Electricity Codes
These pages contain information on the electricity codes that National Grid produces and maintains. Please use the links below for more information on each code and relevant contact details.
Connection and Use of System Code (CUSC)
The Connection and Use of System Code (CUSC) is the contractual framework for charging and connection to, and use of, National Grid’s high voltage transmission system. Find out more about this using the links below.
National Grid charges companies to connect to and use the electricity transmission system. The methodologies that National Grid follows to derive these charges are set out in the CUSC. For more details, follow the link below:
Grid Code
The Grid Code permits the development, maintenance and operation of an efficient, co-ordinated and economical system for the transmission of electricity, and facilitates competition in the generation and supply of electricity and promotes the security and efficiency of the power system as a whole. National Grid and users of its transmission system are required to comply with the Grid Code. Find out more about this using the link below.
System Operator - Transmission Owner Code (STC)
The STC defines the high-level relationship between National Grid as National Electricity Transmission System Operator (NETSO) and Transmission Owners. It is supported by a number of procedures (SOTO Code Procedures or STCPs) that set out in greater detail the roles, responsibilities, obligations and rights etc of the NETSO and the TOs. Find out more about this using the links below.