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Balanced 3 Phase Supply for EVC

Mark Fleming

Hi,

Please could someone advise on the following regarding EV chargers on a balanced 3 phase supply. 

We are proposing to install 3 x 75kw DC rapid chargers from a new DNO connection solely for the EV chargers. The chargers themselves only require 3 phase & earth and the only 230v supply from the new connection is a small anti-condensation heater within the feeder pillar (20w). 

Can I therefor still use the rule of thumb from CoP J4 as Regulation 722.411.4.1 (i) has now been removed from amendment 2? 

When I calculate using Regulation 722.411.4.1 (ii) I end up with a minus number so I assume this shows an earth electrode & PME supply is not suitable?

Thank you in advance.

Mark

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  • +1

    Not if you want to comply with BS 7671:2018+A2:2022

    I guess one worry is that a broken PEN doesn't necessarily effect just a single installation - even if your installation is perfectly balanced with zero N current, the supply CNE could still be a long way from true Earth potential - due to connected loads in neighbouring installations, if the LV network is shared.

        - Andy.

  • 0 in reply to AJJewsbury

    This is always the worry when not coming direct from the transformer and knowing what is connected to neighbouring supplies would be impossible to ascertain. 

    I am only asking about it as we are now have a new rapid DC charger in our portfolio which doesn't require the neutral so I was hoping we might be able to simplify the installation. 

    The other chargers we use all require neutrals and are not balanced and/or have both mode 3 & 4 so its not really been considered before. 

    Thank you for all your input.

Reply
  • 0 in reply to AJJewsbury

    This is always the worry when not coming direct from the transformer and knowing what is connected to neighbouring supplies would be impossible to ascertain. 

    I am only asking about it as we are now have a new rapid DC charger in our portfolio which doesn't require the neutral so I was hoping we might be able to simplify the installation. 

    The other chargers we use all require neutrals and are not balanced and/or have both mode 3 & 4 so its not really been considered before. 

    Thank you for all your input.

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