Transgrid Project Specification Consultation Report: Managing risk on Lines 21, 22, 959 & 92Z (conductor condition)

Market Network Service Provider, National Electricity Market
StageProject Assessment Conclusions Report
ConvenorAEMO NSP
Accepting submissions?No
Submissions close14/05/2024

Transgrid has published the Project Specification Consultation Report (PSCR) to assess options for remediating deteriorating conductor condition on four transmission lines in the Transgrid overhead transmission network (Line 21, Line 22, Line 959 and Line 92Z). Publication of this PSCR represents the first step in the Regulatory Test for Transmission (RIT-T) process.

Transgrid’s overhead transmission network contains sections where the condition of conductors is deteriorating such that they have reached, or are close to reaching, end of life. The deteriorated condition of conductors can be caused by a variety of mechanisms such as:

  • annealing due to bushfire exposure;
  • corrosion initiated by bushfire exposure; and
  • corrosion at mid-span joint locations.

Transgrid has undertaken analysis of conductor condition and deterioration mechanisms across its network, which identified approximately 1,100 km circuit length of conductors that have condition issues that require attention.
If action is not taken, the conductor deterioration is expected to lead to an increasing level of risk going forward, as the likelihood of failure increases. There are safety and bushfire risks under the ‘do nothing’ base case, as well as higher expected costs associated with reactive maintenance that may be required under emergency conditions (‘financial risk’). The proposed investment will enable us to manage safety, bushfire and financial risks on the affected lines.
We manage and mitigate safety and environmental risk to ensure they are below risk tolerance levels or ‘As Low As Reasonably Practicable’ (‘ALARP’), in accordance with our obligations under the New South Wales Electricity Supply (Safety and Network Management) Regulation 2014 and our Electricity Network Safety Management System (ENSMS).

In the PSCR Transgrid presented one credible network option that would meet the identified need from a technical, commercial, and project delivery perspective. This PSCR finds that implementation of Option 1 is the preferred option at this draft stage of the RIT-T process. Option 1 involves targeted replacement of existing conductors along Line 21 (Tuggerah-Sydney North), Line 22 (Vales Point-Sydney North), Line 959 (Sydney North-Sydney East) and Line 92Z (Sydney North-Sydney East).

The estimated capital cost of this option is approximately $36.6 million ($2023-24) +/- 25 per cent. Transgrid is the proponent of the proposed network project. Transgrid welcomes written submissions on materials contained in this PSCR. Submissions are due on 14 May 2024.

In accordance with the requirements of the Rules, a summary of the Project Specification Consultation Report is made available on the AEMO website. A copy of the PSCR can be obtained from Transgrid’s website or by emailing

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