First random trip happened 2 weeks ago, then once in last week. Instant tripping started 3 days ago. Called an electrician, who suspected short-circuit and changed quite a few old sockets, replaced the old mcb(all mcb no rccb). Tested and it lasted for 5 minutes. Suggested full wiring inspection, which is very expensive for my budget. Turned the breaker on again after he left, this time it lasted 6 hours, next time was 16 hours, and then 3 hours, all without plugging in extra appliances, just a fan or a light running occasionally. As of two hours ago it is back to it's instant trip phase.
I would like to know what I might be dealing with here? can't be overload without load? using the same setup for past 4 years, no faulty devices as they are running fine on power outlet from other rooms. Short-circuit? is a major suspect but the irregularity of trips is casting doubt on that too. And is the diminishing interval between the trips any kind of pattern? like static/current buildup if that is even possible.