I have a small house in the country with a metal barn about 50 ft. away. I want to run a feeder from the main panel of the house to the barn. I plan to do the following: 1. Come off a spare 30 Amp 220V break that was orginally for a water well pump we ended up not needing. 2. Run feeder through PVC, 18" underground with the warning ribbon 12" above the conduit. 3. Install a subpanel on the back of the barn. 4. Install a new ground rod at the new subpanel at the barn. 5. The subpanel will have two 20 Amp breaks for 110V circuits for now. My question is, can I run a 10/2 cable for the feeder or does it have to be a 10/3 cable? My understanding is that a ground wire is not to be used between the two structures which is why I will install a new ground rod at the new subpanel. Just wasn't sure if I can use the bare copper conductor in the 10/2 as the neutral for the 220V circuit.