Cable and wire length guidelines
The following table defines cable length guidelines
for the various wire sizes that may be used for
wiring low-voltage (<30 V) input and outputs.
Note:
The required wire sizes and lengths
for high-voltage (>30 V) Relay Outputs are
determined by the load connected to the relay,
and local, national, or regional electrical codes.
Table 4: Cable length guidelines for recommended wire sizes for low-voltage (<30 V) Inputs and
Outputs
Wire size/Gauge and type
Maximum cable length and
type
Assumptions
1.0 mm (18 AWG) stranded copper
457 m (1,500 ft) twisted wire
0.8 mm (20 AWG) stranded copper
297 m (975 ft) twisted wire
0.6 mm (22 AWG) stranded copper
183 m (600 ft) twisted wire
A
0.5 mm (24 AWG) stranded copper
107 m (350 ft) twisted wire
100 mV maximum voltage drop
Depending on cable and the
connected input or output device, you
may have to define an offset in the
setup software for the input or output
point.
1.0 mm (18 AWG) stranded copper
229 m (750 ft) twisted wire
0.8 mm (20 AWG) stranded copper
137 m (450 ft) twisted wire
0.6 mm (22 AWG) stranded copper
91 m (300 ft) twisted wire
B
0.5 mm (24 AWG) stranded copper
61 m (200 ft) twisted wire
100 mV maximum voltage drop
Depending on cable and the
connected input or output device, you
may have to define an offset in the
setup software for the input or output
point.
C
See Figure 6 to select wire size/gauge. Use
stranded copper wire
See Figure 6 to determine cable
length. Use twisted wire cable. N/A
Maximum cable length versus load
current
Use Figure 6 to estimate the maximum cable length
relative to the wire size and the load current (in mA)
when wiring inputs and outputs.
Note:
Figure 6 applies to low-voltage (<30 V)
inputs and outputs only.
Figure 6: Maximum wire length for low-voltage
(<30 V) Inputs and Outputs by current and wire
size
Communications bus and supply
power wiring guidelines
The provides information about the functions,
ratings, and requirements for the communication
bus and supply power terminals. The table also
provides guidelines for wire sizes, cable types, and
cable lengths for when you wire the controller's
communication buses and supply power.
In addition, observe these guidelines when you wire
an SA or FC bus and the 24 VAC supply power:
• Run all low-voltage wiring and cables separate
from high-voltage wiring.
• All SA and FC bus cables, regardless of wire size,
should be twisted, insulated, stranded copper
wire.
• Shielded cable is strongly recommended for all SA
and FC bus cables.
• Refer to the
MS/TP Communications Bus
Technical Bulletin (LIT-12011034)
for detailed
information regarding wire size and cable length
requirements for SA and FC buses.
FAC4911 Advanced Application Field Equipment Controller Installation Guide
10
