Phillip Raymond D'Arcy suffered burns to 33 per cent of his body when a fire started inside an underground petrol tank that he was re-lining with fibreglass on September 11, 2012.

The incident happened at the Caltex petrol station in Kaleen, when Mr D'Arcy was 44.

Mr D'Arcy successfully sued his then-employer, Fuel-Sys Installations, for damages in an ACT Supreme Court trial, but Justice John Burns found that Caltex, the other defendant, was not liable.

Justice Burns ruled that Fuel-Sys was liable for $376,600.67 in damages, covering the money Mr D'Arcy will lose in the future as a result of his injuries, and income tax he is entitled to recover on workers' compensation receipts.

Fuel-Sys was also found to be liable for Mr D'Arcy's losses since the fire, but the exact amount is yet to be determined because Justice Burns did not have access to records showing Mr D'Arcy's income in the last two financial years.

Justice Burns' judgment, published on August 3, says Mr D'Arcy told the court that on the day of the fire, he found "a bunch of fibreglass" on the floor of the tank.

One piece was still hanging from the roof and leaning on a light globe, but when Mr D'Arcy tried to remove the fibreglass from the bulb, elements within the bulb started "burning like a candle".

Mr D'Arcy told the court that as he tried to extinguish the flame, a piece of fibreglass he had in his hand caught fire and he dropped it on the floor of the tank, which ignited.

After failed attempts to put the fire out with an extinguisher, he tried to escape the tank, but only got halfway up the ladder before the flames reached him.

Justice Burns found Fuel-Sys had breached its duty of care to Mr D'Arcy in several ways, including its failure to provide adequate training and flame-reistant personal protective equipment.

While Fuel-Sys accepted the breaches, it argued that Mr D'Arcy had been negligent and contributed to his own situation.

The company said Mr D'Arcy had twice applied fibreglass matting over the air intake service port - the hole designed to allow air to come into the tank - resulting in fibreglass being blown loose.

Fuel-Sys alleged that he had then put himself in danger by trying to rectify the damage, and by staying in the tank to try and put the fire out.

Mr D'Arcy rejected claims he had put the matting over the hole, saying it could have been any one of four workers.

He said he had stayed in the tank because he feared there would be an explosion that would affect people using the service station if he did not put the fire out.

In his judgment, Justice Burns said he could not be satisfied that it was Mr D'Arcy who put the matting over the hole.