Help identifying earthing system

[Vagabondrobb]

Hi everybody,

I’m trying to work out what kind of earthing our house has. We live in Scotland in a house that’s for the most part very old, and relatively remote. We have dedicated overhead wires and transformer delivering to our house (see pic 1). It looks as if it’s just live and neutral coming into the ground. If I follow the cable as it enters the house and into the loft space, it splits into 3 (see pic 2) - perhaps earth bonded to neutral here?
The cable terminates outside the consumer unit, in our hallway (pic 3) where the earth connects to a bus bar.
I have noticed one of the earth cable from the bus spans across the loft and drops into hot water cupboard, but it’s left dangling around a pipe. I assume that was at one time connected to the pipe work??

Cheers!

 

[UNG]

It is difficult to tell from those pictures a wider picture of the distribution equipment might help
Overhead supplies are often TT systems although it is possible that it may be a TNCS given the three connectors in the cable in the loft space
If look look at the transformer and pole it may have an earth cable running down the pole which is bonded / connected to the neutral

 

[Vagabondrobb]

Hi! There is an earth that runs from the top of the pole to the bottom, connecting to the chassis of the transformer on the way down. Doesn’t look to be connected to anything else. Live and neutral come out of transformer into cable which goes straight down pole and into the ground.

I’ve attached a wider pic…

Cheers

 

[Fleeting]

That T&E below the red consumer unit would appear to be the incomer so there is another joint somewhere. That cable should not be connected like that and needs addressing. Earthing system from what we see is TN-S but who knows previous to that because the earthing conductor and neutral are likely to be derived from the same point.

 

[binky]

Hi! There is an earth that runs from the top of the pole to the bottom, connecting to the chassis of the transformer on the way down. Doesn’t look to be connected to anything else. Live and neutral come out of transformer into cable which goes straight down pole and into the ground.

I’ve attached a wider pic…

Cheers

hard to tell from that picture but I would say you have a TT system of some sort. You need to trace the earths from the earth terminal, and it definetly looks a bot of a lash up. eg the main switch has only got the live running through it, it should have the neutral as well.

 

[Vagabondrobb]

That T&E below the red consumer unit would appear to be the incomer so there is another joint somewhere. That cable should not be connected like that and needs addressing. Earthing system from what we see is TN-S but who knows previous to that because the earthing conductor and neutral are likely to be derived from the same point.

That T&E below the red consumer unit would appear to be the incomer so there is another joint somewhere. That cable should not be connected like that and needs addressing. Earthing system from what we see is TN-S but who knows previous to that because the earthing conductor and neutral are likely to be derived from the same point.

Yep, It is all a bit of a mess. How should it be connected?
From the second pic in the original post you can see where the incoming cable from the transformer connects to the T+E - guessing the earth and neutral are bonded there?!

 

[Vagabondrobb]

hard to tell from that picture but I would say you have a TT system of some sort. You need to trace the earths from the earth terminal, and it definetly looks a bot of a lash up. eg the main switch has only got the live running through it, it should have the neutral as well.

We have a manual transfer switch for the generator, the neutral runs straight into that…

 

[Fleeting]

Ah the T&E is in the second pic so strictly speaking it is TN-S. That connection below the red consumer unit needs addressing.
Terra (earth) and N (neutral) enter the building separate (S).

 

[kerching]

There are quite a few PMEs around here where the main switch only breaks the live side

 

[Radiotowers]

Hi everybody,

I’m trying to work out what kind of earthing our house has. We live in Scotland in a house that’s for the most part very old, and relatively remote. We have dedicated overhead wires and transformer delivering to our house (see pic 1). It looks as if it’s just live and neutral coming into the ground. If I follow the cable as it enters the house and into the loft space, it splits into 3 (see pic 2) - perhaps earth bonded to neutral here?
The cable terminates outside the consumer unit, in our hallway (pic 3) where the earth connects to a bus bar.
I have noticed one of the earth cable from the bus spans across the loft and drops into hot water cupboard, but it’s left dangling around a pipe. I assume that was at one time connected to the pipe work??

Cheers!

Hi there, I worked with this stuff for years.
A little info
At the transformer there is 2 earthing arrangements,
First we have the HV earthing, there is an earth connected to the steelwork at the top and an earth connected to the transformer tank , this runs down the pole and off in one direction to the hv earth spikes, the earth wire here will be bare uninsulated so also acts as an earth.
The LV earthing arrangement .
At one LV terminal of the transformer ( neutral point) we have a LV earth connected (star point in a 3 phase transformer). this earth runs down the pole to a separate LV earthing arrangement, it is run in the opposite direction from the HV earth and is run in Insulated earth wire and gets its earthing directly from the earth rods.
The two earths are deliberately separated.


In the house I see a 16 mm twin and earth with a bare earth wire, this T&E will be connected to either an overhead line terminated at the wall , or an underground cable terminated in a wall box , or may be going to an adjacent semi detached house where the connection is made. ( the loft photo seems to show concentric type cables not T&E so going next door?)
If the supply is overhead to the wall and is run in single wires it’s pretty obvious if an earth is supplied as you would see 3 vertically hang wires , if only 2 then there is is no earth supplied.

An important common issue with the bare cable in the T&E is electricians assume this is a network supplied earth, this is not always so.
The block it is terminated in , is in many cases just that ,a termination block only .
In a TT system the bare wire was terminated in such blocks and a earth was picked up from the CUSTOMERS side simply to earth the bare cable and prevent any inductive pick up on the are conductor.
If it were a PME arrangement there would be a link between neutral/ earth and it would be marked as such.

As there appears to be a hole on the side of the cut out, a simple phone call to the supplier will get the network company to visit and change this and you will be a able to confirm the earthing arrangements .

hope this helps a bit

 

[Vagabondrobb]

We have a manual transfer switch for the generator, the neutral runs straight into that

hard to tell from that picture but I would say you have a TT system of some sort. You need to trace the earths from the earth terminal, and it definetly looks a bot of a lash up. eg the main switch has only got the live running through it, it should have the neutral as well.

The earth terminal is connected to the incoming T+E, where

Hi there, I worked with this stuff for years.
A little info
At the transformer there is 2 earthing arrangements,
First we have the HV earthing, there is an earth connected to the steelwork at the top and an earth connected to the transformer tank , this runs down the pole and off in one direction to the hv earth spikes, the earth wire here will be bare uninsulated so also acts as an earth.
The LV earthing arrangement .
At one LV terminal of the transformer ( neutral point) we have a LV earth connected (star point in a 3 phase transformer). this earth runs down the pole to a separate LV earthing arrangement, it is run in the opposite direction from the HV earth and is run in Insulated earth wire and gets its earthing directly from the earth rods.
The two earths are deliberately separated.


In the house I see a 16 mm twin and earth with a bare earth wire, this T&E will be connected to either an overhead line terminated at the wall , or an underground cable terminated in a wall box , or may be going to an adjacent semi detached house where the connection is made. ( the loft photo seems to show concentric type cables not T&E so going next door?)
If the supply is overhead to the wall and is run in single wires it’s pretty obvious if an earth is supplied as you would see 3 vertically hang wires , if only 2 then there is is no earth supplied.

An important common issue with the bare cable in the T&E is electricians assume this is a network supplied earth, this is not always so.
The block it is terminated in , is in many cases just that ,a termination block only .
In a TT system the bare wire was terminated in such blocks and a earth was picked up from the CUSTOMERS side simply to earth the bare cable and prevent any inductive pick up on the are conductor.
If it were a PME arrangement there would be a link between neutral/ earth and it would be marked as such.

As there appears to be a hole on the side of the cut out, a simple phone call to the supplier will get the network company to visit and change this and you will be a able to confirm the earthing arrangements .

hope this helps a bit

Hey, many thanks for that! So I’ve attached a diagram of the pole and transformer (this is how it looks from what I can see, but could be inaccurate - I can’t see clearly how things are connected around that middle box for example).

Regarding the cable - it enters the house underground (running aprx 15 meters from the pole). It then runs up the wall into the gables where it enters the loft space. The only place I can see the cable “terminating” is at the point where it joins the T+E (The pic from in the loft). From here the T+E runs down toward the main switch where it terminates and splits off (the pic showing the bare earth). We don’t have any neighbours.

Is the cut out in this case the black box the line enters (containing the main fuse)? It doesn’t look much like the cutouts I’ve seen…

Much appreciated!

 

[Radiotowers]

Hi there,
As the T&E is white and the concentrics are black I would agree there is another termination somewhere.
In many rural properties especially farms ,the main supply would run into a farm building first and then loop into the the farm house.
The black box at the meter box with red wire connected to is just a single phase fuse cut out, along with the black henley blocks they are just the single versions of a conventional combined cable head. In a lot of meter locations there is no room for one big unit so singles are fitted. This type of supply would have been fitted by the linesman.
Your isolation switch has only the phase conductor running through it , this was the standard isolator fitted up until a few years ago.

The new type isolation switch , switches both live and neutral , but its important to note that the neutral disconnects last and connects first otherwise you get can a lost neutral fault occurring.

I know a lot of electricians look at the set up and dont think its meets the latest IEE regulations , they never did . The network businesses work to the Electricity at work regs ,even though a lot of the stuff no longer meets this


At the LV side of the transformer you simply have the neutral/ earth connections connected together then splitting off to the service cable as neutral and earth, and the phase from the transformer going to the LV fuse and then to the live core of the service cable.
My initial view of this if I turned up would be network supplied earth , before I tested.
SP Energy networks would respond as a safety check to confirm your supply arrangements and get the cut out changed.( spotted the old SSEB stickers I used to fit !)

 

[roys]

Hi there,
As the T&E is white and the concentrics are black I would agree there is another termination somewhere.
In many rural properties especially farms ,the main supply would run into a farm building first and then loop into the the farm house.
The black box at the meter box with red wire connected to is just a single phase fuse cut out, along with the black henley blocks they are just the single versions of a conventional combined cable head. In a lot of meter locations there is no room for one big unit so singles are fitted. This type of supply would have been fitted by the linesman.
Your isolation switch has only the phase conductor running through it , this was the standard isolator fitted up until a few years ago.

The new type isolation switch , switches both live and neutral , but its important to note that the neutral disconnects last and connects first otherwise you get can a lost neutral fault occurring.

I know a lot of electricians look at the set up and dont think its meets the latest IEE regulations , they never did . The network businesses work to the Electricity at work regs ,even though a lot of the stuff no longer meets this


At the LV side of the transformer you simply have the neutral/ earth connections connected together then splitting off to the service cable as neutral and earth, and the phase from the transformer going to the LV fuse and then to the live core of the service cable.
My initial view of this if I turned up would be network supplied earth , before I tested.
SP Energy networks would respond as a safety check to confirm your supply arrangements and get the cut out changed.( spotted the old SSEB stickers I used to fit !)

What year did you first go to Cumbernauld

 

[Vagabondrobb]

Hi there,
As the T&E is white and the concentrics are black I would agree there is another termination somewhere.
In many rural properties especially farms ,the main supply would run into a farm building first and then loop into the the farm house.
The black box at the meter box with red wire connected to is just a single phase fuse cut out, along with the black henley blocks they are just the single versions of a conventional combined cable head. In a lot of meter locations there is no room for one big unit so singles are fitted. This type of supply would have been fitted by the linesman.
Your isolation switch has only the phase conductor running through it , this was the standard isolator fitted up until a few years ago.

The new type isolation switch , switches both live and neutral , but its important to note that the neutral disconnects last and connects first otherwise you get can a lost neutral fault occurring.

I know a lot of electricians look at the set up and dont think its meets the latest IEE regulations , they never did . The network businesses work to the Electricity at work regs ,even though a lot of the stuff no longer meets this


At the LV side of the transformer you simply have the neutral/ earth connections connected together then splitting off to the service cable as neutral and earth, and the phase from the transformer going to the LV fuse and then to the live core of the service cable.
My initial view of this if I turned up would be network supplied earth , before I tested.
SP Energy networks would respond as a safety check to confirm your supply arrangements and get the cut out changed.( spotted the old SSEB stickers I As the T&E is white and the concentrics are black I would agree there is another termination somewhere.

In many rural properties especially farms ,the main supply would run into a farm building first and then loop into the the farm house.
The black box at the meter box with red wire connected to is just a single phase fuse cut out, along with the black henley blocks they are just the single versions of a conventional combined cable head. In a lot of meter locations there is no room for one big unit so singles are fitted. This type of supply would have been fitted by the linesman.
Your isolation switch has only the phase conductor running through it , this was the standard isolator fitted up until a few years ago.

The new type isolation switch , switches both live and neutral , but its important to note that the neutral disconnects last and connects first otherwise you get can a lost neutral fault occurring.

I know a lot of electricians look at the set up and dont think its meets the latest IEE regulations , they never did . The network businesses work to the Electricity at work regs ,even though a lot of the stuff no longer meets this


At the LV side of the transformer you simply have the neutral/ earth connections connected together then splitting off to the service cable as neutral and earth, and the phase from the transformer going to the LV fuse and then to the live core of the service cable.
My initial view of this if I turned up would be network supplied earth , before I tested.
SP Energy networks would respond as a safety check to confirm your supply arrangements and get the cut out changed.( spotted the old SSEB stickers I used to fit !)

That SSEB sticker is dated March 1987! I was just 3 years old…

Thanks again for such a comprehensive answer - really appreciated. I can’t for the life of me find this termination block. I take it as a given that many things aren’t done to the correct standards around here - have seen fair bit of evidence of that in houses around these parts. Buildings are very old with bits added on over many generations, and qualified tradespeople just aren’t easy to come by.

So I should call SPEN and ask them to to do a safety check?

Many thanks!

 

[Radiotowers]

What year did you first go to Cumbernauld

Oh I came in as a temporary spark initially doing the storage heater contracts, then we got privatised and a lot of guys went to the contracting division then cegulec then alsthom. Just pure luck I was working as a shift electrician at the time

 

[Radiotowers]

That SSEB sticker is dated March 1987! I was just 3 years old…

Thanks again for such a comprehensive answer - really appreciated. I can’t for the life of me find this termination block. I take it as a given that many things aren’t done to the correct standards around here - have seen fair bit of evidence of that in houses around these parts. Buildings are very old with bits added on over many generations, and qualified tradespeople just aren’t easy to come by.

So I should call SPEN and ask them to to do a safety check?

Many thanks!

Yip , they should not charge for a safety check, (ask) but wait till after the holidays, during the day if you can.

 

[Captain Kirk]

Don't even look at the pole there is nothing there which relates to or can help the consumer. There will be both HV earths and LV earths at the pole for the power company equipment only. There will be a neutral/earth connection at the LV neutral in all cases , but only for the star point.

Any TNC-S/PME should be provided by concentric cable only or converted old lead sheath armoured cable, inside the building. There are some post 2002 overhead PME supplies in Scotland but again will be concentric cable with a Series 5 or greater cut out in the property. From what I see in the attic it should be treated as TT full stop unless the downlead is replaced and verified otherwise by the DNO.

This can only be verified by an insulated linked N-E terminal in the property accompanied by the green PME earthing label. All TNC-S supplies must be confirmed by a Ze loop impedance test which must be 0.35ohms or less. If this value is not achieved and the installation is claimed to be TNC-S then this must be reported to the DNO. If the value exceeds 0.8 ohms then it must be treated as TT even with DNO earth. The DNO is only obliged to supply an earth in new post 2002 supplies. All new or reinforced U/G or overhead TNS and TNC- S supply downleads installed after 1970 will have PVC concentric cable.

The DNO can charge for a visit that does not relate to a DNO inspection/fault/repair. They are not obliged to supply a retrospective earth connection to TT installation.

These requirements are governed first and foremost by the ESQCR regs.

This is not a matter which can be decided upon by committee or viewing photos. Only the DNO can give a formal indication of the earthing system for use on installation and condition reports.

Ex SSEB Distribution electrician and NOSHEB engineer

 

[Fleeting]

Don't even look at the pole there is nothing there which relates to or can help the consumer. There will be both HV earths and LV earths at the pole for the power company equipment only. There will be a neutral/earth connection at the LV neutral in all cases , but only for the star point.

Any TNC-S/PME should be provided by concentric cable only or converted old lead sheath armoured cable, inside the building. There are some post 2002 overhead PME supplies in Scotland but again will be concentric cable with a Series 5 or greater cut out in the property. From what I see in the attic it should be treated as TT full stop unless the downlead is replaced and verified otherwise by the DNO.

This can only be verified by an insulated linked N-E terminal in the property accompanied by the green PME earthing label. All TNC-S supplies must be confirmed by a Ze loop impedance test which must be 0.35ohms or less. If this value is not achieved and the installation is claimed to be TNC-S then this must be reported to the DNO. If the value exceeds 0.8 ohms then it must be treated as TT even with DNO earth. The DNO is only obliged to supply an earth in new post 2002 supplies. All new or reinforced U/G or overhead TNS and TNC- S supply downleads installed after 1970 will have PVC concentric cable.

The DNO can charge for a visit that does not relate to a DNO inspection/fault/repair. They are not obliged to supply a retrospective earth connection to TT installation.

These requirements are governed first and foremost by the ESQCR regs.

This is not a matter which can be decided upon by committee or viewing photos. Only the DNO can give a formal indication of the earthing system for use on installation and condition reports.

Ex SSEB Distribution electrician and NOSHEB engineer

Can you state the document to which the information in paragraph 3 is taken from.