SIMULTANEOUS CONTACT QUESTION - 2 x EV vehicles parked next to each other

Scenario

A remote block of 3 garages, 2 will be fed from separate properties via 40m of 10mm EV SWA connected to 2 individual new CU's

( no cars will be parked inside the garages but charged on the drive in front of the garage door)

1 property is TNC-S - Ze 0.30 Ohms and the other is visually a TNS but with Ze 0.32 Ohms and similar L-N reading.

The 2 chargers will have Pen fault protection and the relevant RCD protection as usual.

There are underground services within 1 -10m of a potential TT rod so could be problematic and a maximum 2.5m between separate garage earth rods is possible.


The concern is simultaneous contact between the 2 vehicles.

Regulation 411.3.1.1 states that “simultaneously accessible conductive parts shall be connected to the same earthing system individually, in groups or collectively.”

I am currently waiting for UK Power networks to confirm the 2 properties are connected to the same earthing system.


The questions are:

Is Pen fault and RCD protection enough when connecting both cars to TNS/TNCS or is there anything else we can do?

Is separate TT earth rods along with simultaneous risk assessment the safest option in this case?

Thank you


I've attached a sketch of the current proposal to help explain.
PDF

Parents
  • Dean,

    Obviously as you have indicated and good advice from Graham, and maybe its a remote option that could be considered.

    And that would be to install or erect some kind of "Wall/partition" between the two EV charging bays, to prevent similtaneous contact? Might not look pretty and obviously something a car could hit if not being carefull, but if done correctly could perhaps give an option if UKPN confirm the worst, just need to consider the fire rating and combustible nature of any "Wall/partition".

    Cheers GTB 

  • Are we not even allowed to have wooden fences near an EV charger now?

  • Thank you GTB, this could be an option, i was also thinking of maybe putting 2 chargers on one property with load balancing. One of the clients could use RFID to charge the cost to the main electricity account holder. 

    Just another thought!

  • Are we not even allowed to have wooden fences near an EV charger now?

    That might depend on your insurance company's perspective ... and that is not said in jest ... but BS 7671 of course doesn't really have any beef with it.

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