Carrier 50CR - Manual (Page 16)

16
GROUND SCREW
(IN SPLICE BOX)
BLU
YEL
BLK
GROUND
LEAD
SINGLE-PHASE
CONNECTIONS
TO DISCONNECT
PER NEC
3-PHASE
CONNECTIONS
LEGEND
NEC – National Electrical Code
Field Wiring
Splice Connections
NOTE: Use copper wire only.
L1
L3
L2
C99057
Fig. 17 -- Line Power Connections
A05303
Fig. 18 -- Control Plate
The low--voltage circuit is fused by a board--mounted automotive
fuse placed in series with transformer SEC1 and R circuit. The C
circuit of transformer circuit is referenced to chassis ground through
a printed circuit run at SEC2 and metal control board mounting
eyelets. Check to be sure control board is mounted securely using
both factory--installed screws.
ACCESSORY INSTALLATION
A. Accessory Electric Heaters
Electric heaters may be installed in 50CR per instructions supplied
with electric heater package. See unit rating plate for
factory--approved electric heater kits.
NOTE: Units installed without electric heat should have a
factory--supplied sheet metal block--off plate installed over heater
opening. This reduces air leakage and formation of exterior
condensation.
B. Outdoor Air Thermistor (OAT)
A 2--screw terminal strip is provided for connection of an outdoor
temperature thermistor. This strip is marked OAT.
NOTE: While the installation of an outdoor temperature sensor
using the Infinity control board OAT terminals is optional, certain
Infinity features (ComfortHeat, electric heat lockout, auto humidity
control) will be lost.
OAT input is used to supply outdoor temperature data for system
level functions and for temperature display on User Interface.
Using two wires of field--supplied thermostat wire cable, wire one
lead of thermistor to one screw terminal and the other lead to
remaining screw terminal; there is no polarity to be observed. It is
strongly recommended that two wires be used to connect the
thermistor to eliminate noise interference in temperature reading. If
there are not two spare wires available in cable, one wire may be
used to connect thermistor to OAT screw terminal 1 and the other
lead of the thermistor can be wired to 24--vac COM (C) wire. OAT
screw terminal 1 is terminal located closest to the ABCD system
communications and is marked with a small number 1 next to the
terminal strip.
NOTE: Mis--wiring OAT inputs will not cause damage to either
Infinity control or thermistor. If the thermistor is wired incorrectly,
no reading will appear at User Interface. Re--wire thermistor
correctly for normal operation.
C. Humidifier Connections
The Infinity control board terminal marked HUM is provided for
low voltage (24--vac) control of a humidifier. No humidistat is
required as User Interface monitors indoor humidity. When
commanded to operate humidifier, the unit control will energize the
HUM output to turn humidifier on and de--energize HUM output to
turn humidifier off. Wire HUM and C terminals directly to
humidifier as shown in Fig. 14.
SPECIAL PROCEDURES FOR 208--V OPERATION
Be sure unit disconnect switch is open.
Disconnect the yellow primary lead from the transformer. See unit
wiring label. (See Fig. 15, 16 and 18)
Connect the yellow primary lead to the transformer terminal labeled
200--v.
50C
R