Round 12,000 houses and companies in north Wicklow and south Dublin are struggling energy cuts since round 7pm on Thursday night.
A spokesperson for ESB Networks mentioned the worst affected areas had been Bray, Greystones, Delgany and Shankill.
The outage was traced to a fault at an ESB substation within the Fasaaroe space of Bray, whereas there was additionally a associated drawback with a high-voltage cable in the identical space.
The spokesperson mentioned emergency crews had been working at repairing the fault and it was hoped electrical energy provides can be restored earlier than the tip of the night time.
ESB Networks has apologised to all clients affected by the outage.