Abstract: Over the course of several days, two employees were installing central air conditioning equipment in a residence. They had installed some of the new air conditioning equipment in the attic. When they had put the final screws into the frame of an air vent to keep it in place, one of the drywall screws had penetrated the insulation on a conductor in a nonmetallic-sheathed cable supplying a three-way light switch. However, the ground fault, which had energized that portion of the ductwork, went undetected. When the employees returned to the job 2 days later, they went into the attic to install flexible duct. One of them touched a galvanized pipe while he was in contact with the energized ductwork. The employee, who was perspiring heavily from working in the attic, was electrocuted.