Work Safety Commissioner Greg Jones said principal contractor Nikias Diamond Property Developments had been charged with an alleged failure to comply with a health and safety duty, as had company director Dimitri Stramarcos. The maximum penalty under the legislation for an individual was $150,000, a duty holder $300,000 and a corporation $1.5 million, he said.

Work Safe also alleges failures on behalf of two subcontractors working on the site, Feel Style and BCC Building.

The boy, on a Year 10 program for teens at risk of dropping out of school, fell through a void on to concrete at the site of the new Coles supermarket on Horse Park Drive, injuring his spine and breaking bones.

The accident happened on October 27 2016.

The apprentice was just two days into the job, the building union said at the time, and was lucky to be alive.

Mr Jones said the young person had been standing on a ladder placed next to a stairwell opening, with no fall protection around the opening. The young person had fallen six metres on to concrete when they stepped off the ladder.

The worker had received broken bones as well as spine and internal injuries after falling through the void.

The significant injury was easily avoided, he said.

The investigation had looked at induction, training, supervision, health and safety practices and fall protection.

“Following the investigation WorkSafe ACT alleges that there were deficiencies identified across many of these areas as it related to the principal contractor and company director, and this is reflected in the charges laid,” Mr Jones said.

“There is a duty for employers to ensure as far as practicable that workplaces are safe and this allegedly did not occur in this instance.

“In addition, but to a lesser extent, there were also failures on behalf of the subcontractors on the site which are subject to the enforceable undertakings.”

A Nikias Diamond spokesman  said the company was sorry the incident had occurred and it would continue to fully cooperate with the WorkSafe investigation.

"We have reviewed our safety procedures as a result of this incident," he said. "This incident has been a timely reminder to all companies, workers and subcontractors that safety is our number one priority."

The boy was on site as part of the Master Builders' now defunct Kids Assist program, which was aimed at Year 10 students at risk of not completing high school.

The chief executive of Master Builders ACT, Michael Hopkins, said the association had suspended the Kids Assist program following the injury. "No incident like this should occur and the [association] has cooperated fully with WorkSafe ACT throughout the course of its investigation," he said.

The program had helped 500 teenagers over 16 years and safety procedures meant injuries were rare, Mr Hopkins said. "This incident was by the far the most serious."

Mr Jones said the injury would have"a profound and lasting impact for the young worker but also those who witnessed it, his friends and family”.

“I cannot express strongly enough how critical it is for employers and contractors to ensure that all protections are in place when it comes to workers working at a height," he said.

Feel Style and BCC Building have entered into binding agreements with WorkSafe to make improvements.

WorkSafe said Feel Style would give a $30,000 cash donation to the Spinal Injury Unit at the Canberra Hospital, provide building and construction services to government-connected not-for-profit Hands Across Canberra, worth $60,000 over three years, train an employee in work health and safety, and organise an industry safety training workshop to share lessons learned around falls from heights and young workers.

BCC Building had also committed to provide building and construction services to Hands Across Canberra, also worth $60,000 over three years, organising an industry safety training workshop on falls from heights and young workers ($20,000), training an employee in work health and safety, and a $30,000 donation to the spinal unit.