Exterior lighting is being blamed for a fire that heavily damaged a two-story house Saturday afternoon on Valley Glenn Drive.The house, owned by John A. Ellenburg, suffered considerable structural damage, especially to its rear section, from the Saturday afternoon blaze.The fire was reported by neighbors as flames became visible behind the residence. No one was home at the time of the fire.According to sheriff’s deputy Jason Satterwhite, it is believed the fire was sparked by some exterior wiring that was being used to power exterior accent lighting. Once touched off, the fire climbed the back of the house, engulfing an overhanging portion of the back portion and the eaves of the home.