The north Canberra man has been accused of "destructive impulsivity" for allegedly setting an O'Connor complex on fire last August.

A judge said things could "go off the rails catastrophically" if the man, aged in his 30s, was let out of custody.

READ MORE: Man charged with arson after O'Connor fire

Police documents previously tendered to court claimed the man called ACT Ambulance Services just after midnight on August 14, saying he had burned a house down.

Police, firefighters and paramedics found three empty townhouses in a two-storey O'Connor complex up in flames.

The man was arrested at the scene and eventually taken to Canberra Hospital for a mental health assessment.

On Thursday, defence lawyer Elizabeth West told the court the alleged arsonist had completed programs to address drug and relationship problems while in jail.

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"[He] never thought he would face a term of imprisonment," Ms West said of her client, who has been in custody for eight months.

Ms West said while the man was not eligible for most residential rehabilitation programs because of the arson charge, he was highly likely to be accepted into a day program.

In opposing bail, prosecutor Katrina Marson said the man appeared to have an "extreme reaction" when feeling unheard or wronged.

"[Allegedly] setting fire to a premises because, in the accused words, nobody was listening demonstrates a retaliative and destructive impulsivity," Ms Marson said.

She said while the man's ex-partner was not in the building when he allegedly set it on fire, he had previously been charged with four family violence offences against the woman.

Ms Marson claimed in one incident, the accused had called his ex-partner's three-year-old son a "f--got", told him to "s--k my d--k", and threw him across the room.

Defence lawyer Ms West said the accused man was no longer in a relationship with his ex-partner and did not know where she or her son lived.

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Chief Justice Lucy McCallum said while she commended the man's rehabilitation efforts, it was too big a risk to let him out on bail before his trial.

"I'll be frank, I'm most concerned [his mental health] problems are complex," Chief Justice McCallum said.

"[He may need] complex, multidisciplinary treatment over a lengthy period."

Chief Justice Lucy McCallum said those issues included "what appears to be anger management", being a potential "threat to women", and drug addiction.

Chief Justice McCallum said while the ex-partner was not a direct witness, she was a circumstantial one.

"Usually when these cases go off the rails, they go off the rails catastrophically," she said.

The Canberra Times has not named the man to protect the identity of his former partner.

His trial is scheduled to begin on May 23.

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