You cannot post a reply to this discussion. If you have a question start a new discussion
Needing to meet mcb zs with ln loop.
Former Community Member
Where an rcd is relied on for fault protection due to high zs it has been suggested to me that the loop between live Conductors needs to be less than the mcb max zs. I can't find anything on this anywhere but he said he had this confirmed by an niceic assessor. Have I got it wrong ?
When testing a RCD protected TT installation where the circuit Zs tested live to CPC could be over a hundred ohms and still satisfactory I may do a live to neutral loop test and if the test result is more than the max MCB Zs I would consider further investigation is required.
When undertaking minor works on an existing circuit you need to be able to quickly assess the condition of the existing circuit and completely stripping it down to undertake extensive testing is generally not a real possibility.
When testing a RCD protected TT installation where the circuit Zs tested live to CPC could be over a hundred ohms and still satisfactory I may do a live to neutral loop test and if the test result is more than the max MCB Zs I would consider further investigation is required.
When undertaking minor works on an existing circuit you need to be able to quickly assess the condition of the existing circuit and completely stripping it down to undertake extensive testing is generally not a real possibility.
