THE sister of electrocuted Rockhampton teenager Rueben Barnes has told how she had to deal with her brother's death just seven months after her mother succumbed to cancer.

Rueben was killed at 16 after entering an electrified roof cavity on November 18 2009 to install foil insulation.

Sunny Barnes, 29, gave a heart-rending statement to the Royal Commission investigating the disastrous insulation scheme.

She also made a brief appearance in front of the commission on Friday.

In her statement, Ms Barnes - who was 25 at the time - tells of a brief chat with Rueben as he watered their late mother's garden.

"I asked him what he was doing and we just had a general talk about the garden," she said.

"As I left to go to get ready for work, I waved goodbye to Rueben.

"That was the last time I saw him alive".

She would later be shown his remains by the same doctor who counselled the family when her mother died in April that year.

"It was a shock and hard to accept because (Rueben) looked normal other than a small burn mark behind his ear," she said.

She said her brother's employers Arrow were responsible for running their business poorly "to make a quick buck".

"However, the option to run it this way was there, thanks to the Commonwealth Government," she said.

The father of Matthew Fuller - the first installer killed in the scheme, addressed the commission at length, describing his four-year fight to have a royal commission look into the bungled program.

Kevin Fuller told how Matthew became "cannon fodder" for the scheme after losing his job during the Global Financial Crisis.

He praised the humanity of former Labor minister Greg Combet and then-Opposition Leader Tony Abbott who vowed to launch a royal commission if the Coalition won power.

He said former prime minister Kevin Rudd "disgraced himself" at their first meeting.

The commission's Brisbane hearings this week heard from former Labor ministers Mark Arbib, Peter Garrett and Mr Rudd.

Each accepted responsibility for the botched home insulation stimulus scheme.

Before its cancellation in February 2010, the program would ultimately take the lives of four young men.

Each politician sought to blame bureaucrats for not delivering critical advice or warnings that could have prevented the fatalities.

Mr Combet spoke of his work as the responsible minister trying to clean up after the program once it was cancelled.

The commission is to resume on Monday.