I'm building a small micro hydro system which should be well suited to a single plug and play GTI to start with. I'm building it to be expandable, if everything works out well. I have an unused 120/240v. line (2 hots, neutral, ground) available and would like to use it. I understand most small GTI's are stackable, but can they be stacked on opposite legs of a typical 120/240v. electrical system , utilizing a common neutral? Thanks, all .