OP
Specialist
Thanks for that, but if you are testing at the Consumer on the 1 side of the RCD, and everything is isolated are you are doing L-N on the ringmain, will other circuits on that RCD affect the result of the circuit being tested???
If you want to do an Insulation test on a Circuit from the CU: Isolate by opening the Main Switch / RCD, Turn off all MCB's. Test from the Circuit side of the MCB with everything Switched off, if you have a low resistance between any conductors on the circuit you are testing then identify the L/N/E for that circuit & remove from the CU. Now do your Insulation test again to see if the fault still remains, if it does then re-check that everything on the circuit is definately turned off / unplugged. If you prove that everything is disconnected then you can start looking for a fault.