Christmas Eve, and Chris McNally was winding down for the holidays. The repair crews were knocking off and many of them dropped in to wish their boss, the manager of the ESB's southern region, all the best.

Ignoring the noise from the gale outside, Mr McNally returned their greetings and turned his mind to thoughts of Christmas with his wife Mary and their children in Cork.

By lunchtime, the wind was howling outside the control centre in Wilton, Cork, and there were unmistakable signs that he wouldn't be finishing work early that day.

In fact, it was five days before Mr McNally stood himself down from the state of emergency he declared after the worst storm in over 20 years cut through from the south-west, tearing up trees, pulling off slates and, most importantly for the ESB, downing power lines throughout the State.

What followed was the greatest supply crisis faced by the ESB since its foundation. The storm cut a swathe through the company's distribution system, leaving at its height up to 135,000 homes without power.

The timing was terrible. Bad weather continued into Christmas Day, the amount of daylight available for carrying out repair work was at a minimum and staff were just beginning their holidays.

Yet a week later, every single home has been reconnected, most of them in time to cook the Christmas turkey.

Only now are repair crews returning to their bases, exhausted but euphoric, after successive days of 12-hour shifts in difficult and often dangerous terrain. There were complaints from the public, but given the scale of the damage and the time of year, far fewer than might have been expected. By the end of the week, says Mr McNally, the thank-you cards and calls were streaming into the Wilton offices.

Operation Christmas brought a Blitz-style response from staff at all levels, many of whom missed their Christmas dinner to volunteer for duty. With military precision, crews were moved around the country as needs dictated, and more than 1,000 staff were deployed to deal with the damage.

It was 2 p.m. on Christmas Eve before Mr McNally received a warning of bad weather. But winds of up to 120 m.p.h. were already battering the Cork coastline. "There was a warning, but the severity of the weather caught us by surprise."

Alarm bells started ringing. Area supervisors called in with reports of fallen lines. In the control centre, the computer screens of the Supervisory, Control and Data Acquisition (SCADA) system started flashing the same message.

SCADA was the ESB's secret weapon in the war against the storm. Major faults are identified almost instantaneously, often before the customers are even aware of them. If there is a break in the line, SCADA will identify an alternative route for distributing power to affected homes.

At the tap of a keyboard, circuits are opened or closed. Major breaks can be rectified by remote control. If a line goes down, SCADA is used to break the circuit, making it safe for repair crews to work locally. As Christmas Day progressed, the alarm spread to other regions. In the east, the storm peaked at about teatime, and about 10,000 homes were cut off. Staff poured back into the regional control centre in Leopardstown. Pink and yellow pins proliferated on the schematic supply map to indicate the growing crisis. At 2 a.m. the centre was taking 900 calls from an anxious public.

"It wasn't until lunchtime on Christmas Day that I realised this was really big. It was clear we weren't going to get it finished quickly," Mr McNally recalls. A national emergency was called within the ESB, and the southern region appealed for crews from other regions.

Once the other areas had dealt with their own problems, staff travelled from as far as Donegal and Louth to help out.

"We had to feed them and find accommodation. But the most important thing was to blend them with our own staff. You can't have `foreign' crews working in networks they are not familiar with. They'd spend all day looking at the maps."

Mr McNally says fixing electricity supplies is specialised work. "I was disappointed to hear people calling for the Army to be brought in. This work is too dangerous for that. Staff were working in storm conditions, working with fallen lines in difficult terrain."

Meanwhile, the public was going berserk. Wilton received 17,000 telephone calls on Christmas Eve alone. Most of these were dealt with by a series of taped phone messages, but more than 3,000 callers were answered personally.

A local radio station in Cork caused major difficulties by wrongly stating that supplies would be restored by the evening of Christmas Day. Nothing could be done to counter this because, in contrast to the ESB staff, the station had taken the day off and left a taped news bulletin to plug the gap.

But public anger abated quickly as large areas of the country were reconnected. Engineers concentrated on restoring the high-tension sections of the supply first.

They still relied, however, on individual householders to tell them about small faults. Thousands of homes could be reconnected at the flick of a switch, but a single fault in a remote area could take days to repair.

Everywhere, trees were the main culprit. More than 1,000 poles were damaged nationwide, many in areas made inaccessible by fallen trees. Two helicopters were brought into service to provide aerial information about the damage.

By last Tuesday it was mission accomplished, as the last houses were reconnected. The successful outcome has given the ESB a useful fillip at a time of rapid change. Although highly profitable at the moment, it needs more price rises to fund a £1 billion revamp of its infrastructure, and its monopoly over the Republic's electricity business is to disappear shortly.

Mr McNally is more concerned with mopping-up operations, "poles at embarrassing angles and the like". "It was incredible. In spite of all the difficulties, morale was high and there was a great buzz. I'm proud of my staff and I think the country can also be proud of them," he says.