Originally Posted by Wet Willie
So in essence I can run 220 through my existing 10/2 with ground into a box (of some sort) and pull 220 from box to pump AND use just one conductor and ground from "box" to power 110?
No You can not do that.
It may work, but it will not meet code.
The ground conductor is not meant to be a current carrying conductor.
You can use it for 120 or 240, but not both.
Theory only works perfect in a vacuum.