Around 18,000 homes in Northern Ireland are still without electricity following heavy snowfalls and strong winds last night.
Northern Ireland Electricity said its crews, assisted by ESB colleagues from over the border, are working on the problem.
However, it could take a number of days to clear the backlog.
NIE spokeswoman Sara McClintock said: "Access to faults remains our biggest problem.
"We will continue with all of our efforts to restore customers as soon as is humanly possible, but in many cases our crews are struggling through snow drifts up to six feet in depth."
Northern Ireland Water said some pumping stations experienced power interruptions affecting supplies.
Northern Ireland's World Cup qualifier against Russia was called off for a second time due to an unplayable pitch at Windsor Park.
Motorists are being advised to make only essential journeys and to exercise caution due to ice and flooding if they do travel.
Elsewhere, gardaí are advising motorists to take extra care in areas that experienced flooding yesterday.