A Canberra developer will pay a fine of $180,000 after a schoolboy broke his neck on a worksite.

The ACT Industrial Court on Monday fined development company Nikias Diamond over the 2016 accident, after the developer earlier pleaded guilty to charges of breaching its safety obligations.

The court heard that a 16-year-old boy, who was participating in a school program on the site, was called to climb down a ladder positioned next to an open void.

As he descended the ladder, he fell six metres backwards into the hole, breaking his neck and injuring his spine.

He has reportedly suffered serious ongoing pain since, is unable to pursue his ambition to become a carpenter, and can only study part time.

Magistrate Glenn Theakston noted the safety measures for open voids were inadequate.

“Falling through an unmarked and uncovered void was certainly not a remote possibility, but rather a real possibility,” he said.

“I note that the defendant concedes that this risk is notorious.”

The boy was onsite with a contractor called BCC Building, while a second contactor, Feel Style, was also working on the site.

Both companies have paid penalties of $132,000 and agreed to enforceable undertakings.

But the head company, Nikias Diamond, was charged with failing its safety duty, and received a $180,000 penalty.

Mr Theakston noted that some issues with voids on the site had not been addressed.

“The voids could have very easily have been covered had the defendant, through its officers, insisted that occur,” he said.

“The defendant had a range of simple measures available to it to persuade Feel Style to take such action.”

Mr Theakston said while there was a general understanding that there is an exclusion zone around voids, he found signage did not communicate that.

Nikias Diamond director Dimitri Nikias issued a statement saying the company accepted the conviction, but raised the role of other parties too.

“Magistrate Theakston was critical of other parties but noted that he did not have jurisdiction to consider their failings,” the statement said.

“We understand that WorkSafe ACT has entered into enforceable undertakings with the other parties and the role of the ACT Education Directorate has not been examined.

“Nikias Diamond fully acknowledges its role in the health and safety of all workers on its sites and maintains excellent systems to protect them.”

ACT work safety commissioner Greg Jones said he expected a fine twice as high as the one handed down. The maximum penalty was $1.5 million, but the offending was found to be on the lower end of the scale.

“WorkSafe had an expectation of a more substantial deterrent,” he said.

“We were thinking that this fine was a little bit underdone, we were expecting a higher penalty to provide a deterrent effect on that.

“We were very … concerned that any worker, especially a young worker, can be injured in a situation which is very easily avoidable by having voids or risks of falls from heights appropriately managed on site.”