
13
SenTRI4 fire system
Battery Standby and Loop load calculator tool
The ‘Battery standby and loop load calculator’ tool can be downloaded from
www.smstoolbox.co.uk website by registered users.
Loop Cable length
The loop cable length is defined as the sum of the length of cable used on the main
loop plus that used on all the spur circuits off the main loop having system devices.
Loop device load and length calculations
There can be up to 200 devices on a loop cable of up to 2Km when using Loop Card
(SENTRI4-LPC-EN), where both device count and cable length are dictated by the
number of alarm devices on the loop and how they are positioned, distributed or
lumped together.
What are Lumped and Distributed alarm device loads?
Example of Lumped alarm device load
SENTRI4
Control panel
AV
AV
AV
AV
AV
AV
AV
AV
Where 35% of the alarm devices are
lumped together in 1/4 segment , , or of a loop.
AV
AV
C
D
AV
This example
shows lumped devices
along cable length .
SENTRI4
Control panel
AV
AV
AV
AV
AV
AV
Distributed alarm devices are evenly
spaced along the entire length of the loop cable
from end to end.
AV
AV
AV
AV
AV
AV
AV
AV
AV
Example of Distributed alarm device load
AV
AV
- Audio Visual Sounder / Strobe
- Audio Visual Sounder Strobe devices
- Sensor only devices
- Other system devices
key:
B
A
C
D
B
A
D
Distributed alarm device load
Where the alarm load is distributed along the entire length of the loop using:
1.5mm² cable, the loop length can be up to 2Km with up to 200 devices.
2.5mm² cable, the loop length can be up to 2.5Km with up to 200 devices.
Lumped alarm device load
If the alarm devices are lumped together on a loop circuit then there is a trade off
between the number of alarm devices and loop cable length possible, see also loop
card leaflet which can be downloaded by registered users from www.smsfire.co.uk.
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