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 4: 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
297 m (975 ft) twisted wire
0.6 mm (22 AWG) stranded copper
183 m (600 ft) twisted wire
183 m (600 ft) twisted wire
A
24 AWG stranded copper 107 m (350
ft) twisted wire
107 m (350 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.
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
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 Figure 8 to estimate the maximum cable length
relative to the wire size and the load current (in mA)
when wiring inputs and outputs.
Figure 8: Maximum Wire Length by Current and
Wire Size
Communication bus and supply power terminal blocks, ratings, and
requirements
Table 5: Communication bus and supply power terminal blocks, functions, ratings, requirements, and
cables
Terminal block/Port label
Terminal labels
Function, electrical ratings/
Requirements
Recommended cable type
+
-
FC Bus Communications
COM
Signal Reference (Common) for bus
communications
FC BUS
2
SHLD
Isolated terminal (optional shield drain
connection)
0.6 mm (22 AWG) stranded, 3-wire
twisted, shielded cable recommended
VMA1617 and VMA1632 VAV Controllers Installation Guide
11
