133
Step 5 — Make Electrical Connections
POWER SUPPLY
The electrical characteristics of the available power supply must
agree with the unit nameplate rating. Supply voltage must be with-
in the limits shown. See Tables 5-10 for electrical and configura-
tion data.
FIELD POWER CONNECTIONS (SEE FIG. 58)
All power wiring must comply with applicable local and national
codes. Install field-supplied, branch circuit fused disconnect(s) of
a type that can be locked off or open. Disconnect(s) must be locat-
ed within sight and readily accessible from the unit in compliance
with NEC Article 440-14 (U.S.A.). See Tables 5-10 for unit elec-
trical data.
Maximum wire size that the unit terminal block or non-fused dis-
connect will accept is 500 kcmil.
POWER WIRING
All power wiring must comply with applicable local and national
codes. Install field-supplied branch circuit fused disconnect per
NEC of a type that can be locked OFF or OPEN. Disconnect must
be within sight and readily accessible from the unit in compliance
with NEC Article 440-14. In the power box,
7
/
8
in. holes are pro-
vided for power entry. The holes will need to bee enlarged to ac-
cept the appropriate conduit. NEC also requires all conduits from
a conditioned space to the power box(es) be sealed to prevent air-
flow and moisture into the control box.
The 30XA units require 1 or 2 power supplies, depending on the
unit and circuit voltage. See Tables 5-8 for chiller electrical data.
Cooler and pump heaters, if factory-installed, are wired in the con-
trol circuit. Heaters on chillers with the optional control transform-
er will be capable of operation only when the main power supply
to the chiller is on. On chillers with separate control power, the
heaters are capable of operation whenever the control power is
supplied.
FIELD CONTROL POWER CONNECTIONS (SEE FIG. 58)
All units require 115-1-60 control circuit power, unless the control
transformer option is installed.
Terminals TB5-1 and TB5-2 are provided for field installation of a
chilled water (fluid) pump interlock (CWPI). The chilled water
(fluid) flow sensor (CWFS) is factory installed. These devices are
to be installed in series. Contacts must be rated for dry-circuit ap-
plications capable of handling a 24-vac at 50 mA load.
An accessory remote on-off switch can be wired into TB5-9 and
TB5-10. Contacts must be rated for dry-circuit applications capa-
ble of handling a 24-vac at 50 mA load.
Terminals 11 and 13 of TB5 are for control of the chilled water
pump 1 (PMP1) starter. Terminals 13 and 15 of TB5 are for con-
trol of the chilled water pump 2 (PMP2) starter.
CARRIER COMFORT NETWORK
®
COMMUNICATION
BUS WIRING (SEE FIG. 59)
The communication bus wiring is a shielded, 3-conductor cable
with drain wire and is field supplied and installed in the field.
The system elements are connected to the communication bus in a
daisy chain arrangement. The positive pin of each system element
communication connector must be wired to the positive pins of the
system elements on either side of it. This is also required for the
negative and signal ground pins of each system element. Wiring
connections for CCN (Carrier Comfort Network) should be made
at TB (terminal block) 3. Consult the CCN Contractor’s Manual
for further information. See Fig. 59.
NOTE: Conductors and drain wire must be 20 AWG (American
Wire Gage) minimum stranded, tinned copper. Individual conduc-
tors must be insulated with PVC, PVC/nylon, vinyl, Teflon
1
, or
polyethylene. An aluminum/polyester 100% foil shield and an
outer jacket of PVC, PVC/nylon, chrome vinyl, or Teflon with a
minimum operating temperature range of –4°F (–20°C) to 140°F
(60°C) is required. See Table 11 for a list of manufacturers that
produce CCN bus wiring that meet these requirements.
It is important when connecting to a CCN communication bus that
a color coding scheme be used for the entire network to simplify
the installation. It is recommended that red be used for the signal
positive, black for the signal negative, and white for the signal
ground. Use a similar scheme for cables containing different col-
ored wires. At each system element, the shields of its communica-
tion bus cables must be tied together. If the communication bus is
entirely within one building, the resulting continuous shield must
be connected to a ground at one point only. If the communication
bus cable exits from one building and enters another, the shields
must be connected to grounds at the lightning suppressor in each
building where the cable enters or exits the building (one point per
building only).
To connect the unit to the network:
1. Turn off power to the control box.
2. Cut the CCN wire and strip the ends of the red (+), white
(ground), and black (–) conductors. Substitute appropriate
colors for different colored cables.
3. Connect the red wire to (+) terminal on TB3 of the plug,
the white wire to COM terminal, and the black wire to the
(–) terminal.
WARNING
Electrical shock can cause personal injury and death. Shut off
all power to this equipment during installation. There may be
more than one disconnect switch. Tag all disconnect locations
to alert others not to restore power until work is completed.
IMPORTANT: The 30XA units have a factory-installed
option available for a non-fused disconnect for unit power
supply. If the unit is equipped with this option, all field
power wiring should be made to the non-fused disconnect
since no terminal blocks are supplied.
CAUTION
Do not use interlocks or other safety device contacts connected
between TB5-9 and TB5-10 as remote on-off. Connection of
safeties or other interlocks between these 2 terminals will re-
sult in an electrical bypass if the ENABLE-OFF-REMOTE
contact switch is in the ENABLE position. If remote on-off
unit control is required, a field-supplied relay must be installed
in the unit control box and wired as shown in Fig. 58. Failure
to wire the remote on-off as recommended may result in tube
freeze damage.
1. Teflon is a registered trademark of DuPont.
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