Specifications

82
Diagrams are for reference only.
Consult the appropriate installation sheet for wiring details.
TM
REFERENCE SECTION
SIGNATURE DATA CIRCUIT MAXIMUM WIRE LENGTH CALCULATIONSSIGNATURE DATA CIRCUIT MAXIMUM WIRE LENGTH CALCULATIONS
SIGNATURE DATA CIRCUIT MAXIMUM WIRE LENGTH CALCULATIONSSIGNATURE DATA CIRCUIT MAXIMUM WIRE LENGTH CALCULATIONS
SIGNATURE DATA CIRCUIT MAXIMUM WIRE LENGTH CALCULATIONS
where: L
Max
= maximum total cable length in feet
C
pf/Ft
= Cable capacitance in picofarads per foot
Note: A short circuit on a Signature data circuit can disable the entire circuit. In order
to limit the effect of a single short circuit on the SDC, SIGA-IB Isolator Bases or SIGA-
IM Isolator modules can be installed at strategic points in the circuit.
Step 2:Step 2:
Step 2:Step 2:
Step 2: Use Tables C-2, C-3, C-4, and C-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).
L
Max
500,000
C
pf/F
=
Table C-2 through Table C-5 provide the maximum allowable branch length for any
detector, module, SIGA-UM, and wire gauge combination. Using the wire distances
specified in the tables ensures that the circuit does not exceed the maximum circuit
resistance of the Signature data circuit.
Note: To calculate the wire distance with respect to circuit resistance, the tables assume
that the circuit is end-loaded (all devices are clustered more towards the end of the
circuit) and the circuit uses standard non-shielded wire.
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)