THE CAMPAIGN FOR REAL EARTHING

I certainly agree that a TN-S system with separate, not feebly-sized, PE conductor with multiple earthing is preferable to the existing 'PME' for shock safety, though not in initial cost. If allowed to work on feeling and technical quality I'd choose it for new build and renovation. I'm not confident how it would compare in cost/benefit to other measures that could be taken with electrical or other safety. Estimated figures for the extra cost would be interesting. Perhaps just saving the cost of concerns about car-charging could make it worth it in new builds.  Then the trouble is that different parties bear the two costs, so, as John notes, it's the regulator that needs to lay down the rules for utilities. With some regret I think it's unlikely to happen. If it did, I wonder how soon it would be before the environmental advantage (lower loss, "more potential for PV integration" etc) of bonding N and PE at various places would be discovered and implemented.  


The only safety advantage I see for TN-C-S is that multiply-earthed neutral helps to reduce equipment damage from overvoltage during a broken neutral (as was already mentioned in this thread).  If this damage could involve fire (which has been a discussion point at least in Scandinavia, and which I've heard claimed from Australia) then there's a safety aspect besides just cost of equipment damage. Some AFDDs (arc-fault detectors) include disconnection of their circuit at 270V, besides their AFDD and RCBO functions. On the down-side, this arguably makes dreams of gettings adequate broken-neutral safety with "fairly well balanced loads" harder to achieve, if the lightest-loaded phase will trip completely as soon as there's a moderate imbalance that pushes voltages just beyond their normal range.


'MEN' (AU/NZ): practically, it's PME by another name. Perhaps slightly different rules for the installation regarding whether an earth electrode is required at the installation. Correspondence with a retired Australian utility engineer has done nothing to reassure me that their implementation avoids any of the familiar troubles of a system in which a single break in a conductor that's not subject to regular inspection and testing can cause immediate danger due to normal loads. I wasn't aware of the 2018 accident (in an earlier link), but am not surprised. They've had much attention to broken neutrals, e.g. in Sydney and Tasmania.  Sydney plumbers are urged to take plenty of precautions. In Tasmania the utility is still offering what's basically a plug-in loop-tester with alarm, for permanent use by households. If the ground resistivity is really too high for TT to work nicely with modern RCDs, then: a) I agree with earlier commenters about the lack of shock danger, and b) it's clearly a waste of effort hoping that an earth electrode on the neutral will 'control' the potential if the neutral breaks on the supply side. 


Ufer (concrete-encased electrode): it's a person's name, not an acronym (cf. U.F.E.R. in an earlier comment).

SWER: yes, they seem to have tamed this adequately in some sparsely populated places. The linked presentation asserts successful use in India, though I've heard that in at least one region there it's applied with shared MV/LV earth electrode (certainly not in the AU/NZ prescription!) which has made it far from a nice system.

I certainly agree that a TN-S system with separate, not feebly-sized, PE conductor with multiple earthing is preferable to the existing 'PME' for shock safety, though not in initial cost. If allowed to work on feeling and technical quality I'd choose it for new build and renovation. I'm not confident how it would compare in cost/benefit to other measures that could be taken with electrical or other safety. Estimated figures for the extra cost would be interesting. Perhaps just saving the cost of concerns about car-charging could make it worth it in new builds.  Then the trouble is that different parties bear the two costs, so, as John notes, it's the regulator that needs to lay down the rules for utilities. With some regret I think it's unlikely to happen. If it did, I wonder how soon it would be before the environmental advantage (lower loss, "more potential for PV integration" etc) of bonding N and PE at various places would be discovered and implemented.  


The only safety advantage I see for TN-C-S is that multiply-earthed neutral helps to reduce equipment damage from overvoltage during a broken neutral (as was already mentioned in this thread).  If this damage could involve fire (which has been a discussion point at least in Scandinavia, and which I've heard claimed from Australia) then there's a safety aspect besides just cost of equipment damage. Some AFDDs (arc-fault detectors) include disconnection of their circuit at 270V, besides their AFDD and RCBO functions. On the down-side, this arguably makes dreams of gettings adequate broken-neutral safety with "fairly well balanced loads" harder to achieve, if the lightest-loaded phase will trip completely as soon as there's a moderate imbalance that pushes voltages just beyond their normal range.


'MEN' (AU/NZ): practically, it's PME by another name. Perhaps slightly different rules for the installation regarding whether an earth electrode is required at the installation. Correspondence with a retired Australian utility engineer has done nothing to reassure me that their implementation avoids any of the familiar troubles of a system in which a single break in a conductor that's not subject to regular inspection and testing can cause immediate danger due to normal loads. I wasn't aware of the 2018 accident (in an earlier link), but am not surprised. They've had much attention to broken neutrals, e.g. in Sydney and Tasmania.  Sydney plumbers are urged to take plenty of precautions. In Tasmania the utility is still offering what's basically a plug-in loop-tester with alarm, for permanent use by households. If the ground resistivity is really too high for TT to work nicely with modern RCDs, then: a) I agree with earlier commenters about the lack of shock danger, and b) it's clearly a waste of effort hoping that an earth electrode on the neutral will 'control' the potential if the neutral breaks on the supply side. 


Ufer (concrete-encased electrode): it's a person's name, not an acronym (cf. U.F.E.R. in an earlier comment).

SWER: yes, they seem to have tamed this adequately in some sparsely populated places. The linked presentation asserts successful use in India, though I've heard that in at least one region there it's applied with shared MV/LV earth electrode (certainly not in the AU/NZ prescription!) which has made it far from a nice system.