Size of earth on tncs system

[fredrico]

Am i right in saying that you had a 10mm earth wire from the service head to the consumer unit on a tncs supply, measure the ze, and use this value to work out your fault current, and put it into the adiabatic equation, then if the value was ok, leave the 10mm in place, instead of replacing it with a 16mm earth wire?? If there were 16mm tails from the cut out to board.

 

[Deleted member 26818]

Yes.
As a long as the earth conductor is separate (i.e. has a value for k of 143), then 10mm² will be fine for all BS 1361 and BS 88 fuses up to and including 100A.