Shop owners will be thousands of dollars out of pocket after the lunchtime power cut in Auckland's CBD.
The outage extended through large parts of Parnell, stretching into Newmarket and a portion of Symonds Street.
Vector said power was fully restored by 2pm.
RNZ reporters said electricity had been restored on Queen Street by about 1pm, but had been unstable and dropping in and out.
One inner city resident said shop owners on Anzac Avenue all came out to the footpaths shortly after the power went out in her apartment.
Next Generation Gym was evacuated. One gym-goer who was in the pool at the time was told to get out.
In a tweet, Auckland Transport apologised for the inconvenience after trains were disrupted at Britomart train station.
It said the station was closed due to the outage and the nearby Downtown Ferry Terminal was also affected, though ferries were continuing to run.
Auckland Transport also said a number of traffic signals were not working because of the outage, and give way rules apply.
Lines company Vector said it was investigating the outages. It said it was remotely redirecting power flows to as many affected people as possible.
It had electricians working on the issue now, but said customers in the areas should prepare to be without power for some time.
In a tweet, Vector said staff were assessing the extent of the "large outage" from Quay Street to Parnell.
@AklTransport Traffic lights at Shortland Street and Queen Street are off at 12:30pm. It’s a bit chaotic— Bob Jewers (@BobJewers) January 22, 2020
RNZ reporter Chen Liu said power was returned to the Britomart train station by about 1pm but had been interrupted several times this afternoon.
Auckland Transport said after 1pm that trains would not be departing from the downtown Britomart Station.
Instead, all Southern, Western and Ōnehunga lines would finish at Newmarket train station, which was not affected.
The Eastern Line would terminate at Ōrākei train station.
Commuters were told to expect delays.
A message over the loudspeaker said: "Please expect delays and possible cancellations due to a network facility matter."
UPDATE 1 - 12:55PM— Auckland Transport (@AklTransport) January 23, 2020
Due to the power outage trains will not be departing from Britomart. Southern, Western and Onehunga lines will be terminating at Newmarket train station. The Eastern Line will be terminating at Orakei train station. Please plan ahead using alternative PT.
A High Court hearing also had to be rescheduled due to the power cuts.
All non-essential court staff were sent home with court security, the site manager and only a skeleton staff remaining.
Heart of the City chief executive Viv Beck said the power outage caused regrettable effects to lunchtime trading.
The McDonald's restaurant at Britomart was closed.
The restaurant manager said three hours outage would mean a hefty loss.
"We are in the busy lunch rush, it was about 12.20[pm] or 12.25 and then all of a sudden the power goes.
"We decided to close the restaurant and give full refunds to the customers, and then we asked if they want to sit in the lobby or stand outside for a while until we sorted out the issue, what the reason is.
"Then I checked with our other restaurant, the East Street McDonald's, they also don't have power.
"Still the issue is not fixed because we have our internal system is crashed ... because of the sudden power cut. So they are still working on it, to fix the menu boards, fix the kiosk ...
"All the machines are off ... we have to redo the food safety check before we open and serve to the customers, so it's critical, that's why we are taking time so everything we are serving to the customer is safe.
He said they could not ask staff to go home or go on break either, and the food would be going to waste.
There were a large number of construction workers waiting to go back to work while the power was out.
Suraz Dhrungana, a construction worker from Nepal, said they had to walk down from the 27th floor.
"We had to walk down to the stairs, and came down here, no traffic light working, everything was off and even the McDonald's - now working very hungry, you know.
"Were still waiting to go up. It's been half an hour and just waiting for the power to come back."
Another construction worker, Stephen Toia, said there were concerns about going back into the building's 36th floor in the heat if power had not been restored to the fans.
"Everything stopped - lifts, fans, power - in our building, a forty-storey building. So we've decided to evacuate just due to health and safety reasons.
"We've come down to find that traffic light were also off as well and a few of our neighbouring buildings, McDonald's and H&M clothing building as well.
"About three fire engines have arrived to the site beside us, so we're not sure whether the cause of the power outage is from that or from something else."
"We're due to go back anyway, and we haven't been advised from any phone calls yet from any supervisors ... if there's no power then we're probably a bit worried, concerned about going back up there due to the heat and no fans going."