An apprentice has shown me this from esc.org website questions and answers
Can anyone else confirm 6mm is ok on PME, when you look at the regulation in the book it doesn't say anything at all about 6mm can stay, I've always upgraded to 10mm on PME, and this apprentice is telling me I don't need to...Look at this he says... (Contradicts its self to me)
Q2.12
When carrying out electrical work on an installation forming part of a TN-C-S system, is it necessary to upgrade existing 6 mm² protective equipotential bonding to 10 mm²?
Not necessarily. If the existing 6 mm² bonding connects all the extraneous-conductive-parts to the main earthing terminal, has been in place for a significant time and shows no signs of thermal damage, then it may not require to be upgraded.
Regulation number(s) 132.16 544.1.1