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TT or PME..best practice?

Evening all,


I’m currently looking into running a submain approx 100m buried from a PME supply to a small outbuilding (timber frame, metal sheet clad) that is being used next to a glamping tent as a place to cook and shower etc. The sub main will be a 16mm SWA..I was initially going to run a 3 core SWA or potentially a 2 core SWA with a seperate 10mm CPC (slight cost reduction) with the later option. I’ve since thought that perhaps a TT install would suffice, and, as possibly in the future I might be asked to extend the power into the tent, which, would require a TT setup. Any thoughts of this from a safety point or preference, also, if deciding on a TT and running a 2 core SWA as a submain which would obviosuly be a cost saver compared to a 3 core, however, would it be best practice to still have a CPC available seeing as a trench is now open...future proofing....? just as a side note, the metal sheets will be bonded to earth and any plumbing in the building is plastic pipes, also, this isn’t a question about cable selection i.e. the sub mains might be 16 or 25mm once I know exactly what the client wants, this question relates to the earthing setup. Thanks in advance!.

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  • Zoomup:




    lyledunn:

    Graham,

    do you mind expanding on item 2?




    I think that Graham is implying that any sudden disconnection of the loaded 100m cable, may induce a large Voltage whilst the magnetic field collapses in it, that might damage connected equipment or even the insulation of the cabling. The S.P.D.s would adsorb that high Voltage and limit damage.


    Z.


     




    I was thinking more in terms of lightning and surge protection "zoning", what in the US are sometimes called "ground windows"

Reply

  • Zoomup:




    lyledunn:

    Graham,

    do you mind expanding on item 2?




    I think that Graham is implying that any sudden disconnection of the loaded 100m cable, may induce a large Voltage whilst the magnetic field collapses in it, that might damage connected equipment or even the insulation of the cabling. The S.P.D.s would adsorb that high Voltage and limit damage.


    Z.


     




    I was thinking more in terms of lightning and surge protection "zoning", what in the US are sometimes called "ground windows"

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