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Simultaenous Contact

Dom

Good afternoon all, 

I am seeking the collective views of the group regarding the issues we are currently encountering within the EV installation environment in relation to simultaneous contact.

In simple terms, we are seeing a significant number of installations where customers have lamp posts located within their driveways. In many of these cases, it is not possible to achieve the recommended 2.5‑metre separation distance.

My position is that, where physical separation cannot be achieved, the application of layered protection at the EV charge point and associated switchgear would leave the customer in no worse position than prior to the installation. It is accepted that the proposal only outlines protection on the vehicle, but there are no other solutions for industry, are we with the protection detailed taking enough measures to carry out an install and in affect leave the install without a subsantial increase in risk?

My proposed approach to managing simultaneous contact risk would follow a structured hierarchy as set out below:

  • Can the maximum separation distance be achieved?
  • Can barriers or enclosures be installed to prevent simultaneous contact?
  • If neither of the above options are achievable, can layered protection provide an acceptable level of risk mitigation?

With layered protection, the proposed measures would include:

  • Installation of a compliant open‑PEN (O‑PEN) protective device
  • Provision of a double‑pole 30 mA Type A RCBO
  • Use of a charge point - M3 21 mA protection

Based on the above, the assumption is that, if all protective measures are correctly installed and verified, the installation would incorporate:

  • Automatic disconnection within the required times
  • Residual current protection
  • Open‑PEN fault detection

This combination of protections would significantly reduce the likelihood of a fault condition persisting for any meaningful duration.

On this basis, the key question for consideration is:

Where physical separation and barriers are not achievable, would it be considered acceptable to proceed with installation relying on this layered protection approach?

Parents
  • 0

    This is the kind of issue we are seeing folks.

  • 0 in reply to AJJewsbury

    If the main fault issue is a PEN / Broken PEN then surely that is an issue for the DNO to implement a monitoring system not the humble Electrician or the humble home owner.  Probably a round table discussion for IET and ESQR team?

  • 0 in reply to Dom

    Another thought, what about a possible voltage offset between the CPCs of adjacent properties as I'm pretty sure not all the installers check the electrode resistances.  Maybe a simple answer could be to build a wall between the properties and maybe fork off around the street lamp.  This would then give you a physical fire proof barrier which COULD remove the Simultaenous Contact issue all together.  Not sure what the correct height for the wall would be but lets say for the sake of this discussion about let say 1m50cm

  • 0 in reply to AJJewsbury

    Very common to cycle the 3 phases for houses in turn as you go down the street but lights often are on their own radial so small groups of  street lights can be isolated for maintenance.  As such they could be on any phase, and maybe not even the same transformer.  

    That opens an even bigger can of worms.


    It might be safer to charge the car stealing a supply from the street lamp, and certainly cheaper until you are found out ! Joking aside, the sort of situation in the picture is both unavoidable with on street charging and horrid.

    The neatest solution would be some kind of a non-conducting street lamp sleeve., but I'm not aware of one.

    Mike.

  • 0 in reply to mapj1

    What about the classic UK concrete lamp post from 1930 to 1990's.  Granted they were a bit heavier and .............

  • 0 in reply to Sergio Fernandez

    classic UK concrete lamp post  well, yes,  although  partly conducting when wet of course. Ideally when combined with the related 

    classic UK TNS earthing,  also starting from about 1930.. .   Sadly both seem to have largely gone.

    The interconnection of earths to street lamps and adjacent house supplies is the sort of thing that only the DNO can sensibly keep control or have records of, and even they may well not.
    Mike.

  • 0 in reply to Sergio Fernandez

    Hi Sergio - the barrier is a good idea and forms part of our process, however the practicalities of building structures for sim contact around lap posts in gardens is nor accepted well by clients

  • 0 in reply to Dom

    Totally understand.  Postal workers and delivery drivers also dislike them (Walls) as it makes them walk further

  • 0 in reply to Dom
    Dom said:
    This is the kind of issue we are seeing folks.

    That situation looks remarkable familiar.

    Fortunately, I am separated from the street lamp, which is more or less on the boundary, by a 2 m high brick wall.

    By contrast, the neighbours will need to be careful where they put the EVCP for their recently-purchased Jaguar.

  • 0 in reply to Chris Pearson

    Yes Chris - however the argument would be, the car can be parked at the end of that drive. If there is a 7.5 metere lead as standard then there is a sim contact risk there. The reality is there is a risk there as soon as an installer walks away from that property. There is no legal agreement dictating or limitating where that car is parked. 

  • 0 in reply to Dom

    Mind you with a 7,5m lead for a lot of houses, even ones with some sort of driveway,  it is actually perfectly possible to park next door, or on the pavement, and maybe the roadside for that matter, and still uncoil enough lead to plug in an EV.

    Do we worry about adjacent houses charging EVs on the street ? There must be a similar concern if we do. 
    It is perhaps just as well that most modern garden electrical items like mowers, hedge trimmers and pressure washers are double insulated or this would be a problem we already had, and more so, as very few folk will grip firmly  onto a car for very long while its plugged in, unlike a power tool. 

    The govt seems happy to allow on street charging from cables to the house, so this is probably already happening.

    https://www.gov.uk/guidance/apply-for-the-electric-vehicle-ev-pavement-channels-grant


    https://www.gov.uk/government/publications/cross-pavement-solutions-for-charging-electric-vehicles/cross-pavement-solutions-for-charging-electric-vehicles

    Mike.

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