Crews have begun upgrading the distribution network to support the installation of a Rapid Earth Fault Current Limiter at the Koroit zone substation.

It is the fourth location in the south-west to have the new technology installed, with devices already installed in Camperdown and Colac and work progressing at Terang.

Work is also expected to start later this year at Hamilton.

When all south-west devices are completed, a network of 5573km of high voltage power lines will be fitted with the REFCL system, including 28 feeder lines covering 50,000 customers.

REFCL devices are claimed to operate like a large switch on the network and reduce the chance of a spark occurring if a power line comes into contact with the ground or a tree limb.

REFCLs are being installed in some of the state's highest bushfire risk areas, as directed by the Victorian Government in response to recommendations from the Victorian Bushfires Royal Commission after the 2009 Black Saturday bushfires.

Powercor's REFCL technical director Andrew Bailey said the program aimed to provide additional bushfire protection for south-west communities, with the devices operating on power lines within the Otway Ranges and other high-risk areas.

"As we face more extreme summer seasons, Powercor's bushfire mitigation activities are keeping communities safer by reducing the risk of fires starting from assets," he said.

The installation involves crews upgrading the surrounding distribution network to ensure power lines and other infrastructure is compatible with the device.

Mr Bailey said the works would involve some planned power outages to compete work safely.

He said customers would be notified directly in advance of any planned outages.

"We appreciate any power outages are inconvenient so we take steps to minimise the impact on the community as much as possible," he said.

"We thank customers for their understanding as we work to further improve the safety of our network."

The Koroit REFCL will be operational prior to the 2021/22 summer fire season.

Mr Bailey said that last summer, Powercor had REFCL devices installed in 10 locations and they operated in heightened sensitivity settings on total fire ban days, activating more than 100 times.

"Powercor has a dedicated team of engineers, planners and crews working to ensure the devices are installed safely and are operating in line with performance requirements," he said.

"The REFCL is just one of a series of safety devices on the network, designed to reduce bushfire risk and improve safety."

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