"Not if all they are changing is one pendant for another, which was the case I stated. How would the cpc at the MET suddenly become disconnected if that part of the system hasn't been touched? And if polarity is reversed they'll soon find out about it when the lights won't switch off, or on. I agree that in an ideal world it would be tested bu in the context of changes to the Regs 2011 there is ambiguity rtegarding DIYers not in possession of suitable test equipment, in which case someone who does have such equipment should be called in to test, but in the real world, not many people are going to get a sparky in to change a pendant"
"How would the cpc at the MET suddenly become disconnected"
It might not be connected in the first place - testing it would confirm any new class 2 would be safe, similarly polarity say on ES lampholders. Ideally these tests should be done for safety even though the job might be non-notifiable.
"in the context of changes to the Regs 2011 there is ambiguity rtegarding DIYers not in possession of suitable test equipment,"
Which Regs or part thereof are you referring to?