Maximum Cable Length Versus Load Current; Max Wire Length By Current And Wire Size Graphic; Sa/Fc Bus And Supply Power Wiring Guidelines - Johnson Controls IOM1711 Installation Manual

Table 3: Cable length guidelines and recommended wire sizes for low-voltage (<30 V) Inputs and
Outputs
Guide- line Wire size/Gauge and Type
1.0 mm (18 AWG) stranded copper
0.8 mm (20 AWG) stranded copper
A
0.6 mm (22 AWG) stranded copper
0.5 mm (24 AWG) stranded copper
1.0 mm (18 AWG) stranded copper
0.8 mm (20 AWG) stranded copper
B
0.6 mm (22 AWG) stranded copper
0.5 mm (24 AWG) stranded copper
See Figure 9 to select wire size/gauge. Use
C
stranded copper wire
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.
Maximum cable length versus load
current
Use Figure 9 to estimate the maximum cable length
relative to the wire size and the load current (in mA)
when wiring inputs and outputs.
Note: Figure 9 applies to low-voltage (<30 V)
inputs and outputs only. The required wire
size and length for high-voltage (>30 V) Relay
Outputs is determined by the load connected
to the relay and local electrical codes.
Max wire length by current and wire
size graphic
Figure 9: Maximum wire length for low-voltage
(<30 V) Inputs and Outputs by current and wire
Size
Maximum cable length
and type
457 m (1,500 ft) twisted wire
297 m (975 ft) twisted wire
183 m (600 ft) twisted wire
107 m (350 ft) twisted wire
229 m (750 ft) twisted wire
137 m (450 ft) twisted wire
91 m (300 ft) twisted wire
61 m (200 ft) twisted wire
See Figure 9 to determine
cable length. Use twisted
wire cable.
SA/FC bus and supply power wiring
guidelines
Table 4 provides information about the functions,
ratings, and requirements for the communication
bus and supply power terminals; and guidelines
for wire sizes, cable types, and cable lengths when
wiring the controller'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.
IOM1711 and IOM2711 Input/Output Module Installation Guide
Assumptions
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.
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.
N/A
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