In the interests of science (who am I kidding?
) I just filled my jug-style kettle to the maximum mark and timed it.
Starting from cold, with exactly 3 Imperial pints of water (that's 3.6 U.S. pints) it took 5 mins. 25 secs. to boil and switch off.
That's with a 2.2kW element. I didn't bother to measure the starting water temperature, but apparently across England it comes out the underground pipes at a fairly constant 50 degrees.
If that's the case, and using rough figures, I make that about 85 - 90% efficiency.
By my reckoning, a 3kW version running at similar efficiency would have taken just a shade over 4 minutes.
[This message has been edited by pauluk (edited 11-07-2004).]