
4188-1075 issue 3_Part 2_08/14 7
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
Total
Alarm
Current
Loop cable length in Km including spurs using 1.5mm² cable B
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)
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
225 mA
250 mA 190 160 130
275 mA 190 150 130 100 70
300 mA 170 130 100 70 n/a n/a
325 mA 180 150 120 90 n/a n/a n/a n/a
350 mA 170 140 110 70 n/a n/a n/a n/a n/a
375 mA 160 130 100 70 n/a n/a n/a n/a n/a n/a
400 mA 170 140 110 70 n/a n/a n/a n/a n/a n/a n/a
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
Total
Alarm
Current
Loop cable length in Km including spurs using 2.5mm² cable B
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)
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
200 mA
275 mA
300 mA 190 170 150
325 mA 180 170 150 120 100
350 mA 180 150 120 110 100 80 60
375 mA 190 170 150 120 100 80 60 n/a n/a
400 mA 190 170 150 130 110 90 70 n/a n/a n/a n/a
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 A, use Table 1.
b. Use the calculated total alarm current Aand the known loop cable length Bto look up in Table 2 or 3the maximum number
of devices Cthat can be connected to the loop.
For example if the total alarm current Ais 350mA when using 1.5mm² loop cable that is B1.5Km in length, then Table 2 tells
you for lumped alarm devices the maximum number of devices allowed on the loop must be limited to C70 devices.
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 A, use Table 1.
b. Use the total alarm current Aand the known number of devices on the loop to look up in Table 2 or 3and work out the
maximum length of loop cable allowed Bfor the connection lumped alarm devices.
For example if the total alarm current Ais 225mA and if 200 devices Care required on the loop, then Table 2 tells you the
maximum loop cable length Bcan be 2Km for lumped alarm load, when using 1.5mm² loop cable. However Table 2 tells you if
2.5mm² loop cable is used then the cable length can be up to 2.5Km.