The family of a Yallourn Power Station worker killed while performing routine maintenance in 2018 has labelled WorkSafe Victoria's initial decision not to prosecute Energy Australia as "cruel".

The power station operator was today fined $1.5 million in relation to the worker's death, which it conceded at a plea hearing was "avoidable" and "preventable".

Graeme Edwards, 54, was performing routine maintenance on a circuit breaker at Yallourn Power Station when it exploded, burning 90 per cent of his body. 

He died a day later in the Alfred Hospital.

Investigations found a panel that was supposed to protect workers from contact with the arc flash was not secured properly.

It was also found there were inconsistencies in the way staff were trained to carry out the "racking" procedure compared with the staff manual provided and Mr Edwards was not wearing adequate protective clothing, which would have minimised burns.

Three years after Mr Edwards' death WorkSafe filed charges against EnergyAustralia.

Initially, the regulator ruled it would not be investigating further but unions pushed for answers and action.

'Decision was cruel'

The family said WorkSafe's actions prolonged their suffering.

"To the management of EnergyAustralia, we have been deeply distressed by the loss of our brother Graeme and hope that if there is anything that can be learnt here today, it is that human safety must always come before profit," the family said in a statement.

"To WorkSafe, we are still confused about why you initially chose not to prosecute this case on the grounds that it did not meet burden of proof when it clearly did," the statement read.

"It is our opinion that the public servants who made this decision should provide an explanation for this to us and to the community."

Mr Edwards' friend and mining and energy secretary for the Construction, Forestry, Maritime, Mining and Energy Union, Mark Richards, said outside court he had pushed for WorkSafe to prosecute the company and believed legislation needed to change.

"It's a travesty of justice to be honest, to take four years and three months to finally have this day in court," Mr Richards said.

"There's a two-year statute of limitations on prosecution and WorkSafe didn't prosecute at the two-year limitation and therefore it had to go through a section 131 of the act to have this happen.

"It's disappointing there's no industrial manslaughter charges to be laid but that's because this incident happened ... prior to the new legislation."

WorkSafe declined the ABC's request for comment.

Company pleaded guilty

When delivering her impact statement at the plea hearing in December, Mr Edwards' mother, Elizabeth, spoke of her grief and dismay surrounding the handling of her son's death.

The company pleaded guilty to three charges of failing to provide a safe work environment at the hearing.

Melbourne County Court Judge John Carmody said if the company had not pleaded guilty, it could have been fined a total of $2.2 million.

"None of this process here will change anything in terms of the effect and son and or brother's death has had but that is the system we have," Judge Carmody said. 

Energy Australia operations and projects executive Michael Hutchinson said the company had made changes.

"Energy Australia offers its deepest sympathies to Graeme's family, friends and workmates and we acknowledge the impact that Graeme's death has had," Mr Hutchinson said.

"Since the events of November 2018, we have put in place a series of additional safety procedures and improvements at the station to ensure there can be no repeat of this tragic incident."