So if there is plastic incoming service and a test shows the metallic pipework to be above 23000 ohms to the MET should the existing 10mm2 bond be removed or would it be deemed to be doing no harm as I can't see how it could introduce an unwanted potential difference as the pipework is earthed through the CPC of the boiler anyway.
If the same scenario but under 2300ohms the regs recommends main bonding. Why 10mm for this? Makes sense with a metallic incoming and pme but 10mm seems an unjustifiable size if the incoming is plastic. When would it ever be carrying a large amount of current without disconnection of supply?