Humm, maybe time to resurrect the "Campaign for Real Earthing"?

(I'm still rather taken with the modified TN-S approach where neutral earthing is through a resistance (I think it was proposed in one of the Cahier technique papers ages ago) - while you need RCDs (TT style) for ADS it pretty much guarantees that PE stays reasonably close to true earth - even during faults).

    - Andy.

There are some conditions that the neutral earthing resistor  does not guard against - and the grounding to terra firma of any one phase  like that barn in the incident described above, is one of them.It also means that the topology of mains filters needs to be changed a bit to reduce standing CPC currents.

The other approach commonly taken in parts of Africa, and south America, while beyond the pale here, is  of not using an earth connection at all, and if you really need to earth something  it has to be a TT variant. In places where the risk of network side failure is much higher than it is here that actually becomes the safest sensible option.

Consider if you were downstream of this transformer or one like it - would you want PME ?

Note the method of installing and testing (7 mins in ) for an earth is also not one we would recognize

Power of opportunity supplies  in war zones and disaster relief might well be similar quality.

Mike

There are some conditions that the neutral earthing resistor  does not guard against - and the grounding to terra firma of any one phase  like that barn in the incident described above

Indeed - nothing's perfect but the vast majority of faults I suspect are L-PE rather than L-true earth, so still an improvement. (I suspect the barn incident would have been L-PE via the steel conduit - its was the fact it was TT that introduced the resistance to true Earth. Had it been supplied from a NER version of TN-S with the conduit connected to the supply PE (and/or the barn frame bonded) then the barn frame, and everyone else's PE would have remained close to 0V - the voltage difference be created between Earth and N (and thus Earth an Ls) rather than between anything people should ordinarily be touching, even if the RCD failed to trip. The low earth fault currents also make it far easier to protect wiring against faults to true earth - as simple braiding or foil screens make more than adequate c.p.c.s.

is one of them.It also means that the topology of mains filters needs to be changed a bit to reduce standing CPC currents.

Yes EMI issues (and SPDs) was something I had in the back of my mind. If the NER was chosen to give an earth fault current of say 1A - i.e. about 230Ω - it might see to be similar to a TT installation in terms of Zs - and in normal circumstances N would still be close to Earth potential (at least comparable to a TN-S or TT system). Certainly still some thinking to do on the subject, but maybe has some potential still.

Nice videos by the way At least there was an attempt at testing, which is more than can be said for some even over here. I can't help thinking that the procedure might have been devised with a filament lamp in mind - the much lower currents through what looked to be an LED one surely undermine things a bit. I don't give much for the longevity of galv steel with all that sodium chloride though.

   - Andy.

There are some conditions that the neutral earthing resistor  does not guard against - and the grounding to terra firma of any one phase  like that barn in the incident described above

Indeed - nothing's perfect but the vast majority of faults I suspect are L-PE rather than L-true earth, so still an improvement. (I suspect the barn incident would have been L-PE via the steel conduit - its was the fact it was TT that introduced the resistance to true Earth. Had it been supplied from a NER version of TN-S with the conduit connected to the supply PE (and/or the barn frame bonded) then the barn frame, and everyone else's PE would have remained close to 0V - the voltage difference be created between Earth and N (and thus Earth an Ls) rather than between anything people should ordinarily be touching, even if the RCD failed to trip. The low earth fault currents also make it far easier to protect wiring against faults to true earth - as simple braiding or foil screens make more than adequate c.p.c.s.

is one of them.It also means that the topology of mains filters needs to be changed a bit to reduce standing CPC currents.

Yes EMI issues (and SPDs) was something I had in the back of my mind. If the NER was chosen to give an earth fault current of say 1A - i.e. about 230Ω - it might see to be similar to a TT installation in terms of Zs - and in normal circumstances N would still be close to Earth potential (at least comparable to a TN-S or TT system). Certainly still some thinking to do on the subject, but maybe has some potential still.

Nice videos by the way At least there was an attempt at testing, which is more than can be said for some even over here. I can't help thinking that the procedure might have been devised with a filament lamp in mind - the much lower currents through what looked to be an LED one surely undermine things a bit. I don't give much for the longevity of galv steel with all that sodium chloride though.

   - Andy.