Abstract: AN ELECTRICIAN WAS STANDING IN FRONT OF A FLOOR-MOUNTED, OPEN-FRONT SWITCHBOARD, CONNECTING AWG #3/0 INSULATED COPPER CONDUCTORS TO 480/277-VOLT, 3-PHASE, 3-POLE CIRCUIT BREAKERS. AN APPRENTICE WAS SQUATTING OR KNEELING AT THE LEFT SIDE OF THE SWITCHBOARD, REACHING THROUGH ITS FRAME AND HOLDING THE CONDUCTORS. THESE CONDUCTORS ENTERED THE SWITCHBOARD THROUGH THE FLOOR. AS THE ELECTRICIAN WAS BENDING OR SHAPING A CONDUCTOR, THE BARE END OF THE CONDUCTOR CONTACTED THE ENERGIZED 277-VOLT, LINE-SIDE TERMINAL OF ANOTHER BREAKER INSTALLED IN THE SAME SWITCHBOARD. THE OTHER END OF THE CONDUCTOR WAS COILED INSIDE A PANELBOARD ENCLOSURE IN A DIFFERENT ROOM, AND THE BARE PORTION OF THIS END OF THE CONDUCTOR WAS IN CONTACT WITH THE GROUNDED METAL ENCLOSURE OF THE PANELBOARD. THE RESULTING ARC TRAVELLED TO OTHER TERMINALS IN THE SWITCHBOARD AND AN ELECTRICAL EXPLOSION ENSUED. THE ELECTRICIAN RECEIVED SECOND DEGREE BURNS OVER 35.5 PERCENT OF HIS BODY AND THIRD DEGREE BURNS OVER 37 PERCENT OF HIS BODY. HE DIED IN THE HOSPITAL ABOUT 18 HOURS AFTER THE ACCIDENT. THE APPRENTICE ELECTRICIAN AND THE ELECTRICIAN'S SUPERVISOR WERE ALSO INJURED, BUT WERE NOT HOSPITALIZED. (THE SECOND PAGE OF THE ORIGINAL OSHA 170 REPORT, WHICH PRESUMABLY DESCRIBED THEIR INJURIES, WAS MISSING.)