Index of Significant Events in the NEM

This page contains an index of significant events that have occurred through the history of the NEM, in reverse chronological order, complete with links to additional documentation and discussion where available.

This record will evolve over time through future iterations, hence the authors would appreciate your suggestions in terms of other events to be included. Data collated prior to January 2016 is sparser, deliberately, just to ensure the list is manageable.

2023 Calendar Year

23rd September 2023 – South Australia experiences ultra-low demand, largely due to mild spring weather and rooftop solar generation. Market demand momentarily goes negative to -14MW on this day. Operational demand hit a low of 23MW almost one week prior.
31st August 2023 – AEMO release 2023 ESOO, which forecasts significant reliability gaps over the 10-year outlook period under their central scenario.
19th May 2023 –  Energy Ministers agree to incorporate an emissions reduction objective into the National Electricity Objective, National Gas Objective and the National Energy Retail Objective.
28th April 2023 – Liddell Power Station is officially retired after its final unit (Unit 1) ceases operations.

25th April 2023 – Grass fires in NSW cause the temporary shutdown of Beryl Solar Farm.

22nd April 2023 – A market suspension is placed on the VIC region for approximately 24 hours, following a glitch in SCADA systems.

17th March 2023 – Brief market suspension of the NSW region following a service interruption of SCADA system.
February 3rd February 2023 – The Reserve Trader is dispatched in QLD.

2022 Calendar Year

November 12th November 2022 – Storms damage part of the Heywood interconnector, and as a result, South Australia becomes electrically islanded from the rest of the NEM for roughly one week.
October 14th October 2022 – 530MW of load is lost in Tasmania and trip of Liapoota – Palmerston 220kV lines and Basslink.
September 29th September 2022 – The Energy Security Board’s ‘Health of the NEM’ and the AER’s ‘State of the Market” reports are released just one day after the QLD Government publishes several major policy announcements in their ‘Energy and Jobs Plan’.
June 24th June 2022 – The market suspension is lifted after nine days.

15th June 2022The AEMO announce a suspension of the market after declaring that conditions meant it was “impossible to operate the spot market”.

12th June 2022Administered Pricing commences in the QLD after the region’s cumulative price hits it’s threshold.

May 30th May 2022 – Wholesale gas prices in Victoria hit the Cumulative Price Threshold.
1st April 2022 – Liddell Unit 3 ceases operations, the first of the four Liddell units to do so.
2nd March 2022 – Hazelwood Cranbourne No. 4 500 kV line trip.
February 10th February 2022 – Trip of Sydney North 330/132 kV Transformer and 132 kV busbar.

1st February 2022 – The Reserve Trader is dispatched in QLD, and IPRM drops to 5%.

January 27th January 2022 – Trip of Eildon Power Station No. 2 220 kV Bus.

1st January 2022 – Trip of Bell Bay No. 3 and No. 4 Potlines.


2021 Calendar Year

December 15th December 2021GenInsights21 released.
November 21st November 2021 – For the first time, market demand for a region in the NEM goes negative. Market demand in South Australia drops to -46MW on a mild Sunday afternoon. Six days later, the region’s market demand went into negative territory again when it hit -43MW.
October 1st October 2021 – Five-Minute Settlement commences.
September 19th September 2021Minimum demand in NSW hit a record new low on Sunday 19th, superseding the record set one week prior.
July 30th July 2021 – The Victoria Big Battery, which had just began commissioning, caught fire.
June 11th June 2021 – Output at the Yallourn site suffered following flooding at the neighbouring Yallourn coal mine.

21st June 2021 – Gas supply and low wind conditions drove some periods of tight supply.

May 25th May 2021 – Callide C4 unit suffered a catastrophic failure.

17th to 20th May 2021 – Periods with large price forecast differences occurred in VIC, SA & NSW (evening periods).

March 12th March 2021a fire at Torrens Substation triggered a trip of Barkers Inlet power station and extreme prices.  Articles about this event are catalogued here:
January 24th January 2021 – the AEMO suffered a total loss of SCADA data, which impacted on its ability to dispatch and manage the electricity system.

24th January 2021 – Bushfires in South Australia caused the trip of several transmission lines connecting into Cherry Gardens substation in the Adelaide Hills:


2020 Calendar Year

December 15th to 17th December 2020 – The NSW region saw price volatility – with Reserve Trader dispatched.
October 13th October 2020 – The QLD dispatch price spiked to $15,000/MWh as a result of interactions of the constraint set ‘Q-BCNE_821’.
March March 2020 – the National Electricity Market saw some impacts of measures implemented to address the risks of COVID-19.
February 19th and 20th February 2020 – Rebid reasons for Eraring indicate ash plant issues contributed to multiple unit outages. Bayswater unit 2 also experienced a unit trip mid-month, taking 6 days to return to full availability.
January 31st January 2020 – Towards the end of a day of extreme temperatures in the southern regions, a weather system uprooted transmission towers on the Heywood interconnector, leading to the islanding of South Australia from the rest of the NEM.

10th January 2020 – Both Eildon to Mt Beauty 220kV lines tripped and after reclosing tripped again and remained out of service. Following this, the power system was not in a secure state and constraint automation was used to manage the risk, primarily through formulations which adjusted interconnector flows.

4th January 2020 – Bushfires through the Snowy Mountains caused the separation of the NSW and VIC regions.


2019 Calendar Year

December 21st December 2019Trip of Mt Piper to Bayswater and Mt Piper to Wollar 500 kV lines and Trip of Mt Piper Unit 1.
November 16th November 2019 – South Australia was islanded from the rest of the NEM.
October 9th October 2019 – there was a trip of Both Potlines at Alcoa Portland Aluminium Smelter.
August August 2019 – Market notices documented directions in SA that were necessary to maintain power system security on 9th & 10th, 17th – 21st, 23rd, 30th & 31st ; more days than any other month in the year.
January 24th and 25th January 2019 – A heatwave through VIC and SA triggered Reserve Trader and load shedding. An AEMO incident report regarding the load shedding in Victoria during the very hot days of 24 and 25 January 2019.

Late January 2019 – Multiple occasions (14th-18th, 22nd, 29th, 30th) of high afternoon and evening prices (in association with hot weather) forecast yet generally not eventuating due to rebidding.


2018 Calendar Year

August 25th August 2018 – Both QLD and SA were islanded from the rest of the NEM via a rare ‘double islanding’ event.
February 16th February 2018Calliope River to Boyne Island trip, Gladstone 1 Trip and Loss of No.3 Potline at Boyne Island.

17th February 2018: Trip of both Chalumbin to Woree 275 kV lines due to lightning, 30 MW generation and 204 MW Load lost.

January 18th February 2018Trip of Rowville 500 kV Busbar, Rowville to South Morang 500 kV line, LYB1 Generator and 600 MW of Load.


2017 Calendar Year

November 13th November 2017 Inadvertent Loss of Load in Tasmania during testing of testing of AUFLS.  319 MW Load lost for 49 minutes.
March 3rd March 2017 : Torrens Island Switchyard fault, Loss of Multiple Generators totalling 610 MW

12th March 2017 Basslink trip resulting in 383 MW of Load shed in Tasmania.

February Early February 2017 – High temperatures driving demand QLD. In many instances forecasts for high prices between 14:00 and 20:30 only partially eventuated (1st – 13th Feb).

8th February 2017 – SA System Event, High demand, Forced Outages and Load shedding to restore system security.

10th February 2017 – NSW System event. Record demand (14,181 MW), Forced Outages and Tomago Smelter load reduced to restore system security.

January Late January 2017 – High temperatures driving demand in QLD. In many instances forecasts for high prices between 14:00 and 20:30 only partially eventuated (20th – 31st Jan). High overnight temperatures on the 21st in Brisbane.


2016 Calendar Year

December 20th December 2016 Trip of Sheffield to Georgetown 220 kV lines with Loss of Generation and Load.

1st December 2016 South Australian Separation Event.

September 28th September 2016 – South Australia suffered the ‘SA System Black’ event after a major weather event. This article provides an index to relevant reports completed by the relevant bodies.
July 31st July 2016Trip of both Farrell to Reece 220 kV lines and Reece Power Station, likely due to Lightning.  239 MW generation lost.

Mid-July 2016 – Network outages to complete augmentation works on the Heywood Interconnector between Victoria and South Australia materially reduced its capacity (AER 13 September 2016, Electricity spot prices above $5000/MWh South Australia, 7 July 2016).  Average daily prices were above $500/MWh from 6 July to 8 July, and above $400/MWh 12 July to 14 July 2016.

June 13th June 2016 – The Basslink cable was returned to service on 13th June 2016 (after having been out of service since 21st December 2015).
May May 2016 – Northern Power Station in South Australia closes.  The last day of generation was on 10 May 2016.
February 9th February 2016 – Trip of Gordon to Chapel Street & Liapootah to Wayatinah and Wayatinah to Catagunyah and Generation lost.


2015 Calendar Year

December 12th December 2015 – The Basslink interconnector was disconnected due to an undersea fault approximately 100km off the Tasmanian coast.
November 1st November 2015 – Load Shedding South Australia 1 November 2015, SA operated as an Island for 35 minutes.
August 2nd August 2015 – Underfrequency Load Shedding in Tasmania.
February 3rd February 2015Trip Heywood to Tarrone and Moorabool to Tarrone 500 kV lines and APD Potlines.
January 21st January 2015 – North Queensland Power System Events. Multiple Transmission lines and NQ Hydros Tripped.


2014 Calendar Year

December 11th December 2014: Trip of Mullumbimby to Dunoon to Lismore 132 kV Line, And 3.6 MW load at Dunoon.

10th December 2014Loss of Basslink and Transmission lines in Tasmania, 10 and 16 December and 23 Feb 2015.

October 23rd October 2014Trip of Liddell to Tamworth 330 kV line and Bayswater Unit 3.
August 28th August 2014 – The Warburton Review was released. Its recommendations included a scaling back of the Renewable Energy Target.  The review was heavily criticized as not being a truly independent review and being too pro-coal.
July 14th July 2014Simultaneous Trip of Torrens Island B3 and B4.  System in unsatisfactory state afterwards.
May 9th May 2014 Trip of APD to Heywood to Tarrone, Moorabool to Tarrone and APD Busbar.
March 19th March 2014Trip of Bannaby to Mt Piper 500 kV transmission line, and Bayswater Unit 4.
January 15th January 2014Trip of Red Cliffs to Horsham, Red Cliffs to Wemen to Kerang 22 kV transmission line and Loss of Load.

5th January 2014Trip of Rowville to Yallourn 220 kV transmission line and Multiple Wind Farms.


2013 Calendar Year

December 23rd December 2013Both Millmerran Units Tripped.

11th December 2013Trip of Upper Tumut 330 kV Busbars, and loss of generation from Upper Tumut.

November 17th November 2013 Trip of Sydney West busbar and Sydney West to Liverpool 330 kV transmission line, and observed decrease in demand.
October 21st October 2013Both Callide C Units tripped.

13th October 2013Trip of Rowville to Thomastown 220 kV line and Multiple Wind Farms.

13th October 2013Trip of Bayswater to Mt Piper 500 kV line and Wallerawang Unit 7.

September 8th September 2013Trip of Tarrone to Moorabool 500 kV, loss of 345 MW generation and Islanding of Macarthur WF.

29th September 2013Trip of Ringwood to Rowville 220 kV line and Multiple Generators.

July 4th July 2013Trip of Alcoa Portland to Heywood to Tarrone and Tarrone to Moorabool 500 kV line, and Island of Macarthur WF.
June 21st June 2013 – Fire in Yallourn caused three Units to trip.

Mid-June 2013 – In SA,  many instances of forecasts for high evening prices did not eventuate due to rebidding.


2nd March 2013Trip of Chalumbin to Woree 275 kV lines , Loss of generation at Barron Gorge Power Station, and 214 MW of load

9th March 2013Both Millmerran Units Tripped.

21st March 2013Lightning strikes and Load reductions at Pacific Aluminium Potline.

February 26th February 2013Loss of Both Units Northern Power Station after trip of Davenport 275 kV line.
January 27th January 2013 – Loss of Multiple Units at Gladstone Power Station during Wet weather.

26th January 2013 – Trip of Gladstone to Calliope River 275 kV line and Gladstone Unit 1.

25th January 2013 – Trip of Sydney South to Wallerawang, Ingleburn to Wallerawang 33 kV lines and Trip of Wallerawang Unit 8 during bushfires.

8th January 2013 – Trip of Canberra to Capital and Capital to Kangaroo Valley 330 kV lines, Trip of Multiple WF’s during bushfires.


2012 Calendar Year

June 29th June 2012 – A 5.4 magnitude earthquake directly underneath the Latrobe Valley tripped 3 of 4 Loy Yang A units and 1 Yallourn unit due to vibrations.  Approximately 1955 MW of generation was affected, 400 MW of Load shed, of which 200 MW was in Tasmania with UFLS.
March 28th March 2012 – the trip of the Sydney West 132 kV busbar resulted in up to 170 MW of customer load being interrupted.
February February 2012 – Last generation from Playford B Power Station in South Australia.  It was then mothballed that same year.  Permanent closure was announced in October 2015.


2011 Calendar Year

December 1st December 2011 – A trip of Chalumbin to Woree 275 kV line resulted in loss of 132 kV supply and 188 MW of load in the Cairns area.
February 2nd and 3rd December 2011 – Cyclone Yasi which was a Category 5 Tropical Cyclone had a big effect on North Queensland.  Twelve 132 kV transmission lines tripped out of service due to damage from high winds, one substation and one power station automatically disconnected from the grid.  Reduced demand in North Queensland caused high voltage levels on the 275 kV transmission network.


2010 Calendar Year

October 24th October 2010 – Failure of an earth wire caused the trip of the Kurri to Rothbury 132 kV line resulting in 300 MW of load being shed when all three Potlines tripped.
July 7th July 2010 – The trip of 132 kV busbars at Sydney North resulted in a number of transmission lines off loading and 148 MW of customer load interrupted.

29th July 2010 – An operating error at the Point Henry smelter resulted in the trip of the 220 kV busbar and 105 MW load shed.


2009 Calendar Year

November 28th November 2009Three major transmission lines in NSW tripped during severe weather and bushfires.  Over 1400 MW of load was interrupted or shut down as a consequence.  243 MW of load was interrupted from the Argenton/Merewether substation, 400 MW from the Hydro Aluminium smelter and 840 MW of load reduced from the Tomago smelters when it was manually shutdown.

5th November 2009Calvale to Tarong 275 kV line tripped as well as Tarong Unit 2.

July 2nd July 2009 – A failure of a current transformer in the Bayswater switchyard led to Eight generating Units tripping offline for a total loss 3,205 MW, multiple transmission lines being disconnected and over 100 MW of Load shedding.
March 8th March 2009 – Severe electrical storms led to the trip of both Chalumbin to Woree 275 kV lines tripping resulting in a loss of supply to Far North Queensland.
February 7th and 8th February 2009 – Extreme weather and bushfires led to separation of Victorian and New South Wales regions. There was also load shedding in Victoria.
January 29th January 2009The NEM experienced is highest-ever level of NEM-wide peak demand with extreme temperatures in southern regions and significant bushfire. These extremes in temperature subsequently led into the ‘Black Saturday’ bushfires on February 7/8 across Victoria and parts of Tasmania, South Australia and NSW.

22nd January 2009 – System Black Event in North Queensland when Ross to Strathmore 275 kV lines tripped.  NEMMCO declared a System Black at 1736 hours as more than 60% North Qld demand had been interrupted.


2008 Calendar Year

October 31st October 2008Low reserves and high prices in NSW.
July 1st July 2008 – The Snowy region ceased to exist, with generators formerly in the Snowy region assigned to the NSW and VIC regions.
March March 2008Sustained high temperatures across many days for South Australia.
February 28th February 2008 – Queensland separated from NSW, caused by a failure of a disconnector at the Armidale 330 kV substation.


2007 Calendar Year

December December 2007 – Through 2007 and into 2008, the same weather pattern delivered low rainfall levels and ‘The Millennium Drought’, which impacted on electricity supplies in a number of ways.  By the end of June 2007, Lake Eucumbene at Snowy was down to 50GL of usable capacity (<3% active water level).
October 24th October 2007 – Multiple Outages in NSW region when Mt Piper to Marulan 330 kV line tripped due to a lightning strike, and the 330 kV Main Bus at Mt Piper tripped due to a wiring error.

29th October 2007 – Simultaneous outage of two 330 kV transmission lines in Southern NSW.

June 20th June 2007 – Loss of Boyne Island Smelter No.1 and 3 Potlines and Gladstone 4 Generating Unit.
January 16th January 2007 – Separation of Victoria and Snowy regions when bushfires crossed under the path of significant transmission interconnection between Snowy and Melbourne, leading to a large amount of load shedding. Several articles are collated here:


2006 Calendar Year

April 21st April 2006 – Trip of No. 2 and 6 132 kV buses at Boyne Island due to a single phase fault resulted in loss of supply to No.2 Potline. Unit 3 at Gladstone also tripped due to under voltage on the 6.6kV supply.
March 20th March 2006 – Cyclone Larry resulted in twelve outages significant damage on the 132 kV transmission network and loss of customer load.
January January and February 2006 – Multiple fires burning across south eastern Australia


2005 Calendar Year

May May 2005 – The Tasmanian region joined the NEM – initially as an islanded region with no interconnection capacity, until the Basslink interconnector commenced.


2004 Calendar Year

August 13th August 2004A current transformer in the Bayswater switchyard exploded which resulted in Three Bayswater Units tripping and as well as three other Units: Eraring 2, Vales Point 6 and Redbank.

2003 Calendar Year

November November 2003 – No.1 Bus Trip at Tarong, due to current transformer failure resulting in Five 275 kV lines being tripped or offloaded.

2002 Calendar Year


2001 Calendar Year

January January 2001 – Bushfires trip the Vic – Snowy interconnector under high export conditions, resulting in numerous units trips in Victoria

2000 Calendar Year

November November 2nd 2000 – A wildcat strike by union officials in support of Industrial action at Yallourn saw several power stations in the Latrobe Valley involved, severely restricting generation at Yallourn and Hazelwood power stations, and completely shutting down Loy Yang A (whilst) Loy Yang B was unaffected).

1999 Calendar Year


1998 Calendar Year

December 13th December 1998 – The NEM commences operations.