A power surge equivalent to 800,000 kettles being switched on is expected for England's World Cup game on Sunday.
England are preparing to face Ecuador in the World Cup
National Grid forecasts an increase in electricity demand of 2,000 megawatts as TV viewers brew up half-time cuppas.
England, who face Ecuador on Sunday, attracted a surge of 1800MW for their most recent match against Sweden.
The biggest rises ever recorded were for England's World Cup semi-final in 1990 (2,800MW) and an episode of drama The Thornbirds in 1984 (2,600MW).
National Grid says it has researched a wealth of information ahead of the World Cup to try to ensure it is not caught out by sudden power surges during matches.
This included figures from previous World Cups and whether the final whistle coincides with the end of a film on another channel.
National Grid operations manager Alan Smart said: "We saw an increase in demand during England's match against Sweden on Tuesday.
"With the crucial game on Sunday demand could increase further, particularly if the game goes to penalties and the country's interest in England's success intensifies.
"Should England reach the quarter-finals even greater demand surges could be recorded."
The power surges are mainly down to people making cups of tea, switching on lights and getting drinks from fridges during breaks in the action.
Sunday's match in the first knock-out round of the tournament kicks off at 1600 BST.
Top 10 TV power surges:
- World Cup semi-final (England v West Germany) - 2,800MW (4 July, 1990)
- The Thornbirds - 2,600MW (22 January, 1984)
- World Cup quarter-final (England v Brazil) - 2,570MW (21 June, 2002)
- World Cup (England v Nigeria) - 2,340MW (12 June, 2002)
- EastEnders (Who shot Phil Mitchell?) - 2,290MW (5 April, 2001)
- Dallas (Who shot JR?) - 2,200MW (8 May, 1985)
- The Darling Buds of May - 2,200MW (20 April, 1991)
- Rugby World Cup Final (England v Australia) - 2,110MW (22 November, 2003)
- Coronation Street - 2,100MW (18 April, 1994)
- World Cup (England v Argentina) - 2,100MW (3 June, 1998)