Abstract: A THREE-WORKER CREW WAS INSTALLING A HEATING AND AIR CONDITIONING DUCT SYSTEM IN A BATTERY CHARGING ROOM. THE DUCT WORK WAS LOCATED ABOUT 6 FEET, 9 INCHES ABOVE THE FLOOR. THE LEAD WORKER REMAINED AT GROUND LEVEL, WHILE THE OTHER TWO EMPLOYEES WERE WORKING FROM A SCAFFOLD, PERFORMING THE INSTALLATION. THREE DUCT SECTIONS HAD BEEN INSTALLED, AND THE TWO EMPLOYEES BEGAN INSTALLING THE THIRD, WHICH HAD TO BE POSITIONED ABOVE A CABLE TRAY CONTAINING ENERGIZED, BUT INSULATED, ELECTRIC CONDUCTORS. A PIECE OF 0.75-INCH-THICK PLYWOOD THAT WAS 16 INCHES WIDE HAD BEEN LAID ACROSS THE 30-INCH WIDE CABLE TRAY TO SUPPORT THE 40-INCH-BY-20.5-INCH-BY-22.5-INCH DUCT SECTION. THE BODY OF THE DUCT WAS 16 INCHES WIDE WHERE IT WAS TO BE SUPPORTED BETWEEN CEILING HANGERS THAT WERE ALSO 16 INCHES WIDE. ONE OF THE TWO EMPLOYEES REMAINED ON THE SCAFFOLD WHILE HIS COWORKER WALKED ONTO THE CABLE TRAY. THE TWO EMPLOYEES THEN MANEUVERED THE DUCT TO FIT BETWEEN THE HANGERS. THE DUCT FELL OFF THE PLYWOOD, CUTTING THE INSULATION ON A 120-VOLT CONDUCTOR. THIS ENERGIZED THE DUCT SECTION, WHICH WAS WEDGED BETWEEN THE METAL SIDE OF THE CABLE TRAY AND A PIECE OF METAL CONDUIT ATTACHED TO THE CONCRETE WALL. THE EMPLOYEE ON THE CABLE TRAY WAS SITTING OR SQUATTING ON THE SIDE RAIL OF THE TRAY WITH THE DUCT IN HIS LAP, GRASPING THE DUCT ANGLE IRON FLANGE WITH HIS HANDS. THIS EMPLOYEE WAS ELECTROCUTED. THE EMPLOYEE ON THE SCAFFOLD RECEIVED AN ELECTRIC SHOCK WHEN HE TOUCHED THE DUCT (THOUGH FOR SOME REASON HE WAS NOT LISTED ON THE OSHA 170 FORM AS BEING INJURED). HE WAS ABLE TO RELEASE THE DUCT AND CLIMB DOWN FROM THE SCAFFOLD. THE PLANT MAINTENANCE ELECTRICIANS MEASURED 120 VOLTS BETWEEN THE DUCT AND GROUND BEFORE RETRIEVING THE DEAD EMPLOYEE.