Cable And Wire Length Guidelines; Maximum Cable Length Versus Load Current - Johnson Controls F4-CV Series Installation Manual

Table 5: I/O terminal blocks, functions, ratings, requirements, and cables
Terminal Block label

Cable and wire length guidelines

Table 6 defines cable length guidelines for the various wire sizes that may be used for wiring low-voltage (<30 V) input
and outputs. 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 6: Cable length guidelines for recommended wire sizes
Guideline Wire size/gauge and type
A 1.0 mm (18 AWG) stranded copper
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
0.5mm (24 AWG) stranded copper 107 m (350
ft) twisted wire
B 1.0 mm (18 AWG) stranded copper
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
0.5mm (24 AWG) stranded copper 107 m (350
ft) twisted wire
C See figure labeled Maximum Wire Length by
Current and Wire Size to select wire size/gauge.
Use stranded copper wire.

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.
Terminal labels Function, ratings, and requirements
BO-C or BO-Cn Binary Output - 24 VAC Triac (Internal Power)
Connects BO-C/BO-Cn to 24~COM when activated.
Internal Power Source:
30 VAC maximum voltage to load
0.5 A maximum output current
1.3 A at 25% duty cycle
40 mA minimum load current
F4-CV Series VAV Terminal Equipment Controllers Installation Guide
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 labeled Maximum Wire
Length by Current and Wire Size to
determine cable length.
Use twisted wire cable.
Note: Figure 11 applies to low-voltage (<30 V) inputs
and outputs only.
To determine wire size and
maximum cable length
See Guideline C in Table 6.
Assumptions
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.
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.
N/A
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