We are becoming a separate company

In April 2019, the Electricity System Operator is becoming a separate company within the National Grid Group. Find out more about what this change will mean.


Electricity codes form the framework and rules for operating the British electricity transmission network. Each of the codes focuses on a different area of the industry. Find out more about the following areas of codes.

Code modifications search

Modifications (Mods) are raised to propose changes to a number of different codes. They can revise any part of the code that they relate to.

Current or concluded modifications can be searched for by name or ID. They can also be filtered by current or concluded. By clicking ID, Name, Status and Last updated you can sort modifications to suit your requirements.

Codes calendar

The codes calendar contains code meetings (previous and upcoming), as well as other key dates and events across all electricity codes.

Go to the calendar

Connection and Use of System Code (CUSC)

The CUSC is the contractual framework for connection to, and use of, the National Electricity Transmission System (NETS).

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Grid Code

The Grid Code (GC) is the technical code for connection and development of the National Electricity Transmission System.

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Security and Quality of Supply Standards

The Security and Quality of Supply Standards (SQSS) set out criteria and the methodology for planning and operating the National Electricity Transmission System.

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Code Administration Code of Practice

Developed by code administrators and users, the CACoP aims to facilitate transparency of the code modification process and help protect the interests of small market participants.

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System Operator Transmission Owner Code

The System Operator Transmission Owner Code (STC) defines the relationship between the transmission system owners and the system operator.

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European network codes

European network codes (ENC) cover grid connections, markets, and system operation, providing a sustainable, secure, and competitive electricity market across Europe.

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Balancing framework and the Balancing and Settlement Code (BSC)

Documents required by our licence and details relating to the electricity balancing system (EBS) project.

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Standing groups

Giving industry participants the opportunity to discuss codes-related issues in further detail. These issues may be relevant to one or more of the codes.

Find out more