CMP330/374 Connection and Use of System Code (CUSC) proposed changes

Details of outcome 

The Gas and Electricity Markets Authority (the Authority) has decided to reject CMP330/374, including both the Original Proposal and WACM1. 

The proposal was developed alongside CMP414, which was intended to introduce the wider legal and operational framework necessary to support these changes. 

Following the withdrawal of CMP414, the Authority concluded that implementing CMP330/374 would not provide a coherent or workable basis for delivering the intended policy outcomes. The Authority therefore determined that neither the Original Proposal nor WACM1 better facilitates the Applicable CUSC Objectives and decided not to approve the modification. 

Code modification description 

CMP330 was raised by National Grid Electricity System Operator (now National Energy System Operator (NESO)) to allow new transmission-connected users to construct connection assets greater than 2km in length. CMP374 was raised to extend contestability for transmission connections and provide greater flexibility in how connection assets could be delivered. The proposals were subsequently amalgamated into CMP330/374. 

The modification sought to support competition and increase flexibility in the delivery of transmission connection assets. However, the proposal relied on the implementation of CMP414, which was intended to establish the wider governance, legal and operational framework required for the new contestability arrangements. Following the withdrawal of CMP414 by NESO in June 2026, the Authority assessed CMP330/374 against the prevailing circumstances and concluded that it should not be approved.