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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?

  • 0 in reply to lyledunn

    That's my point. The car cannot be part of the installation.

    If the charging lead plugs in to the EVCP, as opposed to being attached, that is not either.

    This brings me back to the balcony solar PV discussion and where the boundaries of BS 7671 lie.

  • 0 in reply to Chris Pearson
    Chris Pearson said:
    That's my point. The car cannot be part of the installation.

    It doesn't have to be.

    Class I equipment relies on protection in the installation, so the installation needs a means to ensure that exposed-conductive-parts of Class I equipment are so connected.

    The equipment to be considered doesn't need to be part of the electrical installation.

    lyledunn said:
    But is the car an exposed conductive part? To be such, it needs to fit the definition and so must be considered "equipment". As per 113.1, the regulations only apply to equipment that is selected for the installation. 

    No, but the car can have exposed-conductive-parts.

    See the definition of 'Class I equipment' in BS 7671.

    More importantly, according to BS EN 61140, which applies to electrical equipment and installations, a Class I appliance or item of electrical equipment connected to an installation, and the installation, the system providing ADS is treated as one system, and the earthing and bonding of the installation, and the protective bonding system in the appliance, are required to be treated as one protective bonding system.

  • 0 in reply to Chris Pearson

    I belive the nearest exposed conductive part, so yes it would be the car. I also have issue with the 2.5 metre distance. I belive this may be taken from the placing out of reach measurement. The averge finger to finger span is around 1.75 metres - I think it would be good to get some clarity on this as well. 

  • 0
    Dom said:

    This is the kind of issue we are seeing folks.

    The recommended approach here is to contact the DNO/IDNO and ask them if the two properties and lighting column are connected to the same earthing system before deciding on anything. With cross-pavement charging, this is only going to be a more frequent issue.

    In this particular case, I'm guessing it may well not be permitted to erect a fence or barrier due to either planning constraints, or covenants or other terms in the deeds.

    As a last resort, A722.5 provides a solution, but it's not cheap, might have inrush issue, and might take a lot of space.

    At the end of the day, BS 7671 (and HD/IEC 60364 series) had the provision well before work was started on EV charging standards, so I'm up for saying this is not necessarily a BS 7671 issue, but the EV charging standards agreeing on Class I rather than Class II for the LV charging system ?

  • 0
    Dom said:
    I also have issue with the 2.5 metre distance. I belive this may be taken from the placing out of reach measurement. The averge finger to finger span is around 1.75 metres - I think it would be good to get some clarity on this as well. 

    The clarity is provided in BS 7671 (and IEC/HD 60364 series, IEC 60364-4-41). It could not be more plain.

    Simultaneously accessible is explained quite clearly in Regulation Group 417.3, including Figure 417. The 2.5 m is clearly stated in terms of an interpretation of 'simultaneously accessible'

    The basic principle is in the NOTE to Regulation 417.3.2:

    We wouldn't ever use the 'average finger to finger span' but an arm span that a large percentage of the population is guaranteed to be under. The P95M (95th percentile male) value of arm span, means that 95 % of males will have an arm span less than the value, and that is 1.90 to 1.96 m ... hence, when calculations are carried out by DNOs for their earthing systems, which aligns with the approach for HV standard BS EN IEC 61936-1 and BS EN 50522, they will use a value of 2 m.

    However, the value in IEC/HD 60364-4-41 and BS 7671 is likely to be the P95M arm span, holding something conductive of length 250 mm ish in each hand, or holding something conductive of length up to 500 mm in one hand.

    Don't forget, HV standards for touch/step potential are usually mainly applied within the boundaries of substation fences (or similar) where only skilled, instructed or supervised persons, wearing appropriate clothing and footwear, are intended to be present. BS 7671 on the other hand has to be suitable for 'ordinary persons' for the most part.

  • 0 in reply to gkenyon

    Our process is to contact the DNO to confirm the earthing system, however we are now in a posistion where the DNOs are saying this is the responsibilty of the installer rather than the DNO and they are unable to support. I am unsure if this is down to the fact there are to many asks on them at present.

  • 0 in reply to Dom

    Yes, they might be finding the demands difficult ... but the installer can't determine the answer any other way. 

    I do sympathise.

  • 0 in reply to gkenyon

    Thanks Graham - I knew the note was present, the point I would challenge is the 2.5 metre. However you have clearly articulated where this figure comes from. I do feel there may be a case to look at this in terms of the additional 250mm-500mm hand held point however I also see the importance of the worst case sceanrio. What would be benficial is looking at the stats behind actual events and quantifying what we have seen over the years. Granted this does not elliminate the risk but like O-pen it provides detail into the level of occurence. 

  • 0 in reply to gkenyon

    In terms of looking at the EV COP risk assessment - step 3. Where we have a tethered charge point of say 5 metres, would it be deemed safe to say that if we add the distance of charger lead, the EV car (max UK size) and then the 2.5 metre distance that this would be sufficient precaution? I appreciate that car type can change but by taking this into account have steps been taken to matigate that risk?

  • 0 in reply to gkenyon

    Can ESQCR 2002 help?

    R.15 obliges a DNO to keep a map of underground parts of the network and to make it available for inspection, etc.

    R. 28 obliges a DNO to state the type of earthing system.

    Both are available to somebody who has reasonable cause, which I feel sure must apply.

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