Most of Taupō is without power due to a switchboard fault at the Wairakei substation.
A fault was reported by Transpower to the local supplier Unison just before 9am.
Unison spokesperson Danny Gough said staff were working with haste to repair the fault.
"Transpower are there with their staff working with some haste and from what we can gather there appears to be an issue with the switchboard at the substation.
"So they're inspecting that, understanding the issue and then they can come up with a plan."
He said the fault had wiped out most of the city.
"The Wairakei substation is responsible for supplying power into the wider Taupō region and as a result of the fault that has affected power supply to approximately 15,000 customers.
"We have the wider Taupō area, out as far as Turangi and the surrounds. So really the main populist and urban areas of those regions."
He thanked people for their patience and urged them to keep an eye on the Facebook page for updates.
"We appreciate people's frustrations and the impact it's having on their lives especially on a Monday morning so we do thank everyone for their continued patience."