I NEVER use UF cable any more! I always bury the grey PVC pipe. Use a minimum of 3/4". You can pull regular NM through it, though I prefer THHN. The cost of pipe, and wire is often less than the UF cable. Remember that a piece of tape can change the color of a wire. Bury your pipe, vacumm a "rat" through it, connect to a pull rope to string on "rat". Pull rope back through pipe, and then attach the wires to be pulled. The string on the "rat" will tell you how long to get wire. Be sure to add at least ten feet for connections at each end. If you should ever have to add another circuit, or change conductors, you already have a hole under the ground.