100mA RCD Incomming NOT TT but PME

[Risteard]

I thought he had mentioned that it was because of a high Ze

That's definitely not what he said.

 

[Deleted member 26818]

Nope, nothing to do with high Ze, in fact one would expect very low Ze in such situations.
As to the why of it, I have no idea, I do not work for a DNO.
It sticks in my mind because the DNO installed the RCDs, then washed their hands of the devices, handing over ownership to the consumer.
Only mentioned it, as a possible explanation as to why the device is present.