EMPLOYEE WAS CLIMBING A 12' STEP LADDER CARRYING A 5"" ELECTRIC GRINDER. THE GRINDER ON/OFF TRIGGER SWITCH BUMPED AGAINST A LADDER STEP CAUSING THE GRINDER TO TURN ON AND OPERATE WHILE THE TRIG GER SWITCH WAS DEPRESSED. THE GRINDING DISK THENTOUCHED AGAINST EMPLOYEE'S FINGER CAUSING INJURY.