Abstract: THREE EMPLOYEES OF AN ELECTRICAL CONTRACTOR WERE INSTALLING EQUIPMENT AND WIRING FOR A CONTROL CENTER IN AN ASPHALT PLANT UNDER CONSTRUCTION. THE POWER FOR THE PLANT HAD BEEN ENERGIZED FOR ABOUT 2 WEEKS. TWO OF THE EMPLOYEES WERE INSTALLING A LUG ON A GROUNDED BUSBAR AT THE BASE OF A PANELBOARD, WHICH CONTAINED 3 VERTICAL BUSBARS ENERGIZED AT 277 VOLTS. ONE OF THESE EMPLOYEES, A JOURNEYMAN ELECTRICIAN, WAS WORKING WITH A SCREWDRIVER; THE OTHER, AN APPRENTICE, WAS HOLDING A NUT WITH A WRENCH. THE END OF THE WRENCH CONTACTED ONE OF THE ENERGIZED BUSES, RESULTING IN AN ELECTRICAL EXPLOSION. THESE TWO EMPLOYEES RECEIVED FIRST, SECOND, AND THIRD DEGREE BURNS TO THE HANDS, ARMS, UPPER TORSO, NECK, AND HEAD. THE APPRENTICE ALSO RECEIVED AN ELECTRIC SHOCK. THEY WERE HOSPITALIZED FOR THESE INJURIES. A THIRD EMPLOYEE RECEIVED MINOR BURNS ON HIS HANDS AS HE WAS PUTTING OUT THE FIRE ON THE HAIR AND CLOTHING OF ONE OF THE OTHER TWO INJURED EMPLOYEES.