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Transmission Interface Arrangements

NIE Networks is the owner of the transmission system and is required to develop, construct and maintain the transmission system in accordance with its Transmission Licence and the Transmission Interface Arrangements (TIA).

SONI is the operator of the transmission system and is required to plan and operate the transmission system in accordance with its Transmission Licence and the TIA.

NIE Networks and SONI (the Parties) each have an obligation under their Transmission Licences to prepare, obtain the Authority’s approval of, have in place and implement the TIA. The TIA sets out the commercial and operational arrangements between the Parties to ensure the efficient and co-ordinated planning, development, construction, maintenance and operation of the Transmission System.

The TIA Amendment Register

The Parties are required by Section O, Paragraph 2.3 of the TIA to establish and maintain the Amendment Register which shall set out:

  1. details of proposed amendments to the TIA
  2. the current status and progress of each proposed amendment
  3. the current status and progress of each approved amendment, and
  4. other matters as the Parties may consider appropriate.

This information can be downloaded using the links below (when relevant).

To receive notifications of changes to the Amendment Register please submit your contact details to Jenni.McKeown@nienetworks.co.uk.


TIA Document


TIA Subsidiary Documents


TIA Proposed Amendment Reports

  • Proposed Amendment Report 1 – NIE Networks – Distribution Connections Requiring Transmission Works

    Proposed Amendment Report 1 – consultation period open 5 April – 2 May 2023

    NIE Networks and SONI (the Parties) have carried out a review of the provisions in the Transmission Interface Arrangements (TIA) regarding connections to the Distribution System which require transmission works.

    NIE Networks concluded from the review that there are certain matters which, in NIE Networks’ opinion, need to be resolved and NIE Networks has now drafted a Proposed Amendment Report in accordance with the Governance process defined in the TIA.

    Part A of the Proposed Amendment Report sets out NIE Networks’ proposed amendments and the justification for these amendments.

    Part B of the report sets out SONI’s view of NIE Networks’ proposed amendments.

    In accordance with Paragraph 2.2.4.9 of Section P of the TIA, the Parties now wish to consult on these proposed amendments. The Proposed Amendment Report can be found on each Party’s website at nienetworks.co.uk/tia and soni.ltd.uk/transmission-interface-ar and views are invited on the proposals.

    Responses to this consultation should be submitted by email to Jenni.McKeown@nienetworks.co.uk or info@soni.ltd.uk.

    The closing date for receipt of responses is Tuesday, 2 May 2023.

    The Parties will review all representations received, produce an ‘Amendment Report’, containing a summary of representations, and submit it to the Utility Regulator for its consideration.

    View Report


TIA Amendment Reports

  • Amendment Report 1 – NIE Networks – Distribution Connections Requiring Transmission Works

    Amendment Report 1 – 28 July 2023

    NIE Networks and SONI (the Parties) have carried out a review of the provisions in the Transmission Interface Arrangements (TIA) regarding connections to the Distribution System which require transmission works.

    NIE Networks concluded from the review that there are certain matters which, in NIE Networks’ opinion, need to be resolved. The consultation period on the Proposed Amendment Report closed on 2 May 2023.

    In accordance with sub-paragraph 2.2.4.11 of Section P of the TIA, the Parties have now finalised and agreed an Amendment Report and submitted to the Authority for its consideration.

    View Report