In article , Wayne says...

So the VFD is only supposed to be grounded by conduit and nothing else.

This also implies that the lathe is only grounded through the conduit
and nothing else.

I shouldn't also have a green ground wire run through the conduit from the
service
to the VFD and lathe in addition to the conduit.

To make it clear, you most likely would not run into any
ground loop issues by running a green wire all the way
back to the service entrance.

I would personally do this if it were my installation.

Many codes allow the conduit itself to be used in place
of the green wire as a grounding conductor. I don't think
any codes prohibit putting a green wire in the pipe as well.

This means you would have to run that wire back from the
sub-panel to the service entrance, as it does not exist there
at the moment.

Jim


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