AN expert has told the Supreme Court he saw half a dozen areas of clashing marks on the Colac-Camperdown power lines when he examined them in the Pomborneit Hall.
Dr Trevor Blackburn was cross examined before Justice Jack Forrest as part of a class action against Powercor after the 2009 Black Saturday fire at Weerite and Pomborneit.
Dr Blackburn was called as one of five experts for plaintiff Terrence Place. Dr Blackburn agreed with a suggestion from Justice Forrest that he was unable to definitively say that the clashing marks that he’d seen were consistent with Black Saturday.
When cross examined by counsel for Powercor David Curtain, Dr Blackburn said arcing power lines could occur without power lines clashing but if they were brought close enough in proximity.
On Wednesday last week the court heard Dr Blackburn, a visiting associate professor at the school of electrical engineering and telecommunications at the University of New South Wales, said Kerry Lynne Callow’s earlier testimony that she witnessed power line arcing was consistent with the behaviour of an arc and was an excellent description.
Justice Forrest suggested that given Ms Callow was a layperson and had to make observations very quickly, he asked Dr Blackburn if there was any reason to think that it was anything other than an arc. “What she saw and what she described was a quintessential arcing behaviour for a very high voltage arc under the action of strong wind,” he said.
Justice Forrest said that didn’t answer the question of what caused the arc.
The court heard from expert Geoffrey Walsh, called by counsel for Powercor.
When cross examined by Tim Tobin, Mr Walsh said he suspected the involvement of foreign material to cause the arc.
“This piece of foreign matter, did that come into the arc after the arc had been created, or was it involved in the creation of the arc,” Mr Tobin asked.
“I don’t know,” Mr Walsh said.
Mr Tobin said Mr Walsh’s hypothesis of what happened was dependent on it being possible in the wind for a foreign material to move south for a period of time coincidental with the arcing occurring, then reverse against that wind and go back towards the power lines.
“That’s my idea,” Mr Walsh said.
The case continues.