TS41-24 and EREC S34 Working Group

Project Description

ENA Technical Specification 41-24, “Guidelines for the Design, Installation, Testing and Maintenance of Main Earthing Systems in Substations” (a D-Code Annex 1 document) was published in 1992 and is still widely used today. It is now in need of a review and update to account for new technology and developments in International, European and British Standards.

Key documents are:

  • IEC/TS 60479-1 “Effects of current on human beings and livestock – Part 1: General aspects”
  • IEC/TR 60479-5 “Effects of current on human beings and livestock – Part 5: Touch voltage threshold values for physiological effects”
  • BS EN 50522 “Earthing of Power Installations exceeding 1kV ac”
  • IEC and EN 61936-1 “Power installations exceeding 1kV ac – Part 1: Common Rules”
  • HSE Recommendations to BSI Committee PEL/99 on application of IEC/TS 60479

In parallel, it is proposed to revise ENA Engineering Recommendation S34, “A Guide for Assessing the Rise of Earth Potentials in Substations” which forms some of the background to ENATS 41-24. The work of revision of ENATS 41-24 will be done by a Working Group of the ENA Earthing Co-ordination Group with the assistance of an external Consultant. The Consultant will attend, and provide technical input to, Working Group meetings and carry out background analysis and calculations, inter alia, in the following areas:

  • touch step and transfer potentials;
  • interpretation of standards in respect of separation of HV and LV earths;
  • development of risk assessment methodology.

The calculations will be carried out using the CDEGS software package (including RESAP, MALT, MALZ modules) or equivalent.

Project commencement date: June 2012

Target completion date: 31 December 2016

Working Group Membership

As of August 2016

Jim Paine Northern Powergrid (Chairman)
John Baker Scottish and Southern Electric Power Distribution
Graham BrewsterWestern Power Distribution
Dongsheng Guo National Grid Electricity Transmisson
Steve TuckerUK Power Networks
David Crawley ENA (Co-ordinator)
Mark Davies Edif ERA (Consultant)
Rob WellerEdif ERA (Consultant and lead author)

Working Group Meetings

At each meeting, a new draft prepared by the Consultant is discussed and modified. The changes to the draft serve as the minutes of the meeting.

For draft versions prior to 2016, please contact David Crawley at david.crawley@enaconsulting.org

Date of meeting Draft of S34Draft of 41-24Other docs
2 February 2016 - ENAClick hereClick here
13 April 2016 - ENAClick hereClick hereClick here
28 June 2016 - ENAClick hereClick here
20 September 2016 - ENAClick hereClick here
2 November 2016 - ENAClick here
6 December 2016Click here
14 March 2017Click hereClick here
3 May 2017Click here Click here
15 August 2017Click here
Click here
11 October 2017 Click here
Click here


A public consultation was opened on Friday 8 December 2017 seeking responses from interested stakeholders on the latest revision drafts of both TS 41-24 and S34. The consultation will close Friday 26 January 2018. Full details of the consultation can be found via the Consultations home page - http://www.dcode.org.uk/consultations.html