"Much of the wiring is not as it is shown in the diagrams," he said.
That had not been a problem for the last 60 years, but the issues were now being discovered as crews worked to connect the system to the new station at Ngāwhā. The cause of Tuesday's outage had been found by "switching everything off," while Thursday's had been caused simply by changing a corroded fuse, which was not correctly marked.
"We're fixing faults that have been there forever," Shaw said.
"The challenge now is to ensure that we don't continue finding ourselves in this situation, but I can't be confident that there won't be more. There is still about two months' work to be done."
He emphasised that the outages had not been caused by human error, adding that once the fault had been found, which was not always a simple process, it took about 20 minutes to "reboot" the supply.
"It's very frustrating," he said.
"I understand the impact these outages have on people, and all I can do is apologise, and repeat that no one did anything wrong.
"Once we repair this equipment we will be inspecting all our main lines in the area with thermal imaging cameras to identify any hot spots that could cause further outages."
Meanwhile the two major outages earlier in the week had tested the line company's communications systems, which had not coped well.
"Our call centre was overwhelmed, and our outage centre failed," the company said on its Facebook page.
"These were the first outages since we automated the outage centre by connecting it to our network control system. Previously all outages were manually loaded. This is especially disappointing, as we want the outage centre and app to be the principal system that customers go to for information.
"We are close to fixing the issues, and we encourage people to subscribe to the website outage centre or download the app from Apple or Android. We expect the fix to be completed today."
Questions had also been asked about the company's generators, and why they did not kick in when the outages occurred. The generators at Taipā and Omanaia did start, although the main feed had been restored by the time they had 'run up, but Kaitaia's have yet to be automated. The generators there are scheduled for testing this week, and will then be commissioned.
That process had been delayed by the Covid-19 lockdown, the work not being deemed essential. Physical work had been completed in late March, before the level 4 lockdown took effect.
Once automated the generators, in Bonnetts Rd, would kick in in about 30 minutes, possibly a little longer, after the main supply was lost. The supply would not be lost at all in the event of a planned outage.
"It might not have looked like it this week, but everyone is doing a good job," Shaw added.
"We're just having to fix problems that are not of our making as they arise, and unfortunately that it is having a real impact on a lot of our customers.
'It's been cold this week too, which has increased power consumption, so all this could not have happened at a worse time."
