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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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  • 0
    As a complete guess and a throw it out there ideas (some are stretching it a bit though):


    Does the supply arrive at the shed as a TN system of some sort and then become a TT System? And has the 100mA RCD been installed downstream of the TN divide?  

    705.411.1 (iii) - "all other circuits"  such as slurry pumps or mixers may have a 300mA RCD on them - or not have any at all - perhaps there is a afault on one of these circuits?

    Water pumps/pressure jet set maybe..........You only mentioned the one 100mA RCD - so perhaps that covers everything?

    All that slurrey/soil would possibly insulate those (one or more) metal slatts over the slurrey pit affecting the ohms to earth reading and how well its connected to earth, que in a fault current, And then the cow steps on a well earthed slat with its front or back legs and bam.........just guessing here though.

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  • 0
    As a complete guess and a throw it out there ideas (some are stretching it a bit though):


    Does the supply arrive at the shed as a TN system of some sort and then become a TT System? And has the 100mA RCD been installed downstream of the TN divide?  

    705.411.1 (iii) - "all other circuits"  such as slurry pumps or mixers may have a 300mA RCD on them - or not have any at all - perhaps there is a afault on one of these circuits?

    Water pumps/pressure jet set maybe..........You only mentioned the one 100mA RCD - so perhaps that covers everything?

    All that slurrey/soil would possibly insulate those (one or more) metal slatts over the slurrey pit affecting the ohms to earth reading and how well its connected to earth, que in a fault current, And then the cow steps on a well earthed slat with its front or back legs and bam.........just guessing here though.

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