rcd trip

[ezekiel]

could someone explain this statement?

if the RCD still tripped when the MCB was off? That will tell you if it is Phase/earth or Neutral/Earth.

 

[Spark123]

More likely N-E fault however there is a slight chance it could be L-E with a load across L-N. If it was L-E on a TN system I'd expect it to trip the MCB. Best check with an IR tester after all loads removed.

 

[davy_owen_88]

If you switch off a single pole MCB you only isolate the phase conductor, this (in a perfect world) removes the possibility of that circuit being responsible for a P-E fault as there will be no current flowing through the phase conductor. Because the majority of MCB's are only single pole, the neutral and earth conductors are still connected to the system so a N-E fault can still occur on a circuit that has the phase isolated, due to parallel paths created by the neutral conductors connected to the same neutral block.

 

[ezekiel]

very clear - thanks