A spur constitutes 1 twin or 1 single SO, NOT 2 sockets, if the RFC he is coming from is 2.5mm then why use 4mm, maybe that;s all he had, seeing as he doesn't answer I guess we will never know.
uI worked as an Electrician for the FCO spent many years working overseas in many countries, if you have Families it'not as good as it sounds, being single not so bad, sometimes years, months and weeks, living like tramps sometimes, pm me for details of countries.
Note you cannot test fot current flow with a volt stick, only a dubious voltage will be senses these testers are an Electricians worst enemy ,totally unreliable, prone to picking up static voltages etc.
As an aside it will be difficult to issue cert after the event, as the tester will need to see evidence of how the install was installed in the first place, that's how I see it anyway, others may disagree.
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