The ones that failed were used up until the time of testing. Most of the sticks are 8 foot long. We work on lines that are 24,900 volts. A one foot section tested at 75,000 volts fails doesn’t mean the entire 8 foot stick would allow voltage to travel all down the stick. If there was a big gouge in the stick the whole length of it, then yeah.
We can use them to work on 115,000 volt lines due to their length. So technically just a 2 foot section of stick has enough insulation to keep us safe. But no thanks, I will use the whole 8 feet. Lol. These sticks take a beating bouncing around in trucks. We keep them in bags or in PCV tubes to keep them from damaging each other.
Ah okay that makes sense. Essentially a good 8 foot stick would have a max of 525kv if each foot is rated to 75kv, since the 8th foot would would hit the end? Not that an 8ft stick is used on that high of a line but just thinking max it could insulate from.
Exactly, testing at 75kv per foot leaves plenty of room for error if a portion of the stick was to get damaged or dirty. Plus we have a Minimum Approach Distance we have to go by also.