Lord Jim, In Electrical Inspection of Existing Dwellings by Douglas H., et al, it says "The code allows a 3-wire feed to the seperate building, using the neutral as a grounding conductor, ONLY when there are no other continuous conductive paths between the buildings. A conductive path could be metal water piping, a concrete sidewalk, a metal fence, or even a telephone line. In practical terms then, a 4-wire feed is needed almost every time a subpanel is installed in a second building." Capitalization and italics exactly as the text shows it. What do you think about a PVC water line? Is the water itself a potential conductor, or is a metal pipe the only significant concern? Brian G.