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Installation Manual
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WIRING
Indoor Unit Communication Cable Connections
Note:
Failure to follow any of these power and communications wiring guidelines or instructions will likely cause
communications errors and unit malfunction.
Polarity matters. When connecting the communications cable conductors at each Multi V system compo-
nent, be careful the conductor connected to the IDU(A) terminal on the outdoor unit is connected to the
A/3(A) terminal at each indoor unit. The conductor connected to the IDU(B) terminal on the outdoor unit
must be connected to the B/4(B) terminals at each indoor unit. Cross connecting the A/3(A) and B/4(B)
terminals will cause communications errors and system malfunction.
Don’ts
• Never use wire caps and never splice communications cables.
•
Star and Wye communications cable configurations are not acceptable.
• Never connect zone controllers or other central control products such as AC Smart, PDI, or LG building
management system gateway products to the IDU/ODU communications cable.
• Keep communications cables away from line voltage wiring, lighting ballasts, and other devices emit-
ting EMF energy. Maintain a minimum of two (2) inches between line voltage wires and communica-
tions or zone controller cables.
• Field provide a minimum of 18-2 AWG, stranded and shielded, PVC or vinyl jacket communications
wiring between the indoor units, heat recovery boxes (if applicable), and outdoor units.
• The outdoor/indoor unit communications cable must be run between components in a daisy chain
configuration. Star or wye configurations are not allowed.
• Refer to the wiring connection diagrams for the appropriate unit (Figure 34 through Figure 40)
Connect the communications cables to the A/3(A) and B/4(B) terminals at indoor units and/or heat
recovery units. Maintain polarity throughout the communications bus. Be sure A/3(A) terminals are
connected to A/3(A) terminals and B/4(B) terminals are connected to B/4(B) terminals.
• Ground the shield of the communications cable at one end only, at the master outdoor unit.
Note:
The minimum distance required between power wires and the communications cable is voltage/amperage
dependent and in cases where either are relatively high the minimum distance may be more than two (2)
inches. Refer to the appropriate LG Multi V Outdoor Unit Engineering Manual on www.lg-vrf.com for detailed
information.
Communication Cable Connection
Note:
When connecting the communications bus between the outdoor unit, indoor unit(s), and heat recovery unit(s),
it does not matter what physical path or route the wire takes. The installer may use discretion when choosing
the order the components are connected to the communications bus, but must maintain the daisy chain and
polarity configuration.
1. If not already done so, read Connecting Power and Control Wiring on the previous page.
2. Remove a knock-out plug from the control box. Remember the communications cable and the power
cable must enter the control box through different knockouts.
3.
Field-install a plastic or rubber grommet in the knockout hole to prevent wire chaffing.
4. If using conduit, connect the conduit to the control box using field-provided fittings and industry best-
practice procedures.
5. Provide at least three (3) to four (4) inches of slack cable at each indoor unit.
6. Secure the communications cable to the inside surface of the control box using a field provide nylon
wire clamp.
7. Strip approximately half of an inch of insulation from each communications cable conductor. At each
indoor unit, insert the conductors under the terminal screw.
