I have seen many instances of these things boiling dry- to the immediate failure of the element.
Cheap plastic kettles in the US are usually 1kW. We have one, and swear by it. When we go to visit a friend who doesn't have one, we go out and buy one as a gift. Beats heating up teawater on the stove. Sure, I often forget and leave it boiling longer than I intended, but I have yet to boil it dry. They're cheap enough to indulge a controlled experiment, although I have never wanted to do that.
Bottom line: 120V, 1kW. Aren't the kettles down under (and presumably in the UK) a higher wattage? (And 240V of course.) I suspect these factors could alter the degree of fire hazard.
I am not a firefighter but I do say I must doubt that one could open the door to a kitchen fully engulfed in flames without at least some burns!
