Insulation resistance fault on two way switch.

[Cornubian]

Hi all just thought I'd clear this thread up- after all that fuss and trying all the options above- I really didn't want to rip the wall down again and so just changed the switches [customer had supplied his house with Click mode modules]. Tested again and the tests were perfect! Sometimes it's easy to overlook the most simple solution!

Thanks for your help lads.