INJURED AND OTHER EE WERE ASSIGNED TO REPLACE 2 BREAKERS IN LCK1 UNIT SUBSTATION. THE BREAKERS WERE K1A AND CH. THE BREAKERS WERE OPENED AND DISCHARGED, THEN RACKED OUT TO THE DISCONNECT POSIT ION. THE BREAKER DOORS WERE THEN OPENED AND THE TRIP SETTINGS WERE TRANSFERRED TOT THE REPLACEMENT BREAKERS. FIRE AND FLASH FROM THE EXPLOSION ESCAPING THE STARTER CUBICLE BURNED BOTHS EE'S.