There is also electronic selectable sensitivity to adjuct from 0.1A to 1A cut off.

Anyway having it trip during lightning isn't good as it try block surge from entering your electrical appliances.

Btw MCB is meant for overload cut off. It trips whenever the load (amperage) goes beyond the rated. Usually it trips when Live wire shorted to Neutral. ELCB trips whenever there is leakage on Neutral. For example, Live or Neutral wire is leak to the earth, it trips.

To test how good is your electrical grounding, get a MEGA tester or insulation tester. Calculation based on OHM.