Sorry, I forgot about the impedance question.
Impedance values aren't too bad around here, I can often register 50 or 60 ohms. But I know that in some parts of the country it can be difficult to get values anything like that low. It's these difficult areas which were the places in which PME was originally employed.
Karl,
One point you may not be aware of is that the typical residential ground rod in Britain is generally only about 4 ft. these days, as opposed to the 8 ft. rods used in America.
Tex,
Did Austria really rely on just a 10A OCPD and a local rod to clear an earth fault? The loop would need to be 22 ohms or less even to get 10A flowing, nevermind enough to open the fuse in a reasonable period of time.
What sort of grounding systems were used way back?
