Dr Donald Ewart was also damning of regulator Energy Safe Victoria for not allowing him to examine the site of the bushfire start to provide expert opinion about the condition of that pole and neighbouring poles.

A nearby pole was later found to be see-through during independent tests.

Dr Ewart openly laughed in the Supreme Court sitting in Melbourne after being presented with sections of an ESV report about the bushfire.

He was giving evidence in the trial involving victims of The Sisters/Garvoc bushfire taking action against electricity giant Powercor and inspection service provider Electrix.

Under cross-examination, it was put to Dr Ewart that the ESV report said when the pole was cut for testing, active termites were found to be infecting the pole and a picture showed the pole No. 4 cavity and the termites.

Dr Ewart started laughing in court, explaining the insects shown were clearly ants.

He said he did not detect any active termites in pole No. 4 from the Sparrow Spur line which fell in 104km/h winds and caused one of four major fires in the south-west on St Patrick's Day last year.

The assertion there were active termites in the pole was repeated a number of times in the ESV report.

Dr Ewart said he expected that the pole had been significantly rotted for around a decade or more.

"I didn't go and inspect the site, and they didn't let me go and see the nearby poles for comparison. So I'm a bit hamstrung there, but understanding these sorts of timbers, it would be many years before it began to hollow to anything like that extent," he said.

"It looks like the pole had termites in it at, at least, one stage. It might have been two or three species over the life of the pole.

"The pole was significantly degraded. In my opinion based on the visual evidence had been so for many years.

"A competent inspection of the pole in 2017 would, in my opinion, have found virtually the same evidence of degradation at present as at failure in March and observed by me on May 18, 2018.

"Sounding of the pole would have been able to indicate a loss of integrity above the top of the bracing."

The court previously heard that an inspection on November 20, 2017, was just a visual check which took as little as 90 seconds.

Dr Ewart said that his examination of what remained of the pole after the bushfire found massive degradation.

He said pieces of fallen timber inside the pole indicated clear evidence of a hollow.

"You can see that the outside of the pole is not nearly as burned as the middle of the pole. And, to me, that suggests that the fire had gone up through a cavity," he said.

"If you talk to firies and foresters, they're always worried about widow-maker hollow trees because of the way they burn.

"They'll commonly say, you know, Roman candle or something, fire will race up a hollow, and that appears to be what's happened here."

Dr Ewart described it as "very strange" that ESV did not allow him to visit the site of the pole where the fire started, like he had in other bushfire cases.

"So I wasn't particularly enamoured of that. Normally you would look at the situation," he said.

"You might be aware that I was involved in the Parkerville case and there as soon as I was called up I went to the site and inspected around, located the various species of termite that could have acted on the pole as quickly as I could, so I knew what would have been active in the area at that time."

Dr Ewart said it would have been nice if the top of the pole hadn't burned but you could still see what happened from the burned remains.

"Whether or not it was a completely empty void or whether it was partly filled from above is always hard to tell, but the pictures of the hole with the fire still happening clearly showed a void," he said.

The trial continues.

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