I can't find a decent explanation anywhere - and I know that there are some quite savvy electricians here.
So - please can anyone explain what *could* have happened.
How can they get a shock from a faulty cable buried under ground - what path did the electricity likely take through their body.
Two threads already...
Simplified..... The cable is at a high AC voltage relative to "earth", but the ground has a measurable, non zero, resistance.
The voltage at the cable is, say, 415V AC. This is driven by the National Grid. The voltage gradient across the ground's resistance to zero volts can be measured as a logarithmic curve starting at (say) 415 Volts, with the gradient reducing effectively to zero at possibly 10 or
20 metres. So, as a horse has front and back legs about two metres apart, if it's walking towards the faulty cable, its front legs will be at a higher voltage than the back legs. Current will flow up the front legs, through the body, and down the back legs, passing through the heart and lungs on the way. As it approaches the cable, the voltage and, hence the current, will increase. This currrent, if sufficiently large, can stop the heart beating, and interfere with breathing causing death. Reportedly, this would occur with about 60 volts between front and hind legs, so it would happen when the horse got within a few metres of the defective cable.A person standing next to the horse, even with bare feet, but not touching it, would feel nothing, as their feet are normally much closer together, and the current would, at worst, travel up one leg, though the hip area, and down the other, avoiding the heart and lungs. In this case, people holdng the reins reported a tingling as from a slight electric shock, as they were a short distance away from the front legs, and the reins were wet, so conducting electricity via the horse's front legs, neck and mouth and through the person's body to ground.
The cable reportedly removed since was at a rather higher voltage than
415 volts, so the voltage gradient would have been higher, causing death further away from the cable.Hope this helps.
We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember gasman saying something like:
Covered ad nauseum above.
Many thanks - just the job - sorry I had not see other thread.
Why?. Surely the ground is a linear conductor?..
Yes, sort of. However, the area through which the current passes follows something between a square law and a cube law, as the voltage dissipates through a hemisphere, more or less. This gives a higher resistance per linear metre along the radius the closer you get to the cable.
It's not completely uniform, either, as the composition and specific resistance of the ground varies. The existence of nearby conductors, such as cable armour on adjacent cables or metal pipes also affects the field.
I did say I'd simplified things.....
It'll be bound to drop off faster than linear since the juice is not just distributed on a thin line. It'll be a hemisphere from where the leakage point is, roughly.
No. THe earth connection is a point conductor, into a ground of finite resistivity.
Consider the current paths available to an electrode poked into the gorund with a resistivity of X ohm.m
ALL the current will be pasing through the small hemisphere close to the electrode. The current density close to the electrode is very high. The voltage gradient around the electrode is high ( V=IR )
As the cutrrent 'flares out' into the earth in an infinite hemisphere, the cross-section of the earth becomes effectively infinite, with infinite parralell current paths.
So, 'Far Away' from the electrode, the current density tends to zero, due to the large x-section area of earth, and so the voltage drop accross the earth's resistance tends to zero. ( V=IR ).
It'ss all due to the current density close to the electrode.
correct.
That's true for a leakage 'point'. I would guess the leakage was much worse than can be achieved from a point. A scenario might be more along the lines of a corroded metalic sheath which no longer has electrical continuity to the cable ends, followed by a fault connecting from a live conductor to a section of the disconnected metalic sheath, resulting in a line rather than a point ground contact, and a much better ground connection capable of passing more current into the ground.
As may be but in this particular instance point to point along a surface path from one electrode to 't other?..?.
Be interesting to get around to doing some experiments in the back yard;).. When I fell a bit more like it;!.
Now answer me this question;!..
Why is it as yet that no one has come up with anything of a cure for the freakin common BLOODY COLD THAT I'VE GOT!!!.
The two points are on the radius of a circle, which in turn is a minutely thin slice of the whole hemisphere.
Treat it, and it goes in a week, leave it and you're stuck with it for seven days......
Standing, or better still lying prone, in the Newbury parade ring would greatly reduce the severity of your cold, at least on a relativistic basis - relative to your other ailments.
Since there is no cure, and many of the "treatments" are just counteracting the symptoms which are your body's methods to get rid of it, it's more like: Treat it, and it goes in a couple of weeks, leave it and it goes in a few days.
Rhinovirus (which is responsible for lots of colds, but not all) is very easy to get rid of at first sign of a cold, IME. The virus multiplies at about 33C, which is why it lives in your nose where the airflow keeps it below core body temperature. Spending an hour in a really hot bath with steamy bathroom (switch off the extractor fan;-) so you're breathing moisture saturated air at probably 40C (never measured it) stops the virus spreading and allows your body to quickly kill it. Even if you miss the early signs and this window to kill it instantly, the hot steamy bath can still very significantly reduce the discomfort, and I suspect shorten the cold. YMMV...
I don't know if a really hot bath is safe for everyone, so be careful if you have any other medical problems.
Written:
Quite saw one report the the horses that died where in front of the others. The horses behind were steered back onto onto a rubber walk way rather than walking on the grass
Now I thought Electro convulsive therapy had gone out of fashion these days;?..
Which of course will be differing densities at various layers and then the moisture of ye ground, soil makeup etc etc..
Thats not the problem now, its the bl^^dy feeling worn out for a week or two afterwards;!..
Still must get around to seeing how that works out in practice. I remember as kids me and a mate used to use a couple of stakes in the ground for a phone system that worked quite well over a couple of hundred yards or so!.
Stakes were around 50 odd feet apart..
Well nice to know that its not worth investigating ;!.. Not!...
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