The only time I've been exposed to a serious arc flash event was when someone closed a breaker for the first time. I was working on a panel with a 600HP soft starter in it and I finished, so I told the guy in the other room that I was done and I started to close the doors of the panel. Just as the local disconnect handle interlock engaged with the door, he closed the breaker in the switchgear feeding the soft starter. The local disconnect was open, but they had nicked a LINE SIDE conductor in the conduit and it vaporized, blowing a fireball out at me. Because the doors were almost closed and the interlock held, the blast was deflected mostly up and down so it torched my boots and singed my eyebrows and hair where the safety glasses didn't cover. I did NOT, by some miracle, wet myself... Ever since then I always stand to one side rather than directly in front of anything.
In the investigation as to how that nicked conductor was allowed to be there, turned out they meggered everything, then pulled the conductors BACK into the conduit in order to remove and re-install the back panel for the soft starter. But they failed to re-megger the conductors again, ASSuming they were OK after being pulled back into the conduits.