How reliable is the power supply?
Source: AER, State of the energy market 2025. Interruptions longer than 3 minutes. Years run 1 July to 30 June.
Two measures are used. SAIDI is the average number of minutes each customer is without power in a year. SAIFI is the average number of interruptions. In 2023-24 the 1.58 interruptions per customer were made up of 0.95 everyday unplanned interruptions, 0.31 from major events and 0.32 planned ones.
Why some areas lose power more often
The AER points to geography. Urban networks have short lines, many interconnections and a high share of underground cable, which is protected from storms, trees, birds and vehicles. Rural lines are long, mostly overhead and often radial, with no second path to restore supply, so faults affect people for longer.
| Network | Underground |
|---|---|
| EvoenergyACT | 59% |
| CitiPowerVIC | 51% |
| Endeavour EnergyNSW | 44% |
| AusgridNSW | 40% |
| EnergexQLD | 38% |
| JemenaVIC | 36% |
| United EnergyVIC | 26% |
| Power and Water CorporationNT | 24% |
| SA Power NetworksSA | 22% |
| AusNetVIC | 18% |
| PowercorVIC | 12% |
| TasNetworksTAS | 12% |
| Essential EnergyNSW | 6% |
| Ergon Energy NetworkQLD | 6% |
Reliability costs money
Making a network more reliable means more investment, which customers pay for through network charges. The AER notes that NSW and Queensland relaxed their reliability standards from 2014 after concerns that reliability spending was pushing bills up, but the assets built to the old standards are still being paid off.
If your supply is unreliable
Networks must meet reliability standards, and in several states pay customers who suffer long or frequent outages. See our guide to power outage compensation.
Common questions
In 2023-24 the average customer in the national market had 1.58 interruptions longer than three minutes, adding up to 393.8 minutes without power, according to the AER.
The system average interruption duration index: the average total minutes a customer is without power in a year. SAIFI is the average number of interruptions.
Generally, yes. The AER notes underground cables are protected from storms, trees, birds and vehicle collisions. They cost more to install and can take longer to repair when they do fail.
Sources
Every rate on this page comes from the regulator or the regulated retailer. Last checked October 2026. Prices include GST unless we say otherwise.