AL_n wrote
NT wrote

sometimes filament lamps arc over when
they fail, causing a very large current surge.

I only have one incandescent bulb on the affected floor. It is a 150W
bulb. However, it has not blown. All the other bulbs are fluorescent or LED.

You dont usually get intermittent faults in those that blow the breaker.

Its much more likely to be in what you did several weeks ago.

Corse it can be a coincidence too.

Could be a water leak.