As I understand it, he's talking about the situation in which the 'L' of a floating generator got accidentally connected to true earth, so that the 'N' (and CPCs) were then all at supply voltage above true earth.
In general systems should be designed as far as possible to disconnect faults as soon as they have occurred (and in the meantime keep fault voltages to a minimum), not wait until the fault gives someone a shock and then rely on the current flowing though the victims body to trigger disconnection of the fault.
and, in any event, the situation could not arise within a properly constituted equipotential zone.
Sure but in reality if there is a power supply from a generator to farm buildings it WILL get used to supply outdoor equipment. Therefore IMO faults to real earth must be considred and therefore the system must be tied to real earth.
In general systems should be designed as far as possible to disconnect faults as soon as they have occurred (and in the meantime keep fault voltages to a minimum), not wait until the fault gives someone a shock and then rely on the current flowing though the victims body to disconnect the fault.
Agreed, and I really only mentioned the RCD as an afterthought, to indicate that would give some protection against serious electrical shock in the (IMO extremely unlikely) event of the scenario you described arising and someone subsequently using Class I equipment from the circuit outside of the equipotential zone (i.e.'outdoors').
I agree that very little is impossible, so maybe one should design for it, but the more I think about it, the more it seems that incredibly unlikely/ contrived circumstances would be necessary for your postulated scenario to arise. I wonder if you had any specific hypothetical situations in mind? On the face of it, if all of the CPCs (and exposed-conductive-parts), all extraneous-conductive-parts within the building and all the metalwork of the generator itself were connected to the generator's 'N', it seems to require a lot of imagination to postulate how an accidental connection/fault between the other side of the genny ('L') and true earth could arise without that 'L' conductor coming into contact with either 'N' or CPC of the installation, and hence without a protective device operating. I'd be interested to know what sort of hypothetical scenario you had in mind.
FANTASTIC. You get half a dozen electricians telling you this is a specialist job and along comes Einstein to tell you that to ignore the concerns as he doesn't really think you need to worry.
JohnW2 is NOT a trained electrician. Get this wrong and you could kill somebody.
This is not a DIY job, especially given you have already stated you have no experience in this area.
FANTASTIC. You get half a dozen electricians telling you this is a specialist job and along comes Einstein to tell you that to ignore the concerns as he doesn't really think you need to worry. JohnW2 is NOT a trained electrician. Get this wrong and you could kill somebody. This is not a DIY job, especially given you have already stated you have no experience in this area.
I don't usually moan too much about what people say about me, but I think this is more than a bit unfair. I most certainly did not tell anyone to "ignore the concerns". On the contrary, I asked for education. As you correctly quoted in your message, I started what I wrote with:
I must be missing something, because I have always had difficulty in understanding a lot of what I read and hear about generator supplies, so I'd be grateful for some education.
.. and then in response to the 'encouraged' response from Emvee you've quoted, I responded with the warning:
Well, as I said, since my reasoning seems to fly in the face of much of what is written and said on this subject, I feel that I must be missing something - in which case you may be missing it as well!
Do they sound like the words of an Einstein who is telling people "to ignore the concerns as he doesn't really think you need to worry"?
I still don't understand and am eagerly awaiting that education. The only relevant and specific response I've had so far (to my question about what a connection to earth actually achieves) is valid, but relates to a hypothetical situation so seemingly unlikely that I'm struggling to imagine how it could arise (and I'd welcome answers to that, too). Far from telling people to "ignore concerns", I'm actually still waiting for someone to explain to me why the (specific) concern exists. I am not, and never have been, talking about whether or not this should be a DIY job - that's an entirely different matter.
The Einstein bit was a bit harsh, so apologies for that.
However, there is nothing in any of Emvees posts to suggest he has the required knowledge to install a generator to be used as he has described.
He has said he has buired plastic conduit, but it's okay as there will never be any power being supplied when he's not there to prevent anybody putting a spade through the conduit.
He's also said there will only ever be class II equipment being used, so he's not too worried about shocks.
He has had advice to get a pro in, but he wants to ignore that advice.
Well, I took the 'Einstein' bit, per se, as more of a compliment than anything else, so no need for an apology about that It was the suggestion that I was telling people "to ignore the concerns as he doesn't really think you need to worry"? that I reckoned was rather harsh!
He has said he has buired plastic conduit, but it's okay as there will never be any power being supplied when he's not there to prevent anybody putting a spade through the conduit.
However, I don't think any of that has anything to do with the questions I asked (which were clearly not directed at him, since he doesn't know the answers any better than I do).
Are you perhaps in a position to answer my questions?
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It was the suggestion that I was telling people "to ignore the concerns as he doesn't really think you need to worry"? that I reckoned was rather harsh!
