Dodgy kettle?

Here is a possible theory:

A heating element is simply a metal tube filled with insulation and with a heating wire in it.

If the tube corrodes and develops a pinhole leak, water will get in, providing a path for electricity to flow from heating wire to metal tube and hence to earth.

With a safety switch, this current only has to be a few tens of one thousands of an amp for the safety switch to operate, if one is present.

If one isn't present, many amps, or tens of amps may flow from the heating wire to the tube, until the fuse blows. These amps, or tens of amps, can cause very localised heating of the water - leading to steam being created and being created faster than it can escape through the pinhole that the water got in through. The result could be a very high pressure build up in the tube - enough possibly to cause it to explosively rupture. The very hot, high pressure steam that escapes through the rupture could cause the ejection of quantities of scalding hot water and very hot steam.

Yes a safety switch does detect that some current is going to earth - in this case, from the heating element to the tube. The whole point is then that the safety switch will operate so quickly that the fault won't last long enough, or become big enough to produce the energy neeed to rupture the outer tube.

I haven't seen this warning - but then I haven't bought a kettle for years. I suspect that very few people have been injured in this way but that the lawyers want to cover their companies backs..

I have every circuit in my house protected with "safety switches" - with the exception of the freezers.

Tried the freezers and had problems, or never even attempted it?

Just curious.