Perhaps you can shed some light on this condition for TNCS systems in the Irish Rules. I can only see that as RE decreases RB becomes more onerous but to be honest I am not really getting the essence.
If we took the DNO earth resistance RB as 20 ohms then the consumers earth rod could have a maximum resistance of 5.26 ohms.
I took 20 ohms as that is the accepted maximum given for a DNO transformer earth in the English books, without guidance I don’t see how you can do the maths and get an answer.
So I reserve the right to change my mind and change the answer, maybe because I have completely misread the question.
When installing the earth rod can you test the rod and the DNO earth terminal separately, then use the test results obtained to do the calculation?
If we took the DNO earth resistance RB as 20 ohms then the consumers earth rod could have a maximum resistance of 5.26 ohms.
I took 20 ohms as that is the accepted maximum given for a DNO transformer earth in the English books, without guidance I don’t see how you can do the maths and get an answer.
So I reserve the right to change my mind and change the answer, maybe because I have completely misread the question.
When installing the earth rod can you test the rod and the DNO earth terminal separately, then use the test results obtained to do the calculation?
