This type of heater is the main reason why we here are prohibited from using any water heaters - even electrical kettles - in ANY type of building except private house (which of course will not save us from people who dont care about it or cant care - when there's no money to buy anything more safe).
No fuses, no protection, nothing - all safety is "get lucky enough to not forget about it or your house will burn down".
It is simple as that - just pure resistive load that heats itself with plastic handle that melts quite quickly if you don't put it in water or put it for too long.