It's been revealed that Middlemore Hospital was forced to use emergency generators for weeks at its busy Manukau Superclinic after a major power failure.
Also, circuit breakers and two generators, including one at its children’s hospital, did not perform as they should during a power failure across Middlemore’s main site in Otahuhu in October 2017.
This cut was caused by high voltage cables tripping, the DHB said today.
The generators – the second being in the McIndoe Building, which houses the national burns centre - did not kick in for nine minutes instead of immediately, so patients had emergency lighting in that time.
The circuit breakers would now be upgraded under a remediation programme, the DHB said.
Another power cut three weeks ago was due to a transformer problem affecting large parts of Mangere, and hospital generators kicked in as they should.
The power supply issues are the latest in a litany of building woes for the Counties Manukau District Health Board at the country's busiest hospital.
At the Manukau Superclinic, one of two high-voltage cables blew last April and could not be fixed.
The clinic juggled emergency generators and mains feeds while Vector replaced both cables with larger capacity ones.
It's unclear if this disrupted patient services (though some surgeries did have to be called off due to a power cut at the superclinic in early 2016, according to media reports).
"We have experienced one significant fault," the board said.
"CM Health does not consider that the electrical power supply to the Manukau Superclinic is unreliable."
However, Greg Simpson, who oversaw all of the DHB's buildings for almost a decade till the end of 2016, sees it differently: "The Manukau Superclinic has been in a risky position for power supply, that's true, for some years," he said.
The board only confirmed the superclinic power cut after RNZ went to it after getting a tip-off. The acting chief executive, Gloria Johnson, had told us just last week that the "board and management have no desire to hide information about the challenges we face".
The DHB said it was spending $3 million on upgrading other parts of the clinic's power supply.
This showed the superclinic needed a boost just to keep operating, let alone for any significant expansion, Mr Simpson said - "not a good place to be".
"There is no spare capacity, but it is reliable until demands exceed its capacity," he said.
The clinic was built just 17 years ago and Mr Simpson said the DHB had very accurate forecasts about burgeoning demands - but there had been no money to extend it and trying to simply boost the power supply on its own made no sense.
The power cut last year was "waiting to happen" and the board knew it.
"We've been making noises for the last, gosh, six or eight years," Mr Simpson said.
He said his team was used to patching up the clinic's power supply systems in a bandaid-type approach.
"It's the only approach we could take given that we actually didn't have any money to do anything else.
"Basically the whole of the maintenance programme [across Middlemore Hospital] has been reactive."
Instead of an international best-practice of 2 percent to 3 percent of asset value as a maintenance budget, he was getting less than half the $15m a year Middlemore needed, he said.
"The board has been naive - to not put funding into critical infrastructure because clinical services take precedence, is naive."
More "hidden" costs lurked underground in services like water, sewage and compressed air lines that were at the end of their life, he said.
"Perhaps it takes a failure for proper financial attention to be given."
Questions remain over just who knew what and when about the hospital's litany of building woes, and what was done about it.
The board said it became aware it had four badly leaking buildings between 2012 and 2013.
However, a hospital maintenance worker, who RNZ has agreed not to name, said that warnings went to the board three years before that.
Mr Simpson said he was confronted at the start, in early 2008, with a mental health unit leaking so badly it had had to be demolished.
From 2013 until he left, he said he found his position was "severely" curtailed and building decisions were made without him because he had disagreed over some matters.
"Where you bypass your experts ... I think it's atrocious," he said.
As for the other four leaking buildings, he said it took three years, from 2012, to get designs and approval to reclad them, and then other obstacles, including reaching a settlement with builder Hawkins, delayed a start on repairs which in the best-case scenario could have begun in 2015.