Power won't be restored until at least the early evening after a massive outage in the Taupo area.
Unison spokesman Danny Gough said around 16,000 customers had been affected and it would be several more hours until power was restored.
"It will be at least early evening until we have full restoration. There has been a fault with a Transpower transformer at the Wairakei grid exit point."
Gough said Unison was doing all it could and there was 'great urgency'.
A large area of the Taupo district has been affected by a power outage.
Unison spokesman Danny Gough said Transpower had an issue at the Wairakei grid exit point.
"I think we have large swathes of Taupo if not most of it off. We will keep people updated on the Unison Facebook page."
According to the Unison website thousands of customers have potentially been affected.
Gough said there was nothing Unison could do because it was the national grid that was affected but it was working with Transpower to get power restored as soon as possible.
More information can be found at the Unison outages page.