In July 2018, the 18th Edition of the IET wiring regulations were published and specific guidance was given to the installation of charging stations for electric vehicles. There were several clarifications over previous editions and new requirements introduced. Therefore this document details the response from EO Charging with a view that this may help inform our installation partners and customers.
The regulations were published in July 2018 and is intended to come into effect on 1st January 2019. They can be purchased from the IET here - https://electrical-shop.theiet.org/books/bs-7671/bs-7671-2018.cfm
Specific areas of interest
Section 722 of the regulations specifies all of the requirements for electric vehicle charging installations. This section will highlight key requirements (marked in italics as <IET>) and also EO’s response (marked as <EO>).
Section 722.311 – Maximum Demand and Diversity
<IET>A dedicated final circuit shall be provided for the connection to electric vehicles
<EO> It is not possible to “daisy chain” the power to the charging stations. Each charging station shall have one dedicated supply with a dedicated RCD.
<IET> Where the final circuit supplies more than one charging point no diversity shall be allowed. Diversity may be allowed for a dedicated distribution circuit supplying multiple electric vehicle charging points if load control is available
<EO> if there is no load control, then the stations must have the full supply available e.g. if there are four 22KW stations then there must be 88KW available at all times.
However EO provide load control devices. The EO ALM unit (EO ALM Installation Guide) is available for the EO Basic and EO Mini products. The EO Genius also has Load Management options including scheduled, static and fully automatic (section 5 of EO Cloud User Guide).
Therefore diversity can be allowed with the correct use of EO’s load control products.
Section 722.411.4.1 – PME Earthing Systems
<IET> A PME earthing facility shall not be used as the means of earthing for the protective conductor contact of a charging point located outdoors or that might reasonably be expected to be used to charge a vehicle located outdoors.
<EO> This will mean that the use of an earthing rod is the primary mechanism for providing an earth connection for the charging station. The earth electrode should have a measured impedance of less than 150ohms in all normally expected conditions (e.g. summer or winter) to reliably charge all vehicles.
NOTE - The 18th edition also specify three scenarios where the use of PME is permitted. For example in the use of large 3 phase installations, the site’s earth is directly connected to the transformer and when a specific device is fitted to isolate all terminals in the case of a fault. However these 3 scenarios are the exception and not the intended norm.
Section 722.511.101 – 61851
<IET> EV charging equipment shall comply with the appropriate parts of BS EN 61851 series
<EO> All of our charging stations have been designed in accordance with 61851. Our products are currently undertaking external testing for certification against the IEC 61851 standard.
Section 722.512.2 – External Influences
<IET> Where installed outdoors, the equipment shall be selected with a degree of protection of at least IP4X …to protect against water splashes
<IET> Where installed outdoors, the equipment shall be selected with a degree of protection of at least IPX4…to protect against ingress of very small objects
<EO> All of our charging stations are designed with a minimum standard of IP54. The limiting factor being the socket.
Section 722.531.2 – RCDs
<IET> Each charging point incorporating a socket outlet or vehicle connector complying with BS EN 62916, protective measures against DC Fault current shall be taken, except where provided by the EV charging equipment. The appropriate measures, for each connection point, shall be as follows:
- RCD Type B; OR
- RDC Type A and appropriate equipment that provides disconnection of the supply in case of DC fault current above 6mA.
<EO> All of the EO Charging stations are available with a DC leakage detection feature, called DCL. This feature will open all the live conductors in the presence of 6mA DC Leakage Current. Therefore if this feature is fitted to the station, then the station can be installed with a Type A RCD for compliance with the regulations. This combination of DCL + Type A RCD is significantly cheaper than a Type B RCD. For example a Type A RCD is around £30 to £40 whereas a Type B RCD is around £200 to £300.
However, for scenarios such as public installations, then it may be prudent to consider specifying a higher specification RCD to ensure reliable operation. For example some vehicles can introduce harmonics and transients onto the mains which can cause nuisance tripping and so a transient resistant RCD may be a more suitable option. Consider the type of installation and choose the RCD appropriately.
Additionally other standards may apply for certain installations which have different requirements e.g. ZE Ready.
718.104.22.168.201.2 – Portable Sockets
<IET> Portable socket outlets should not be used but tethered vehicle outlets are allowed
<EO> Tethered options are available for the EO Mini and EO Basic stations
722.214.171.124 – Height of installation
<IET> The lowest part of any socket outlet shall be placed at around a height of 0.5m to 1.5m from the ground.
<EO> Install the unit at a convenient height for the user.
EO Charging welcome the introduction of the 18th Edition of the IET wiring regulations. The key points to highlight are:
- EO charging stations are compliant with the 18th
- EO can provide Load Control devices for the EO Basic, EO Mini and EO Genius charging stations to allow diversity in the installation.
- With the DC Leakage detection feature (DCL) fitted to the EO charging stations, then it is possible to install a type A RCD. However consider the application as higher grade RCDs may be required
- Do not use a PME earthing system rather install a dedicated earth spike for each station to ensure a reliable charging session.
EO looks forward to working with our installation partners to ensure successful installation and operation of the charging stations which will result is hassle free charging for our customers and drivers.
Chief Technical Officer
Further Technical Support
All EO Charging technical documentation is published in the EO Resource Centre, this is found at: https://www.eocharging.com/service-support/
The EO Support team can be reached at:
- Email: firstname.lastname@example.org
- Phone: +44 (0) 333 77 20383