edison sault's only generating station was the saint marys falls hydropower plant located on the st. marys river in downtown sault ste. marie. during the night when demand was low, the company was able to sell power from this small dam to larger companies such as upper peninsula power company and consumers energy. edison sault's transmission system voltage is 138,000 volts. the subtransmission system voltage is 69,000 volts. the distribution system voltage is 13,200 volts.