I live in Europe, my house is serviced with a 230 V, 4.5 kW single phase line.
In my main panel I have a combined RCD + overcurrent breaker, 30 mA/25 A, and then several overcurrent breakers for various circuits, a few 16 A for outlets and a few 10 A for lights.
The combined breaker trips very rarely, two or three times a year. I have not been able to find a pattern, except it normally happens in the early morning, 5 am or so. It does not seem to be weather related, or anything related, but I have very limited data points.
I have contacted the electrician who made the wiring in my house, as this person lived there for some time, and he suggested it might be a humidity problem, and given me the option to upgrade to a class A RCD - I currently have a class AC - or to install a delayed RCD.
Both options seems very poor to me, as I'd like to root cause the problem rather than put a band aid on it.
Is there any possibility to investigate this topic further, given especially that it occurs so seldom? I am okay searching for the issue myself, but I do not have a current clamp that is good enough to investigate this issue and before investing in it I'd like to have any idea where to look.
I did measure the neutral-to-ground voltage, and it is basically zero, so it does not seem I have any high current flowing there.