29
SYSTEM OPERATION
NOTE: If supply voltage is 208V, lead on primary of
transformer(s) must be moved from the 230V to the 208V
tap. Refer to wiring diagram on unit for details.
Main power wiring should be sized for the minimum circuit
ampacity shown on the unit’s dataplate. Size wires in
accordance with the ampacity tables in Article 310 of the
National Electrical Code. If long wires are required, it may
be necessary to increase the wire size to prevent excessive
voltage drop. Wires should be sized for a maximum of 3%
voltage drop.
CAUTION
To avoid risk of property damage, personal injury or
fire, use only copper conductors.
CAUTION
To prevent improper and dangerous operation due to
wiring errors, label all wires prior to disconnection
when servicing controls. Verify proper operation after
servicing.
NOTE: A weather-tight disconnect switch, properly sized
for the unit total load, must be field or factory installed.
An external field supplied disconnect may be mounted on
the exterior panel.
Ensure the data plate is not covered by the field-supplied
disconnect switch.
•
Some disconnect switches are not fused. Protect the
power leads at the point of distribution in accordance
with the unit data plate.
•
The unit must be electrically grounded in accordance
with local codes or, in the absence of local codes, with
the latest edition of the National Electrical Code ANSI/
NFPA 70, and/or the Canadian Electrical Code, CSA
C22.1, Part 1. A ground lug is provided for this purpose.
Do not use the ground lug for connecting a neutral
conductor.
•
Connect power wiring to the electrical power block
located within the main control box.
Gas Control box
note: depending on the options installed, the location of
the components may vary in some models
WARNING
Operating the unit with an improper line voltage or
with excessive phase unbalance can cause damage to or
failure of the unit. Such damage or failure is not covered
under the unit’s warranty.
Areas Without Convenience Outlet
It is recommended that an independent 115V power
source be brought to the vicinity of the roof top unit for
portable lights and tools used by the service mechanic.
NOTE: Refer to local codes for requirements. These
outlets can also be factory installed.
Units installed on Roof Tops
Main power and low voltage wiring may enter the unit
through the condenser end of unit or through the roof
curb. Install conduit connectors at the desired entrance
locations. External connectors must be weatherproof.
All holes in the unit base must be sealed (including those
around conduit nuts) to prevent water leakage into
building. All required conduit and fittings are to be field
supplied.
Supply voltage to roof top unit must not vary by more than
10% of the value indicated on the unit data plate. Phase
voltage unbalance must not exceed 2%. Contact your
local power company for correction of improper voltage or
phase unbalance.
Summary of Contents for DRG0361DL00001S
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