Good stuff,
And worth being reminded of frequently. I've spent a few years working in mines and electrical safety is a regular feature at the daily toolbox talks. Lots of info, videos and gory gory photos of what's left of people after HV is done with them.
Electricity just doesnt obey rules at high voltage. Lots of mines generate their own power, and it comes in weird combinations. One place I worked at had a 100,000A (yep!) 200V DC feed running through solid copper bus bars the size of railway sleepers. Used it for electro winning copper back out of an acid solution. That thing wasn't fun to be anywhere near, completely friend every kind of electronic device.
Another place had their main HV feed from their power station set to trip and come back online after 15 seconds 3 times in a row before going permanently offline. This was stressed at safety meetings regularly, but a sub contractor came in with a 220tonne crane one day and contacted it. Tripped. Climbed down from the cab. Came back online. Tripped. Climbed back into the cab to get his smokes (!). Came back online. Tripped. climbed back down.
They quarantined the crane for 48 hours much to the operators dismay, without pay. The tyres caught on fire the following day. I don't know what happened to the crane, but it was the modern type, fully computer controlled. All the electronics were fried.
Another site had a komatsu 930E 300tonne dumptruck make contact with HV. They quarantined it and sure enough, a few hours later the tyres (which are about 2 stories high) exploded. Being split rims, they sent the rim 4 or 500 yards away. Nobody was injured.
Know your voltage, and keep your distance!
Shaun
