I will relate all information that I can possibly give as I have no idea how to even diagnose this issue.
I live in a hot, dry country with 240V supply. The house I just bought here, has it's lights wired through 2 separate 10A circuit breakers. For some reason earth leakage was bypassed for the lights when I bought the house. A electrician rewired the entire lights circuit and made sure that earth leakage is not bypassed anymore.
After the rewiring we started to have a weird issue. The main earth leakage circuit breaker trips randomly.
With randomly I mean that I am unable to detect a pattern.
Times between this happening have been 1 week, 1 week, 4 weeks, 2 weeks and 2 days. 2 times it was raining at other times it was dry and hot. Once it happened in the morning while other times it happened in the afternoon. 3 times it happened without ANY lights being on.
When this happens, I am unable to reset the earth leakage breaker unless I switch off one of the lights breakers. (Always the same breaker) If I try to reset the breaker without switching off the lights breaker earth leakage trips again.
None of the lights have any timer functionality. They are all just light switches connected to standard lights. (Some LED)
The only odd wiring is a 2-way switch for a bedroom.
Now comes the weird part. After the breaker trips I need to wait several hours (more than 3 hours each time, usually overnight), and then everything is fine again. I can reset all breakers and everything works as it should, until the issue happens again some days or weeks later.
Has anyone had a similar issue? Any suggestions on diagnosing the issue would be appreciated.