Portions snipped out...

There are two grounds: the power ground (which should be white) and the
safety ground (which should be green or bare). In a properly installed
conduit system, the conduit may also serve as the safety ground. The two
should be tied together in the Main box, but nowhere else. The ground
bus
in the Main should also have a wire to a ground stake.


Should you run a "backup" safety ground through the conduit, it should
connect to the boxes (sub panel to VFD box) and to the frame of the
lathe.
The purpose of the safety ground is to trip the breaker if something
shorts.
Other than that, the safety ground should NEVER conduct power.


This is the part that confuses me.
....The two are tied together in the main box, nowhere else...
But it is ok to ground through the conduit and a ground (green) wire?
Am I not tying it together somewhere else?
Or maybe that refers to adding something like another ground rod
by the lathe.

Wayne D.