Accelerated Loss of Mains Change Programme


This is an industry led project delivered by National Grid ESO, Distribution Network Operators, and Independent Distribution Network Operators to accelerate compliance with new requirements in the Distribution Code.

National Grid ESO and GB Distribution Network Operators (DNOs) / Independent Distribution Network Operators (IDNO) are undertaking electricity transmission and distribution industry led initiative managed on behalf of the Distribution Code Review Panel.

The purpose of the initiative is to consider Loss of Main (LoM) protection and their settings. The aim being to reduce the risk of inadvertent tripping and reduce system balancing issues by giving National Grid ESO greater latitude with regards to system RoCoF limits.

It is a requirement of the Distribution Code that all owners of generation installed prior to February 2018, and where the generation equipment is not type-tested, to comply with new setting requirements for the interface protection in accordance with EREC G59.  Owners of generation have to comply with the Distribution Code and have until May 2022 to comply with these modified interface protection requirements.  After that date owners who have not made the change will be the subject of an enforcement programme.

To help owners of generation make the necessary changes, through ENA, National Grid Electricity System Operator (NGESO), the Distribution Network Operators (DNO) and Independent Distribution Network Operators (IDNO), have set up a database to allow generators to register their intention to make settings changes and to facilitate the development of a prioritised delivery programme. This database is expected to be available to generators by the end of  August 2019. It is intended that generators who make the settings changes will be recompensed by the DNO / IDNO they are connected to according to the degree of work involved in making the changes.

The documents and links below are intended to provide further information and guidance as to how generators can become involved with this setting changes programme.

Included in the links below there is a request for feedback on how National Grid Electricity System Operator (NGESO) and network operators (including both distribution network operators and independent distribution network operators) propose to deliver the accelerated loss of mains protection changes programme required by the Distribution Code and to ensure that the industry has an opportunity to comment on our approach and highlight potential areas for improvement.

These documents and this webpage will be updated as the programme develops.

Submit an application                                                                                                                                                                                                                                                              

  • Connected generators are requested to register their intention to make settings changes through the database set up for that purpose This database will allow generators to submit all of the information required to assess the registration and consider it for the settings change programme.
  • It is intended that generators will undertake the settings changes themselves through their own contractors or site management teams. Where a generator does not have these facilities a list of contractors available to undertake the setting changes on behalf of the generator can be found here
  • FAQs – As the programme progresses replies to queries will be posted here.
  • Further information regarding issues raised by other stakeholders involved in the LoM project can be found here.
  • National Grid Electricity System Operator (NGESO), the Distribution Network Operators (DNO) and Independent Distribution Network Operators (IDNO) are in the process of acting upon the feedback provided in response to the “Request for Feedback” issued in May. This includes seeking further feedback from inverter manufacturers. The open letter on this specific topic is here although views from any stakeholder are also most welcome. 

Getting Involved                                                                                                                                                         

Below are links to documents detailing how generators and contractors can get involved with the accelerated loss of Mains Programme.                              

Project governance                                                                                                                                                           

Project governance documents will be available here as they are developed and agreed.                        

Stakeholder Information

Further stakeholder information can be found here and in the links to documents below. This will be developed as the programme progresses.

  • Slides from stakeholder events held in London and Glasgow in April 2019 detailing the purpose and programme can be found here

Contact us

If you have any questions regarding the request for feedback on the accelerated loss of mains protection settings programme please do not hesitate to contact us at the email address below

  • [email protected]
  • Links to National Grid and DNO/IDNO email boxes concerned with the assessment and delivery of the programme can be found here. Please check who your DNO/IDNO is here before contacting these addresses.