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Step 6 — Make Electrical Connections
FIELD POWER SUPPLY — Unit is factory wired for volt-
age shown on nameplate.
When installing units, provide a disconnect, per NEC
(National Electrical Code) requirements, of adequate size
(Table 2).
All field wiring must comply with NEC and local
requirements.
Route power lines through control box access panel or unit
basepan (Fig. 4 and 5) to connections as shown on unit wiring
diagram and Fig. 11.
Operating voltage to compressor must be within voltage
range indicated on unit nameplate. On 3-phase units, voltages
between phases must be balanced within 2% and the current
must be balanced within 10%.
Use the following formula to determine the percentage of
voltage imbalance.
Percentage of Voltage Imbalance
EXAMPLE: Supply voltage is 460-3-60.
AB = 452 v
BC = 464 v
AC = 455 v
Determine maximum deviation from average voltage:
(AB) 457 – 452 = 5 v
(BC) 464 – 457 = 7 v
(AC) 457 – 455 = 2 v
Maximum deviation is 7 v.
Determine percent voltage imbalance:
= 1.53%
This amount of phase imbalance is satisfactory as it is be-
low the maximum allowable 2%.
Unit failure as a result of operation on improper line voltage
or excessive phase imbalance constitutes abuse and may cause
damage to electrical components.
FIELD CONTROL WIRING — Install a Carrier-approved
accessory thermostat assembly according to the installation in-
structions included with the accessory. Locate thermostat as-
sembly on a solid wall in the conditioned space to sense aver-
age temperature.
Route thermostat cable or equivalent single leads of no. 18
AWG (American Wire Gage) colored wire from subbase termi-
nals through conduit in unit to low-voltage connections as
shown on unit label wiring diagram and in Fig. 12.
NOTE: For wire runs up to 50 ft, use no. 18 AWG insulated
wire (35 C minimum). For 50 to 75 ft, use no. 16 AWG insu-
lated wire (35 C minimum). For over 75 ft, use no. 14 AWG
insulated wire (35 C minimum). All wire larger than no. 18
AWG cannot be directly connected to the thermostat and will
require a junction box and splice at the thermostat.
Set heat anticipator settings as indicated in Table 3. Settings
may be changed slightly to provide a greater degree of comfort
for a particular installation.
The correct power phasing is critical in the operation of the
scroll compressors. An incorrect phasing will cause the
compressor to rotate in the wrong direction. This may lead
to premature compressor failure.
= 100 x
max voltage deviation from average voltage
average voltage
Average Voltage =
455 + 464 + 455
3
=
1371
3
= 457
Percentage of Voltage Imbalance = 100 x
7
457
IMPORTANT: If the supply voltage phase imbalance is
more than 2%, contact your local electric utility com-
pany immediately.
Fig. 10 — Make Electrical Connections
TB1 MAXIMUM WIRE SIZE
LEGEND
Fig. 11 — Field Power Wiring Connections
UNIT
50TJ
VOLTAGE
208/230,380 460 575
All
350 kcmil 2/0 2/0
EQUIP —
Equipment
GND —
Ground
kcmil —
Thousand Circular Mils
NEC —
National Electrical Code
TB —
Terminal Block
RH
RC
Y1 Y2
W1
W2
GC
X
L
X
C
G
W2
W1Y2
Y1
R
REMOVABLE JUMPER
RED
BLU
PNK
ORN
VIO
BLK
BRN
WHT
THERMOSTAT ASSEMBLY
UNIT LOW-VOLTAGE CONNECTIONS
Fig. 12 — Field Control Thermostat Wiring