mkissin:

In general, I agree, but there’s lots of corner cases. What about the tiny cord for my alarm clock? It’s probably 1mm2, and being protected by the upstream 20a MCB? It’s very possible for the cord to become damaged and by the time the MCB trips it could be very hot.

It’s obviously not a huge problem, but one that is protected against by shifting the fuse into the plug rather than the alarm clock.

Chances of a fault that is not a short inside the alarm clock causing only 25-30 amps to flow for long enough that the cable is a concern before the clock melts itself is something I cant think of an occurrence that would cause to happen.

Mechanical fault to the cable will either blow itself clear, or trip the breaker, or both.

The issue is double adapters still being sold and putting those at the end of a 1mm cable and then sticking 2 heaters on it. That wont overload the breaker. That will cook the cable. Thats why double adapters are a stupid idea and need to go away.