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Draft for Public Comment: IET Code of Practice for Electrical Energy Storage Systems 2nd edition

The draft of the 2nd Edition of the IET Code of Practice for Electrical Energy Storage Systems, which our Principal Graham Kenyon co-authors, is now available for public comment on the IET web-site.

Comments can be submitted until 10 July 2020.

This IET Code of Practice, which brings together approaches from various standards including BS 7671 to provide authoritative and comprehensive guidance on the subject, is referenced by the recently published MCS Battery Storage Standard.

IET Wiring Matters Article on the 4th Edition EV Code of Practice

Our Managing Director, Graham Kenyon, has prepared an article for the latest Issue 80 – May 2020 – of the IET’s Wiring Matters industry publication. looking at the the key changes in the 4th Edition of the IET Code of Practice for Electric Vehicle Charging Equipment Installation.

As Graham is the technical author of the publication, the article provides a unique perspective on the technical aspects.

Read the article here

The online course for EV charging equipment installation has also been updated to reflect the 4th Edition of the IET Code of Practice, and Amendment 1 (2020) to BS 7671:2018.

Fourth Edition of the EV Code of Practice now available

The 4th Edition of the IET Code of Practice for Electric Vehicle Charging Equipment Installation is now available. Our Managing Director, who is the lead author of the publication, provides a commentary on the key changes and new information.

The 4th Edition, available from the IET, is updated to BS 7671:2018 + A1:2020, and also includes:

  • guidance for on street installations updated to cover a wide range of situations
  • new information on load unbalance in three-phase installations
  • guidance on the selection and use of new open-PEN detection
  • guidance on the dangers associated with TT islands, and safe separation distances below ground for earth electrodes
  • Amendment 1 (2020) to BS 7671:2018 in its entirety

Open PEN detection where PME conditions apply

Regulation 722.411.4.1 (iii), (iv) and (v) permit the use of protective devices which detect open-circuit protective earth and neutral (PEN) conductors in the PME supply.

These devices are relatively new, and there are no product-specific standards available at present. The 4th Edition provides the guidance that installers need to select and install these new protective devices.

The device described in 722.411.4.1 (iv) is only suitable for installations with single-phase supplies, and should not be used for single-phase charging equipment in a three-phase installation. An important feature of the wording in 722.411.4.1 (iii) and (iv) is that the devices shall not be capable of re-closing onto the conditions they detect are hazardous. In order to provide equivalent safety, a device described in 722.411.4.1 (v) must also have the same feature.

A new approach to phase unbalance in three-phase systems

Our Managing Director has developed a new approach to determining whether exception (i) to Regulation722.411.4.1 applies in a three-phase system. This method removes the need for calculations using the formulas in Annex 722, A722.1 and A722.2, and relies only on knowledge of the worst-case unbalance conditions, and either use of a lookup table, or application of a rule-of-thumb.

This method is described fully in Annex J of the IET Code of Practice for EV Charging Equipment Installation 4th Edition.

Updated guidance on deriving a TT earthing arrangement from a TN supply

Unsafe installation practices have been observed where a separate TT supply is used for electric vehicle charging equipment. Further, this approach may not offer any benefit at all in small curtilage properties, such as a common semi-detached dwelling.

New and extended guidance is now included, to help designers and installers:

  • determine when it is unsafe to employ a TT earthing arrangement in installations with TN supply earthing arrangements
  • understand the risks associated with driving electrodes
  • ensure adequate separation distances below ground, between exposed-conductive-parts connected to different earthing arrangements
  • ensure an adequate separation distance below ground between the TT earth electrode, and buried conductive parts connected to the TN earthing arrangement, and understand that in certain cases, distribution network operators require a greater separation distance

Other new or revised guidance

There is an update to the section on Vehicle as storage, including new material by Dr Andrew Crossland and Mark Collins of Advance Further Energy, and new arrangements for installation of EVSE in prosuming installations by our Managing Director. The section on Integration and smart infrastructure has also been updated to include new material from Cameron Steel of Silver EMS.

The DNO notification process has been updated, and guidance is now included on earthing arrangements for the installation of Mode 4 (DC rapid charging) EVSE, some of which employs isolation between the AC source and the DC vehicle charging supply.

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MCS launches new Battery Storage Standard

In January 2020, MCS launched its new standard for battery energy storage, MIS 3012.

The new standard, completed with the assistance of our Managing Director, Graham Kenyon, as technical author, outlines the requirements for battery storage systems that MCS certified installers will use to design, supply and install electrical energy (battery) storage systems.

Read more about the launch on the MCS website.

The standard may be downloaded from the MCS Standards and Tools Library.

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Amendment 1:2020 to BS 7671:2018

3 February 2020 heralded the publication of the first amendment to BS 7671:2018 Requirements for electrical installations (IET Wiring Regulations 18th Edition). Graham Kenyon discusses an important aspect of this update.

The changes will support the rollout of electric vehicle charging equipment infrastructure.

Use of a PME earthing terminal

The principal change introduced in Amendment 1 relates to Regulation 722.411.4.1. This makes it possible to use the emerging technology of open-PEN detection devices, which were not available when BS 7671:2018 was published. This change should be well-received in the industry, as it is not always practicable, or safe, to derive a TT earthing arrangement, where other parts of the installation have a different earthing system such as TN-C-S (PME) or TN-S.

Single-phase supplies

The PME earthing terminal may be used for installations with a single-phase supply (to the whole installation) where:

  • An additional earth electrode is provided that meets the requirements of 722.411.4.1 (ii). It may be impractical to achieve a low enough earth electrode resistance in many single-phase installations.
  • A single-phase open-PEN detection device is used, that complies with 722.411.4.1 (iii), (iv) or (v). A device complying with (iii) will require a measurement earth electrode in single-phase installations. A device to (iii) or its equivalent in (v) may be installed in or near the charging equipment, or upstream of the charging equipment. A device to (iv) or its equivalent to (v) is intended to be installed in or near the charging equipment.

Three-phase supplies

The PME earthing terminal may be used for installations with three-phase supplies (to the whole installation) where:

  • The three-phase installation is sufficiently well balanced so that it is unlikely that the touch voltage will exceed 70 V rms if the PME supply neutral breaks, according to 722.411.4.1 (i).
  • An additional earth electrode is provided that meets the requirements of 722.411.4.1 (ii). Depending on the anticipated worst-case phase unbalance, it may be possible to achieve a low enough earth electrode resistance in three-phase installations.
  • An open-PEN detection device is used, that complies with 722.411.4.1 (iii) or (v). The device may be installed in or near the charging equipment, or upstream of the charging equipment. If the device is upstream in a three-phase portion of the network, it may protect single-phase charging equipment downstream. Where a device to (iii) requires an earth electrode, it may be installed on single-phase circuits or in/near single-phase charging equipment.

The relevant distribution network operator (DNO) should be consulted regarding the use of open-PEN detection devices for on-street installations. Street lighting supplies are often effected through three-phase distribution mains and therefore would typically be classed as three-phase supplies for the purposes of Regulation 722.411.4.1.

What is the problem with deriving a TT earthing system for the charging equipment as an alternative for PME supplies?

The problems with deriving a TT earthing system from a PME supply in a particular installation may include:

  • Ensuring sufficient separation below ground from buried metalwork connected to the PME earthing system. If too little separation is provided, the vehicle is, for all practical purposes, connected to the PME earthing system.
  • Simultaneous contact assessments are required, between the charging equipment/vehicles and extraneous-conductive-parts and exposed-conductive-parts connected to the original installation earthing system.
  • The possibility of returning a touch voltage in PME broken neutral situations, for someone standing next to the vehicle on charge, if they are standing above buried metalwork or extraneous-conductive-parts connected to the PME earthing system. This may be just as hazardous as the original PME risk, under certain ground/soil conditions.
  • The possibility of striking buried services if driving rods or excavating to install earth electrodes.

The above situations are more likely to be found in small curtilage properties, such as many dwellings.

Further guidance – 4th Edition of the IET Code of practice for EV charging equipment installation

The 4th Edition of the IET Code of practice for EV charging equipment installation is due to be published very soon. This is a major update with extensive guidance on Amendment 1:2020, and the topics discussed in the article.
Improvements include information on:

  • Use of open-PEN detection devices.
  • Issues with TT systems, including recommended separation distances underground.
  • Improved risk assessment forms.
  • Phase unbalance in three-phase systems, including a table and rule-of-thumb which can be used to avoid complex calculations.
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Graham discusses electric vehicle charging infrastructure challenges

In this interview following the London electric vehicle charging infrastructure strategy launch, at the IET, Savoy Place, London, on Monday 17 June 2019, Graham discusses the challenges that, particularly in UK cities, must be overcome to realise our climate change and pollution commitments.

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Graham supports the Mayor of London’s plan for electric vehicle charging infrastructure

Our Managing Director, Graham Kenyon, was pleased to support London Mayor Sadiq Khan’s launch of the plan for the electric vehicle charging infrastructure in London on Monday 17 June 2019.

Graham, Chair of the IET’s Wiring Regulations Policy Committee, author of the 3rd Edition of the IET’s Code of practice for electric vehicle charging equipment installation, chaired a technical question and answer session as part of the launch event.

Read more about the launch in this IET Member News article.

Photo from IET Member News article
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New on-line course for electric vehicle charging equipment installation

G Kenyon Technology Ltd, as a content partner with the IET Academy, has developed an on-line course for designers and installers of Electric Vehicle Charging Equipment Installations.

Book now with the IET Academy

Learn on-line, at your own pace

Course Overview

This course will cover: the design of electrical installations for, and specification of, electric vehicle charging equipment installations; the requirements detailed in Section 722 of BS 7671:2018; and recommendations of the IET Code of Practice for Electric Vehicle Charging Installations, 3rd Edition. It provides an understanding of the key requirements for protection against electric shock, including selection and use of earthing systems, and introduces vehicle-as-storage, wireless power transfer (WPT) and smart infrastructure installations.

Book now with the IET Academy

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Working safely with energy storage and smart control technologies

Imaged linked from IET Wiring Matters web-site

Many electrical installations now incorporate new technologies, including embedded generation and home or building automation systems. As use of these technologies becomes more widespread, we need to be ever mindful that control of power to a circuit no longer relies on simple human switching operations. Electrical energy storage technologies that are capable of operating in island mode, continue to provide power when the grid is isolated.

Some incidents that have occurred recently when implementing energy storage systems outside the UK prompted Dr Andrew Crossland and myself to write an article for IET’s Wiring Matters. The article highlights the risks, and discusses safe isolation.

Click here to read the article in IET’s Wiring Matters.

Further guidance on electrical energy storage systems can be found in the IET Code of Practice for Electrical Energy Storage Systems.

Note: G Kenyon Technology Ltd cannot be held responsible for the contents of other web-sites linked from this post.

December 2018 Corrigendum available for BS 7671:2018

IET publishes Corrigendum for the 18th Edition

The IET have today (20 December 2018) published a Corridengum to BS 7671:2018 (IET Wiring Regulations 18th Edition).

To download the Corrigendum, please visit the IET’s dedicated BS 7671 web page.

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