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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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    you may find a garden fork and a croc clip makes a better temporary earth, especially if like me your longer screwdrivers are insulated.  Expact a Ze of 50-500 ohms from the garden fork in full depth.

    For contact onto concrete, tarmac or other 'hard' surfaces a contact can be made with a salt water soaked old towel or similar and a bundle of bare wire or a stainless steel pan scrubber pressed into service if you only need to pick up enough to make a volt meter indicate (no good as a real safety of life earth of course but OK for finding voltages over a 'footprint' sort of area.)

    Ze in such a case is a bit nebulous but is a representative  measurement phantom for the situation of a sweaty bare-foot contact, and much more convenient and humane than using a real persons foot.

    Be aware that you will see some  DC anyway, as the saltwater and the electrodes form a crude battery, and both ends are most unlikely to be identical voltages. voltages at 50Hz AC however, should be considered as more real, though if it all vanishes when any current is drawn, it is not serious. If however you can get mA to flow then investigation is needed.

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    you may find a garden fork and a croc clip makes a better temporary earth, especially if like me your longer screwdrivers are insulated.  Expact a Ze of 50-500 ohms from the garden fork in full depth.

    For contact onto concrete, tarmac or other 'hard' surfaces a contact can be made with a salt water soaked old towel or similar and a bundle of bare wire or a stainless steel pan scrubber pressed into service if you only need to pick up enough to make a volt meter indicate (no good as a real safety of life earth of course but OK for finding voltages over a 'footprint' sort of area.)

    Ze in such a case is a bit nebulous but is a representative  measurement phantom for the situation of a sweaty bare-foot contact, and much more convenient and humane than using a real persons foot.

    Be aware that you will see some  DC anyway, as the saltwater and the electrodes form a crude battery, and both ends are most unlikely to be identical voltages. voltages at 50Hz AC however, should be considered as more real, though if it all vanishes when any current is drawn, it is not serious. If however you can get mA to flow then investigation is needed.

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