Nothing, it's quite irrelevant. What matters is the length of the plastic sections.
Metal pipes, taps, radiators, baths etc. only count as extraneous-conductive-parts requiring bonding if they can "introduce a potential." If these items are fed through plastic pipework sections of at least one metre in length and are not in contact with any structural metalwork they are deemed to be electrically "floating," so don't need including in the supplementary bonding. Otherwise they do.
That's exactly how I understand it to be, but evidently not m inspector
-- Jquinn
OK The latest version is in the van. My desk copy is the yellow covered one.
It states "Supplementary bonding of short lengths of copper pipe (less than 0.5m in length) installed where the pipes are visible, is not necessary."
I haven't checked the brown covered OSG it might be something that has changed, after amendment 2.
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