I'm a bit confused by that statement. I thought that the great majority of 'final' distribution circuits were 3-phase, even when only one of the phases was delivered to each (residential) property. ... or were you perhaps thinking about 'loss' of the neutral connection just to a single consumer? [I don't think that anyone talking about 'lost neutrals' has specified where the 'loss' is located]
Well, all he says is 'the neutral to my cottage'. You are presumably interpreting that as meaning 'the neutral which only goes to my cottage' (or, at least, which only goes to a few premises) but, from what he'd written, he could have meant, or included, neutral faults far more upstream than that, couldn't he?
Agreed (even though my house is an exception which proves the rule
) - but I thought that, in urban situations, the single phase supply to most residential properties was one phase (plus neutral) of a 3-phase supply?
Even those 'outdoor hazards' will, in practice only usually apply to bare-footed individuals, or someone who somehow manages to have one hand on the ground and the other on the 'hazard'. Even leather-soled shoes, and certainly synthetic-soled ones, provide quite a high degree of insulation.
Isn't it (reasonably?) common for a street to have 3 phases in it - different houses being supplied with different ones?
Indeed. At least in terms of urban areas (and probably a lot more areas besides), my undertsanding was that 'common' is probably somewhat of an understatement - I thought it was close to being 'the norm'.
where the risk factors ( number and speed of vehicles ) are visible and can be seen before deciding if or when to cross the road. Country lane or busy motorway. Most people realise the hazards.
also involve factors most of which visible to the person.
Exactly. You are, presumably unwittingly, emphasising my point about the relative risks. Despite the fact that, as you say, the 'generally-accepted' risks I mentioned are in some senses 'visible', and certainly widely known about, they result in thousands of serious injuries and deaths each year. On the other hand, even though the risk is generally not visible, or known about by most people, we are actually debating whether there has ever been even one serious injury or death as a result of a PME neutral/CNE fault during the 50 (or whatever) years of PME. Westie seems to be saying that he's never heard of such a case.
We don't need to look any further than you to see that there are some people who perceive that risk as significant, but that says nothing about the magnitude of the risk in comparison with others. As above, we are not convinced that a PME neutral/CNE fault has ever resulted in a serious injury or death, whether indoors of outdoors. On the other hand, I think we can be pretty certain that the risk of serious injuries as a result of use of the garden equipment, per se, is far greater than the the risk due to electrical supply faults. Regulations and recommendations are, like you, very 'connservative'/cautious.
I understand that, but my comments about the magnitude of the risk remain. The probability of the potential of your equipotential zone rising to a possibly hazardous level relative to true earth is small enough - and, even if it happened, (a) the probability of someone simultaneously touching a wall and an exposed conductive part at the right time would be low and (b) the probability of your getting a enough current due to such a PD flowing through damp walls to represent a serious threat would be extremely small. Multiply three very small probabilities together and you would be getting very close to the infamous 'vanishingly small' risk.
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