I have burried NMDU # 10/2 @ 12" and protected it with 3/4" PT wood. The run starts @ my 200 amp panel and runs through the basement. It will be two seperate runs. One will be on a 30 amp breaker to a sub panel in the garage to feed recepticles and possibly a small welder. The second run is long in two sections. 1st to a junction box on a pool house about 100 ft. away. From there it runs also underground about 200 ft. (total 300 ft. to the end).The idea was to feed lights (for a wood/storage shed) and outdoor recepticles. How much line loss will occur and at what rating should the breaker be. I thinking that I can get away with 20 amps because of the losses?