Questions remain over a potentially "life saving" electrical device being installed to stop bushfires, but the cost appears to be growing and could affect customers.

The state government is rolling out rapid earth fault current limiters across the state, with Ballarat's installation at two substations currently under way - the second phase of rollouts across the state is expected to be completed by April next year.

But detractors say the technology might not prevent fires, or at worst, in combination with other factors, help cause them.

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REFCL devices are designed to cut the power when a line is broken, struck, or hits the ground, and are among measures recommended by the Victorian Bushfires Royal Commission.

Powercor, which is in charge of power distribution and infrastructure in western Victoria, says one of the devices saved a life in Maryborough in the past week - a farmer operating an excavator came into contact with high voltage power lines, and the device identified the contact and reduced voltage "within milliseconds".

According to a Powercor media release, it's understood the excavator operator only noticed he'd contacted the lines on the fifth occasion, when he noticed some tension when moving the excavator's bucket.

Powercor REFCL technical director Andrew Bailey said in the statement the operator, and other workers, were "very lucky".

"While their primary purpose is bushfire prevention, this example highlights the safety benefit of these devices," he said.

"Regardless, we urge all people to be aware of our assets when working near them and take the appropriate precautions."

REFCLs have activated dozens of times this summer, protecting Victorians from potential fires. Powercor currently has 10 REFCL devices operational.

For example, on November 21 last year, the first Code Red day Victoria had experienced in 10 years - REFCLs on the network activated six times for "phase to ground" faults.

This potentially avoided fires on one of the most dangerous fire-risk days of the last decade.

The Warrnambool Standard, which has been investigating the technology following the St Patrick's Day fires in March 2018, and the ABC, have reported the program could cost up to $650 million, and experts have serious concerns about its effectiveness.

Powercor, through a spokesperson, said the device triggers "almost instantly".

"The use of this technology reduces the risk of ignitions by up to 60 per cent," they said in a statement.

"REFCLs are just one part of a mix of innovative technologies used to significantly reduce the relative risk of bushfires caused by high-voltage powerlines, as part of the $750 million Powerline Bushfire Safety Program."

$200 million has also been allocated to a powerline replacement fund, targeting high-risk areas identified by the Victorian Bushfires Royal Commission.

Any costs for customers would be assessed by the Australian Energy Regulator to ensure they're as efficient as possible - the AER estimated the tranche two roll out - which includes the Ballarat works - contributed about $10-$12 to a Powercor residential customer bill a year.

Powercor's also investing in new operators - another 16 apprentices began this month, with three from Ballarat.

READ MORE: Plans around Ballarat for new power lines, terminal to help electricity boom

Beau Glenister, a qualified electrician, and Tom Holmes, an apprentice, joined Brenton Ward, who's worked for Powercor for nine years but is retraining, from a pool of almost 800 people.

Mr Glenister said he was keen to become a linesman, fixing powerlines when they were damaged, because of the flexibility in the role.

"With the linesmen, we go through many different sections - we can do linesmen, we can do meters, we can be jointers, then throughout your time, once you become a qualified linesmen, you can go through other parts," he said.

"For myself (as an electrician), we see it from the meters onward, we don't see how it comes to that part - to come across, it's really interesting."

Mr Ward added the safety focus was important, and the new virtual reality training tools were gamechangers.

"You can actually visualise how far a safe approach distance is to conductors," he explained.

"It's being able to point out things that would normally be live, you can do that in virtual reality, and being in the business for as long as I have, seeing this new stuff is really good."

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