Electric car owners have been warned that if they attempt to boil a kettle while charging their car it will blow the fuse.

The National Grid expressed concerns that an average size 3.5kW battery charger would take 19 hours to fully charge a car battery, even when it is 25 per cent full.

A “thought piece” document obtained by the Financial Times warned that a more powerful 11kW device would still take six hours to charge a car battery and during that time, the use of everyday items such as kettles and ovens would blow the fuse.

“The average household is supplied with single phase electricity and is fitted with a main fuse of 60-80 amps,” the National Grid said.