Re: C4 Racing from Newbury - 2 horses *electrocuted*

Actually, most animals are electrocuted at smaller currents than humans, and even small ground voltages can be disastrous for large quadrupeds, and they have no option to "let go" of the live ground.

This is why (on uk.d-i-y) I always warn of the need to use electricians familiar with these extra risks when working on installations near livestock, when I see a poster talking about such a situation.

Very sad for all concerned.

That horses were more susceptible to electrocution than humans and needed only a very small shock to kill them came as news to me till it was pointed out to me by my horse riding daughter. Terrible really!

Thats why its not unusual to find a lot of cows etc dead after nearby lightning strikes where what's know as the step gradient potential can be very high indeed...

On Sat, 12 Feb 2011 20:01:23 +0000, Sofa - Spud sprachen:

You wouldn't think it, horses must have massive hearts, so would presumably need more current to shock them. Still, they do go round with metal shoes nailed to their feet. Pretty much all human shoes are gonna be plastic or rubber soled.

Bloke on news said the cable'd been untouched for at least 30 years. I suppose maybe the insulation could've worn down. It's interesting to see posts from people who know about this sort of thing, something you never get on the news.

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"hey let's educate the brutes, we know we are superior to them anyway, just through genetics, we are gentically superior to the working class. They are a shaved monkey. If we educate them, they will be able to read instructions, turn up on time and man the conveyor belts, sorted." #

Could you expand on why horses are more susceptible than humans please Andrew?

I don't doubt you, but one would think a huge great horse would be more resistant?

In article , The Medway Handyman writes

They're big animals, so more of a potential difference (a larger voltage, in other words) appears between the front and hind legs. The current then travels through the body via the heart. Result: dogmeat.

A human standing on the same ground only has the p.d. developed between their feet. And humans don't as a rule wear shoes with metal soles.

"it's the volts that jolts, but the mills that kills"

I would have thought that any 3ph 440V and upward cable underground should be armoured and the armour sheathing earthed. Any leakage should have tripped a breaker somewhere unless someone has been fiddling/ botching to get the race going. I wonder if we get any info on what caused it ? (Cynic Mode switched on) Don

Nearly all animals need far fewer "mills that kills" (current) through them to electrcute them than humans do. I don't know if it is known why humans are more resistant to electrocution than most other species, but I don't think the 6 or so generations since the widespread use of electricity is long enough for darwinism to be a factor, unless there had been an electrocution pandemic, whereas it's actually very rare.

Most humans will have experienced an electric shock, know what it is, and know what to do to stop it. None of that is true of most animals, and as I said before, when an animal is being electrocuted by the ground, it can't "let go".

When you have current leaking through the ground, it causes a voltage difference across the ground. Let's say we're standing on a piece of ground which has a voltage difference of 10V/foot. Your feet are probably about a foot apart, and even with bare feet, you wouldn't even feel 10V. Even if you did, the current path (up one leg and down the other) isn't going to kill you. A horses feet might be 6' apart, so it's going to have 60V across it. Futhermore, that will be across the chest (heart, lungs) and much more debilitating. Metal shoes will make better ground contact, pressing right into the damp soil, although it's a very serious problem for unshoed livestock too.

Mains supply cables don't have earth leakage detection. (Some higher voltage supply cables do.) I don't know if all old cables had a full metalic sheath. SWA (Steel wire armoured) cables are liable to the steel rusting away if the outer sheath gets damaged, and we've heard the race course suggest any cable must be > 40 years old (although that's not old for an underground cable).

Modern high voltage cables are normally singles and can't use steel armour (unbalanced magnetic field from a single cable), so the protection is copper, but it's rather more there to guarantee a short to earth if the cable is damaged, than it is for mechanical protection. Mechanical protection is provided by very tough plastic coverings.

A quote from the DailyMail....

Marching Song's part-owner Graham Thorner said the fallen horse had 'great potential'.

Probably aluminium cable from the 70s. Corroded badly by now.

Bigger wheel^Wlegbase.

More volts developed across them from the ground. See above.

section?

There are a surprising number of Google hits for .

So far I have seen reports that "a cable had been found". No-one has yet reported that the cable was damaged or faulty and one of todays papers stated that one horse "had burns about its mouth". Its being reported to the uneducated by the unknowing as is usual in such matters with the media. Me - I'll wait for proper results thanks.

Surely the problem is damaged insulation rather than corroded aluminium.

Shocking!

Paradoxically, it's actually *easier* to induce fibrillation in larger hearts (though there are a number of other relevant factors, such as the amount of fibrosis - which tends to increase with age).

That certainly places horses at a disadvantage. The other crucial point is that a larger proportion of the current flowing through horse's limbs will pass through the heart. If we get receive an electric shock through our legs, most of the current will flow through nether regions and not the heart. It's a different story for a shock via the arms of course. We don't normally touch the ground with our forelimbs, whereas horses do!

Francis

Is Newbury a short circuit?

Now, we need to get our feet/hooves on the ground...