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UNITS WITHOUT THRU-BASE CONNECTIONS (ELEC-
TRICAL CONNECTIONS)
1.
Install power wiring conduit through side panel open-
ings. Install conduit between disconnect and control box.
2.
Install power lines to terminal connections as shown in
Fig. 26 on page 16.
Voltage to compressor terminals during operation must be
within voltage range indicated on unit nameplate. On 3-phase
units, voltages between phases must be balanced within 2%
and the current within 10%. Use the formula shown in the ex-
ample below to determine the percent of voltage imbalance.
Operation on improper line voltage or excessive phase imbal-
ance constitutes abuse and may cause damage to electrical
components. Such operation would invalidate any applicable
Carrier warranty.
Example: Supply voltage is 230-3-60
A
B
C
AB = 224 v
BC = 231 v
AC = 226 v
MOTOR
(224 + 231 + 226)
Average Voltage
=
Determine maximum deviation from average voltage.
(AB) 227-224 = 3 v
(BC) 231-227 = 4 v
(AC) 227-226 = 1 v
Maximum deviation is 4 v.
Determine percent of voltage imbalance.
% Voltage Imbalance = 100x
This amount of phase imbalance is satisfactory as it is below the maximum allow-
able 2%.
IMPORTANT: If the supply voltage phase imbalance is more than 2%, contact
your local electric utility company immediately.
FIELD CONTROL WIRING
The 48KC unit requires an external temperature control
device. This device can be a thermostat (field-supplied) or a
PremierLink™ controller (available as factory-installed op-
tion or as field-installed accessory, for use on a Carrier Com-
fort Network
®
or as a stand alone control) or the RTU Open
Controller for Building Management Systems using non-
CCN protocols (RTU Open is available as a factory-installed
option only).
THERMOSTAT
Install a Carrier-approved accessory thermostat according
to installation instructions included with the accessory. For
complete economizer function, select a two-stage cooling
thermostat. Locate the thermostat accessory on a solid wall in
the conditioned space to sense average temperature in accor-
dance with the thermostat installation instructions. Typical
low-voltage connections are shown in Fig. 37.
681
=
=
227
3
3
4
=
1.78%
227
Typical
Thermostat
Connections
C
G
W2
W1
O/B/Y2
(Note 1)
(Note 2)
Y1
R
Note 1: Typical multi-function marking. Follow manufacturer's configuration
Instructions to select Y2.
Note 2: Y2 to Y2 connection required on single-stage cooling units when
integrated economizer function is desired.
Field Wiring
Fig. 37 — Low-Voltage Thermostat Connections
If the thermostat contains a logic circuit requiring 24v
power, use a thermostat cable or equivalent single leads of
different colors with minimum of seven leads. If the thermo-
stat does not require a 24v source (no "C" connection re-
quired), use a thermostat cable or equivalent with minimum
of six leads. Check the thermostat installation instructions for
additional features which might require additional conductors
in the cable.
For wire runs up to 50 ft. (15 m), use no. 18 AWG (Amer-
ican Wire Gage) insulated wire [95°F (35°C) minimum]. For
50 to 75 ft. (15 to 23 m), use no. 16 AWG insulated wire
[95°F (35°C) minimum]. For over 75 ft. (23 m), use no. 14
AWG insulated wire [95°F (35°C) minimum]. Wire sizes
larger than no. 18 AWG cannot be directly connected to the
thermostat and will require a junction box and splice at the
thermostat.
Thermostat Wiring, Units Without Thru-Base Connection
Kit
Pass the thermostat control wires through the hole provid-
ed in the corner post; then feed the wires through the raceway
built into the corner post to the control box. Pull the wires
over to the terminal strip on the upper-left corner of the Cen-
tral Terminal Board (CTB). See Fig. 38.
NOTE: If thru-the-bottom connections accessory is used, refer to
the accessory installation instructions for information on routing
power and control wiring.
21
Central
Terminal
Board
X
C
T
H
G
E
R
W2
M
O
W1
S
T
Y2
A
T
Y1
R
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