@ mapj1


Surely they should round down Zs values in the Guidance Note 3 Inspection and Testing 17th Edition A3 rather than rounding the figures upwards.


Adjusted to 80% as per appendix 14 = 1.456 Ω


Round down to 2 decimal places = 1.45 Ω


All digital Fluke and Megger loop impedance meters I have used are accurate enough to tell the difference between 1.45 Ω and 1.46 Ω . 


Taking into account all that we know about breaker tolerances and circuit load/voltage variations, if something is defined as the maximum then surely it should it should never be acceptable to have a value higher than the maximum as far as the regs are concerned. 


I see no logical reason for the IET to round the figures upwards instead of rounding the figure downwards if wanting to display to 2 decimal places.

@ mapj1


Surely they should round down Zs values in the Guidance Note 3 Inspection and Testing 17th Edition A3 rather than rounding the figures upwards.


Adjusted to 80% as per appendix 14 = 1.456 Ω


Round down to 2 decimal places = 1.45 Ω


All digital Fluke and Megger loop impedance meters I have used are accurate enough to tell the difference between 1.45 Ω and 1.46 Ω . 


Taking into account all that we know about breaker tolerances and circuit load/voltage variations, if something is defined as the maximum then surely it should it should never be acceptable to have a value higher than the maximum as far as the regs are concerned. 


I see no logical reason for the IET to round the figures upwards instead of rounding the figure downwards if wanting to display to 2 decimal places.