exporting earth

[Voltimax]

Yawn, read something else then

Since I'm a member of this forum too, I'm allowed to express my opinion and did so.

If you guys can't get this sorted between you so it doesn't keep permeating into all manor of threads, then I think you need to find a carpark somewhere and have a bloody big scrap, because that's the only way you'll sort it.

You can come back with flippant remarks if you like, but I've never known a subject to be whipped so hard before. You'll never agree so just agree to disagree will you? Either that or sticky a topic purely for this. It really is getting boring. Not so much the subject, but the constant bickering.

 

[ADS]

Hi Voltimax,

I, too, am bored that the subject keeps cropping up - to the point where I won't argue my side anymore.

From now on, when someone comes up with the corker "I know your not supposed to export the earth.....", I just point them in the direction of the two relevant publications.

One, a 'Wiring Matters' article, published by the IET, and the other 'GN8', also published by the IET.

If they can't take the advice from the IET (the people who write the regs), then sod them, let them carry on rodding. O)

 

[m4tty]

I'm not getting involved but interested in how you would do it voltimax? Export or rod it?

Or should we do a poll lol

 

[Voltimax]

I'm not getting involved but interested in how you would do it voltimax? Export or rod it?Or should we do a poll lol

We should leave it! Or go to the carpark and scrap it out. Last man standing is the one who's right ROTFWL

I must apologize re-reading my post I come across like an angry miserable old so and so. I just hate to see the arguing that's all.

I will tell you my thoughts though matty. I don't export personally, the reason is I was taught from an early age not to. That said I'm aware that the IET say it's fine to do so. I have had my Napit assessor tell me I can also. However I have come into contact with the DNO on many occasions through the course of my 20+ years in contracting and they don't like it. This is a subject that will never be settled whilst the IET say one thing and the DNO say another. Bottom line is that if your job involves you with the DNO, you'll be doing it their way end of. I have an article written here by a guy called Geoffry Stokes. He tells why it is undesirable to export TN-C-S/PME what ever you want to call it. When I have time I may copy it for all to see.

 

[ADS]

We should leave it! Or go to the carpark and scrap it out. Last man standing is the one who's right ROTFWL I must apologize re-reading my post I come across like an angry miserable old so and so. I just hate to see the arguing that's all.

I will tell you my thoughts though matty. I don't export personally, the reason is I was taught from an early age not to. That said I'm aware that the IET say it's fine to do so. I have had my Napit assessor tell me I can also. However I have come into contact with the DNO on many occasions through the course of my 20+ years in contracting and they don't like it. This is a subject that will never be settled whilst the IET say one thing and the DNO say another. Bottom line is that if your job involves you with the DNO, you'll be doing it their way end of. I have an article written here by a guy called Geoffry Stokes. He tells why it is undesirable to export TN-C-S/PME what ever you want to call it. When I have time I may copy it for all to see.

Please do, I'd love to read it, because he wrote GN8, and in that he says it's perfectly fine

 

[Voltimax]

Oh it isn't that long, so here you go.

Where installations are supplied from a PME supply it is often impracticable to extent the earthed equipotential zone to remote buildings because of the intervening ground which exhibits a 'true earth' potential. This potential will be negative with respect to the PME earth (at least when some load is being supplied) and for this reason extending the zone would be undesirable.

(Taken from: A Practical Guide to the Wiring Regulations by Geoffrey Stokes)

The guy has many letters after his name :Applaud

Make of the article what you will

 

[ADS]

Yeh, that bits understandable.

That's why you wouldn't run an earth out from the main building to a steel structured out-building, because, as he says, if you were standing on true earth and touching the steel frame of the building (which would be bonded to the PME earth) then there would be a difference in potential and a risk of shock.

In those circumstances a seperate earthing system for the outbuilding would be required.

In a normal brick-built outbuilding, with no extraneous conductive parts, it wouldn't be an issue

 

[Voltimax]

Well ADS each to his own, I should point out though that the author makes no distinction in how the remote building is constructed

 

[ADS]

Well ADS each to his own, I should point out though that the author makes no distinction in how the remote building is constructed

Yes, but you have to take into account that you would need to be able to touch the two parts that are at differing potentials.

So, to touch the earth, you'd be standing outside on it - but now you have to touch something that is connected to the installation earthing system at the same time - bit tricky on a brick building.

The other thing that doesn't make sense is that the exact same principle that he is talking about would apply to the main building as well as the remote building, so I don't get the point.

What I'm trying to say is, any problem that you can throw up at the outbuilding, about pme earthing being run to that outbuilding, I can present the exact same problem at the main building.

For example, take the difference in potentials with true earth and the PME earthing - well that will be the same, any bonded/earthed metalwork in the main building will be at a different potential to true earth......so what's the difference?

 

[Voltimax]

Well I find it amusing actually that you now disagree with the man who you were once touting. As to the point? How should I know, he wrote the book, I didn't. I would suggest he's just as confused as you lot.

Getting away from the subject, but not the principle I can almost liken this to a situation that happened in the Shotokan world.

Master Kanazawa 10th Dan of Shotokan Karate, the highest rank that can be attained, traveled to England to conduct a training seminar.Whilst the students were training, Master Kanazawa stopped a student and told him that the technique he was performing was incorrect. The student retorted "but Sensei, I'm performing it as it is in your master text". Master Kanazawa fell silent for a moment and then replied "Book is wrong!"

Not arguing with you, but it just amuses me that those we look to for guidance are just as infallible as we are, and their memories are just as short

 

[ADS]

Not arguing with you, but it just amuses me that those we look to for guidance are just as infallible as we are, and their memories are just as short

Could be, or maybe with GN8 he was going with the general consensus of the IET, as it's their publication, whereas with the 'Practical Guide', it's more in line with his own personal viewpoint.

As we've seen, it's a pretty hard topic to get agreement on.

 

[Voltimax]

As we've seen, it's a pretty hard topic to get agreement on.

I'll drink to that Guinness ROTFWL

 

[steptoe]

Yes, but you have to take into account that you would need to be able to touch the two parts that are at differing potentials.So, to touch the earth, you'd be standing outside on it - but now you have to touch something that is connected to the installation earthing system at the same time - bit tricky on a brick building.

The other thing that doesn't make sense is that the exact same principle that he is talking about would apply to the main building as well as the remote building, so I don't get the point.

What I'm trying to say is, any problem that you can throw up at the outbuilding, about pme earthing being run to that outbuilding, I can present the exact same problem at the main building.

For example, take the difference in potentials with true earth and the PME earthing - well that will be the same, any bonded/earthed metalwork in the main building will be at a different potential to true earth......so what's the difference?

with PME it is earthed as it enters the house, and is also bonded directly to gas and water,

so all services etc should in theory be at the same potential,

in an out building though, and we have no control over how far away it is,

it could be 200m away and built on slate so the earth may well be in excess of 200ohms , we cannot control this,

and therefore the potential between provided earth and factual earth could be quite substantial, if not LETHAL .

this is why exporting PME or TNCS is ILLEGAL .

 

[a1]

Voltimax,

What edition is that from? Third Edition?

 

[Voltimax]

Yeah, just so happened to have it sitting in this room. You'll tell me it's out of date, which it is, maybe that's why he says otherwise in GN8. That said, shouldn't make any difference. I was brought up on the 15th edition and we were not allowed to export earthing back then for the same reason.

 

[initforthemoney]

this is why exporting PME or TNCS is ILLEGAL .

Any proof to back that up??

 

[a1]

Voltimax,What edition is that from? Third Edition?

Yeah, just so happened to have it sitting in this room. You'll tell me it's out of date, which it is, maybe that's why he says otherwise in GN8. That said, shouldn't make any difference. I was brought up on the 15th edition and we were not allowed to export earthing back then for the same reason.

Yes Mate,

He has got another one out for BS7671:2008

A Practical Guide to The Wiring Regulations

17th Edition IEE Wiring Regulations (BS 7671:2008) By Geoffrey Stokes & John Bradley

I have it in PDF.

 

[Voltimax]

Has he changed his view out of interest?

 

[a1]

I will PM you a link now Mate...

I haven't had a good look mate, but here's a little something...

 

[Voltimax]

That diagram is in the third edition also and it always confused me because as you can see from the previous passage, he contradicts himself. He has changed the wording now in the 'smaller installations-remote buildings' section now:

Where an installation supplied from a PME network also serves a remote building with an uninsulated floor (such as a garage), it may be impracticable to use the PME earth as the means of earthing for the circuits in that building. Indeed the ED may not allow such use of the PME earth. Persons in such remote buildings have been known to experience a sensation of electric current when touching exposed-conductive-parts or extraneous-conductive-parts connected to the PME earth, due to the voltage that exists between 'true' earth and the PME earth when the network is supplying load.

So what he saying is that if the remote building has an insulated floor, then it's ok to export. If it's a earthen floor, or non-insulated, then it's not ok.