Units Without Thru-Base Connections; Field Control Wiring - Carrier Legacy 548J07 Installation Instructions Manual

BRASS FITTING FOR 3 TO 6 TON UNITS.
Fig. 33 — Thru-Base Connection Fittings (Units Built On
or Prior to 4/14/19)
HIGH VOLTAGE
CONDUIT
CONNECTOR
AUXILIARY
POWER
SUPPLY
(OPTIONAL)
Fig. 34 — Thru-Base Connection Fittings (Units Built On
or After 4/15/19)
Check tightness of connector lock nuts before connecting elec-
trical conduits.
Field-supplied and field-installed liquid tight conduit connec-
tors and conduit may be attached to the connectors on the base-
pan. Pull correctly rated high voltage and low voltage through
appropriate conduits. Connect the power conduit to the internal
disconnect (if unit is so equipped) or to the external disconnect
(through unit side panel). A hole must be field cut in the main
control box bottom on the left side so the 24-v control connec-
tions can be made. Connect control power conduit to the unit
control box at this hole.

UNITS WITHOUT THRU-BASE CONNECTIONS

1. Install power wiring conduit through side panel openings.
Install conduit between disconnect and control box.
2. Install power lines to terminal connections as shown in
Fig. 23.
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 below to deter-
mine the percent of voltage imbalance. Operation on improper
line voltage or excessive phase imbalance constitutes abuse
and may cause damage to electrical components. Such opera-
tion would invalidate any applicable Bryant warranty.
% Voltage Imbalance:
max voltage deviation from average voltage
= 100 x
LOW VOLTAGE
CONDUIT
CONNECTOR
HIGH VOLTAGE
CONDUIT
CONNECTOR
BRASS FITTING FOR
3 TO 6 TON UNITS
LOW VOLTAGE
CONDUIT
CONNECTOR
average voltage
Example: Supply voltage is 230-3-60
A B C
MOTOR
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 maxi-
mum allowable 2%.
IMPORTANT: If the supply voltage phase imbalance is more
than 2%, contact your local electric utility company
immediately.
NOTE: Check all factory and field electrical connections for
tightness.

FIELD CONTROL WIRING

The 548J unit requires an external temperature control device.
This device can be a thermostat (field-supplied) or the RTU
Open Controller for Building Management Systems using non-
CCN protocols (RTU Open controller is available as a factory-
installed option only).
THERMOSTAT
Select a Bryant-approved accessory thermostat. When electric
heat is installed in the 548J unit, the thermostat must be capa-
ble of energizing the G terminal (to energize the Indoor Fan
Contactor) whenever there is a space call for heat (energizing
the W1 terminal). The accessory thermostats listed on the unit
price pages can provide this signal but they are not configured
to enable this signal as shipped.
Typical
Thermostat
Connections
C
G
W2
(Note 2)
W1
O/B/Y2
(Note 1)
Y1
R
Note 1: Typical multi-function marking. Follow manufacturer's configuration
instructions to select Y2. Do not configure for O output.
Note 2: W2 connection not required on units without electric heating.
Field Wiring
Fig. 35 — Low-Voltage Connections
Install the accessory thermostat according to installation in-
structions included with the accessory.
22
AB = 224 v
BC = 231 v
AC = 226 v
(224 + 231 + 226) 681
= =
3 3
4
= 1.78%
227
Central
Terminal
Board
X
C
T
H
G
E
R
W2
M
O
W1
S
T
Y2
A
T
Y1
R
227