Abstract: A FOUR-MAN CREW WAS INSTALLING A SUBSTATION IN AN EMPTY ROOM IN A COMPUTER MANUFACTURER'S BUILDING. THE CONSTRUCTION PLANS CALLED FOR EIGHT 10-FOOT-LONG, 0.625-INCH-DIAMETER COPPER RODS TO BE DRIVEN INTO THE GROUND UNDER THE CONCRETE FLOOR WITHIN THE ROOM. EIGHT HOLES HAD BEEN CUT INTO THE FLOOR TO EXPOSE THE EARTH. THE CREW THEN USED A PNEUMATIC HAMMER TO DRIVE THE FIRST ROD INTO ITS HOLE, WHICH WAS ABOUT MIDWAY ALONG THE SOUTH WALL OF THE ROOM. THE SUPERVISOR (EMPLOYEE #1) AND ANOTHER WORKER (EMPLOYEE #3) OPERATED THE HAMMER, WHILE THE OTHER TWO EMPLOYEES SUPPORTED THE ROD. WHEN THE ROD REACHED A DEPTH OF ABOUT 6.5 FEET, IT PENETRATED A 13.2-KILOVOLT UNDERGROUND POWER LINE. ALL FOUR EMPLOYEES WERE HOSPITALIZED FOR THE ELECTRIC SHOCKS THEY RECEIVED.