Earthing Arrangements Explained + Photo's

[Hohmage]

Hi aesmith, yes, my main concern is with the safety of the earthing. I was originally concerned that the system was TT or similar, and so the CU required a 100mA RCD. At present it has no RCDs at all. As someone else said, the earthing arrangement that I do have here could deteriorate underground. Similarly with the outbuildings, I wondered if earthing rods were required and am still unclear on that one, because some folk say you can never have too much earthing. If he system here is TN-S, then I should worry less. SSE is installing a new substation couple of miles away from here right now, so I will ask again for someone more technical to visit. Thank you for your help.

 

[Knobhead]

Is it a posh TT? Earthing cable comes down a big pole?

The three wire is an old way of N→E connection. It moves the LV earth rod away from the MV earth rod.

 

[Hohmage]

The three wire is an old way of N→E connection. It moves the LV earth rod away from the MV earth rod.

Hi Tony, thank you for this. However, being a layman (but really wanting to know more about the subject) I don't understand where the HV would be at the house, let alone the earths. Could you point me in the right direction of a simple explanation please? Many thanks.

 

[Knobhead]

Look for voltage gradients.

 

[GLENNSPARK]

That'd be TNS then. (?)
Further research needed, when I'm totally C[SUB]2[/SUB]H[SUB]5[/SUB]OH free!

for more reading :

http://kisdwebs.katyisd.org/campuses/THS/teacherweb/chemapgt/Teacher Documents/AP reactions.pdf

 

[Hohmage]

Look for voltage gradients.

Thank you Tony. Lots to trawl through on the web, but I found these useful and confusing at the same time:

https://www.ergon.com.au/__data/ass...5/Distribution-System-Earthing-Guidelines.pdf

http://www.ussu.co.uk/ClubsSocietie...g Documens/L2+ Electrical/REF BS7430 2011.pdf

 

[Silly Sausage]

The three wire is an old way of N→E connection. It moves the LV earth rod away from the MV earth rod.

Come on Tony, please explain what CEW is in simple terms, maybe with one of your infamous drawings! (If you're feeling in a generous mood! )
I just can't visualise it.

 

[Silly Sausage]

for more reading :

http://kisdwebs.katyisd.org/campuses/THS/teacherweb/chemapgt/Teacher Documents/AP reactions.pdf

Cheers Cock! I've sussed it.
Cerium Tungsten Electrodes.





That link takes me back to school chemistry, nightmare!
Who let you back in?

 

[Knobhead]

Just because you asked Archy

How it was explained to me at the EMEB collage.

Around each of the earth rods there will under earth fault conditions be a voltage gradient in the ground. In order for the MV and LV to be interconnected the LV earth electrode must be <2Ώ. Higher and the site is referred to by the DNO as hot and no direct MV→LV earth connection is allowed.
Therefore the LV earth has to be moved away from the MV equipment earth. This is to prevent a MV earth fault migrating to the LV system.

My drawing for OH supply

DNO drawing for ground mounted

 

[GLENNSPARK]

Just because you asked Archy

How it was explained to me at the EMEB collage.

Around each of the earth rods there will under earth fault conditions be a voltage gradient in the ground. In order for the MV and LV to be interconnected the LV earth electrode must be <2Ώ. Higher and the site is referred to by the DNO as hot and no direct MV→LV earth connection is allowed.
Therefore the LV earth has to be moved away from the MV equipment earth. This is to prevent a MV earth fault migrating to the LV system.

My drawing for OH supply

DNO drawing for ground mounted

and when you think about it Tony...its just common sense isn`t it...

differing potentials n all that lot...

 

[shanky887614]

Ah so when a lot of people install earth rods they are potentially increasing the chance of nuisance tripping

 

[Knobhead]

Ah so when a lot of people install earth rods they are potentially increasing the chance of nuisance tripping

Only if they link N→E. Which as we all know they shouldn't.

 

[Silly Sausage]

Ta Tony, I'll have to get back later on this one.
I need a clear head!

 

[Knobhead]

This is a thread from many moons back. Imported N→E fault.

http://www.electriciansforums.co.uk...eral-electrical-forum/21227-tingley-taps.html

 

[GLENNSPARK]

and i`ll say this as well Tony..

one of the neighbours up until recently had issues with extranious in his house with voltage sitting on it..

then he said one day the DNO came out and were doing something...
ever since then the extranious in his house has been clear....

hmm.....

 

[Knobhead]

The DNO’s also have another crafty trick with MV OH earthing. You may have seen section switches on OH lines. If you look there will be an earth running from the switch metalwork to the ground. It isn’t a rod, there will be a mat.
The idea is that the ground the operator is standing on is at the same potential as the switch metalwork. Where it gets tricky is approaching the switch, I was taught “the shuffle”. You don’t go striding up to the switch as there could be a ground voltage gradient, you shuffle towards it not putting one foot fully in front of the other.

PS I don’t like MV OH lines.

 

[DPG]

Cows are more sensitive to the gradient effect because of the distance between their legs (this applies to some TV 'celebrities' as well). Luckily most cows don't need to operate MV switchgear - they normally stick the the LV stuff. Daz

 

[Hohmage]

PS I don’t like MV OH lines.[/QUOTE]

Oh boy, this is all filling me with confidence, not! So, as a poor soul who has to live with an overhead supply, is there anything I can do/have done to make it safer? Apart from avoid crawling about on all fours! The DNO is clearly not concerned until some poor sod discovers a fault!

 

[Knobhead]

The advantage of having sheep and cattle in the field is you know there’s a ground voltage gradient around the switch. Dead sheep and cows tend to give it away.

 

[Knobhead]

Oh boy, this is all filling me with confidence, not! So, as a poor soul who has to live with an overhead supply, is there anything I can do/have done to make it safer? Apart from avoid crawling about on all fours! The DNO is clearly not concerned until some poor sod discovers a fault!

If you know there's a fault, supplies gone off etc. Don't go nosing around the MV gear, simple as. If you're that woried, talk to the DNO. If you're on a farm then it's worth a phone call.

Remember I’m talking of fault conditions, not the everyday life of country folk.

 

[Hohmage]

The advantage of having sheep and cattle in the field is you know there’s a ground voltage gradient around the switch. Dead sheep and cows tend to give it away.

Okay, thank you Tony. I usually do my best to keep the sheep out, but will now go and tear holes in the fence.

 

[GLENNSPARK]

The advantage of having sheep and cattle in the field is you know there’s a ground voltage gradient around the switch. Dead sheep and cows tend to give it away.

yes Tony...

 

[zap]

Can anyone identify which type of supply this is please?
It looks like 16mm2 twin and bare earth.

 

[topquark]

Nope, not from that pic, but I'd hazard a guess that's a submain with EMT, the question is where from.

 

[zap]

I think it's a 60's build council semi near Poole, Dorset. It's no longer council though.
I'm not sure how to proceed. I suppose a call to the dno should be the next step.

 

[topquark]

Where is the service fuse? Is this flats (possibly three phase with a phase/flat etc). That doesn't look like the main head to me.

 

[zap]

It's a semi-detached house with a pre-paid meter and cut out within the same enclosure (I think!).
The property is some distance from me so I'll ask the client (a friend) for another picture showing the content of the enclosure and when I get it I'll post it here.

 

[zap]

Deleted... only I haven't worked out how to delete the photos! Help!!

 

[zap]

Where is the service fuse? Is this flats (possibly three phase with a phase/flat etc). That doesn't look like the main head to me.

Sorry for the delay, 415V ???

View attachment 22379View attachment 22380View attachment 22381

 

[Engineer54]

The incoming cable looks like a split concentric and so will be TN-S. I assume that the G/Y earth cable is the main earth to the remote CU. If in doubt test for TNC-S!!

 

[zap]

The incoming cable looks like a split concentric and so will be TN-S. I assume that the G/Y earth cable is the main earth to the remote CU. If in doubt test for TNC-S!!

Thanks Eng. Yep, G/Y is the main earthing conductor. I'm sure determining the pfc will reveal.

 

[DPG]

Why do you say 415V ? Daz

 

[zap]

Why do you say 415V ? Daz

the information on the cut out (pic 3) says:

series 7 415V BS1361 100A type IIb

 

[DPG]

Though it might be that. Don't assume it's 415V because it says it on the side. In a similar way, don't assume it's a 100 amp fuse because it says 100A on the fuse carrier. Daz

 

[zap]

Why do you say 415V ? Daz

post #129 3rd image

 

[zap]

Though it might be that. Don't assume it's 415V because it says it on the side. In a similar way, don't assume it's a 100 amp fuse because it says 100A on the fuse carrier. Daz

Yeh, sorry, my system went a bit lala for a few minutes. I don't assume anything. Assumptions bite! But point taken...

 

[Engineer54]

That's the BS fuse voltage rating.... lol!!

 

[zap]

Though it might be that. Don't assume it's 415V because it says it on the side. In a similar way, don't assume it's a 100 amp fuse because it says 100A on the fuse carrier. Daz

Right you are, not to assume.
After obtaining some temporary seals from the DNO I looked inside the carrier and this is what I found.

Brush
30 Amp
60 LR
Certified
440V AC 4
BS88 - 1952
Class 3
Made in England

The print on the fuse had faded so there may be errors in the above info.

The DNO were contacted again and they're sending an engineer to address the issue.

 

[Engineer54]

Just shows you how long that service fuse has been in place. My parents house only had a 40A service fuse and a 40A meter for donkeys years. Then got updated out of the blue to 60A fuse and 100A meter. Later still, Mechanical meter replaced with digital meter and fuse/tails uprated to 80A/16mm....

 

[Silly Sausage]

Brush
30 Amp
60 LR
Certified
440V AC 4
BS88 - 1952
Class 3
Made in England

Non of your Chinese rubbish!

 

[Engineer54]

Non of your Chinese rubbish!

lol!! Ah, ...But for how long??

 

[GLENNSPARK]

Just shows you how long that service fuse has been in place. My parents house only had a 40A service fuse and a 40A meter for donkeys years. Then got updated out of the blue to 60A fuse and 100A meter. Later still, Mechanical meter replaced with digital meter and fuse/tails uprated to 80A/16mm....[/QUOTE]

and it held for all that time....


which begs me to ask what the point in this excercise was?

 

[Knobhead]

Non of your Chinese rubbish!

What happened to Brush Engineering?

I had the misfortune of installing one of their LV panels. Biggest pile of junk I’ve ever come across. So bad I got division engineering involved and we chucked all the outgoing switches away. Replaced them with System 4 gear.

 

[GLENNSPARK]

What happened to Brush Engineering?

I had the misfortune of installing one of their LV panels. Biggest pile of junk I’ve ever come across. So bad I got division engineering involved and we chucked all the outgoing switches away. Replaced them with System 4 gear.

hmm..

well heres a famous product out of Brush`s loughborough works:



and something from BR Derby....but with Brush electrical plant & gear:



each gave 30 years of good service...the only issues were with the Sulzer twin bank diesel engines they used

 

[Silly Sausage]

I've got a fantastic book, 'Diesel Traction. Manual for Enginemen', 1962, great book.

Also got one for 'Railway Steam Locomotive Enginemen'. More of Geordie's era.

 

[Geordie Spark]

I've got a fantastic book, 'Diesel Traction. Manual for Enginemen', 1962, great book.

Also got one for 'Railway Steam Locomotive Enginemen'. More of Geordie's era.

I have that one and I have "2750 - Legend Of A Locomotive" which is a fictional story about an A3 Class Gresley Pacific named "Papyrus" that I've seen many times written by H.C. Webster. (I think I have some for diesel as well but let's not go there!)

I first stumbled upon it in the school library and was so impressed with it I wanted to nick it!

It's a very rare book and a couple of years ago the idea popped into my head that I would like to read it again but nobody had ever heard of it. Somehow, by fair means or foul, Tidyboiler managed to find a copy for me.

It's so well written with some great drawings that it's possible to learn to drive a Gresley Pacific class from it and that's how at the tender age of 18 I ended up driving this:

 

[Engineer54]

Just shows you how long that service fuse has been in place. My parents house only had a 40A service fuse and a 40A meter for donkeys years. Then got updated out of the blue to 60A fuse and 100A meter. Later still, Mechanical meter replaced with digital meter and fuse/tails uprated to 80A/16mm....

and it held for all that time....


which begs me to ask what the point in this excercise was?

No idea, no upgrades were ever asked for/requested. Not just my parants house, but the whole estate, street by street!! lol!! Talking about a period from 1952 through to 2005. It was around final year, they changed the meter for a digital one and upgraded the service fuse and the braided VIR 7/064 tails for 16mm....

 

[GLENNSPARK]

No idea, no upgrades were ever asked for/requested. Not just my parants house, but the whole estate, street by street!! lol!! Talking about a period from 1952 through to 2005. It was around final year, they changed the meter for a digital one and upgraded the service fuse and the braided VIR 7/064 tails for 16mm....

it would have been interesting to have clamped the tails at full demand back then...

and again recently...

compare the results......

 

[GLENNSPARK]

I have that one and I have "2750 - Legend Of A Locomotive" which is a fictional story about an A3 Class Gresley Pacific named "Papyrus" that I've seen many times written by H.C. Webster. (I think I have some for diesel as well but let's not go there!)

I first stumbled upon it in the school library and was so impressed with it I wanted to nick it!

It's a very rare book and a couple of years ago the idea popped into my head that I would like to read it again but nobody had ever heard of it. Somehow, by fair means or foul, Tidyboiler managed to find a copy for me.

It's so well written with some great drawings that it's possible to learn to drive a Gresley Pacific class from it and that's how at the tender age of 18 I ended up driving this:

theres six of these in existance:

Mallard....a static display in the national railway museum York

Bittern...in steam at southall railway centre

Union of south africa...in steam at thornton yard

Dominion of canada...a static display at the canadian railway museum

Dwight D eisenhower...a static display at national rail museum green bay wisconsin

Sir nigel gresley...in steam at north york moors railway

 

[Engineer54]

it would have been interesting to have clamped the tails at full demand back then...

and again recently...

compare the results......

Well i can tell you that while Mum & Dad where living there, hob cooking was always Gas, as was heating and hot water, eg shower!! Though i did install a power shower pump in the latter years... lol!! So it was never really a high usage property, especially after my sister and myself had left the house