Could be
- faulty rcd
- something plugged into a socket with earth faults. You should definitely try unplugging things, especially any heaters
- faulty light fitting
-outside light on same circuit full of water
Any real electrician could test each circuit and measure the Earth leakage.
Some electricity is regularly going an unintended route, basically going missing in action, and this safety device is operating in case it’s going through a person. It’s likely the fault was there before he started.
There is also an unlikely possibility that the smart meter in close proximity is causing it to trip. This is unusual but can happen.
Does it always trip at the same time of day?
Basically you need to get someone competent in. The first tests are simple and if a fault is measurable it shouldn’t be that hard to find it.
