PEABODY – Faulty electrical wiring is believed to be the cause of the three-alarm fire at Essex Place in Peabody on Monday.Fire Chief Steve Pasdon said Wednesday that the fire was “accidental due to faulty electrical wiring in a bathroom fixture.”In contrast to what was earlier reported, the unit in which the bathroom fixture ignited was in fact an occupied room. Fire Inspector Joseph DiFranco, Jr. said that people were currently residing in the unit and the fixture was an existing fixture, not something that was undergoing repairs.”I’m not sure what happened,” said DiFranco. “A condition was created which caused resistant heating, which in turn caused the fire.”The fire broke out around 1:11 p.m. and quickly spread throughout the first and second floor walls and ceilings, causing nearly 20 residents to evacuate.Twenty-year Peabody fire fighter Steve Franzosa had to bail out of a rear third floor window, sliding down a ladder head first into the arms of Wakefield Fire Chief Dave Parks. Pasdon said he believed Franzosa may have lost the seal on his air mask and was overcome by smoke. He was treated for smoke inhalation at the Lahey Clinic and released shortly after 5 p.m.Twelve units were affected by the fire, six of which were completely damaged by smoke, water, and fire.Pasdon said that many residents were taken to the Holiday Inn for the night, although he’s not sure about current placements.