Parts of the province were left without power for several hours
A government minister has called for a swift report into a power cut which left tens of thousands of people in Northern Ireland without electricity.
Problems at two power stations resulted in many homes and businesses being left without power for several hours on Thursday.
The province's main power station at Kilroot, near Belfast, shut down because of a technical fault.
This happened during scheduled maintainance at Ballylumford power station near Larne, which was producing much less electricity than normal.
As a result, Northern Ireland Electricity was left without 25% of the power it normally needed to supply demand.
However, power was restored to all customers by about 1900 GMT.
Stormont Enterprise Minister Ian Pearson has called for a swift report
from NIE about the matter.
He said he had been assured that what happened was "extremely rare" and it would be thoroughly investigated.
Ian Pearson said matter would be investigated
At Ballylumford, 23 people worked through the night to restore full supplies.
NIE said it did all it could to minimise disruption during the power failure.
Speaking on BBC Radio Ulster Robin Greer said the company was pleased with how its emergency plan worked.
"We did what was our job in such circumstances which was to bring in the emergency plan, to stabilise the grid, to find emergency supplies and to get the system sorted out as quickly as possible," he said.
"We think that system worked very well although that is not to in any sense underestimate the pain and frustration customers felt but we did what our side of the job was last night."
However, Wesley Henderson from the General Consumer Council said emergency planning needed to be revised.
"This happened not because of lines falling down or wind or anything like that, this was about the generation availability," he said.
"We need to make sure that consumers can be reassured when a big incident happens that there is a plan and that they can call for back up right away."
At the height of the crisis,
NIE introduced a series of rotated power cuts to ensure that customers were not without electricity for too long.
The worst affected areas were parts of Counties Down and Antrim, including parts of Belfast, where some traffic and street lights were also affected.
NIE said that the interconnector from Scotland had been operating normally and it had brought additional electricity to the province to counter the problems.