Licensed electricity distribution businesses, or Distribution Network Operators (DNOs) in Great Britain, are obliged under Condition 21 of their licences to maintain a Distribution Code detailing the technical parameters and considerations relating to connection to, and use of, their electrical networks.


Electricity North West

Northern Powergrid

Scottish and Southern Electricity Networks

SP Energy Networks

UK Power Networks

Western Power Distribution


Eclipse Power Networks

Energetics Limited

ESP Utilities Group

GTC (comprising both ETCL and IPNL licences)

UK Power Distribution Limited

Energy Assets Networks Limited

Fulcrum Electricity Assets Limited

Harlaxton Energy Networks Limited

Leep Electricity Networks Limited

Murphy Power Distribution Limited

Utility Assets Limited

Vattenfall Networks Limited

The GB Distribution Code

All DNOs currently operate the same version of the Code, and the Code is maintained by the Distribution Code Review Panel. All modifications to the Code have to be approved by Ofgem.

Issue 31: Published May 16 2018

This version of the Code has been revised to allow for compliance with the European Network Code Requirements for Generators achieved by the introduction of two new Engineering Recommendations (EREC) G98 and G99. Click on the relevant link for a copy of the new EREC G98 or EREC G99

Distribution Code Issue 31 is effective from 17 May 2018 and replaces Distribution Code Issue 30

PLEASE NOTE: The Distribution Code Issue 31, G98 and G99 are incorrect in stating that compliance is required from 17 May 2019.  The actual effective date when compliance is required is 20 days earlier - ie 27 April 2019.  We will update all three documents as soon as possible - but this is a formal process requiring approval by Ofgem.  We will aim to do this as soon as possible.

Click here to download a copy of Distribution Code Issue 31

Authority Decision can be found here.

Issue 32: Published May 24 2018 (effective from 1 July 2018)

This version of the Code has been revised as a result of modifications to annex 1 qualifying standards Engineering Recommendations (EREC) G59 and G83. G59/3-3 has been modified and is now referenced as G59/3 Amendment 4, and G83/2 has been modified and is now referenced as G83/2 Amendment 1.

The modifications made to EREC G59 and EREC G83 mandate that all type tested generators, commissioned on or after 1 July 2018, shall demonstrate stability for appropriate RoCoF and vector shift disturbances. These modifications are:

  • That the rate of change of frequency (RoCoF) criterion used for Loss of Mains protection must be 1Hzs-1 with a definite time delay of 500ms.
  • That vector shift protection technique should not be used as Loss of Mains protection for generators using discrete relays as part of loss of mains protection scheme and that the generation must not trip for vector shifts of up to 50º.
  • That type-tested generation includes stability tests to prove immunity to RoCoF and vector shift less than the above criteria.

A minor update to Guidance Note 2 has also been made to reflect this change.

PLEASE NOTE: Although version 32 has been published it will not become effective until 1 July 2018. It has been published so manufacturers are aware of the required modifications to G83 and G59 in advance of the date of effect.

Click here to download a copy of Distribution Code Issue 32

Copy of EREC G83/2 Amendment 1 can be found here.

Copy of EREC G59/3 Amendment 4 can be found here.

Authority Decision can be found here.

For previous versions of the GB Distribution Code click here

Distribution Code User Guide
The guide gives a high level overview of the Distribution Code, and is aimed at anyone with an interest in the Distribution Code. It contains information about the regulatory structure in Great Britain and Europe and also provides a simple explanation of the various sections of the Distribution Code.

Click here to download the current version of the GB Distribution Code User Guide

Annex 1 and Annex 2 Documents

Some requirements of the Distribution Code are implemented through other industry documents. They are listed in Annex 1 of the Distribution Code, and are mostly Engineering Recommendations. These documents typically cover certain technical areas in detail, such as connection of generation, switchgear ratings and supply quality planning limits.

There are other industry documents which are not implemented via the Distribution Code, but do have a material impact on distribution network users. These are listed in Annex 2 of the Distribution Code.

Standards and other documents referenced in Annex 1 and Annex 2 of the Distribution Code are available for free and can be downloaded at the following link:

Click here for Annex 1 and Annex 2 documents

Standard Governance Procedure

DNOs or Users may bring proposals for modifications to Annex 1 Standards and Annex 2 Standards for consideration by the DCRP Panel. DNOs and Users bringing forward proposals for modifications to Annex 1 Standards and Annex 2 Standards shall set out in general terms the aims of their proposal and the likely impact, including costs.

Further information on how to submit a modification can be found here.

Useful Links

Association for Decentralised Energy (formerly the Combined Heat & Power Association)

Association of Meter Operators

Department for Business, Energy & Industrial Strategy (formerly DECC)

Energy UK

Major Energy Users’ Council

Meter Operation Code of Practice Agreement (MOCOPA)

Microgeneration Certification Scheme

National Grid

National Grid
The Grid Code


Renewable Energy Association

Renewable UK

Solar Trade Association

Sustainable Energy Association (formerly Mircropower Council)