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Safe Disconnection to Undertake Work.

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Scene. An old farm building now used as a double glazing frame maker's workshop.


The supply comes from an old shed about 40 metres away, where the meter is. The old shed has some 70s/80s rusty M.E.M. isolators that feed several S.W.A. cables that exist the shed in many directions underground. I suspect that one feeds the main farmhouse, another a rented cottage and the others various farm buildings. There is no clear labelling of the isolators.


What is the best way to locate the frame maker's  building supply where I have to work?


Somewhere I have a circuit i/d set, if I can find it, but that will need access to the live parts and I do not wish to turn off the wrong isolator.


Z.


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  • 0
    I think that Andy is right with the farm supply. It probably is P.N.B. as it has a single black cable running to ground at the main cutout position connected to the main metal switch fuse from a neutral block. So essentially the L.V. earth electrode is at the farm's intake position rather than at the big pole transformer which is in a field some distance away. I presume that the H.V. earth electrode is at the pole transformer, but can't be sure. So in the past, if the farm was considered just one consumer it was supplied with a P.N.B. supply. The L.V. earth electrode is situated at the farm's intake position rather than at the pole transformer. Zs at the remote building where I was working, was less than 0.5 Ohms so earthing is good. At the farm intake position Ze would be even lower. The farm has no P.M.E. label displayed.


    Z.
Reply
  • 0
    I think that Andy is right with the farm supply. It probably is P.N.B. as it has a single black cable running to ground at the main cutout position connected to the main metal switch fuse from a neutral block. So essentially the L.V. earth electrode is at the farm's intake position rather than at the big pole transformer which is in a field some distance away. I presume that the H.V. earth electrode is at the pole transformer, but can't be sure. So in the past, if the farm was considered just one consumer it was supplied with a P.N.B. supply. The L.V. earth electrode is situated at the farm's intake position rather than at the pole transformer. Zs at the remote building where I was working, was less than 0.5 Ohms so earthing is good. At the farm intake position Ze would be even lower. The farm has no P.M.E. label displayed.


    Z.
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