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.
Table 3: Cable length guidelines
Guideline
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 7 to select wire size/gauge.
Use stranded copper wire.
See Figure 7 to determine
cable length. Use twisted
wire cable.
N/A
Maximum cable length versus load
current
Use the following figure to estimate the maximum
cable length relative to the wire size and the load
current (in mA) when wiring inputs and outputs.
Note:
The following information applies to low-
voltage (<30 V) inputs and outputs only.
Figure 7: Maximum wire length for low-voltage
(<30 V) Inputs and Outputs by current and wire
size
Communications bus and supply power
wiring guidelines
Table 4 provides information about the functions,
ratings, and requirements for the communication
bus and supply power terminals; it additionally
provides guidelines for wire sizes, cable types, and
cable lengths when wiring the expansion module's
communication buses and supply power.
In addition to the guidelines in Table 4, observe
these guidelines when wiring 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 the SA and FC buses.
IOM2723 Input/Output Module Installation Guide
8