Garage earth

Hellmooth · Oct 30, 2016

westward10 said:
Holding little regard, not me. Since PME became common practice back in the seventies mainly as a cost cutting exercise the problems of a lost neutral was deemed an acceptable risk. If correct bonding/earthing is in place within a premises the loss of a neutral should cause no hazard, there is a risk however if someone were in contact with any part of the internal earth and true earth outside. The loss of a neutral is slim but possible, it as also possible Kelly Brook will knock at my door tonight to massage my feet. The garage the op talks of has no requirement for bonding and the only risk should the loss of neutral occur is if he is touching the internal earth with true earth, an acceptable risk.

No super like button yet..

GMES · Oct 30, 2016

Hellmooth said:
No super like button yet..

Here you go!!!!

Last plumber · Oct 30, 2016

westward10 said:
Holding little regard, not me. Since PME became common practice back in the seventies mainly as a cost cutting exercise the problems of a lost neutral was deemed an acceptable risk. If correct bonding/earthing is in place within a premises the loss of a neutral should cause no hazard, there is a risk however if someone were in contact with any part of the internal earth and true earth outside. The loss of a neutral is slim but possible, it as also possible Kelly Brook will knock at my door tonight to massage my feet. The garage the op talks of has no requirement for bonding and the only risk should the loss of neutral occur is if he is touching the internal earth with true earth, an acceptable risk.

Good point. Thanks for that.

Last plumber · Oct 30, 2016

Well gents, I knew this thread would be mildly controversial and I appreciate all the input it's had over the past days. Thank you all for taking the time to give your experienced opinions.
I suppose there are for's, against's, if's, but's and possibilities on both sides of the argument, as there are in many situations.
It's never as black and white as we'd like. At the end of the day, I think it comes down to which method carries the least risk.
P.s. I haven't forgotten the CSA asked for earlier, I'll let you know when I've looked

bigspark17 · Oct 30, 2016

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westward10 said:
Holding little regard, not me. Since PME became common practice back in the seventies mainly as a cost cutting exercise the problems of a lost neutral was deemed an acceptable risk. If correct bonding/earthing is in place within a premises the loss of a neutral should cause no hazard, there is a risk however if someone were in contact with any part of the internal earth and true earth outside. The loss of a neutral is slim but possible, it as also possible Kelly Brook will knock at my door tonight to massage my feet. The garage the op talks of has no requirement for bonding and the only risk should the loss of neutral occur is if he is touching the internal earth with true earth, an acceptable risk.

So a cross body electric shock is an acceptable risk to take in your installations isit? Im sure you dont tell your customers that. I know a lost dno is rare as chickens teeth but in CAN happen, i belive it should not be overlooked so lightly

Last plumber · Oct 31, 2016

bigspark17 said:
[

So a cross body electric shock is an acceptable risk to take in your installations isit? Im sure you dont tell your customers that. I know a lost dno is rare as chickens teeth but in CAN happen, i belive it should not be overlooked so lightly

No, not at all. I am merely trying to weigh up the situation and come to a logical decision, based on the opinions of educated and experienced engineers.

I am sure that it is just as possible to get a shock using the other method. An earth rod can become disconnected I'm sure. That is the reason I am thinking through things instead of rushing in blind.
Which would be more likely, in your opinion ?
Loosing the mains neutral or the earth cable becoming disconnected from the rod ? There is still an RCBO on this too don't forget !

bigspark17 · Oct 31, 2016

An rcbo wont disconect the supply through loss of neutral. ? Yes an earth rod connection could get disconnected but this would not bring the installation earth live!

westward10 · Oct 31, 2016

bigspark17 said:
An rcbo wont disconect the supply through loss of neutral. ? Yes an earth rod connection could get disconnected but this would not bring the installation earth live!

You are quite correct it won't.

westward10 · Oct 31, 2016

Last plumber said:
No, not at all. I am merely trying to weigh up the situation and come to a logical decision, based on the opinions of educated and experienced engineers.

I am sure that it is just as possible to get a shock using the other method. An earth rod can become disconnected I'm sure. That is the reason I am thinking through things instead of rushing in blind.
Which would be more likely, in your opinion ?
Loosing the mains neutral or the earth cable becoming disconnected from the rod ? There is still an RCBO on this too don't forget !

Are you likely to be exposed to true earth and the PME earth in the garage at the same time.

bigspark17 · Oct 31, 2016

Hence my question reg building structure, if theres no exposed structural steel or extraneous parts id aloso have no problem with exporting the pme. If there is then the supply cable csa will need to be confirmed to see if its suitable to be used as a cpc and bonding conductor from MET or EMT. Also woudnt have a problem TT ing the outbuilding.

westward10 · Oct 31, 2016

bigspark17 said:
Hence my question reg building structure, if theres no exposed structural steel or extraneous parts id aloso have no problem with exporting the pme. If there is then the supply cable csa will need to be confirmed to see if its suitable to be used as a cpc and bonding conductor from MET or EMT. Also woudnt have a problem TT ing the outbuilding.

No I agree but he says bonding isn't a requirement and the only metal parts is the garage door which probably isn't extraneous.

uksrevivor · Oct 31, 2016

mykey said:
View attachment 34098

That has had me in stitches lol brilliant

Last plumber · Oct 31, 2016

bigspark17 said:
An rcbo wont disconect the supply through loss of neutral. ? Yes an earth rod connection could get disconnected but this would not bring the installation earth live!

I did think that ( about the RCBO not working in that situation).
The garage is concrete sectional type.
Not had chance to look at cable yet, maybe tomorrow.

Last plumber · Oct 31, 2016

uksrevivor said:
That has had me in stitches lol brilliant

Yes, me too. Hilarious !

Last plumber · Nov 2, 2016

bigspark17 said:
Hence my question reg building structure, if theres no exposed structural steel or extraneous parts id aloso have no problem with exporting the pme. If there is then the supply cable csa will need to be confirmed to see if its suitable to be used as a cpc and bonding conductor from MET or EMT. Also woudnt have a problem TT ing the outbuilding.

The csa of the armouring is 22.27 mm square
The cable is three core 6mm

Whilst we're on this subject. If the neutral was lost, surely we would have the same dangers inside the house the supply comes from ?

Garage earth

Hellmooth

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GMES

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bigspark17

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Last plumber

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bigspark17

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westward10

westward10

bigspark17

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westward10

uksrevivor

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