About 3,000 homes were left without electricity after vandals set fire to a substation, officials have revealed.
Northern Ireland Electricity (NIE) said those who started the blaze in the Joymount area of Carrickfergus on Friday night were lucky to be alive and left a clean-up operation expected to cost tens of thousands of pounds.
The PSNI has appealed for information on the arson attack in the town centre.
NIE duty incident manager Randal Gilbert said the firm's first priority when the alarm was raised at 8.20pm was to make the area safe, with an emergency team restoring power to all but 60 properties by 10pm.
The rest had supplies restored from alternatives sources by the early hours but it is estimated that permanent repairs will take a number of days.
Mr Gilbert said: "This morning it is clear that the substation and several of the underground cables supplying it have been damaged beyond repair.
"We currently have teams off-site building a replacement substation and teams onsite salvaging and repairing the network in the vicinity of the substation. This work will be ongoing throughout the weekend."
Mr Gilbert said he cannot stress strongly enough how dangerous it is to tamper with electricity substations.
He added: "Substations contain live equipment energised at several thousand volts of electricity.
"These vandals were lucky to make it out with their lives. As it is, they caused considerable inconvenience to the local community and local businesses."