The Federal Court on Thursday awarded penalties of $137,000 against the CFMMEU and official Richard Hassett.

The incident took place during work on the Living City project in June 2017.

"During the unlawful entry onto the project site. Mr Hassett put the safety of workers at risk by climbing into the cabin of a crane while it was being operated,' the Australian Building and Construction Commission said.

"At the time of his reckless actions, he defied a clearly visible sign advising 'No unauthorised interruption of operator during crane operation.'

"The following day, despite being told it was unsafe, Mr Hassett again climbed into the crane cabin while it was being operated, compromising workers' safety on a second occasion.

"In handing down penalties, the court found the union official had acted in an improper manner and failed to comply with occupational health and safety requirements while on the site."

Comment was being sought from the union.

The court found: "It was serious because it was very dangerous, which Mr Hassett must have known, and it was serious because Mr Hassett gained entry to the site purportedly in respect of safety concerns, only to place the crane operator and others potentially in harm's way."

"And it was made all the more serious by the fact that when he was told to get off the crane, he refused."

Mr Hassett and the union were fined in 2018 over two incidents in Hobart.

The ABCC said the new penalties took total penalties imposed on the union and its officials past $4 million.