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Farm Outbuilding Office & TT Earthing etc.

Zoomup

The wild geese are migrating now. We can see them overhead flying south as they appear out of the morning mists, calling to each other as they fly in large numbers in a large V formation. Then they disappear back into the high level mists. Some say that they will fly to S. Africa.

Wild Geese Flying - Bing video

Meanwhile, a local smallholder who keeps four footed animals, has built a new wooden building to be used as an office and farm storage unit. The new proposed office is only about 25 metres square.

He asked me about installing a few sockets and lighting in the new building.

Presently the nearest supply is a plastic cased TT earthed consumer unit.

Near to the new build there are two earth electrodes used solely by the electric fencer unit. These are run in parallel. How far away from any TT L.V. installation earth electrode should they be?

Will the electric fencer interfere in any way with I.T. equipment?

Shall I supply the office with P.M.E. earthing, or shall I TT it?

I have my own thoughts on these matters, but wish not to have missed any safety issues.

There is a miniature Shetland pony that can't eat regular grass. It is allergic to it. Its hay has to be “sterilised” in a hay steamer rated at just under 3kW.

Thanks,

 

Z.

 

 

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    If the floor is wooden, the tingle risk of PME is largely negated, and by the sound of it I reckon either  will be fine.  

    You could confuse the unwary and use the PME earth and still put an electrode in parallel.  If the floor had been concrete you could have asked for a tap point onto the re-bar. (though 2 taps a few m apart is nicer as it allows for a high current through test which is reassuring.)

    If you use the PME, I'm assuming the fencers will never be plugged into this building, but supplied from batteries or elsewhere, and more generally that there will not be leads trailing out for any other more outdoors kit in the future.

    Given you are fitting an up front  RCD, the change to TT is trivial, perhaps one plastic gland and a link..

    Mike.

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    mapj1: 
     

    If the floor is wooden, the tingle risk of PME is largely negated, and by the sound of it I reckon either  will be fine.  

    You could confuse the unwary and use the PME earth and still put an electrode in parallel.  If the floor had been concrete you could have asked for a tap point onto the re-bar. (though 2 taps a few m apart is nicer as it allows for a high current through test which is reassuring.)

    If you use the PME, I'm assuming the fencers will never be plugged into this building, but supplied from batteries or elsewhere, and more generally that there will not be leads trailing out for any other more outdoors kit in the future.

    Given you are fitting an up front  RCD, the change to TT is trivial, perhaps one plastic gland and a link..

    Mike.

    Thanks Mike.  An office  TT earth electrode will be too close to the electric fencer electrodes for my liking. I will stick to P.M.E. just for the office. The fencer will remain TT supplied on its existing supply.

    Z.

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    Zoomup: 
     

    Thanks Mike.  An office  TT earth electrode will be too close to the electric fencer electrodes for my liking. I will stick to P.M.E. just for the office. The fencer will remain TT supplied on its existing supply.

    Z.

    Provided there are no buried extraneous-conductive-parts, that is OK, otherwise the electric fence electrode would still be too close.

    There is perhaps another solution which hasn't been discussed … export TT from another building (if there's overhead on the demand) … no need for a new electrode for the second building if you also export a protective conductor from the other TT building.

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    gkenyon: 
     

    Zoomup: 
     

    Thanks Mike.  An office  TT earth electrode will be too close to the electric fencer electrodes for my liking. I will stick to P.M.E. just for the office. The fencer will remain TT supplied on its existing supply.

    Z.

    Provided there are no buried extraneous-conductive-parts, that is OK, otherwise the electric fence electrode would still be too close.

    There is perhaps another solution which hasn't been discussed … export TT from another building (if there's overhead on the demand) … no need for a new electrode for the second building if you also export a protective conductor from the other TT building.

    That could be done as well. A nice idea. The proposed new installation is a small wooden building with no extraneous-conductive-parts, so no main bonding is required, Everything will be plastic inside the building, cable insulation, mini-trunking and wiring accessories.

    Z.

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