An Adelaide construction site supervisor who doused an apprentice in flammable liquid and set his clothes on fire has pleaded guilty to breaching the Work Health and Safety Act.

Key points: Tad-Mar Electrical supervisors Luke Daniel Chenoweth and Jeffrey Mark Rowe are being prosecuted by SafeWork SA

Tad-Mar Electrical supervisors Luke Daniel Chenoweth and Jeffrey Mark Rowe are being prosecuted by SafeWork SA The tribunal was told the victim could have suffered second-degree burns

The tribunal was told the victim could have suffered second-degree burns Chenoweth will be sentenced at a later date, Rowe was fined $12,000

Tad-Mar Electrical employee Luke Daniel Chenoweth and fellow supervisor Jeffrey Mark Rowe were prosecuted by SafeWork SA over the incident at a worksite in Woodville in April 2017.

Prosecutor Laura Willows told the South Australian Employment Tribunal (SAET) that Chenoweth squirted flammable liquid onto the boot of a 19-year-old apprentice — who the ABC has chosen not to name.

"He let the flames on his boot go out and he didn't say anything, he just wanted to get away from Chenoweth," she said.

"Chenoweth followed him and squirted some more liquid onto the crotch area of the complainant.

"It was at this point the complainant became particularly scared … so he ran away."

However, Ms Willows said the two supervisors followed the apprentice and both squirted more lighter fluid on the young worker's shirt and ignited it.

"[The apprentice] felt intense heat instantly and he was pulling his shirt away from his skin and waving his arms to try and put the flames out," she said.

"He could smell burnt hair and he was worried he had been seriously burnt."

'The apprentice could have suffered second-degree burns'

The court heard the apprentice would have suffered second-degree burns if his shirt was left on his body for another 20 seconds.

Ms Willows told the court the apprentice was subjected to ongoing bullying in the lead-up to the incident.

She said the apprentice had previously been tied to a ladder with duct tape, had his arms and face covered with silicon and permanent marker and had been locked in a shipping container.

The court heard Chenoweth had also failed to ensure that the apprentice received medical assessment for an electric shock and subjected him to frequent verbal abuse.

"The defendant was in a position of authority on the building site being supervisor and the victim was an apprentice," Ms Willows said.

"There was clearly a power imbalance."

Counsel for Chenoweth Martin Anders, told the court his client — who was 26 years old at the time of the incident — "fell prey" to an unhappy culture on the worksite.

"He joined the workplace as a juvenile, as a teenager and wanted to fit in," he said.

"He wanted to achieve in that workplace and that involved not only being good at his job … but it also involved falling into a culture and pattern of behaviour … that he would never normally engage in."

The incident happened on a construction site (file image). ( Clarissa Thorpe, ABC News )

The court heard Chenoweth had himself been bullied while at work.

"He was the victim that became the perpetrator," Mr Anders said.

Former supervisor remorseful over 'horseplay act'

Mr Anders said his client was remorseful and was otherwise a man of good character.

Chenoweth will be sentenced at a later date.

He faces a maximum penalty of five years imprisonment or a $300,000 fine, or both.

Earlier this year, Rowe was convicted and fined $12,000 by the tribunal for his involvement.

The tribunal accepted the incident was "horseplay which got out of hand".

Counsel for Rowe — who lost his employment with Tad-Mar Electrical after the incident — had previously told the tribunal that it was "hijinks gone wrong".