Staff at The Irish Times were evacuated and production was delayed last night after a fire started at an ESB sub-station next to the Fleet Street building in Dublin.
A 10kv transformer, which serves the Westmoreland Street, Fleet Street and College Green areas, went on fire causing a black-out in the newspaper offices and surrounding buildings.
Four units of the fire brigade put out the blaze after ESB electricians made the transformer safe by cutting its electricity supply.
More than 100 staff were evacuated after the alarm was raised at about 7.20 p.m.
A spokesman for the ESB, Mr Michael Kelly, said: "We were notified at 7.23 p.m. Our staff went directly to the scene where they met the fire brigade."
The ESB emergency crew, comprising two network technicians and a supervisor, switched off the power supply from a building 100 yards from the transformer.
Firefighters then extinguished the blaze using foam.
Mr Kelly said the exact cause of the fire was not clear, although an initial inspection suggested the transformer overheated.
He confirmed there was a blast from inside the room where the device was located at street level next to The Irish Times building in Fleet Street.
The force of the explosion, combined with the heat, caused the room's external doors to be bent outwards.
As the firefighters found themselves unable to open the doors, they smashed a number of windows to let the smoke out of the room.
Mr Kelly said the transformer, which converted a 10,000-volt power supply to 220 volts, was "very badly damaged and it looks like it will have to be replaced".
He said: "We will be working with our customer to carry out whatever works need to be put in place to have things back to normal as soon as possible."
He said the transformer mainly served The Irish Times but was used by other premises in the area.
Staff re-entered the building at about 8.40 p.m., working off The Irish Times' own generator.
Mr Kelly said the ESB was seeking to return supply to other buildings in the area by linking them to a different source.