I just finished a 24' X 30' pole building and want to install a 100 amp panel. The main panel in the house is 200 amp service about 130 feet away. What size / type copper wire should I use and what size underground conduit should I use? How deep should the conduit be buried. Thanks PTC

#2 THHN/THWN or XHHW Copper, or #1 XHHW aluminum will produce just under 2 % voltage drop for a fully loaded to 80% for a 100 amp feeder.

In either case I would use no smaller than 2" PVC, due to the length, and allow for expansion.

If this is residential, 18 deep, otherwise 24 " deep.

Be sure to have a #6 equipment grounding conductor, and keep the neutral insulated at the subpanel.