Montreal Fireball: Spectacular Flash Explained

So, the explanation can be simply paraphrased as

"Yeah, powerlines do that sometimes. So what"?

The daily fatality figures, quoted in the story, due to arc exposure in the US seem alarmingly high.

I believe that is misquoted and refers to incidents rather than deaths...most are burns, which can be quite severe....

http://www.falconengr.com/arc-flash-facts.htm

So in the first posting of this tcmtech nailed it first.

Yes - Jacob's Ladder on a massive scale. My old buddy Bear would be thrilled. (he had one in his dorm room at college)