Carrier 542E - Manual (Page 6)

HIGH-VOLTAGE
PIGTAIL LEADS
-FIELD SPLICE
BLK
BLK ^
RED
1
/ r
/ r-Tok F1ELD-SUPPL1E(
POWER
SUPPLY
3-PHASE
UNITS ONLY SWITCH
A79244
Figure 9—Field High-Voltage Connections
IV. ELECTRICAL CONNECTIONS
WARNING: The unit cabinet must have an uninterruptedj
unbroken, electrical ground to minimize the possibility of
personal injury if an electrical fault should occur. This
ground may consist of electrical wire connected to the unit
ground lug in the control compartment, or conduit approved
for electrical ground when installed in accordance with the
National Electrical Code and local electrical codes. A failure
to follow this warning could result in the installer being lia­
ble for the personal injury of others.
CAUTION: A failure to follow these precautions could result
in damage to the unit being installed;
1. Make all electrical connections in accordance with the
National Electrical Code and local electrical codes
governing such wiring.
2. Use only copper conductor for connections between the
field-supplied electrical disconnect switch and the unit.
DO NOT USE ALUMINUM WIRE.
3. Ensure that high-voltage power to the unit is within the
operating voltage range indicated on the unit rating
plate. On 3-phase units, ensure that phases are balanced
within 2%. Consult the local power company for correc­
tion of improper voltage and/or phase balance.
4. Insulate low-voltage wires for the highest voltage con­
tained within the conduit when low-voltage control
wires are run in the same conduit as high-voltage wires.
5. Do not damage internal components when drilling thru
any panel to mount electrical hardware, conduit, etc.
6. Make sure that the service conductors used between the
electrical service panel and the field-supplied electrical
disconnect switch do not have a current capacity less
than the copper wire specified, and do not create a total
voltage drop in excess of 2% of the rated voltage of the
unit.
NOTE: When using aluminum conductor from the electrical
service panel (power supply) to the disconnect switch (where
local codes permit the use of aluminum wire), make the con­
nections in accordance with the National Electrical Code.
Prepare all aluminum wire immediately before installation
by “brush-scratching” the wire, then coating the wire with a
corrosion inhibitor (such as Pentrox A). Be sure that the
entire connection is completely covered to prevent an
electrochemical reaction that will cause the connection to
fail very quickly. Do not reduce the effective size of the wire
by cutting off strands to fit the wire into a connector. Always
use properly sized connectors.
A. High-Voltage Connections
The unit must have a separate electrical service with a field-
supplied, waterproof fused disconnect switch at, or within
sight of, the unit. Refer to the imit rating plate for max­
imum fuse size and minimum circuit amps (ampacity) for
wire sizing. Tables II and III show recommended wire sizes
and lengths based on rating plate data.
The field-supplied disconnect switch box may be mounted on
the unit over the high-voltage inlet hole in the control cor­
ner panel. See Figure 3 or 4. Be sure that the disconnect box
does not interfere with the removal of the blower access
panel.
Proceed as follows to complete the high-voltage connections
to the unit:
1. Connect ground lead to chassis-ground connection when
using a separate ground wire.
2. Connect high-voltage power leads to unit high-voltage
pigtail leads. Single-phase units have two black pigtail
leads. Three-phase units have two black and one red pig­
tail lead. See Figure 8, Figure 9, and unit wiring label.
Use a suitable wire splice connector or wirenut to make
each high-voltage connection. Tape each completed con­
nection.
B. Special Procedures for 208-V Operation
WARNING: Make sure that the power supply to the unit is
switched OFF before making any wiring changes.
When operating sizes 018 thru 036 single-phase units or
sizes 036 thru 060 208/230-volt three-phase units at 208
volts, disconnect the red transformer-primary lead from the
contactor. See the unit wiring label and Figure 8. Remove
the tape and cover from the terminal on the end of the blue
transformer-primary lead. Save the cover. Connect the blue
lead to the contactor terminal from which the red lead was
disconnected.
Using the cover removed from the blue lead, insulate the
loose terminal on the red lead. Wrap the cover with electri­
cal tape so that the metal terminal can not be seen.
NOTE: If a blower motor speed is changed, insulate all
unused motor leads following the same procedures described
for the transformer leads.
C. Low-Voltage Connections
The recommended heat pump room thermostats for heat
pump operation with or without supplemental electric
heaters are P/N 34427DP115 (subbase included) for auto­
matic system changeover and P/N 34427DP118 (subbase
included) for manual system changeover. These thermostats
have an emergency heat (EM. HT.) switch and red indicator
light.
Heat pump room thermostat P/N 34427DP87 (subbase
included) can be used for heat pump operation without sup­
plemental electric heaters. This thermostat provides for
manual system changeover and does not have an emergency
heat switch.
NOTE: When a supplemental electric heat package is being
used, see the Installation Instructions packaged with the
heater to complete system low-voltage wiring connections.
Locate the room thermostat on an inside wall in the space to
be conditioned where it will not be subjected to either a cool­
ing or heating source, or direct exposure to sunlight. Mount
the thermostat 4 to 5 feet above the floor.
Use No. 18 AWG color-coded, insulated (35°C minimum)
wires to make the low-voltage connections between the ther­
mostat and the unit. If the thermostat is located more than
100 feet from the unit (as measured along the low-voltage
wires), use No. 16 AWG color-coded, insulated (35°C
minimum) wires.
A grommeted, low-voltage inlet hole is located in the panel
adjacent to the control access panel. See Figure 3 or 4. Run
the low-voltage leads from the thermostat, thru the inlet
hole, and to the low-voltage terminal board. See Figure 8.
Connect the low-voltage thermostat leads to the terminal
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