light switch terminals 'live' when off

[Raybuild]

How is this 'switched live' 'capacitively coupled' to live (everything is insulated)

Any two conductive items separated by an insulator form a capacitor. A change of voltage on one will affect the voltage on the other. sheets of tin foil separated by very thin paper or other insulator make capacitors for use in electronics ( there are many other types of capacitor ). Two insulated wires running side by side form an un-intentional capacitor ( stray capacitance )

and if so why does this 'capacitive coupling' NOT happen in the down stairs lighting where this scenario is NOT happening

Probably due to a shorter lengths of live to switched live stray capacitance and/or longer lengths of switched live to neutral stray capacitance which will leak away energy that crossed the live to switched live.

the only other equipment I have is a couple of Voltmeters (one analogue and the other digital) - I know that these are NOT to be used with Mains Voltage but I can test for continuity.

If the meter has a range 0 to 250 AC then with care they can be used to measure voltages up to mains voltage.[/quote]

Bernard : You seem to have a higher and more academic knowledge of this area and I suspect allot more - thank you and may i get back to you later. At the moment I've had to 'change hats' and put my 'plumbers hat' on to solve another problem in that area.

Also being new to this 'forum chat' I haven't got the hang of using it properly ie regarding the use of 'quotes' and replying to a reply let alone using the correct language and terms - there also seem to be allot of 'morons' out there with nothing else to do. Perhaps when i get a little more proficient I'll tell these idiots a bit more about the achievements I've attained without any formal training or education.