It looks like the atmospheric reaction to some insane scientific experiment: A pulsating orb of electricity creeping down an electrical line, flashing so bright it illuminates the nighttime street in an eerie imitation of daylight. As the camera pans to follow the maruading electrical ball, you expect to see a pair of Delorean tire tracks melted to the pavement--or the evidence of something far more supernatural. But YouTuber Huw Griffiths, in his matter of fact title to the video, calls it an "electrical fireball," implying he certainly saw no metaphysical funny business taking place at the time.
What could have caused such a thing? Let's ask the armchair physicists of Reddit!
"Looks like a traveling arc, similar to a jacobs ladder though im not sure whats propelling it. Maybe its melting the lines causing it to keep moving down," writes skithrow.
SoTupps, who claims to be an "electrical line techinician in training," concurs:
The fireball is definitely an electrical arc probably formed by a fault current in the line i.e. a lightning strike in combo with faulty protective devices. Fault current's travel up-stream (opposite of the usual flow of electricity) until they can be stopped by a protective device (which usually opens the circuit and allows the fault to clear). In this case I believe it was a fuse cutout/lightning arrester combo that finally snuffed out the arc. These are usually installed to protect transformers from dangerous faults such as these. Had that fault reached the transformer.... BOOM! An explosion would be likely.
There are a couple BOOM!s at the end of the clip, though surely not the type of crater-making BOOM! SoTupps is referring to. And since local papers have published exactly zero stories on the event, it's likely the pulsating electrical orb thing didn't leave any significant injuries or property damage in its wake.
Image via Filter Forge/Flickr