Scary thing is the usually these arcs are not the load ( as these breakers normally aren't switched under load ), but just the remaining tension from induction by neighbouring equipment. It essentially tells you that any switched off high voltage line, unless grounded, will kill in an instant when approaching it
In backward countries the utilities don't have a system or a good system in place for a quick utility company inspection of a site before digging so generally the workers just say a prayer before digging.
I worked in substation maintenance for 10 years so this really takes me back, I could tell you some stories of the things I saw...you have to respect high voltage. Most of the arcs were from the 138 & 345Kv switches. Cool video.
