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Motor conductor minimum size

Motor conductor minimum size

Motor conductor minimum size

(OP)
I have an existing 500hp motor drivin through a VFD.  There are parallel 500MCM cables.  There is also a bypass contactor around the VFD.  We plan to upgrade to 600HP motor.  I can limit the output of the drive to 600HP.  If I use the FLA of the new motor 680 x 1.25 then I need a cable good for 850 amps.  I am feeding the drive and by-pass contactor from a LVCB with an 800Amp trip unit set at 800Amps.  I know that the 125% sizing is based on service factor and power factor,etc. Does the NEC allow me to use smaller than a 125% sized conductor if my overcurrent protection is set below that?

RE: Motor conductor minimum size

No.

David Castor
www.cvoes.com

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