I have built a small building on the back of my land that I plan on wiring myself. The electric co-op set a pole and meter about forty feet away, and I plan on going underground service to my panel in the building. Main disconnect on pole under meter. A friend tells me under 2008 code I must run four-wire cable entrance instead of three. Is this correct?
Even if you are not under the 2008 NEC yet, it is best to run four wires from the disconnect to the subpanel in the outbuilding. That would be two hots, a neutral, and a ground. You will need to isolate the neutral bar from the panel enclosure and add a ground bar that is bonded to the enclosure. You will also need to install ground rods at the meter pole AND at the outbuilding.