I am having a barn built about 70-80 feet from my house. I have 400 amp electrical service at my house. What is the most efficient way to provide service to the barn? I will have a power tool workshop and may in the future have a welder. Thanks in advance!
I'm going through the same thing for a shed.
The best thing to do is have an electrician come out, inspect your panel and tell you what you can and can't do. A nice guy will also give you a sketch so that you can DIY the disconnect box, conduit, ground rod and subpanel. You can even pull the wires yourself and wire from the subpanel to your boxes.
I'm leaving the final connections to a pro.
Most places require inspections at certain stages, make sure to have them done or there may be problems when It's time to sell the place.