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Installation Manual
Due to our policy of continuous product innovation, some specifications may change without notification.
©LG Electronics U.S.A., Inc., Englewood Cliffs, NJ. All rights reserved. “LG” is a registered trademark of LG Corp.
Communication Cable Specifications From Outdoor Unit to Indoor Units /
Heat Recovery Units
• Communication cable from Main Outdoor Unit to Indoor Units / Heat Recovery Units is to be LG supplied or eld supplied 18 AWG, 2-con-
ductor, twisted, stranded, shielded. Never splice communications cable. Ensure the communication cable shield is properly grounded to
the Main Outdoor Unit chassis only. Do not ground the Outdoor Unit to Indoor Units / Heat Recovery Units communication cable at any
other point. Wiring must comply with all applicable local and national codes.
• Cable shields between the connected devices must be tied together and continuous from the main outdoor unit to the last component con-
nected and insulated to prevent grounding against the IDU/HRU electrical enclosures.
• Start the communication cable at the main outdoor unit and route to the indoor units / heat recovery units in a daisy chain conguration.
Do not install in a starburst conguration.
• Indoor Unit / Heat Recovery Unit Communication Bus: The communication terminals are labeled differently among the indoor units, de-
pending on type (currently for indoor units: A / B, 3[A] / 4[B], or 3 / 4; for heat recovery units: A / B). Refer to the wiring diagram schematic
found in the indoor unit itself, or to the indoor unit wiring diagrams for more information. Match IDU A and B terminals on outdoor unit to A
(3) and B (4) terminals on indoor units / heat recovery units.
• Insulation as required by NEC and local codes.
• Rated for continuous exposure of temperatures up to 140°F.
• Maximum allowable communication cable length is 3,281 feet.
Heat Recovery Unit
(For Heat Recovery
Systems Only)
Main Outdoor Unit
Indoor Unit Indoor Unit Indoor Unit Indoor Unit Indoor Unit Indoor Unit
Wired Controllers Wired Controllers Wired Controllers
Figure 54: Correct Main Outdoor Unit to Indoor Unit / Heat Recovery
Unit Communication Wiring—Typical Daisy Chain Conguration.
Figure 55: Incorrect Main Outdoor Unit to Indoor Unit / Heat Recovery
Unit Communication Wiring—Starburst Conguration.
HR unit
• Ground wiring is required to prevent accidental electrical shock dur-
ing current leakage, communication problems from electrical noise,
and motor current leakage. Do not connect the ground line to
the pipes. There is risk of fire, electric shock, explosion, physical
injury or death.
• Never ground the shield of the communications cable to the
indoor unit frame or other grounded entities of the building. Inad-
equate connections will generate heat, cause a fire, and physical
injury or death.
• Always verify the communication cable is connected to a com-
munications terminal on the outdoor unit(s). Never apply line
voltage power to the communication cable connection. If contact is
made, the PCBs will be damaged.
• Never use a common multiple-core communications cable.
Each communications bus shall be provided a separate cable (i.e.,
between outdoor unit(s) and indoor units, outdoor units and central
controller(s)). If communications cables of separate systems are
wired using a common multiple-core cable, it will result in a poor
communications signal and unacceptable system operation.
WIRING
Communications Cable Specications
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