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TT earth spike installation Temporary Porta cabin Classrooms

The school supply is a 300Amp incomer on a PME which has a MCCB Panelboard in place. 3no Temporary Porta cabin Classrooms are to be delivered to site which will remain in use for around 3to6 months then removed from site. They are to be wired into 3no x 3phase spare ways located in the MCCB Panelboard. I have suggested they must be independently made into TT supplies to comply with clause 717. The contractor suggests it is OTT because all other services entering the Porta cabin Classrooms will be piped in plastic ie water connection etc. The cabins are cladded so are not your typical metal exteriors. My fear is the loss of Neutral from the PME. All circuits in the classrooms will be 30mA. Would love to know peoples thoughts. Am I over thinking it with it being temporary ?
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  • Former Community Member
    0 Former Community Member

    6.2.3.4 Supplies to other temporary buildings



    For temporary buildings, eg temporary classrooms, a PME earthing terminal may be supplied if the installation is constructed so that a person in contact with the general mass of earth cannot touch any metalwork of the temporary installation and the installation complies with the bonding and earthing requirements of BS 7671. In such cases, a temporary building may be treated in the same manner as a permanent building. A PME terminal shall not be offered for a temporary building which is not constructed as above (e.g. metalclad buildings) .


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  • Former Community Member
    0 Former Community Member

    6.2.3.4 Supplies to other temporary buildings



    For temporary buildings, eg temporary classrooms, a PME earthing terminal may be supplied if the installation is constructed so that a person in contact with the general mass of earth cannot touch any metalwork of the temporary installation and the installation complies with the bonding and earthing requirements of BS 7671. In such cases, a temporary building may be treated in the same manner as a permanent building. A PME terminal shall not be offered for a temporary building which is not constructed as above (e.g. metalclad buildings) .


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