ESB Networks has acknowledged that there has been what it described as "limited impact" on its 2.4 million customers over the weekend due to industrial action by some of its network technicians.
Today, the company confirmed that there had been a fault in Santry on Saturday night affecting around 1,000 customers.
It described this as a "...technical issue with the Medium Voltage network, the nature of which would have left that number of customers overnight without power regardless of the industrial action.
However, it went on: "While crews mobilised and restored power by lunchtime, the duration of the outage may have been longer than would have otherwise been the case."
The network technicians belonging to the Independent Workers Union - which the ESB does not recognise - commenced a work to rule last Monday, and held a 24-hour strike on Friday.
The union claims to represent over 550 of the 1500 network technicians, though recognised unions for the grade - SIPTU, Connect and Unite - put the figure significantly lower.
The IWU members are planning a further two-day stoppage this Thursday and Friday over what they claim is a failure to consult adequately with them over the outsourcing of certain work to external contractors.
ESB Networks argues that the industrial action is unlawful and has threatened to take legal action against the IWU.
However, the company has failed to explain why it has not done so before now, given the risk of disruption to customers.
Earlier, the IWU alleged that their industrial action had delayed work on a major construction project for Facebook in Clonee, as well as the broadband rollout project overseen by SIRO.
Responding to a query from RTÉ, SIRO said it had no comment to make on the matter.
A response is still awaited from Facebook.
ESB Networks said it did not wish to comment in relation to the union allegations about potential disruption to those projects.
However, the company insisted it had detailed contingency plans in place to minimise impact on customers and operations.
A spokesperson said this included an assessment on whether planned outages would proceed as scheduled or were postponed to a later date.
He said ESB Networks staff complete work in accordance with the company's robust safety approval procedures.
"To be clear, all work during this industrial action is in accordance with our safe system of work protocols and approval procedures," he said.
The company has apologised to customers affected by the situation.
