CONTRACTOR ELECTRICIAN WAS STANDING ON A FOUR FOOT STEP LADDER SLIGHTLY ABOVE AND IN FRONT OF A 200 AMP 600 VOLT 3 PHASE DISCONNECT BOX. REALIZING THE BOX WAS ENERGIZED HE PUSHED DOWN ON THE D ISCONNECT LEVER WITH HIS FOOT WHICH CAUSED THE BOX WHICH WAS UNDER LOAD TO ARC OUT.THE ELECTRICIAN SUFFERED 1 ST AND 2ND DEGREE BURNS TO LEFT SIDE OF NECK AND RIGHT HAND AND ARM.