table 1.
A
and the known loop cable length
A
is 350mA when using 1.5mm² loop cable that is
A
, use Table 1.
A
and the known number of devices on the loop to look up in Table 2 or 3 and work out the
A
for the connection lumped alarm devices.
B
is 225mA and if 200 devices
A
can be 2Km for lumped alarm load, when using 1.5mm² loop cable. However Table 2 tells you if
B
B
190 160 130
n/a n/a
C
Maximum allowed devices of any type on a loop for a
n/a n/a n/a n/a
Lumped alarm load only.
n/a = not applicable (condition not allowed)
B
190 170 150
180 170 150 120 100
180 150 120 110 100 80 60
are required on the loop, then Table 2 tells you the
C
blank cell = 200 devices
C
Maximum allowed devices of any type
on a loop for a Lumped alarm load
only.
blank cell = 200 devices
n/a = not applicable (condition not
allowed)
to look up in Table 2 or 3 the maximum number
B
1.5Km in length, then Table 2 tells
B
C
70 devices.
7
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