Thanks for the link Geoff,
i heard from one of the techs here that there is a 'new' electrical safety testing regime that has been agreed - but he didn't have details - heard it from someone, who heard it from someone else. I want a piece of paper to look at. I've seen DB2006 (05) - no surprises there - and nothing new on safety testing procedures.
Most of the systems here do not have isolating transformers, but i think that testing the system 'as a whole' works for me - (but may not be in line with the manufacturers guidelines).