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Metal street furniture without an electrical supply: can it be omitted from a simultaneous-contact assessment?

Sam Kindred

Hi everyone, looking for a bit of help and guidance.

We install on-street EV charging supplied from a dedicated feeder pillar with a three-phase 69 kVA supply. Where the DNO permits PME, open-PEN protection is installed; otherwise, a TT arrangement is used.

My reading of the EV Charging Code of Practice, fifth edition, is that metalwork introducing true-Earth potential needs consideration. However, I regularly see metal crash barriers and signs close to chargers.

Can metal signposts, post boxes and bollards embedded in the ground within 2.5 m of a charging vehicle be omitted from the simultaneous-contact assessment, assuming no electrical equipment or connection to another electrical earthing system, even where they may introduce true-Earth potential?

Does the answer differ between TT and PME? Relevant regulation or guidance references would be appreciated.

Thanks.

 

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    Sam Kindred said:
    Can metal signposts, post boxes and bollards embedded in the ground within 2.5 m of a charging vehicle be omitted from the simultaneous-contact assessment, assuming no electrical equipment or connection to another electrical earthing system, even where they may introduce true-Earth potential?

    Quite simply, yes.

    Reasoning (italicised terms using the definitions in BS 7671):

    These might be extraneous-conductive-parts, but they have no exposed-conductive-parts.

    The 'simultaneous contact' issue of Regulation 411.3.1.1 applies to simultaneously accessible exposed-conductive-parts rather than extraneous-conductive-parts.

    Further, from BS 7671:2008 to present, there is no longer a need to provide 'main' protective equipotential bonding to extraneous-conductive-parts outside buildings (although an indoor car park is an example of being within a building). Having said that,  supplementary local protective bonding, if and where specified, would extend to them from simultaneously accessible exposed-conductive-parts even outside buildings

  • 0 in reply to gkenyon

    Thanks, Graham, really appreciate you clearing that up. This has been a bit of a thorn in my side for a while.

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