What is CUSC (Connection and Use of System Code)?

CUSC (Connection and Use of System Code) explained | EnergyCode

The industry code that governs access to and charging for the national transmission network - it defines how TNUoS charges are calculated and the rules for connecting large generators and supplies.

While DCUSA governs the distribution network, CUSC governs the transmission network - the high-voltage backbone that carries electricity across Great Britain. It's the rulebook for how generators and large customers connect to and pay for using the transmission system.

What CUSC covers:

Connection arrangements for large generators and demand
Transmission Network Use of System (TNUoS) charging methodology
Balancing Services Use of System (BSUoS) methodology
Rights and obligations of transmission users
Change process for transmission-related modifications

CUSC Modifications Process: When changes to transmission charging are needed, they go through a formal CUSC Modification Proposal (CMP) process. Major recent modifications include:

CMP361 - Fixed BSUoS tariffs from April 2023
CMP343 - Changes supporting the Targeted Charging Review

Why CUSC matters: The TNUoS and BSUoS charges on your bill are calculated according to methodologies defined in CUSC. Understanding the code helps explain why charges work the way they do - for example, why TNUoS varies by location (14 zones) or why BSUoS is now a fixed rate.

Governance: CUSC is governed by a panel with representatives from generators, suppliers, network operators, and consumers. Ofgem has ultimate authority to approve or reject modifications.

CUSC

Related terms

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