NESOOFGEMDESNZ
Grid Code
GC0178Workgroup

GC0178: Temporary Overvoltage - Specification of Limits and Clarification of Obligations

NESO (Grid Code)·regulation·medium·12 Mar 2025·source document

What is being proposed

This modification aims to specify limits on temporary overvoltage, clarify the obligations applicable during such events, and address any related issues.

Current status

The Proposal was submitted to the March Grid Code Review Panel where it was agreed unanimously that the modification should follow the Standard Governance route and proceed to Workgroup. Workgroup Nominations opened on 01 April and closed on 01 May. A modification update will be presented to the January Panel, asking for a pause, to allow sufficeint time for a consultant to be appointed. The Proposer will present an updated and detailed timeline and the February Panel meeting. 09/03/2026 A timetable upate with be presented in the April Panel, once a newly appointed consultant has scoped the work to be carried out.

Details

Proposed byNESO
Decision byOfgem
GovernanceStandard Governance (Workgroup)
Impact onHigh impact on Generators, Transmission System Owners, Interconnectors, Transmission Owners
Also affectsSTC

Timeline

Proposal raised12 Mar 2025
Code Administrator Consultation opens4 Sept 2026
Code Administrator Consultation closes5 Oct 2026
Panel vote29 Oct 2026
Sent to Ofgem16 Nov 2026

Analysis

GC0178 seeks to specify limits on temporary overvoltage events and clarify generator obligations during such events. The modification is proceeding through Standard Governance and has been paused to allow appointment of a consultant to scope the work. High impact parties include generators, transmission owners, and interconnectors.

Why it matters

This codifies operational boundaries that generators must meet during grid stress events, potentially imposing new technical compliance costs on generation assets. As such, it shifts voltage management obligations from network operators to generators without yet specifying the economic allocation of these costs.

Key facts

  • Standard Governance route agreed unanimously
  • Workgroup nominations closed 01 May
  • Consultant appointment required before proceeding
  • Cross-code impact on STC

Areas affected

generatorstransmissiongrid connections

Related programmes

RIIO-ET3