Quote Originally Posted by JackC View Post
But I will try to make it as save as possible by introducing an ELU.
An ELU will not work if you do not earth the inverter 'output Neutral', as there is no return path for the detection coil to operate.
I suspect that with all these inverters, there is usually a small value capacitor connected between the inverter output and the 'Neutral' leg of the output plug.
This capacitor cause the typical readings that you get with your multimeter when measuring the output of the inverter.