At my place it's become a regular thing since this summer. Whenever there's heavy rain, my main breaker cuts everything off. I checked the outlets and there's nothing wet inside them. Is this a humidity problem in the panel or something more serious?
When that happens to me at home during storms, it's almost always the residual current device (30mA) that trips, not the main breaker - that's a huge difference. If it's really the 20 or 32A breaker that's tripping, it could be moisture buildup in the electrical panel itself, like condensation creating minor leaks. I'd suggest opening up the panel when it's dry and checking for signs of moisture, rust, or standing water inside; otherwise an electrician will spot right away if it's a failing seal on the box or an actual installation problem.
Is it the circuit breaker tripping or a residual current device? Because if it's an RCD (the little test button), that's clearly a water leak somewhere - either in the panel itself or in electrical conduit that's gotten wet. Water in the panel is pretty likely if you've got roof leaks or sealing issues around the cable ducts. I'd really suggest calling an electrician before this becomes dangerous, it's not something to brush off 😅
Don't mix things up: if it's actually the main breaker tripping (the big one), that's way more serious than a differential switch going off. A diff tripping when it rains is pretty common (moisture, tiny leaks), but a main breaker only trips for overload or short circuit, so you need to check if water's getting into the electrical panel itself, through a crack or a corroded seal at the top. If you want to test it, try sealing the box really well during rain and see if anything changes, but if it keeps happening you definitely need to call an electrician to check the wire insulation inside the panel.
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