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Cattle deaths

lyledunn
Some 10 prize bullocks died in quick succession whilst housed over winter in a cattle shed. The government vet was unable to reach a conclusion on cause but apparently does not discount electric shock as an indirect cause. 

The shed comprises steel columns and trusses with corrugated iron sheeting over. The floor comprises re-Inforced concrete slats over the slurry tank. The pens have steel barriers supported by steel posts all of which are heavily corroded but still making contact with other albeit fortuitously.

The earthing system is TT with the shed steelwork on its own providing a substantially low impedance of 5 ohms using a loop tester. A 100mA RCD protects the rather ropey lighting circuits.defccf32df3c757507a0db6ad0a35f87-huge-a5af3537-8eae-4a3c-9126-68fa60b61ac7.jpg

whilst the floor could be wet, I can’t conceive how a voltage difference could be established even if the steelwork was at 230v

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    Humans have been killed by the gas from slurry pits if the surface crust is suddenly broken.

    I don't see a foundation earth for the cattle to stand on. Their legs are quite far apart.

    It is a strange arrangement. Have you seen one like it elsewhere?

    High value cattle, but is it a high enough value barn?

    Sympathy for the unfortunate farmer and his cattle.


    Angram.
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    are there any electrical supplies for anything other than the lights ? maybe pumps or agitation for slurry or anything like that.

    You'd normally take animals out of a slatted floor building while pumping anyway to avoid gas poisoning, but just wondering.

    ( hse advice on slurry handling )


    I think it might be the sort of building shown in this article  here and also
    cows rescued from slurry
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    The farmer has himself convinced that it is an electrical issue as the fatalities stopped when the supply to the building was disconnected. However, that may be nothing other than coincidence. You can see that the roof is deliberately discontinuous and the sides open and thus the floor could be very wet with water perhaps streaming to the outside. Actually, the pens in which the cattle died have rubber mats fitted over the slats. If the steelwork was made live along with a faulty RCD and a wet floor spilling to the outside then perhaps voltage gradients although small may have been enough to agitate the cattle. They do play really hard and have been known to severely injure each other. I do rather think that the methane possibility might be a better bet.
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    Methane just explodes if you light it,  the hydrogen sulphide is utterly lethal in all but the smallest traces. The whole set up seems a bit rough. An IR check when its raining may reveal something I suppose.


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    I don't know how much electricity it takes to fell an ox, but it seems odd that nobody saw any of the deaths or unusual behaviour and the farmer and his staff were unaffected.
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    This feels like a teaching my grandmother to suck eggs conversation.


    Do the farm buildings share an earth connection through a pipe or cable with the farmhouse or another installation that is TN earthed with circuits that are not RCD protected?


    Do the farm buildings share an earth connection through a pipe or cable with the farmhouse or another installation that is TT earthed with circuits that are RCD protected, but one of those RCDs is faulty rather than the 100 mA RCD that is upfront of the farm buildings installation?


    Andy Betteridge.


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    Angram:


    Sympathy for the ................ cattle.


    Angram.




    The irony, beats a hammer on the head.

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    Sparkingchip:

    This feels like a teaching my grandmother to suck eggs conversation.


    Do the farm buildings share an earth connection through a pipe or cable with the farmhouse or another installation that is TN earthed with circuits that are not RCD protected?


    Do the farm buildings share an earth connection through a pipe or cable with the farmhouse or another installation that is TT earthed with circuits that are RCD protected, but one of those RCDs is faulty rather than the 100 mA RCD that is upfront of the farm buildings installation?


    Andy Betteridge.


     






    Andy, yes, all those issues checked. Mike, no other equipment other than a couple of corroded light fittings. 

    Would anyone care to speculate whether a voltage gradient could be established across the slatted re-enforced concrete floor? Suppose the RCD was indeed faulty and current was limited only by the impedance of the steel frame to earth which was circa 5ohms.

     

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    Chris Pearson:

    ...it seems odd that nobody saw any of the deaths or unusual behaviour and the farmer and his staff were unaffected.




    I understand that a close lightning strike to perhaps a tree can leave a man standing while a horse (or cow) can be killed due to the voltage gradient in the ground. A horse, with four feet, has front and rear feet in contact with the ground at different voltages due to the voltage gradient and is electrocuted, while the human, with only two feet next to each other, sees no voltage difference and survives.

    The suspicion of a voltage gradient does seem sensible, but personally I can't see it happening from the description. Was there some other factor (such as a thunderstorm)?

    Alasdair

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    I understand that a close lightning strike to perhaps a tree can leave a man standing while a horse (or cow) can be killed due to the voltage gradient in the ground. A horse, with four feet, has front and rear feet in contact with the ground at different voltages due to the voltage gradient and is electrocuted, while the human, with only two feet next to each other, sees no voltage difference and survives.



    I remember a couple of similar accounts from my early years in West Wales. The other factor is that the human tends to be wearing insulating footwear in such conditions.


       - Andy.

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