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Mercury Energy says it was unaware that disconnecting power to a south Auckland home could have potentially life-threatening consequences.

Folole Muliaga, 44, died within two hours of a contractor cutting power to her Mangere home at 2pm yesterday.

Today a relative said Mrs Muliaga's family had told the contractor that the mother-of-four was dependent on an oxygen machine, which needed electricity to run.

Mrs Muliaga's son told TV One News that his mother - sitting with the machine - had asked the contractor to give them a chance, but the man had replied he was just doing his job.

However, in a statement this afternoon, Mercury Energy said its preliminary investigation suggested that the contractor was given no indication that disconnection would result in medical danger.

Mercury Energy's General Manager, James Moulder, said: "Our interview with the contractor indicates there was a discussion with Mrs Muliaga, who simply discussed possible bill payment and reconnection timeframes, but did not alert the contractor to her medical situation."

Mr Moulder expressed his sympathy to Mrs Muliaga's family but said: "We were simply unaware that loss of electricity to the household was putting a vulnerable customer at risk."

He said it was believed the correct disconnection practices had been followed.

"Throughout the 6-7 week process of disconnecting the home, and on the day in question, we were not alerted that there was a person resident dependent on a medical device reliant on electricity."

In brief

* Folole Muliaga died two hours after power was cut to her home, disabling her mains-powered oxygen machine

* Her household had fallen behind bill payments to the SOE Mercury Energy since Mrs Muliaga had become sick and unable to work

* However Mrs Muliaga's family has disputed the power bill was overdue, saying the latest bill was not due until June 13

* Mercury Energy said the contractor who disconnected the power was unaware Mrs Muliaga depended on the machine to live

* The Muliaga family said the contractor was told about the machine but said he was just doing his job

* The District Health Board said Mrs Muliaga would not have been sent home if she needed the machine to stay alive

* Mrs Muliaga's son said he delayed calling an ambulance at his mother's request

* SOE Minister Trevor Mallard said he was concerned by the death and asked for an urgent report from Mercury Energy

* Green MP Sue Bradford called for a public inquiry

* Police said the death would be investigated

Mother of four

Mrs Muliaga was the mother of four children, aged from five to 18.

A relative who married into her family, Brenden Sheehan, said the early childhood teacher had been off work since February with an illness.

Mrs Muliaga's husband Lopa, a chef's assistant, had been forced to reduce his work hours in order to care for her.

The family had been in New Zealand for six years, and were confident English speakers, Mr Sheehan said.

When a Mercury Energy representative arrived to cut the power supply, the family had explained the circumstances, and brought the person inside the house to show the representative the oxygen machine, he said.

"They didn't (have a medical certificate) at that moment in time. They clearly could have got one had they been given an opportunity to do so."

Mr Sheehan told Radio NZ: "Someone came to the house at about 2pm yesterday. Both the deceased and her son talked to the person and they told them of the need for electricity and asked them not to turn off the electricity.

"Unfortunately, their protestations were not heard and the electricity was cut off and she passed away shortly afterwards."

He said the family disputed that their power bill was overdue, sayin gthe latest bill - dated May 23 - showed an opening balance, fortnightly payments on May 2 and May 18, and an outstanding balance of $168.40 which had to be paid by June 13.

"It (the bill) shows they have been making regular fortnightly payments on the account."

Mr Sheehan said after the machine went off Mrs Muliaga had become faint, had difficulty breathing, and complained of headaches and being unable to see, before collapsing.

Her son told TV One News his mother had initially asked that he not call an ambulance and when he did so later officers were unable to revive her.

"That is a typical Samoan thing. They don't like their kids to be worried," Mr Sheehan told NZPA.

He said the family was awaiting a post mortem to confirm the cause of death and the woman's husband was a "mess".

"It is just terrible this can happen in New Zealand," he added.

The family is demanding a full investigation into the tragic incident.

Counties Manukau Chief Medical Officer Don Mackie said Mrs Muliaga was sent home from Middlemore Hospital earlier this month.

She had been admitted with a cardio-respiratory complaint and was discharged with a breathing support device, he said.

"We do not expect it to be used 24 hours a day. Most people use them at night, particularly just to support their breathing and to relieve any distress from breathlessness while they are sleeping."

Later, he told Radio New Zealand Mrs Muliaga would not have been sent home if she needed the machine to keep her alive.

"I feel surprised that this has happened... This is not a ventilator at the intensive care level."

The machine just supported someone's ventilation rather than doing all the work for them, he said.

"People who are on this are capable of breathing for themselves... That is why we are surprised that she deteriorated and tragically died so soon after the support was withdrawn and we need to understand more about that."

Dr Mackie said that when patients had needed a letter to support their need for continuous electricity supply the DHB had been "very willing" to provide this.

Political reaction

A spokeswoman for State Owned Enterprises Minister (SOE) Trevor Mallard said he was concerned by the death.

"The minister is taking this incident extremely seriously and will be demanding accountability," she said.

"He has asked for an urgent report from the SOE."

Green Party MP Sue Bradford called for a public inquiry into the death describing the decision to cut the power as "mercenary".

"Is there no social responsibility requirement? No code of conduct? Listening to the company spokesperson this morning it would seem the company sees it as entirely the responsibility of the consumer to make contact, provide documentation and argue their right to be allowed to live," she said.

"Surely there is some flexibility to use compassion and common sense in this type of very rare situation."

New Zealand First deputy leader Peter Brown said today if the power was cut off despite protestations it could kill the woman, those responsible should be charged with murder.

"This was a despicable act and it was possibly the principal cause of the woman's death," he said.

"For senior executives not to be made aware of the circumstances before the power was cut off makes it so much worse."

He urged police to investigate and consider murder or manslaughter charges.

"Nobody, repeat nobody, in this country should die because they have not paid their power bill."

Disconnection procedures

Mercury's James Moulder said Mercury's disconnection procedures were clear.

"If the event there is a medical reason the person needs power, then the disconnect processes are quite different," Mr Moulder said.

He said generally after a bill was sent, it should be paid within 21 days.

Ten to 14 days after that 21-day period a reminder notice was sent and seven to 10 days after that the next month's bill would include a "message saying that the previous month was overdue, please pay otherwise disconnection will occur.

"Seven days after that we send a final disconnect (notice) saying if you don't pay within 48 hours you power is going to be disconnected."

Mr Moulder said that meant disconnection was likely more than a month or six weeks after the initial 21-day period given to pay the bill.

"We always arrange to disconnect while people are on the premises as well. We disconnect in the morning so we can reconnect soon afterwards in the afternoon if payment has been made," he said.

Power was restored to the house about 8am today.

Mr Moulder said there was an additional policy in place to deal with issues of medical need and hardship.

"Once we've been notified that someone is dependent on electricity-powered medical support, we...request evidence from a medical practitioner and then we move into another process which puts them onto different payment terms," he said.

Mr Moulder said the Mercury representative should have told the woman and her son to ring the company and speak to someone about the situation, before the power was shut off.

Mr Moulder would not say how much money was owed on the power bill.

"I don't talk about customer arrangements with anyone but customers."

Legal situation

Police said the death would be investigated.

"We will have a look at the whole circumstances ... and make a decision on what the facts tell us and review that," Inspector Bruce Bird, area commander for Counties Manukau West, said.

Auckland University associate law professor Bill Hodge said there was a provision in the Crimes Act dealing with the duty to avoid any action which endangered life.

"I would say there are some people in the legal section of the police...right now that are looking pretty carefully at that," he told Radio New Zealand.

Manslaughter charges could potentially be laid, depending on what information Mercury had and how it was expressed to them, Prof Hodge said.

The person who went to the house to shut off the power may not have understood the circumstances, he said.

"I want to be very careful about condemning (the person) who cut off the power without knowing specifically what he knew or what she knew."