Electricity has been restored to 25,000 homes and businesses in and around Ballymena.
A fault in the network was reported just before 8am this morning (Monday).
The vast majority of NIE’s customers were back on supply an hour later, with a small number without power on Monday afternoon.
Properties in Cullybackey, Ahoghill, Galgorm, Portglenone, Dunloy and Cloughmills were affected.
An NIE spokeswoman added: “Currently three customers remain off supply while NIE emergency crews carry out repairs to a broken overhead line.
“Investigations are ongoing into the cause of the damage.”