Hi folks,

My family and I are living in a terrace house.
Recently my dad changed our 25-yr old voltage-based ELCB to a newer current-based RCCB (Wylex 2Pole 40A with 100mA sensitivity)

After that it start nuisance tripping a lot during storms, even if the lightning is far away.
When no storm, everything is OK.

I was surprised even 100mA also trips a lot, if 30mA of course I can understand the tripping.

Any RCCB users here on 100mA sensitivity? Do yours trip frequently during storms? If yes, what did you do to mitigate the annoyance?

instead of 40A type maybe try using the 63A type.

In = 40A / 63A indicates the Max carry amp of the RCCB. It means, if you install a 40A RCCB, but you are running 50A of load, it will trip. This protect from overload.

Ioan is the sensitivity of the RCCB. Ideally, Live + Neutral = 0, if Live + Neutral /= 0, leakage happen. But, there's no ideal in real life, so, comes the Ioan where it is the tolerance the device will accept before registering the leakage as a fault, in your case, 100mA.
Generally, for lighting circuit, 100mA is used, 30mA is used for power circuit and 300mA for Air-Con.

As for your problem, how old is your house, particularly, the electrical wiring? The older the wiring, the higher the probability of leakage through wires due to degration of the insulator.

Proper solution, do a complete insulation test to the whole house, or change all the wiring. Improve your house earthing system.

Cheap solution, which profesional do not agree, but client will usually do due to cost saving. Use higher tolerance RCCB or use ELCB instead.

No matter how do it, make sure other than the fuse, there's at least a protection device in place.

didn't realise helpful helob resurrected my thread lol

After some research, I suspect background leakage from the internal wiring (my house is 30+ yrs old).
Say, maybe about 60-70mA worth of background leakage between Live and Neutral.
So the tiniest of surges from lightning could be enough to send the Live-Neutral delta over 100mA => TRIP

damn, now must check all the circuits in the house..mafan