Darwin has been brought to a standstill by a major power outage and isn’t expected to return to business as usual until the afternoon.

The blackout, which stretched about 320km southeast to Katherine, was caused by a tripped circuit breaker.

The incident at the Hudson Creek substation at 1.19am activated a protection system at the Channel Island power station, shutting down its transmission capacity.

The entire city of Darwin, with about 130,000 residents, has been affected, along with Palmerston, Pine Creek and Katherine.

Residents suffered through a sweltering night without fans or air-conditioning, while fire and burglar alarms began to wail as a warning that they were not receiving power.

Fridges and stoves are not working, and most businesses and shops are closed.

Sirens could be heard on the Stuart Highway as emergency services rushed to help residents in trouble.

At peak hour on Wednesday morning, traffic lights were out, schools were closed and public buses were not running.

The Northern Territory government has mobilised emergency management protocols, and told all non-essential public servants to stay home.

Community health services will be closed, although the Royal Darwin Hospital remains fully operational.

Water and sewage services are being supported by generators where possible, the government has advised.

The Mantra Pandanas hotel in Darwin’s CBD evacuated guests at about 1.30am, with about 50 people sitting out the front on the street.

Power & Water Corporation (PWC) says restoration is underway.

Power was restored to Katherine and Pine Creek at about 3am CST, and PWC says some suburbs of Palmerston had at power restored about 9am CST. Four outer Darwin suburbs have also regained power, PWC says.

Treasurer Dave Tollner says power should be fully restored by the afternoon.

PWC has a history potted with power failures, and the government has introduced legislation to move it into three separate government-owned enterprises, with the Opposition claiming it is being primed for privatisation.

On Monday, Mr Tollner said an independent report had found the PWC networks were 27 per cent less efficient than those in other states.

The Utilities Commission has proposed a 43 per cent increase in electricity network charges for the Northern Territory, which the government opposes.

AAP