600V VFD and conductor question

[Deadfrog]

My Electrical Engineer is on holidays and I have some questions regarding to a project I am working that are going to sound pretty dumb but I need to figure this out ASAP. I'm an engineer in training and am confused.

First off, if you spec a 3 conductor XLPE wire, is it assumed that it is 3 conductors + ground, or is this spec'd as a 4 conductor wire?


I am feeding power from a 600V splitter to a VFD with _? conductor #12 AWG in 1/2" EMT conduit

the connector between the VFD and the motor is to be a _? conductor #12 AWG XLPE. The motor is 7.5hp in 1/2" EMT conduit

Is this sized correctly? Could someone fill in the "_?"

Thanks alot for your help as I am lacking confidence.

 

[Deadfrog]

just to clarify the voltage drop is negligible (short runs of wire)

 

[petersonra]

First off, if you spec a 3 conductor XLPE wire, is it assumed that it is 3 conductors + ground, or is this spec'd as a 4 conductor wire?

I would not call anything with 4 conductors a wire. A cord or a cable. Normally i would refer to such a thing as 3/G, or 3 conductors with ground.

I am feeding power from a 600V splitter to a VFD with _? conductor #12 AWG in 1/2" EMT conduit

the connector between the VFD and the motor is to be a _? conductor #12 AWG XLPE. The motor is 7.5hp in 1/2" EMT conduit

if you are using EMT, no ground is required, so it could be 3C (3 conductor) or 3/G (3 conductor with ground).

Is this sized correctly? Could someone fill in the "_?"

A 7.5 HP motor @ 575V or 480V/3 phase would require a minimum of #14. A 7.5HP motor at 230V/HP would require at least #10.

There may be other issues that are not apparent. It might be best for you to get someone more familiar with what is going on to help you. One issue might be whether you can get the cable into a 1/2" piece of EMT. XLPE cables that I have seen are downright huge. I thought they were only normally used on MV applications.

 

[Deadfrog]

Thanks Bob,

I looked into it and you are right, that XLPE is much bigger, I am going to use #14AWG XLPE in 1-1/4" EMT - seems my wiring/conduit calculator has some bugs in it. Thanks for the catch. much appreciated.