3 63 amp RCDs on same circiut

[king_11]

MΩ. Fault has gone. ive isolated that circuit

 

[emc]

Sounds like a non sensicle installation. 100A RCD feeding 63A RCD all 30mA instant... Why? you have discrimination issue immediately. The second MCB seems to serve no purpose - could just be a MCB.

 

[Rockingit]

200 odd MOhms is a perfectly acceptable value, so not sure how you can claim that to be the fault when clearly so many other issues seem to exist. Do the maths, and you'll see why it's not going to be an IR value of 200M that's causing a 30mA RCD to trip.

 

[king_11]

Do you have an IR tester? as what you are discribing could well be an underlying low resistance that on its own is not enougth to cause a tripping situation, but when a suden increase in load is seen it unbalences the RCD. (this is very common)

Correct! You know your stuff mate! #cheers