oh, you mean that
first spark up...
.... depending on the x-former proximity, and impedance, the AIC could exceed your 'main isolator'
....not good.
personally, i position myself at arms length, look only as i position my left
(because i'm a righty), then look away and throw the switch/dico/main,etc..
even if the entire install has been gone over in detail, there could be a bad component (as was your Main Isolator?)
having been flashed hard sticks in your mind does'nt it??