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ELECTRICAL GUIDELINES
WARNING: Installation must comply with specifications from National Electrical Codes and standards (NEC,
VDE, BSI, etc.) regarding wire types, conductor sizes, branch circuit protection, and disconnecting devices.
WARNING: To avoid a possible shock hazard and/or nuisance tripping caused by induced voltages, unused
wires in the conduit must be grounded at both ends. For the same reason, VFD output wires should not
share a conduit with another VFDs output leads, or other power circuits (lighting, motors, etc.).
CAUTION: MC or “Metal clad” cable cannot be used for controller output/motor leads. Both stranded and
solid core varieties must be avoided. Do not use solid core cable of any size or insulation class for motor
wiring. Use of such types of cabling may result in nuisance tripping or premature equipment failure.
Cable types
A variety of cable types are acceptable for variable frequency drive installations. For many installations, unshielded
cable is adequate if it can be separated from sensitive circuits. In all cases, parallel runs of control and motor
cabling should be avoided when unshielded cable is used. Do not use cable with an insulation thickness of less
than 15 mils.
• UL installations in 50º C ambient must use 600 V, 75º C or 90º C wire.
• UL installations in 40º C ambient should use 600 V, 75º C or 90º C wire.
Acceptable unshielded types
THHN, THNW, or similar wire is acceptable for drive installations in dry environments if adequate free air space
and/or conduit fill rate limits are provided. Do not use THHN or similarly coated wire in wet areas. Any wire chosen
must have a minimum insulation thickness of 15 mils and should not have large variations in insulation concentricity.
Acceptable shielded types
The drain conductor included with shielded cables must be connected to both the motor frame and the PE/Ground
terminal of the Variable Frequency Drive.
Location Rating / Type Description
Standard
(Option 1)
600 V, 75º
C or 90º C (167º F or 194º F)
RHH/RHW-2
• Four tinned conductors with XLPE insulation
• Foil shield and tinned copper drain wire with 85% braid
coverage
• PVC Jacket
Belden 29501-29507 or equivalent
Standard
(Option 2)
Tray rated 600 V, 75º
C or 90º C (167º F or
194º F) RHH/RHW-2
• Three tinned copper conductors with XLPE insulation
• 5 mil single helical copper tape (25% overlap minimum)
with three bare copper grounds in contact with shield
• PVC Jacket
Shawflex 2ACD/3ACD or equivalent
Class I & II
Division I & II
Tray rated 600 V, 75º
C or 90º C (167º F or
194º F) RHH/RHW-2
• Three bare copper conductors with XLPE insulation
with impervious corrugated continuously welded
aluminum armor
• Black sunlight resistant PVC jacket overall
• Three copper grounds on #10 AWG and smaller
Output disconnects
A device, such as a contactor, that routinely disconnects and reapplies output power to the motor for the purpose
of starting and stopping the motor cannot be used.
Recommended wire size
A minimum of 14 AWG is acceptable for motor leads. Power feeders to controllers must be governed by the fuse
size included with the VFD and/or required circuit breaker.
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