Carrier A180218C, Installation Instructions Manual

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11
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal injury
or death.
Before installing, modifying, or servicing system, the main
electrical disconnect switch must be in the OFF position. There
may be more than one disconnect switch. Lock out and tag
switch with a suitable warning label.
!
WARNING
4.4.1. Shielded Wire and Communication Bus Configura-
tion
If the thermostat wiring will be located near or in parallel with high voltage wiring,
radio, TV or Ethernet wiring, then four conductor, twisted--pair, shielded cable can
be used to reduce or eliminate potential interference. The shield wire should be
connected to the C terminal, or ground, at the indoor unit. The shield wire should
NOT be connected to any terminal at the Infinity System Control. Connecting the
shield to ground at both ends can cause current loops in the shield, reducing shield
effectiveness.
Connect one pair of the two--pair (minimum) cable to the A and B communication
terminals, and another pair to the C and D terminals at both ends of the cable. The
shield wire should ONLY be connected at the indoor equipment ground or C
terminal. Note that some outdoor units only require the A and B connections. See
the outdoor unit installation instructions for more information.