7
See the unit rating plate for minimum circuit ampacity
and maximum overcurrent protection limits.
• Provide power supply for the unit in accordance with the
unit wiring diagram, and the unit rating plate. Connect
the line-voltage leads to the terminals on the contactor
inside the control compartment.
• Use only copper wire for the line voltage power supply
to this unit. Use proper code agency listed conduit and
a conduit connector for connecting the supply wires to
the unit. Use of rain tight conduit is recommended.
• Optional equipment requiring connection to the power or
control circuits must be wired in strict accordance of all
applicable national and local codes and the instructions
provided with the equipment.
grounding
Warning:
the unit cabinet must have an uninterrupted or
unbroken electrical ground to minimize personal
injury if an electrical fault should occur. do not
use gas piping as an electrical ground!
This unit must be electrically grounded in accordance
with all applicable state, national, or local codes that take
precedence. Use the grounding lug provided in the control
box for grounding the unit.
thermostat connections
• Thermostat connections should be made in accordance
with the instructions supplied with the thermostat and
the indoor equipment.
• Single stage thermostats are recommended for use
with this equipment depending on optional accessories
installed with the unit. Select a thermostat that operates
in conjunction with the installed accessories.
• The outdoor unit is designed to operate from a 24 VAC
Class II control circuit. The control circuit wiring must
comply with applicable local codes having jurisdiction.
• The low voltage wires must be properly connected to
the units low voltage terminal block. Recommended
wire gauge and wire lengths for typical thermostat
connections are listed in Table 1 (page 8)
• The thermostat should be mounted about 5 feet (1.52m)
above the floor on an inside wall. DO NOT install the
thermostat on an outside wall or any other location
where its operation may be adversely affected by radiant
heat from fireplaces, sunlight, or lighting fixtures, and
convective heat from warm air registers or electrical
appliances. Refer to the thermostat manufacturer’s
instruction sheet for detailed mounting and installation
information.
example
:
AB = 236V
BC = 240V
AC = 237V
3. Determine the maximum deviation:
4. Determine percent of
voltage imbalance by
using the results from
steps 2 & 3 in the following
equation.
max voltage deviation
from average voltage
= 100 x
average voltage
% Voltage Imbalance
2
238
100 x
= 0.84%
Example:
2. Determine the average voltage in the power supply.
Unbalanced 3-phase Supply Voltage
Voltage unbalance occurs when the voltages of all phases
of a 3-phase power supply are no longer equal. This
unbalance reduces motor efficiency and performance.
Some underlying causes of voltage unbalance may
include: Lack of symmetry in transmission lines, large
single-phase loads, and unbalanced or overloaded
transformers. A motor should never be operated when a
phase imbalance in supply is greater than 2%.
Perform the following steps to determine the percentage
of voltage imbalance:
1. Measure the line voltages
of your 3 phase power
supply where it enters the
building and at a location
that will only be dedicated
to the unit installation (at
the units circuit protection
or disconnect).
In this example, the measured line voltages were
236, 240, and 237. The average would be 228 volts
(236 + 240 + 237 = 713 / 3 = 238).
The amount of phase imbalance (0.84%) is satisfactory
since the amount is lower than the maximum allowable
2%. Please contact your local electric utility company if
your voltage imbalance is more than 2%.
example:
From the values given in step 1, the BC voltage
(240V) is the greatest difference in value from
the average:
240 - 238 = 2
238 - 236 = 2
238 - 237 = 1
Highest Value
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