Protec Algo-Tec 6300 - LOOP CABLING; 2.3.1 GUIDE TO LOOP CABLE CONDUCTOR SIZES (mm²)

93-509-09 - Issue 2 Rev 2 Page 7 of 20 Copyright Protec Fire Detection PLC
2.3 LOOP CABLING
The main consideration for the loop cable is the loop length. This length must include all sub-loops and spurs.
For example, a loop of 800m with three spurs of 150m must be considered as being 1250m in length.
Notes :- 1. The loop cabling must be wired in fire rated cable. The minimum conductor size is shown
in the tables of section 2.3.1. In countries where local standards permit, the loops can be wired
in ‘Twin Figure 8’ cable but the loop length and load will have to be reduced in accordance
with the lower conductor size.
2. Maximum loop resistance = 16Ω per conductor.
3. It is assumed that devices are evenly spread on the loop. If a large load, eg a number of
sounders, is located at the end of the loop then the volt drop along the cable must be calculated
to ensure that the input voltage to the loop devices remains within the range of 16 to 30V
(peak).
Each address point must be numbered. Sequential address allocation of devices on the loops is not necessary
with a 6300 system but it may prove advantageous for fault finding.
EACH OF THE LOOPS MUST BE WIRED IN A SEPARATE PAIR. WHEN THE CABLE HAS A SCREEN THEN
THE SCREEN MUST BE EARTHED AND CONTINUOUS OVER THE CABLE RUN.
2.3.1 GUIDE TO LOOP CABLE CONDUCTOR SIZES (mm
2
)
Loop Length (metres)
500 550 600 650 700 750 800 850 900 950 1000
Total
Loop
Load
in
Alarm
(mA)
50 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.5 1.5 1.5 1.5
100 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.5 1.5 1.5 1.5
150 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.5 1.5 1.5 1.5
200 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.5 1.5 1.5 1.5
250 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.5 1.5 1.5 1.5
300 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.5 1.5 1.5 1.5
350 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.5 1.5 1.5 1.5
400 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.5 1.5 1.5 1.5
450 1.0 1.0 1.0 1.0 1.0 1.5 1.5 1.5 1.5 1.5 1.5
500 1.0 1.0 1.0 1.0 1.5 1.5 1.5 1.5 1.5 1.5 2.5
550 1.0 1.0 1.0 1.5 1.5 1.5 1.5 1.5 1.5 2.5 2.5
600 1.0 1.0 1.5 1.5 1.5 1.5 1.5 2.5 2.5 2.5 2.5
Loop Length (metres)
1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500
Total
Loop
Load
in
Alarm
(mA)
50 1.5 1.5 1.5 1.5 1.5 2.5 2.5 2.5 2.5 2.5 2.5
100 1.5 1.5 1.5 1.5 1.5 2.5 2.5 2.5 2.5 2.5 2.5
150 1.5 1.5 1.5 1.5 1.5 2.5 2.5 2.5 2.5 2.5 2.5
200 1.5 1.5 1.5 1.5 1.5 2.5 2.5 2.5 2.5 2.5 2.5
250 1.5 1.5 1.5 1.5 1.5 2.5 2.5 2.5 2.5 2.5 2.5
300 1.5 1.5 1.5 1.5 1.5 2.5 2.5 2.5 2.5 2.5 2.5
350 1.5 1.5 1.5 1.5 1.5 2.5 2.5 2.5 2.5 2.5 2.5
400 1.5 1.5 1.5 1.5 1.5 2.5 2.5 2.5 2.5 2.5 2.5
450 1.5 1.5 1.5 1.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5
500 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 N/A
550 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 N/A
600 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 N/A N/A N/A
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