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A neutral a earth fault on a 1 floor of the house is causing ELCB of the other floor to trip. These two RCDs are fed by the two different cables outgoing from the main distribution board .

Trying to find the reasons the fault is not contained within the faulty distribution board. Have checked main earthing as well.

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    Are there any rogue bonds between earth and ground? Sometimes inexperienced DIY-ers will bond neutral to earth in an outlet box.
    – DarthCaniac
    Jan 19, 2017 at 17:33
  • ground floor main DB has a earthing point solidly grounded. Utility service main is a 4 core cable. Earth wires are carried separately to each floor from the main DB
    – Abraham
    Jan 19, 2017 at 21:19

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Anytime a single fault trips two ground fault detectors, the cause is that the circuits are crossed.

Either the neutrals have been tied together somewhere; the hots have been tied together somewhere; or a particular load is drawing hot from one circuit and returning neutral to the other circuit. This can and should trip both ground-fault detectors.

It should be completely OK to share or cross grounds. Of course a neutral-ground fault will also cause a ground-fault detector trip.

I go into more detail in my answer over here. Though the questions seem quite different, they are the same core issue.

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