We have undertaken circuit calculations that utilise Eaton MEM (MEMShield 3) devices. The calculation completes successfully and indicates the Zs values pass.We note that regulation 411.4.7 allows the calculation of Zs to satisfy the disconnection requirement and that this is the Hevacomp calculation method.The circuits have subsequently been tested on site by the contractor and have been noted that the values exceed those deemed to comply within BS7671 Table 41.3 We have provided the calculated values as reassurance however the contractor (to satisfy himself) has referred the issue to the NICEIC.The NICEIC response is as follows:“For the circuits that are not RCD protected if Eaton are able to confirm that their devices have a higher allowed Zs value and they still trip within the required time, thus making the currently failed circuits compliant, their max Zs values can be inputted to the test sheets instead of the ones from BS7671 and should result in the circuit passing.”We have requested published value of Zs from Eaton, which they have provided – but these are the same values as listed in BS7671.The question therefore is where have you sourced your Eaton Zs values? If we can receive this it will give the required credibility to the calculation results to be used within the completion certificate.Regards,