Two weeks after leaving the navy, Luke Bray was killed while working on the damaged roof of a house at Carlton, in the city's south, in February 2017.

Qualified builder Brett Anderson, 36, briefly met Mr Bray when he was touring with his band.

He later hired the 24-year-old to help fix the house's slumped roof after he contacted him over Facebook looking for work.

Speaking at a five-day inquest into Mr Bray's death on Tuesday, Mr Anderson recalled the moment he realised something had gone wrong.

His offsider Sean O'Toole called out to Mr Bray, who had just become engaged to fiance Jamie-Lee Rigby, to ask if he wanted anything from downstairs.

"After the second no response was when I got pretty concerned," Mr Anderson said.

When he rushed over, the unresponsive carpenter had his arm outstretched holding onto an exposed wire.

"I grabbed his shoes I think and just shook it and he didn't do anything," Mr Anderson said.

"I screamed at Sean to basically get a length of timber or something non-conductive to whack him off.

"You're basically told to break their arm if you have to."

With his colleague unable to find anything promptly, Mr Anderson grabbed him by his leather tool belt to pull him away.

Mr Bray couldn't be revived despite resuscitation attempts. An autopsy recorded electrocution as the cause of death.

Mr Anderson has worked in the industry for more than 15 years and said he'd been in plenty of roofs, but would now hire sub-contractors to complete any roofing work on his behalf.

"We don't really do any repair work due to this," Mr Anderson said.

"If there was anything in the ceiling, I'd probably outsource it."

Counsel assisting Sergeant Stephen Kelly said he would not suggest Mr Anderson or his company, Hyspec, contributed to Mr Bray's death.

In his opening remarks, Sgt Kelly said investigators determined there had been an illegal bypass of the electrical mains carried out at the Carlton property.

SafeWork NSW's Craig Hall inspected the roof after Mr Bray's death on February 21 and said on Tuesday that the spliced cable was deliberate and man-made.

Properties in Mount Pritchard and Bardwell Valley linked to former tenant Mariam Hamade's brother, Rabih Hamade, had illegal wiring of similar nature, Sgt Kelly said.

Mr Bray wasn't wearing gloves but his boss said it wouldn't have been feasible to do so while picking up and hammering nails - an explanation Mr Hall accepted.

The inquest, before NSW deputy state coroner Elaine Truscott, resumes on Wednesday.

Australian Associated Press