THOUSANDS of wooden cross-arms could be replaced on rural Victorian power poles this year as controversy grows over the role of faulty power lines in Victoria's tragic bushfires.

The Federal Government is considering a plan which would see all rural Victorian power poles fitted with steel cross-arms by the end of the year.

There are also calls for a major upgrade of single-wire power lines, which were implicated in both the Horsham and Kilmore East/Kinglake fires.

"Time and time again faulty power lines have been identified as a source of terrible fires," Mallee MP John Forrest said.

"Fixing this problem must be part of any response to the current tragedy. "You can't stop bushfires but you can minimise the risk."

The move to replace the cross-arms comes amid reports of a class action over a downed 2km stretch of power line at Kilmore, which some claim caused the deadly Kinglake fires. It also comes as Premier John Brumby announced that "no stone would be left unturned" by the Royal Commission into the fires, to be chaired by retired Supreme Court judge Bernard Teague.

As debate continued to rage over the extent that Victoria's forest management practices, native vegetation controls and planning regulations played in the fires, Mr Brumby said the commission would have "the broadest possible terms of reference and capacity to inquire into all aspects of the fires".

Mr Forrest told federal parliament last week that many wooden cross-arms in rural Victoria were old and badly weathered, posing serious fire risks.

In a strong wind, insulators could be ripped off old cross-arms or sometimes a faulty insulator can drop sparks, he said.

"Either way, where there is a wooden cross-arm, it can feed a fire," Mr Forrest said. "We have to provide assistance to power authorities to replace these timber cross-arms with steel. It is a readily available engineering solution."

It is understood Prime Minister Kevin Rudd has asked Mr Forrest to determine the cost of replacing the wooden cross-arms.

Mr Forrest told The Weekly Times the replacement process by the main power companies was "well under way" but could be sped up by an injection of federal money.

"My engineering assessment is that about $10-15 million would see a substantial amount done by the end of the year," he said.

"I'm encouraged by the interest in this matter by the federal government."

Mr Forrest said there were about 1.1 million poles with wooden cross arms in Victoria, but only a proportion in rural areas outside the major provincial centres.

He said old wooden single-wire-earth-return lines (SWERs) were also a problem, and ideally should be replaced with concrete poles.

But many farmers believe the problem can be fixed by having SWER lines better maintained.

A farmer - a former CFA captain from Derrinallum who wanted to remain anonymous - said breakages in the SWER lines were not uncommon.

"They (the former State Electricity Commission and now Powercor) have been promising for 25 years to replace the wire, and I am still waiting," he said.

"There is a limit to how much you can keep tightening the wire."

SWER lines are the low-cost option of transmitting power in remote or sparsely populated areas.

In many instances lines are constructed across farmland rather than along roadways.

The move to more more powerful electrical appliances requiring three-phase, such as welders and refrigeration, have found the SWER lines wanting.

For this reason, the Victorian Farmers Federation has been pushing for an upgrade of the transmission service to two or three wires.

But because the upgraded powerlines can cost at least five times that of a SWER line, farmers have lobbied for government help.

In 2000, the Victorian Government through its Dairy Power Infrastructure Upgrade Program allocated $8 million to help farmers upgrade.

Last year another $1.8 million was allocated to meet half of a farmer's upgrade cost, estimated to average $20,000.