What type/size of wire should I use for running power from the 200Amp service panel at my house to a subpanel at my wood shop? The length of the run is 300 feet. I need 220V service at the shop and would like to run a 70 amp circuit. I would like the wire to be direct burial, +/- 2 ft deep. Voltage drop limit is 3%.
I was told that I could use #1 THHN copper wire in conduit OR aluminum wire rated for a 100 amp circuit, but was not given a gauge/type of aluminum wire.
What size wire should I use?