TOMAGO Aluminium chief executive Matt Howell said the smelter is back to full capacity, after taking action on Saturday to maintain the stability of the electricity grid.
Mr Howell said the smelter is the country's largest electricity consumer and takes a constant 950MW, or 10 per cent of NSW supply. It is also the largest "interruptible" load and can take around 600MW off the state grid within minutes.
"Tomago Aluminium in cooperation with AGL Energy reduced load by cycling two potlines through a carefully controlled curtailment, thereby avoiding rolling blackouts elsewhere in the state," he said.
"This curtailment process is part of the energy supply contract that has been in place since November 2017 and runs through to 2028."
Mr Howell said NSW was facing a "severe short term energy shortage" as a result of the bushfires when the Australian Energy Market Operator issued a Lack of Reserve, Level 2 notice around 5:30pm on Saturday.
He said Tomago Aluminium's action prevented "an escalation of this situation".
He said it was the first time this year the smelter had to switch off potlines and didn't expect it to be the last.
"This is not typically a demanding period so we expect to be on high alert going forwards into summer," he said.
"Any time we switch off a potline, there is no guarantee that it can be restarted again so the impact is significant - however it is much more preferable to take a potline out of action as opposed to risking the grid collapsing."
Mr Howell said management was "particularly grateful for the actions of site personnel on the day; all emergency response plans were followed and there were no injuries or equipment damage."
Energy Minister Matt Kean urged all NSW residents to preserve power last Saturday, after the Snowy Hydro's transmission lines were damaged.
TransGrid was forced to take the Upper and Lower Tumut substations offline, cutting NSW off from Victoria.
Mr Kean asked consumers to turn off pool pumps, raise air conditioner thermostats, avoid using washing machines, dishwashers or dryers and turn off appliances and lights not in use.
An Ausgrid spokesman told the Newcastle Herald consecutive nightly blackouts in parts of Broadmeadow, Adamstown and New Lambton earlier this week were the result of infrastructure failures and not areas of the network turned off because of supply issues.