CAP189: Standard Gas Insulated Switchgear Ownership Boundaries

CAP189 is raised following a recommendation of the joint Grid Code/ CUSC Gas Insulated Switchgear Working Group, whose report was presented to the May 2010 CUSC Amendments Panel meeting. The Working Group sought to clarify a number of issues identified relating to Gas Insulated Switchgear (GIS) assets. CAP189 specifically seeks to modify the CUSC such that a User requesting a connection to the National Electricity Transmission System, via a GIS substation, will be able to elect one of the following standard ownership boundaries and construction options:

  1. Generator Standard Boundary
  2. DNO Standard Boundary – User builds all the GIS assets
  3. DNO Standard Boundary – User builds their own assets only

The boundary description is intended to reflect the boundary that Generator and DNO Users would typically choose, but the recommendation will allow any User to choose either boundary.

Modification status: Concluded

Last updated: 18 June 2020

Code Administrator Contact: Thomas Derry - [email protected]

Governance Route: Fast track


* High: New build generation connections, DNO connections; new and asset replacement of existing sites. Transmission Owners.

* Medium: National Electricity Transmission System Operator (NETSO) 

* Low: Existing generation

Implemented: 30 January 2012



Workgroup Report

Workgroup meetings and summary papers

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Workgroup Consultation

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Code Administrator Consultation

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Draft/Final Modification Report