OP
GEOFF S
Why are you asking where equivalent conductance is mentioned when you go on to mention equivalent conductance yourself in you second paragraph.
I have no issue with their being other interpretations or however you wish to describe it. If you can provide links to the published documents/guidance which could be referenced if I did not follow the IETs guidance notes and I did have to defend my installation in court then I will consider using that guidance in my work.
Dave the first paragragh asks for the CSA to be half that of the Earthing conductor, so lets say the Earthing conductor need to be 20mm, would a 10mm steel Main protective bonding conductor be okay?
Cheers