About 3,000 homes and businesses are without power in North County Dublin.
Customers in Marino, Clontarf, Artane and Portmarnock have been affected by a fault.
Separately, a group of homes and businesses in Palmerstown and parts of Ballyfermot have gone dark too.
Councillor Christy Burke says some locals in his area rely on the electricity for health reasons:
"There are people who are dependent on electricity for medical machines," he said.
"There are people this morning with their phones gone dead and they can't contact their loved ones.
"I find it totally and utterly unacceptable. No explanation from ESB senior management.
"An enquiry or an investigation by the minister needs to be carried out as soon as possible."
