Aircon Condenser outside Earthing Equipotential Zone

[frank]

Modern inverter driven compressors/condensing units cannot be supplied through an RCD.

If you have taken your mains supply from the consumer unit/dist board on a seperate circuit and then taken a PSC reading that falls within the limits I don't see a problem.

The combined neutral/earth goes all the way back to the centre tap of the supply transformer where it is earthed

As far as the plastic isolator within a water pipe that serves an outside tap, I've never heard of this? Can you elaborate?

I feel that the water would act as a current path anyway, so the plastic 'break' would be rendered useless