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Electrical Installation Guidelines
Hazardous voltage present, work should be performed by a qualified electrician.
Disconnect all power sources before opening any electrical access panels. Personal protection equipment may be
required for entry. After disconnecting power, wait 5 minutes for VFD capacitors to discharge before starting work
inside the control box.
When servicing the unit, motor or VFD may be hot enough to cause pain or injury. Allow to cool before servicing.
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All wiring outside the control box is by others.
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Use wiring that has a temperature rating of at least 90°C.
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Any wiring deviations may result in personal injury or property damage. Manufacturer is not responsible for any
damage to, or failure of the unit caused by incorrect field wiring.
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Use a dedicated ground wire for input power, motor power and control wiring. Do not ground one VFD to another
in a "daisy chain" fashion.
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Keep the grounding wire connections as short as possible.
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Improper grounding may cause premature motor failure.
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All control boxes and VG-BLDC motor assemblies have dedicated disconnect switches.
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Incoming power should always be wired to the disconnect.
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Use appropriate sized wiring and conduit per NEC or local code authority.
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If fan motor is not thermally protected, remote overload protection must be installed having adequate rating as
to voltage, frequency, horsepower, and full load current per phase. Where connected to a circuit protected by
fuses, use time delay fuses.
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Use Class J type fuse or equivalent. VFDs may require fast acting fuses, refer to owner's manual. Install in
compliance with the National Electrical Code (NEC) and local and state building codes.
The purpose of this requirement is to protect electrical components from catastrophic failure and achieve the Short
Circuit Current Rating labeled on the fan.
VFDs may require fast acting fuses because fuse clearing times vary depending on fuse type. Refer to VFD owner's
manual and verify installation compliance.
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Supply conductors and short circuit protection must be sized appropriately, refer to fan label for Minimum Circuit
Ampacity (MCA) and Maximum Overcurrent Protection (MOP)
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For branch circuits containing a VFD for motor control, evaluated to UL 61800-5-1, and the VFD is listed as
suitable for output motor conductor protection, the rating and type of protection shall be permitted to be
determined by the VFD's rated input current rather than motor full load current.
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Refer to specific manuals on individual components (VFD, controls, motor, etc.)
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Keep control wires as short as possible [100 ft. (30.5 m) or less] and separate from high power cables to
minimize interference.
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XHHW motor wire is recommended for ship loose VFD applications when the fan is installed in distances greater
than 25 feet from the control box.
®
DANGER
WARNING
NOTE
USF Motors and Controls
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