Abstract: TWO EMPLOYEES, A JOURNEYMAN HEATING, VENTILATION, AND AIR CONDITIONING MECHANIC AND HIS APPRENTICE, WERE INSTALLING A METAL DUCT IN A CRAWL SPACE UNDER A RESIDENCE. THE MECHANIC WAS PUTTING A METAL ELBOW INTO THE DUCTWORK WHILE HE WAS KNEELING ON A DOUBLE-INSULATED DRILL AND A TROUBLE LIGHT CORD. THE DRILL WAS PLUGGED INTO A RECEPTACLE ON THE TROUBLE LIGHT. THE CORD FOR THE LIGHT WAS, IN TURN, CONNECTED TO AN EXTERIOR RECEPTACLE OUTLET OF AN ADJACENT RESIDENCE THROUGH TWO THREE-WIRE EXTENSION CORD SETS AND A SECTION OF NONMETALLIC-SHEATHED CABLE. THE CORD PASSED THROUGH A DOORWAY ON ITS WAY TO THE CRAWL SPACE. THE BLADES FOR THE EQUIPMENT GROUNDING CONDUCTOR WERE MISSING FROM THE ATTACHMENT PLUGS OF BOTH EXTENSION CORD SETS, AND THE CABLE WAS UNGROUNDED. IT APPEARED THAT THE MECHANIC'S WET CLOTHES CONTACTED ENERGIZED PARTS OF THE CORD AND PLUG CONNECTION THROUGH A DEFECT IN THE INSULATION ON THE CONDUCTORS. THE MECHANIC, WHO WAS IN CONTACT WITH THE GROUNDED METAL DUCTWORK, WAS ELECTROCUTED.