❓ This parliamentary question scrutinizes electricity transmission reliability in Western Australia's South West, focusing on outage data, supply configurations, and future infrastructure planning for growing regional towns. The answer provides some outage data and general planning principles but lacks specific details on future projects and risk assessments.
AnsweredQoN 2318Legislative Assembly
QuestionView source ↗
(1) In relation to electricity transmission reliability and planning in the South West region: For each of the following transmission lines—Margaret River to Busselton, Beenup to Manjimup, and Denmark to Walpole—how many outages have occurred in each of the past 10 years, and what was the duration and cause of each outage:(a) For each of the towns serviced by the above transmission lines, what is the current configuration of electricity supply (including the number of feeder lines and redundancy arrangements)?(2) Given the population growth and increasing demand in towns such as Margaret River, Busselton, Manjimup, Walpole and surrounding areas, why are certain towns serviced by only a single transmission line?(3) What criteria are used by Western Power and the State Government to determine when additional or redundant transmission infrastructure is required in regional areas?(4) Does the current Whole of System Plan include provision for additional or diverse transmission lines into these towns, and if so, what projects are proposed, their timelines, and estimated costs:(a) If no such provisions exist in the Whole of System Plan, what assessment has been undertaken regarding the risks to supply reliability and economic impacts on these regions?(5) Are there any planned upgrades or investments to improve network resilience in the Margaret River to Busselton, Beenup to Manjimup, and Albany to Walpole corridors; and if so, please provide details including scope, budget, and expected completion dates?
(1) In relation to electricity transmission reliability and planning in the South West region: For each of the following transmission lines—Margaret River to Busselton, Beenup to Manjimup, and Denmark to Walpole—how many outages have occurred in each of the past 10 years, and what was the duration and cause of each outage:
(a) For each of the towns serviced by the above transmission lines, what is the current configuration of electricity supply (including the number of feeder lines and redundancy arrangements)?
(2) Given the population growth and increasing demand in towns such as Margaret River, Busselton, Manjimup, Walpole and surrounding areas, why are certain towns serviced by only a single transmission line?
(3) What criteria are used by Western Power and the State Government to determine when additional or redundant transmission infrastructure is required in regional areas?
(4) Does the current Whole of System Plan include provision for additional or diverse transmission lines into these towns, and if so, what projects are proposed, their timelines, and estimated costs:
(a) If no such provisions exist in the Whole of System Plan, what assessment has been undertaken regarding the risks to supply reliability and economic impacts on these regions?
(5) Are there any planned upgrades or investments to improve network resilience in the Margaret River to Busselton, Beenup to Manjimup, and Albany to Walpole corridors; and if so, please provide details including scope, budget, and expected completion dates?
(1) In relation to electricity transmission reliability and planning in the South West region: For each of the following transmission lines—Margaret River to Busselton, Beenup to Manjimup, and Denmark to Walpole—how many outages have occurred in each of the past 10 years, and what was the duration and cause of each outage:
(a) For each of the towns serviced by the above transmission lines, what is the current configuration of electricity supply (including the number of feeder lines and redundancy arrangements)?
(2) Given the population growth and increasing demand in towns such as Margaret River, Busselton, Manjimup, Walpole and surrounding areas, why are certain towns serviced by only a single transmission line?
(3) What criteria are used by Western Power and the State Government to determine when additional or redundant transmission infrastructure is required in regional areas?
(4) Does the current Whole of System Plan include provision for additional or diverse transmission lines into these towns, and if so, what projects are proposed, their timelines, and estimated costs:
(a) If no such provisions exist in the Whole of System Plan, what assessment has been undertaken regarding the risks to supply reliability and economic impacts on these regions?
(5) Are there any planned upgrades or investments to improve network resilience in the Margaret River to Busselton, Beenup to Manjimup, and Albany to Walpole corridors; and if so, please provide details including scope, budget, and expected completion dates?
AnswerView source ↗
Answered
10 June 2026
Responded by
Minister for Energy and Decarbonisation
Response time
9 days
(1)
Denmark to Walpole is fed via the distribution network, not directly via the transmission network.
Busselton to Margaret River transmission line experienced seven outages as a result of weather, infrastructure failure or an unspecified cause. The average duration of these outages was 9 hours and 39 minutes.
Manjimup to Beenup transmission line experienced five outages as a result of weather, bushfire, infrastructure failure or an unspecified cause. The average duration of outage was 15 hours and 22 minutes.
Line outages do not always result in customer outages, as Western Power may be able to back feed some customers through the distribution network depending on configuration.
(a)
Margaret River Zone substation is fed via one single 66kV circuit. Beenup Zone substation is fed via one single 132kV circuit. Busselton Zone substation is fed via a two 66kV circuits and one 132kV circuit. Manjimup Zone substation is fed via two 66 kV circuits and one 132kV circuit. Denmark and Walpole are fed from the distribution network.
(2 - 3)
Western Power monitors demand and reviews network requirements in accordance with the Technical Rules and risk-based planning principles.
(4 – 5)
Each year, Western Power publishes the Transmission System Plan on its website. This plan outlines forecast growth, load and demand in the South West Interconnected System (SWIS).
Western Power continues to work to improve capacity in the South West as demand grows, including through planned expansions to Busselton Zone substation and Picton-Capel line upgrades.
Denmark to Walpole is fed via the distribution network, not directly via the transmission network.
Busselton to Margaret River transmission line experienced seven outages as a result of weather, infrastructure failure or an unspecified cause. The average duration of these outages was 9 hours and 39 minutes.
Manjimup to Beenup transmission line experienced five outages as a result of weather, bushfire, infrastructure failure or an unspecified cause. The average duration of outage was 15 hours and 22 minutes.
Line outages do not always result in customer outages, as Western Power may be able to back feed some customers through the distribution network depending on configuration.
(a)
Margaret River Zone substation is fed via one single 66kV circuit. Beenup Zone substation is fed via one single 132kV circuit. Busselton Zone substation is fed via a two 66kV circuits and one 132kV circuit. Manjimup Zone substation is fed via two 66 kV circuits and one 132kV circuit. Denmark and Walpole are fed from the distribution network.
(2 - 3)
Western Power monitors demand and reviews network requirements in accordance with the Technical Rules and risk-based planning principles.
(4 – 5)
Each year, Western Power publishes the Transmission System Plan on its website. This plan outlines forecast growth, load and demand in the South West Interconnected System (SWIS).
Western Power continues to work to improve capacity in the South West as demand grows, including through planned expansions to Busselton Zone substation and Picton-Capel line upgrades.
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