Load shedding
A combination of planned and unplanned events might impact available electricity reserves in South Australia, or across the National Electricity Market.
These events can include:
- Bushfires
- Extreme weather events such as heatwaves, floods and storms
- High electricity demand
- Transmission network constraints
- Generation or infrastructure outages or critical maintenance
Electricity reserves are managed and monitored by the independent Australian Energy Market Operator (AEMO). When demand for electricity exceeds supply, the system can be at risk of uncontrolled outages.
On these occasions, AEMO may direct SA Power Networks to reduce demand by switching off the supply to some customers to restore the balance. This is known as load shedding.
Expand each section below to learn more.
Load shedding is a systematic process of cutting off supply to customers for a short time in stages, to ensure demand is met by available supply and prevent widespread uncontrolled outages or, at worst, a grid shutdown.
If AEMO directs load shedding, it will give SA Power Networks a supply reduction target. SA Power Networks will act to begin the staged approach to switching off supply to meet that target within minutes.
With high levels of rooftop solar installed in South Australia, heatwaves are less of an issue for network capacity than they have been historically. As a result, load shedding was last used in 2017.
Load shedding is done by pre-determined groups which rotate from event to event. The group which has gone the longest without load shedding will be turned off first. This ensures load shedding impacts are shared fairly across the state.
Critical infrastructure, hospitals, the CBD and significant businesses and facilities such as major shopping centres are exempt from load shedding. The list of exemptions is created by the Office of the Technical Regulator.
The most recent rotation for load shedding is listed publicly: South Australian electricity manual load shedding list.
The maximum time load shedding is allowed to impact a single group of customers is 1 hour. Power restoration after load shedding takes only a few minutes.
If the imbalance across the system has not been corrected by the first round of load shedding, the system will automatically move to the next group.
It is recommended customers affected by load shedding turn off all appliances, leaving a single light switch in the ON position so that they know when power has been restored.
If load shedding is occurring because of a heatwave, avoid opening the fridge or freezer during the event.
Appliances can then be turned back on gradually.
If the power is out for significantly longer than 1 hour, it may be that there is another outage which is independent of the load shedding.