The first one states that even if the supply pipes are plastic, if the piping inside the installation is metal it must be main bonded.
I can see how internal pipework
might become an extraneous-conductive-part, as it
might in places be buried. But if not, aren't you making things more hazardous by connecting something that was isolated to the earth of your supply?
IMO this refers to an installation where the metal pipes traverse multiple areas (rooms), so that if there was a fault anywhere in the installation that resulted in the pipework becoming connected to a live conductor, the entire installation pipework would rise to the potential of that conductor.
And that argument is not regarding the pipe as an extraneous-conductive-part, its treating it an an exposed-conductive-part, and the bonding cable becomes an earthing one.
And once you accept that argument then you'd have to go around earthing anything else metal that "could become live if there was a fault"...
I don't believe it means that metallic piping stubs that are, for example, use solely where visible in, say, a bathroom, for aesthetic reasons, needs to be bonded back to the MET if the rest of the installation is in plastic, even if these are the only metallic sections and there is no other MEB the water system.
The man from IET, he say yes:
I explained exactly the scenario to him. His interpretation made the water pipe an ex-CP, thus requiring bonding.
Hmmmmmmmmmmmmmm....
BUT, regardless of the bonding/PME debate, the situation is dangerous as the cpc is too small to withstand fault conditions should the neutral go open circuit: there is a fire risk.
So would you question the very existence of 6/2.5 cable, and say that any use of it is wrong?
What if it was supplying a shower in the bathroom - would the cpc be adequate?
What if it went to the outhouse but wasn't a sub-main - just had an industrial socket on the end to supply something industrial there - would the cpc be adequate?
According to 54G undersized cpcs are never allowed, but they are used all the time - I assume they are OK according to the calculation in 543-01-03.
So is 6/2.5 ever OK?