@clacke That sounds absolutely terrifying, in no small part because I spend a lot of time learning about home construction and electrical wiring and can't fathom what would even do that.
@ocdtrekkie I imagine some sockets without proper covers.
It didn't happen before, but it happened during the strong typhoon two weeks ago and the strong rain last week, and today only somewhat strong rain (50 mm/h) tripped it. Currently it won't come on again, I'll try again in a bit. I don't have access to the roof.
They dismantled something on the roof after the storm, a shed of some kind. That might have uncovered something that was previously protected.
@clacke If it takes a little while before power goes out and then delays power coming on for hours after the rain stops, it may be a roof leak dripping onto a vulnerable spot in the building's wiring.
(One house where I lived had this problem. Years after I moved away, the landlord sold the house for a fraction of the going price, which makes me suspect they never repaired that and other issues.)
It tripped again, but now I've identified the roof breaker. I should have switched that off when I moved in, as the roof isn't mine.
I wonder how it can trip the 64A main breaker without tripping the 30A roof breaker.
Also, holy hell, 64A? This is just an apartment, my parents have like 20A or 25A for their two-floor house with garage and stuff. Here we have 30A just for the bedroom. 😲