Up to 60,000 Unison customers were affected by power outages over the weekend, a number now significantly reduced but extensive rural damage means 400 could be without power for up to a week.
On Saturday power was cut at 3.30am, then 10am, as heavy snow affected the Transpower transmission line from Wairakei GXP - Hawke's Bay's main power supply.
Since the first outage, Unison relationship manager Danny Gough said they had "every available team" from Hawke's Bay, Taupo and Rotorua working to restore power.
They're working in bitterly cold conditions ... we're really proud of our guys.
"We're going to work as quickly as we can, but we have to make sure the safety of our guys is paramount at all times," Mr Gough said. They had ensure staff were "fit and healthy and ready to go again for the next morning".
"It is hard work for these guys," he said. "They're working in bitterly cold conditions, it's still snowing in some areas, and the ground conditions are really tough, so we're really proud of our guys."
While most of Napier and Hastings had power restored by Saturday afternoon, equipment in Flaxmere had been damaged by the initial Transpower outage, leaving some residents without power until 7pm on Saturday.
Yesterday staff commenced restoration for rural customers and "made good, solid progress", reducing the affected customers by 200.
"Make no mistake, the conditions are very challenging, the damage to the network is extensive and our guys are working in very tough conditions but doing a superb job," Mr Gough said.
Aerial patrols conducted yesterday revealed damage to rural high country areas was significant.
An initial assessment of the Taupo plains showed about 150 33kV poles, and about 50 11kV poles down across the area.
Mr Gough said the area was a "significant concern" due to the extent of damage along the 60km network.
"We're going to leave no stone unturned getting in there and getting power restored, but the fact of the matter is, it is going to take some time."
There was also severe damage for network areas which fed customers in Tutira, Patoka, Puketiri, Esk Valley and Otamauri. Consumers could be without power for a few days.
Ten gangs had been assigned, with support from Centralines, across seven sites to get restoration under way. There were about 20 poles down, with extensive vegetation issues and wires across the ground.
"We also face very tough terrain in this region, so that will be the biggest challenge."
To restore power in areas with tough terrain, Mr Gough said they were lucky to have a well-equipped fleet with modern gear.
They would also use any available resources, calling in industry colleagues, equipmentand helicopters.
To get to lines, Unison staff have also had to clear rubble, trees and other debris, along with figuring out the best way to move the heavy machinery needed across sodden ground or hilly terrain.
Now, Unison would undertake an "extensive restoration effort" to restore power to remaining affected customers.
However, staff were well-trained in such situations. As well as learning from past experiences, they also underwent simulations, and trained in "the harshest conditions".
"While this is certainly a significant challenge, it's a challenge that our guys are more than up for."