Ge Est QS4 - Signature Loop Maximum Wire Length Calculations

System calculations
QS4 Technical Reference Manual A.3
Signature loop maximum wire length calculations
Use this worksheet to determine the maximum amount of wire you can use to construct a Signature loop.
Step 1: Calculate the total amount of wire you can used based on the cable manufacturer's capacitance
per foot rating. Total amount of wire shall not exceed the values listed in Table A-1.
500000
Cable capacitance
÷
pF/ft
Total wire ft
Table A-1: Maximum amount of wire you can use to construct a Signature loop
Wire type 14 AWG / 1.5 mm² 16 AWG / 1.0 mm² 18 AWG / 0.75 mm
2
Twisted pair, nonshielded
25 pF/36 pF/38 pF
13157 ft
(4010 m)
13888 ft
(4233 m)
20000 ft
(6096 m)
Twisted pair, shielded
58 pF/82 pF/84 pF
5952 ft
(1814 m)
6098 ft
(1859 m)
8621 ft
(2628 m)
Nontwisted pair, nonshielded
20 pF/20 pF/20 pF
20000 ft
(6096 m)
20000 ft
(6096 m)
20000 ft
(6096 m)
Step 2: Use Table A-2, Table A-3, Table A-4, and Table A-5 to determine the longest allowable circuit
path based on wire size and type, and the number of detector, module, SIGA–UMs or –MABs installed on
the loop.
In the illustration below, the longest circuit path (shown in bold lines) is 1240 ft (377.95 m). The total
amount of wire comprising the loop is 1740 ft (530.35 m)
FACP
J
J
10 ft
(3.05 m)
200 ft
(60.96 m)
30 ft
(9.14 m)
J
100 ft
(30.48 m)
1000 ft
(304.8 m)
200 ft
(60.96 m)
200 ft
(60.96 m)
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