A blackout covering the whole city of Darwin yesterday has raised concerns for the Northern Territory’s power system.

Chief Minister Adam Giles says problems during routine maintenance left large parts of the state, including the entire capital, with only the ample sunlight to guide them.

Specifically, the event has been blamed on circuit breaker repair work at the Hudson Creek sub-station, wherein some components were removed and seemingly not put back properly.

“There was a snowball effect that saw the cancellation of power right across the Top End,” Mr Giles said.

Several massive Rolls-Royce emergency generators were installed to prop up Darwin’s power grid, after a similar event four years ago.

Chief Minister Adam Giles said they were less than effective.

“With these new generators that were put in place in 2010, they can't immediately be turned back on, they have to be turned back on gradually and slowly.”

Power has been restored in a majority of areas today, after the blackout hit legions of homes and businesses in an area covering hundreds of kilometres from Katherine to Darwin.

“It certainly is disappointing that we have heard about some back-up generators that did not kick in,” Darwin Lord Mayor Katrina Fong Lim told the ABC.

“We are actually pretty lucky it happened just on an ordinary day as opposed to part of a cyclone emergency, which could have had a lot more catastrophic effect.”

Charles Darwin University professor of economics Dr Bill Mitchell said the event should serve as a warning.

He says it shows the vulnerable state of the electricity system, and is an argument against privatisation.

Professor Mitchell said seeing what happens when maintenance falls down shows the risk in selling an essential public asset to a profit-seeking, cost-cutting private company.