That "fizz" one can hear is due to high moisture content in the atmosphere - it appears during rain or bad weather/storms and is called an electrical corona.It can be hear and seen on HV cables and equipment and even on conductive objects in their vicinity when the conditions are right.But this is NOT a FLASHOVER or FAULT.The corona itself is not very dangerous to humans. If the lightning strikes railway overhead conductors,than it can really sometimes arc to wagon's roofs few feet beneth.But that happens very rarely.You are correct about the 'Fizz'. I heard it manty times during my driving career and it is avery unpleasant sound. It was experienced mostly on the north London lines in and around Stratford where the wires were really quite low and in heavy rain the wire would arc onto the wagons, especially freightliner containers. There would be this eerie fizzling sound that filled the air, followed by the flash. I have seen the electricity go down the sides of the wagons. That fizzling sound is probably the last thing anyone getting that close remembers.
As a driver I have seen people do some really stupid things but getting on top of a wagon or coach with 25K of elecrtricity above them has to be one of the worst. It really does make you wonder about some people. Standing at the cab door on a 37 is as close as you want to get.
I remember making comment at the north end of the Bletchley flyover of how close the wire was when at the cab door of an 800 hydraulic and they never appeared on those duties again. You could almost have streched your arm up and touched the wire.
As a rule of thumb we were told not to get closer than nine feet to the wire.
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9 feet is so called a "safety distance".That's not an open-air gap lenght 25 kV will arc to.That's not possible.9 feet distance is given as precaution if people carry long objects such as poles etc.If the worker got a jolt of electricity at distance a little less than 9 feet from wire there must be something else (conductive) between him and OLE.Ladder for example.Yes. I was VERY FIRMLY taught that the 9 foot rule was indisputable. It was supported by the (apocryphal) story of a worker who lost a leg by climbing just a little less that 9ft closer to the conductor. Every one seems to nod knowingly about this poor worker - (though I'm not persuaded that anyone actually knew them).