That last answer is so stupid. It doesn't 'detect how much water is in the kettle'! Try turning your kettle on with no water in it at all - it won't magically shut off.Most modern kettles use a steam based cutoff switches. I have just taken my kettle apart (as it's old and isn't working … Read more
In this a automatic thermometer is installed which is detect high heat of the kettle and switch off the kettle.