Re: If you want to save time
It's a 'worldwide compatibility' thing. Some areas have 10 amp sockets. 2.4kw at 240v is gonna be within 10 amps at 240v, and given the resistance won't change that much, slightly less at 230 or 220v.
It's why modern kettles are rarely the 3kw goodness of yore.
Side note, I wonder if that's why commercial breaks are getting longer, to give the kettle time to boil?