Thousands of homes were left without electricity and heating on Saturday night after a power outage in Craigavon.
Northern Ireland Electricity said around 2500 homes were affected by a disruption to electricity supplies.
However a spokesperson scotched rumours that the power cut was due to vandalism but because of a cable fault.
The power cut happened on Saturday evening at 7.35pm and was due to a fault on an underground cable in the Moyraverty and Drumellan areas of the town.
An NIE spokesperson said emergency crews responded immediately, sectionalising the circuit to pinpoint the exact location of the faulty cable.
“The majority of customers were restored at 9.40pm with remaining groups of customers restored later that evening and the next morning. NIE is investigating the cause of the fault,” she said.