Author -
Submitted By -Lucky Escape!!!
I had just completed isolating and grounding a section of 11kv primary for augmentation of about 25 spans distance in an Australian City. The line crews where setting up to pull the new conductor thru as the old conductors was being removed , it was a long pull about 20 spans including a road crossing across a busy roadway with no police permission to stop traffic due to its heavy congestion . The lineman had set up and started removing ties off pin insulators along the spans the whole regions crew where on site and maybe 13 or more guys where working aloft.
As work progressed one of the conductors started to slip thru near the road crossing and the span started to lower down over the road crossing .
At the same instant a high load travelling at about 50 MPH caught the conductor and dragged it at full speed thru the poles and near the linemans hands snapping off the few remaining ties, the end of the conductor whipping wildly as it accelrated past the men aloft.
I was at the far end of the job and saw the conductor racing along as the truck caught it .
The next instant there was an immense explosion with arcing coming from some secondary wires that was in contact and a street light control box exploded with force that i had never seen before in 18 yrs of trouble work.
The conductor then sprang back from the truck almost hitting some ground workers, hitting traffic and getting tangled in their wheels .
We immediately yelled to all the bystanders not to touch any cables any tried to stop the traffic that had the conductors caught under their cars.
We then walked along the line and was pleased to find that no one had been struck by the conductor that flew past their faces at 50MPH one guy had been hit on his back (somehow) but his injuries where only minor. We ordered everyone to stay clear that was aloft until we could determine the source of the power surge into the grounded work area .
Checks of the 11KV feeders showed no reclose ,(we suspected that the conductor had come in contact with live 11kv down from the worksite) and we still had no source of this mystery surge
About an hour later a patrolling helicopter flew along a 330kv transmission line that was a long way above the work site we had looked at it but considered it impossible for the conductor to reach such a height.
I got out my binoculors and checked the 330kv conductor and found a burn mark!!!!!
The end of the conductor travelling at 50MPH apparently was flipped up with such force as it pulled along the poles that it reached and either contacted or came within arcing distance tripping out the transmission feeder on distance zone one protection.
So the truck and streetlighting control box and some secondary circuits caught up in this where all energised momentaliry at 330kv to ground voltage the streetlight control box took the main fault and was completely destroyed
In the end no one aloft was badly injured none reported feeling any kind of shock .
Their where some very irate car onwers and lots of paperwork but it was unbelievable how such a stage of events can occur with no bad injuries.
If the conductor had struck anyone heavily it could have cut them in half.
Some valuble lessons where learned from this accident regarding traffic control ,conductor holding methods and large workcrew supervision techniques.
And putting safety before fast work methods being forced by deregulation pressures.