Table 6: Cable length guidelines for recommended wire sizes
Guideline
Wire size/gauge and type
Maximum cable length and
type
Assumptions
1.0 mm (18 AWG) stranded copper
229 m (750 ft) twisted wire
0.8 mm (20 AWG) stranded copper
297 m (975 ft) twisted wire
137 m (450 ft) twisted wire
0.6 mm (22 AWG) stranded copper
183 m (600 ft) twisted wire
91 m (300 ft) twisted wire
B
0.5 mm (24 AWG) stranded copper
107 m (350 ft) twisted wire
61 m (200 ft) twisted wire
100 mV maximum voltage drop
Depending on the cable length
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 to select wire size/gauge.
Use stranded copper wire.
See Figure 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.
Figure 9 applies to low-voltage (<30 V) inputs
and outputs only.
Figure 9: Maximum wire length for low-voltage (<30 V) Inputs and Outputs by current and wire size
Communications bus and supply power wiring guidelines
Table 7 provides information about terminal
block functions, ratings, and requirements for the
communication bus and supply power terminals. The
table also provides wire size, cable type, and cable length
guidelines for wiring the communication buses and
supply power.
Important:
Refer to the
N2 Modernization Guide for
Legacy N2 Controllers (LIT-12012005)
for guidelines
when you use this device on an N2 bus.
In addition to the guidelines in Table 7, observe these
guidelines when wiring the FC bus, SA bus, or the 24 VAC
supply power:
• Run
all
low-voltage wiring and cables separate from
high-voltage wiring.
• All FC and SA bus cables, regardless of wire size, must
be twisted, insulated, stranded copper wire.
• Shielded cable is strongly recommended for all FC and
SA bus cables.
M4-CVM VAV Box Controllers Installation Guide
9
