LG Multi V Installation Manual page 24

LOW VOLTAGE COMMUNICATIONS
Communication Cable Connection
High voltages capable of causing severe injury or death are used in this equipment. Do not touch live circuits.
Ensure power is not applied when connecting communications cables. Use a meter to verify if power is con-
nected or not. If power is connected, disconnect power before performing this procedure. Do not work on this
equipment alone. Know how to obtain emergency assistance.
Note:
• When connecting the communications cables between indoor unit(s), heat recovery box(es), and the
outdoor unit, all components must be connected in a daisy chain configuration. Star or Wye configu-
rations are not supported. It does not matter what physical path the wire takes.
• Do not cut or splice communications cable. Communications cable must be two conductor, stranded
and shielded with a minimum size of 18 AWG.
• Ground the communications cable at the outdoor unit end ONLY. Do not ground the cable to the
refrigerant pipes.
1. If you have not already done so, read the Outdoor / Indoor Unit
Communications Installation Guidelines.
2. If necessary, remove the front panel (convertible) or side panel
(ceiling suspended) to gain access to the control box.
3. Remove the cover of the control box.
4. Remove a knock-out plug from the control box. Do not use the
same knock-out as the power input cable.
5. Field-provide a plastic or rubber grommet in the knock-out open-
ing to prevent wire chaffing.
6. If using conduit, connect the conduit to the control box using field
provided fittings and industry best practice procedures.
7. Route the communications cable through the knock-out opening
or through the conduit to the inside of the control box.
8. Provide at least 3–4 inches of slack cable at the indoor unit.
9. Strip approximately 1/2" of insulation from each communications
cable conductor. Be sure not to damage the cable shield.
10. Remove the plastic safety shield from the IDU terminal block.
11. Insert the conductors under the terminal screws as shown in
Figure 19. Be sure to connect the 3A terminal on the IDU to the
IDU A terminal on the ODU, and the 4B terminal on the IDU to
the IDU B terminal on the ODU. Do not cross connect these
conductors.
12. If the communications cable is to be daisy chained to another
IDU, connect the communications cable for that IDU as well.
Connect the shields of the two cables together with a field-pro-
vided wire nut/cap as shown in Figure 21. Ensure the shields are
isolated from the chassis and terminals of the IDU.
13. Securely tighten the terminal screws to prevent the conductors
from coming loose from the terminal block.
14. Reinstall the plastic safety shield on the terminal block.
15. Secure the communications cable to the inside surface of the
24
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Figure 21: Communications Cable Connection at IDU
control box using a field provided nylon wire clamp.
16. Reinstall the cover of the control box.
17. Secure the communications cable in appropriate locations out-
side the indoor unit to prevent damage to the cable or injury to
maintenance personnel.
18. Reinstall the front panel (convertible) or side panel (ceiling sus-
pended) of the unit.
19. If you are connecting more than one IDU, route the daisy-
chained communications cable to the next IDU. If you are con-
necting directly to the ODU, route the cable to the ODU. Be sure
to allow at least 2" spacing between the communications cable
and power cables.
3(A) 4(B)