A North Plainfield man has been charged with setting a blaze Wednesday at an under-construction house that spread to two other occupied homes, officials said Thursday.Jonathan Davies, 26, was charged with aggravated arson and aggravated assault in the fire on Maple Avenue in North Plainfield, the Somerset County Prosecutor’s Office said.Davies is accused of setting the blaze early Wednesday, officials said. The fire was reported to 911 around 2:40 a.m.Davies was seen watching the fire consume the buildings, and was seen leaving and entering the property multiple times, authorities said.The fir…