As for possible mis-communication, although I thought I had been clear, maybe some people do not fully understand what I've been saying ....
I fully understand that what you are saying is illogical or inconsistent.
.... the only conceivable reason for wanting to examine the potential of CPCs (hence any exposed-c-ps) relative to true earth is if one has some reason to think that it might possibly be a 'dangerous' potential difference, a situation in which one should not touch any exposed-c-ps until the matter is resolved.
Do you equally claim that the only conceivable reason for wanting to examine whether one has a L/N reverse, or a L/PE reverse, or an open PE, or any other conditions which the tester detects would be if one had some reason to think that one might possibly have a L/N reverse, or a L/PE reverse, or an open PE, or any other conditions which the tester detects?
If no, why are you singling out one of the functions for special treatment?
"
the only conceivable reason for wanting.... is of one has some reason to think..." is equivalent to "
it would be inconceivable to want... unless one has some reason to think..."
So if your answer to the above question is "yes", is your attitude to all testing that it is inconceivable to do it unless one has a reason to think there is something wrong?
If someone told us that they had 'got a shock' (or even 'a tingle') off the casing of an appliance, we would tell them not to touch any exposed-c-ps until appropriate testing (and remedial work, if necessary) had been undertaken - and we would certainly tell them that they should not rely on a 'neon screwdriver' to do that testing.
Indeed we would, but I've not seen any suggestion here, or in any Schneider literature, that one should plug it in and touch that button to see what's going on if one had had a shock or a tingle from an appliance.
As I've said, I do not regard the Schneider tester as being conceptually or qualitatively different from a neon screwdriver, so would regard that as essentially equally inappropriate, and essentially equally likely to give a misleading 'reassurance' that could put people's lives at risk.
We don't know that it isn't qualitatively different.
I suppose this begs the question as to why Schneider have provided this functionality, and I have no real answer to that. If the intention is to give 'reassurance' that it is safe to touch exposed-c-ps, then (just as with neon screwdrivers) the inherent unreliability of the 'sensing' method is such that any 'reassurance' given could be inappropriate (hence dangerous) reassurance.
We don't know that it is inherently "unreliable".
The way they word the specification of the "threshold" could well mean that under no circumstances will it fail to flag a PE to true earth difference of 35V or more.
But to be sure, clarification from the maker should be sought.
And that applies to declaring it inherently unreliable.
I don't see it as being conceptually much different from 'testing for dead' in the more usual sense. Whether one is talking about a brown-insulated conductor, a CPC or an exposed-c-p, the requirement is to 'prove' that there is not a dangerous potential on something which one might be about to touch. We would not dream of suggesting that it was safe to use a neon screwdriver (hence not the Schneider 'PE test') for that purpose if it were a brown-insulated conductor, so what is different about a CPC?
Again you are being inconsistent.
The Schneider device does not intentionally connect you to a live conductor, it connects you to the cpc. It is no more dangerous to do that than it is to touch a metal accessory or a metal-bodied Class I appliance. Would we not dream of suggesting that it was safe to do those things? And in fact it's probably safer than those things.
Now - I grant you that a false negative from it would give a misleading sense of safety, and that could be dangerous, but
a) we don't actually know if it does give false negatives once the PE rises to a dangerous voltage
and
b) how many people, in the absence of owning a tester like this think "
I've got no way to test if there is a potential difference between my PE and local true earth, so I'd better get an electrician into test it"?
In short, it is not dangerous to use it, and it is hard to see how using it can be worse than not.
