WHILE TROUBLE SHOOTING A 4150 MAIN BREAKER PANEL, EE MAD CONTACT WITH 4160 VOLTS IN THE BUS BAR PANEL NEXT TO THE MAIN BREAKER. EE FAILED TO FOLLOW POSTED PROCEDURES BY VISUAL CONFIRMATION THA T THE KNIFE SWITCHES FOR THE BREAKER WERE DISENGAGED EVEN THOUGH THE MAIN BREAKERE SWITCH WAS IN THE OFF POSITION. THE BREAKER SWITCH SHAFT WAS BROKEN.