Wierd no trip impedance value

[J_Timbers]

Whilst testing the earth loop impedance on a circuit in a church the value given by the regular loop test is 1.74 but when doing it on non trip (with the neutral lead connected) we got >200.

Has anyone any ideas on what could cause that?

Thanks

 

[malcolmsanford]

Did you connect all 3 leads ?

 

[J_Timbers]

All 3 leads were connected. When doing the ZS on the board the 'trip' and 'no trip' loop vaules are the same so the problem is only on this circuit. We thought there might be a neutral problem but every other test carried out on that circuit is fine.

Could it be something to do with a high Ipf? We've tested part of the installation before and it was 4.2ka, but now between live and neutral is comes up as 14!