Northland has been crippled by a mass power outage, with the area unlikely to have electricity for several more hours.

Some businesses have been forced to close and residents are warned to conserve water, avoid flushing the toilet and to turn off electrical devices.

Northpower says the outage, which is believed to affect all of Northland, was caused by a fault on Transpower's national grid.

The affected areas include Dargaville, Maungatapere, Poroti, all Whangarei also all areas North to Hukerenui including, East Coast between Whangārei Heads to Bland Bay.

The area covered by the outage.
The area covered by the outage.

Information on the Northpower website says the estimation restore time is currently "unknown''.

The fault occurred on the Whenuapai-Marsden high voltage line about 9.35am.

The cause of the fault is not yet known.

Fishbone Cafe in Kerikeri is serving tea only this morning after a Northland-wide power cut. Photo / Peter de Graaf
Fishbone Cafe in Kerikeri is serving tea only this morning after a Northland-wide power cut. Photo / Peter de Graaf

A Top Energy spokeswoman said power had been lost across the Far North. The Top Energy faults app is also down due to high demand with people trying to check the extent of the power cut.

Northpower is also experiencing problems with its phone lines, frustrating the ability of customers to receive updates.

While the outage has brought traffic chaos to Whangarei, the effects are less drastic in the Far North, which has only one set of traffic lights on Paihia's Marsden Rd.

A Whangārei Hospital spokesperson said that they had backup generators to ensure operations run as usual.

The outage has disrupted businesses in tourist centres such as Paihia, but there are fortunately no cruise ships visiting the Bay of Islands today. At least one cafe is setting up a generator to ensure coffee keeps flowing.

Westpac Bank in Kerikeri is closed. Photo / Peter de Graaf
Westpac Bank in Kerikeri is closed. Photo / Peter de Graaf

Cafes in Kerikeri are still open but have switched to plunger coffee while their espresso machines are out of action.

Petrol stations have also closed.

A fault on the electricity lines to Northland coincided with scheduled maintenance work on the electricity grid's safety net, leaving to a region-wide outage.

A Transpower spokesman said a fault occurred this morning while crews were working on one of the two supply circuits to the North.

It was unknown what caused the functional circuit to switch off but the maintenance work meant the backup was unavailable.

Whāngārei residents are being told to conserve water and avoid flushing toilets (except where necessary) because "we don't know for sure how long the power will be out...''

"Please also take care on the roads as traffic lights are out,'' a statement on the Council's official Facebook page said.

General manager infrastructure Simon Weston said: "The less stress we put on these systems during the outage, the sooner we will be able to recover when power comes back up.

"We are liaising with power companies and will publicise any information as it comes to hand.''

Joey Johnson at Churchills butchery in Kerikeri, where staff are preparing for a rush on anything that can be barbecued. Photo / Peter de Graaf
Joey Johnson at Churchills butchery in Kerikeri, where staff are preparing for a rush on anything that can be barbecued. Photo / Peter de Graaf

Power will be out for at least two hours and probably longer, says Northpower.

The spokesman said the cause of the outage was unknown.

He said the energy company was having trouble with its phone lines and customers would experience difficulty speaking to the company.

He asked for patience and for people to take care by turning off anything currently plugged in.