Garage earth

[westward10]

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]

View attachment 34098

That has had me in stitches lol brilliant

 

[Last plumber]

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]

That has had me in stitches lol brilliant

Yes, me too. Hilarious !

 

[Last plumber]

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 ?

 

[Midwest]

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 ?

Possible. If you watch Mr JW, he gives a good explanation of types of supplies, 8.30mins for TN-CS, if you don't want to get too bored;

 

[westward10]

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 ?

Steel has a higher resistance than copper and the approximate copper equivalent is 4.0mm.

 

[Pat H]

Yes its amazing how poor Steel is compared to copper. I guess you could go gold wire so GWA but golds soft so less protection.

 

[westward10]

Yes its amazing how poor Steel is compared to copper. I guess you could go gold wire so GWA but golds soft so less protection.

Better scrap value though.

 

[LeeH]

I could see a serious pikey problem using GWA.

 

[Pat H]

That's why we bury it :')

 

[Richard Burns]

Silver is more conductive than gold and harder so you can still have a quality "S"WA!

 

[Pat H]

Wouldn't that be AUWA for gold and AGWA for silver.
And I guess FEWA for Steel (or iron as the closest chemical I could find)

 

[Last plumber]

Possible. If you watch Mr JW, he gives a good explanation of types of supplies, 8.30mins for TN-CS, if you don't want to get too bored;

Thanks very much. I already know all that's in the vid but thanks for your help.
Question is, if the neutral was lost on the supply to the house, then the house would be in the same potentially dangerous state as the garage which is being fed from it. So, what's the difference and why are we bothered about the garage but not the house ?

Not sure I agree with this bit of the video. In the video, he explains about an extension cable supplying say, a caravan outside and that there being a greater possibility of loosing the neutral in that type of cable than there is in the type that is used in the main supply ( concentric), which is very true. However, as the extension cable from house to caravan or house to garage would still have a connection to earth ( if only neutral is broken in that cable or flex ), and that earth would still be connected to the main neutral at the main supply to the property. The problems would surely only arise if the main neutral was broken.

So, what's the point in going all out to create a TT at the garage just in case the main neutral is lost in some freak accident, yet not bother with the house it is being fed by.

In addition, Is there the possibility of different earth potentials being created with an earth rod ?
There are sub stations on my housing estate and a transformer on a pole at the rear of the property.
So if the house is fed from a transformer on the estate and I put an earth rod in the ground within 50 meters of the transformer on the pole, does that matter ?
I realise this is going on and getting deep so I apologise for dragging this out.

 

[Silly Sausage]

I realise this is going on and getting deep ...

As you seem to be really getting in your Earthing, here is some further reading for you.

 

[bigspark17]

Thanks very much. I already know all that's in the vid but thanks for your help.
Question is, if the neutral was lost on the supply to the house, then the house would be in the same potentially dangerous state as the garage which is being fed from it. So, what's the difference and why are we bothered about the garage but not the house ?

Not sure I agree with this bit of the video. In the video, he explains about an extension cable supplying say, a caravan outside and that there being a greater possibility of loosing the neutral in that type of cable than there is in the type that is used in the main supply ( concentric), which is very true. However, as the extension cable from house to caravan or house to garage would still have a connection to earth ( if only neutral is broken in that cable or flex ), and that earth would still be connected to the main neutral at the main supply to the property. The problems would surely only arise if the main neutral was broken.

So, what's the point in going all out to create a TT at the garage just in case the main neutral is lost in some freak accident, yet not bother with the house it is being fed by.

In addition, Is there the possibility of different earth potentials being created with an earth rod ?
There are sub stations on my housing estate and a transformer on a pole at the rear of the property.
So if the house is fed from a transformer on the estate and I put an earth rod in the ground within 50 meters of the transformer on the pole, does that matter ?
I realise this is going on and getting deep so I apologise for dragging this out.

Within the property this is why main equapotential bonding is essential to eliminate potential diference between suppliers earth and extraneuos conductive parts within property. Its no diferent to a shed!

 

[Last plumber]

As you seem to be really getting in your Earthing, here is some further reading for you.

Excellent. I'll read that. Thanks !

 

[Last plumber]

Within the property this is why main equapotential bonding is essential to eliminate potential diference between suppliers earth and extraneuos conductive parts within property. Its no diferent to a shed!

Thanks for coming back.
What I was thinking with the earth rod was :-
The neutral and internal earth ( in house), are combined at the point of entry to my property. The neutral is earthed at multiple points on the way back to the transformer where line and neutral come from.
So, if I'm using the neutral from the house and I put an earth rod in the ground which could be nearer ( and have less resistance) to the transformer on the pole at the rear of the property, does that matter ?
Or are you saying that all earth is potentially the same ?
I could be overthinking this and I won't be offended if you say so.

 

[Pat H]

There are recommendations on earth rod spacings related to transformers but beyond that earth is just earth. Having more "real" earth points just helps nail down your earths at 0V
The problem often is getting a really good earth via a rod. Wet weather is fine but a dry summer can cause higher resistance.
I'm in a similar position with a summer house 20M from my property and have decidede to use an 6mm CSA SWA plus use a local Earth rod as well.
The feed will have an RCD at the house end anyway. No metal at the summer house end but I intend to have a goid local earth anyway.

 

[Richard Burns]

In a house you are within an equipotential zone and unlikely to contact a different potential.
Outside the house it is more likely you will encounter differing potentials.
An earth rod local to the incoming supply can mitigate the PD on loss of PME neutral on TNCS but to make it safe (i.e. low touch voltages) the earth rod would need a resistance of (depending on load) about 5 ohms, which is difficult to achieve.
An additional rod (as opposed to a TT system) local to a remote installation may mean in the case of an open supply neutral that the house load is directed along the circuit earth to the remote rod and generate a significant potential vs earth.