Investigators believe an electrical failure is to blame for Tuesday’s house fire in Lewiston’s Normal Hill area.  Fire crews responded to the blaze at 931 11^th Avenue just before 9:30 AM and spent an hour knocking down flames that caused an estimated $100,000 in damage to the home’s basement, first, and second floors.  No one was at home at the time of the fire, which prompted closure of several blocks in the area for a couple of hours.