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 are approved by Ofgem.

Issue 34: Effective from 7 September 2018

This revised version of the GB Distribution Code is to implement the Demand Connection Code (DCC) into the GB arrangements.

The DCC specifically sets harmonised technical standards for the connection of new transmission-connected demand facilities, new transmission-connected distribution facilities and new distribution systems, including new closed distribution systems. It also addresses the performance requirements for new demand units used by a demand facility or a closed distribution system to provide demand response services to relevant network operators - ie both National Grid and the DNOs. Demand response services are an important instrument for increasing the flexibility of the internal energy market and for enabling optimal use of networks. Historically, generation facilities have formed the backbone of providing technical capabilities to network operators. However, demand facilities are expected to play a more pivotal role in the future.

The elements of the DCC that relate to the connection of demand to the transmission system are reflected in the Grid Code, but they have no impact for customers connected to distribution systems.

The DCC deals with five types of demand response services: two which relate to the modulation of real or reactive power for controlling flows of electricity on networks, and three services that relate specifically to National Grid services, ie transmission constraint management and two services for frequency control. Only the two services relating to flow control on distribution networks are picked up in the revisions to the Distribution Code, with the other three services being specified by National Grid in National Grid documentation.

Of course, distribution connected parties can provide demand side response services to National Grid, but in doing so they will be bound by National Grid’s contractual and technical requirements.

As described above, demand sides services for DNOs relating to the modulation of active power (demand) or reactive power are covered by the DCC. However the DCC only applies to those services that are procured by DNOs from new demand units.

The DCC introduces concepts of a demand facility and the demand unit. A demand facility is a customer’s installation where the customer has arranged all or part of the customer’s demand to be modulated as a service to network operator. Services to parties other than network operators (eg energy suppliers) are not covered by the DCC. A demand unit is a device that can be controlled in relation to the contract for demand side services within the demand facility. It is the age of the demand unit that determines whether the DCC applies or not; demand units installed and commissioned before 18 August 2019 are not required to comply with the DCC.

It is therefore quite possible that a single demand services contract with a network operator will include demand units that were commissioned before 18 August 2019 and do not have to comply with DCC requirements, and demand units commissioned after that date that do have to comply.

A new DPC9 (and associated definitions) have been added to the GB Distribution Code to implement the EU Demand Connection Code

Copy of Distribution Code Issue 34 can be found here.

Proformas referenced in the new DCP9 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)