I had a similar problem. My shop is located 150' from the house and had an underground electric cable between the two buildings. Lost power and electricians determined break in cable between the two buildings. Solution, find the break or run a new cable. Called my rural electric provider and they sent a "electric sniffer" out to check the line. Told me to dig in a certain spot 36" down and I would find the break. They were right on the spot and depth. You may want to give your utility provider a call.