Up to 60,000 properties had their electricity knocked out across Christchurch on Wednesday afternoon before it was restored shortly afterward.
The outage affected nearly 100 suburbs.
Power company Orion says smoke or flames caused the power lines to trip, causing the outage.
Worsleys Road has been closed off to traffic, and Hoon Hay Valley Rd has been shut "due to rubberneckers" according to a council spokesperson.
The council has advised that recreational mountain bikers, walkers and runners should stay off the Port Hills to allow emergency services to work in the fire affected area.
Traffic lights across the city weren't functioning for a time, with drivers urged to take care.
Smoke from the scrub fires on the Port Hills is also choking the city.
The thick smoke is prompting warnings for people to stay indoors and close windows and doors where possible.
One school near the foot of the Port Hills has decided to keep children indoors for the day.
There are also reports of ash from the fires falling in some areas.
Christchurch residents are advised to look out for each other and take extra care during the power outages understood to be still affecting part of the northern, eastern and central city areas.
The outage has affected signalled intersections and motorists are reminded to drive with care and observe the give-way rules.
Police have patrols in the city assisting those affected by the outages.
Adventure Park spokeswoman Anne Newman says fire crews have been evacuated from the area and flames are "ripping" down towards the village.