Abstract: THE PLANT ELECTRICIAN FOR A MANUFACTURING PLANT WAS CONNECTING POWER TO A ROYAL MASTER ROLL GRINDER AT A BUS DUCT DISCONNECT BOX. THE DISCONNECT BOX WAS CONNECTED TO A 600-VOLT BUS 12 FEET ABOVE THE FLOOR. ALL THE WIRING AND CONDUIT HAD BEEN INSTALLED EXCEPT FOR THE WIRING GOING INTO THE DISCONNECT BOX. A WATER PIPE HAD BEEN INSTALLED IN FRONT OF THE DOOR OF THE BOX SO THAT ITS DOOR COULD OPEN ONLY UP TO A 45 DEGREE ANGLE. THE DISCONNECT WAS IN THE OFF POSITION, AND ALL FUSES HAD BEEN REMOVED. THE ELECTRICIAN WAS STANDING ON AN ELEVATED POWER LIFT INSTALLING THE GROUNDING CONDUCTOR TO ITS CONNECTION IN THE BOX WHEN AN ELECTRICAL EXPLOSION OCCURRED. THE ELECTRICIAN HAD APPARENTLY CAUSED A GROUND FAULT. HE RECEIVED FIRST AND SECOND DEGREE BURNS TO HIS FACE AND LEFT ARM. HE WAS HOSPITALIZED FOR HIS INJURIES.