A combination of colder weather and the return of industry from the Christmas break is expected to produce demand for between 49,000 and 50,000 megawatts of electricity at this evening's peak. But electricity generators said there would be 59,000 megawatts of capacity available - more than enough to ensure that the lights do not go out.
The previous record was set on 25 January last year when demand reached 48,800 megawatts. There is a possibility that peak consumption will exceed 50,000 megawatts for the first time later this month. Traditionally the second Tuesday in January - which this year falls on the 14th - has proved to be the day of highest demand.
A dispute has been raging between the Grid and big industrial electricity consumers about the ability of the privatised power industry to meet demand. Several independent gas-fired plants are on interruptible supply contracts which means they can be taken off-line at short notice.
Lisa Waters of the Energy Intensive Users Group, whose members account for a quarter of daily UK electricity demand, said: "The impression we have is that the Grid has no contingency plans. They keep running to our members and offering them huge sums of money to get off the system whenever a problem arises. Nobody is taking responsibility for ensuring there is sufficient capacity to meet demand and the Grid should be worried."
However, a senior source at one of the privatised generators said: "It is in nobody's interests for security of supplies to be called into question. We are working flat out to make sure that we meet whatever demands are put on the system."