Earthing Arrangements Explained + Photo's

[topquark]

Hmm another punt .... I'll go for TNS again.

 

[Silly Sausage]

TNCS...???




Tea 'n' Cups & Saucers. :crazy:

 

[Richard Burns]

Few domestic TNS. One with boxed in earth connection, one with looped supply and one with the "standard" earth clamp!

 

[Silly Sausage]

Spotted what’s wrong with the last picture, compression fittings on gas!

That's I usually think, but the handfull of domestic gas isolators I've fitted on hobs, only been able to find compression valves. Have to check my CORGI registration/training course folder on that one. You being industrial with multiple bar gas lines it's probably a complete No No.

That 'Electric Shock Treatment' poster next to the flailing bond quite amuses me.

 

[Geordie Spark]

Here's mine at home...

TN-S or TN-C-S???

Answers on a postcard :sifone:

Is that curly wire your meter by pass??

 

[Geordie Spark]

Spotted what’s wrong with the last picture, compression fittings on gas!

Nah!! ............ compression fittings are perfectly OK in an accessible place - jut like leccy junction boxes are .......... It's the floating earth that's the problem.

(but you knew that already)

 

[Geordie Spark]

and another one,

View attachment 13146

with associated gas bonding...

View attachment 13147

In pic 1, at the top right hand corner, there's what looks to be a gas Emergency Control Valve & associated pipework which looks to be far too close to the leccy stuff.

(Aye .... aahh knaa it's got nowt to do with earthing etc. aam just showing off)

 

[Silly Sausage]

In pic 1, at the top right hand corner, there's what looks to be a gas Emergency Control Valve & associated pipework which looks to be far too close to the leccy stuff.

(Aye .... aahh knaa it's got nowt to do with earthing etc. aam just showing off)

Spotted!

It was about 3am at the time, out of hours bank inspection.
I'm sure the next guy will pick it up in about 2 years time.
Banks are in pain in the proverbial. I seem to remember it takes them about an hour or so to shut down their main server (or whatever it is) so you can test the one circuit, with some clueless staff member hanging around asking how to do it - ring your IT dept!

 

[Paul.M]

On a TT system an earth electrode (aka earth rod) needs to be installed. The rod needs to be available for inspection and testing, this can be achieved by an earth pit as below.

Or if in a cellar it can be left without an enclosure. I know the picture shows a rod outside next to what looks like a metal gas pipe, I would try and locate it away from the pipe and foundations of the house and into better soil, away from concrete and rubble but if it gives you a good Ra result (Ze for a TT) I would leave unless it causes an issue with the gas incomer. Any thoughts on this?

 

[Engineer54]

but if it gives you a good Ra result (Ze for a TT) I would leave unless it causes an issue with the gas incomer. Any thoughts on this?

1/ As you say installed far too close to buildings external wall.

2/ No thread visable so probably one of those thin twigs, ...Or a threaded rod that's been chopped because they hit rubble (see 1/ above). In both cases this rod is unlikely to be stable through lack of depth!!

3/ Exposed rod to conductor connection, absolutely no protection being offered to the actual connection that is also far too far out of the ground..

4/ Area of influence of the rod will be affected by the metallic pipe, (That's if this rod is achieving anything in the first place...lol!!)

5/ Hmmmm, ...I wonder how long that external unprotected galvanized pipe is going to last? Pretty sure that doesn't meet gas codes, ...none that i know of anyway!! lol!!

 

[jaresquire]

PME
TNS

You decide....

View attachment 13148

Looks TN-S but the PME sticker makes me think otherwise!

 

[Silly Sausage]

Haven't read this yet, 108 pages!, but seems to have relevant info regarding this thread...

http://www.copperinfo.co.uk/earthing/downloads/pub-119-earthing-practice.pdf

 

[Air Conditioner]

Thanks for this Paul. I haven't come across a TT system on-site yet, so great to see what it looks like in reality!!


Sorry meant to quote from the TT rod photo from post 59. Still it saves a bit of space.

 

[Paul.M]

Good points E54, I also wouldn't pig tail the earth cable. Wonder how long the connection will last exposed to the elements like that?

Just a note: Never pig tail a live conductor, you've basically just made an induction coil.

 

[Silly Sausage]

Good points E54, I also wouldn't pig tail the earth cable. Wonder how long the connection will last exposed to the elements like that?

Just a note: Never pig tail a live conductor, you've basically just made an induction coil.

Coil it around the rod...can someone do the maths on that one please?!

 

[lurchio]

This has got me a bit confused, i was initially thinking TNS with the earth coming from the base of the cable but im swaying to TNCS with it running through the fuse..

 

[Richard Burns]

Very similar to the first picture on this thread.
It is possible that the earth does not join the neutral in the head but more likely a "conversion" to TNCS from TNS

 

[Chrisuk]

Hi all, since I'm only in my first year of my Level 2 C&G 2365 electrical installations it's always nice to be able to look at different set ups and recognise what they are, I saw the following and wanted to know if this one is a TN-C-S or TN-S install because I was thinking a TN-C-S but it looks like it's connected to the sheath so that makes it a TN-S install???

Thanks all

 

[telectrix]

TN=S. it's clamped to the lead sheath of the supply cable.

 

[Chrisuk]

Thanks for confirming that for me

 

[Engineer54]

Can't exactly see what type of clamp has been used in your photo, but if it's just a standard/typical pipe earth clamp, then it's not suitable for purpose, only Constant Pressure and Hepworth (think that's the name) clamps that require a tool to secure, are acceptable. 9 out of 10 TN-S cable sheath connections are made via soldered/lead wipe connections, clamps only being retrofitted as or when required!!

 

[Chrisuk]

This is why I uploaded it, I came across the picture online and had an idea but since I'm a trainee was unsure, I certainly knew i had not seen it like that before, obviously I've seen a small percentage of what's to see but this was the 1st time I've seen some sort of clamp!!

 

[telectrix]

clamps usually fitted if the soldered connection has broken off.

 

[44ALLAN]

good thread

 

[GLENNSPARK]

Hi all, since I'm only in my first year of my Level 2 C&G 2365 electrical installations it's always nice to be able to look at different set ups and recognise what they are, I saw the following and wanted to know if this one is a TN-C-S or TN-S install because I was thinking a TN-C-S but it looks like it's connected to the sheath so that makes it a TN-S install???

Thanks all
View attachment 21921

if in doubt then do a Ze...and a Zpn....if the PFC is the same then you can be pretty certain that you have a TN-C-S....
if not then its likely to be TN-S...

TT should be obvious

 

[Engineer54]

On a TT system an earth electrode (aka earth rod) needs to be installed. The rod needs to be available for inspection and testing, this can be achieved by an earth pit as below.

Any thoughts on this?

Just looked back over this thread and should have mentioned that if a rod has an exothermic or brazed welded connection, it doesn't really need or warrant an earth pit enclosure, (but the rod to cable connection should still be protected, say with amalgamating tape) unless it's only for location identification purposes. I would imagine, that in this case it's one of more than one earth rod position, the first having a removable bolted clamp connection for testing purposes.

I'll assume that this rod is a part of an industrial or commercial earthing installation or maybe even a lightning protection system, rather from a domestic installation??

 

[GLENNSPARK]

Just looked back over this thread and should have mentioned that if a rod has an exothermic or brazed welded connection, it doesn't really need or warrant an earth pit enclosure, (but the rod to cable connection should still be protected, say with amalgamating tape) unless it's only for location identification purposes. I would imagine, that in this case it's one of more than one earth rod position, the first having a removable bolted clamp connection for testing purposes.

I'll assume that this rod is a part of an industrial or commercial earthing installation or maybe even a lightning protection system, rather from a domestic installation??

like a nest....

 

[Hohmage]

Hi folks. New member but regular visitor. Thank you for this very interesting thread, in a nice style too. I'm hoping to resurrect it. What do you think of this one then? I'll have more pics to follow, but what does this say to you please?

 

[Hohmage]

Another couple...

 

[Engineer54]

So what do YOU think about them??

 

[Hohmage]

So what do YOU think about them??

Hi Engineer54. The first few posts were along the lines of a quiz, so I was trying to get people guessing. Perhaps it's so obvious it isn't worth asking, in which case I'll go now! I'm no electrician, but have been told what the system is by the DNO. It's fairly unusual and outdated as far as I know, and I thought people might be interested (as the thread suggested). I have more pics, I was waiting to see if folk needed more. I was ultimately going to ask this question which I don't know the answer to: how safe is it and what can I do to make it safer!

 

[Silly Sausage]

As no one is playing Hohmage's game, I'll take a punt...

It's PNB.

Away you go fellas!

 

[aesmith]

What's going on there? It looks like two cables leaving the pole, but three arriving at the house.

 

[telectrix]

i'd like to see it with the red insulation tape removed.

 

[Knobhead]

What's going on there? It looks like two cables leaving the pole, but three arriving at the house.

There will an intermediate pole or poles with an earth rod.

 

[Hohmage]

Hi folks. yes, intermediate pole with earthing. Didn't mean to mislead anyone. The red tape isn't masking anything, it was covering the exposed copper at the meter tails. I'm guessing that the greenish wire to right of main fuse is the earth. I am trying to post more pics, but have just upgraded machine to Windows 8 and am lost!

 

[Silly Sausage]

Come on Hohmage, what did the DNO say?
Exact wording please!

 

[Hohmage]

Come on Hohmage, what did the DNO say?
Exact wording please!

Chap said "CEW". Couldn't get much more from him. I've Googled CEW and found one reference to it on this forum, someone asking a question about it but no one answered. Anyone know?

 

[Hohmage]

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

 

[Silly Sausage]

I've found CEW = Continuous Earthwire. (PME or PNB)

Ask on the IET Wiring Regs Forums, they're bound to know!

 

[Hohmage]

Great, thank you Archy. Did you find much then? It seems that this system is new to some of you - I'd hoped you might find it a bit challenging!

 

[Silly Sausage]

Hahaha....Well I wouldn't have know what it was if it came up and kicked me in the nuts and told me!
I'm still non the wiser.
I'll keep an eye on the IET forums in case you ask over there.

 

[Hohmage]

I found this comment on the IET forum (thanks Archy S): "Up in Scotland as one of the DNOs, CEW or (SEN) is a Continuos earth wire earthing system given to consumers who have an earth loop higher than 0.35 ohms. ie 3 wire single phase system consisting of a phase, neutral and a separate earth. If PME they'd just get a phase and a combined earth/neutral."

This doesn't sound as if it's much better than a TT system, does it? Can anyone say whether I ought to be having my sheds TT'd, based on this comment? I am about to have a RCD-protected split CU installed. 30mA RCDs sufficient? Having seen some shoddy workmanship up here, I want to know exactly what an electrician should be suggesting!

 

[aesmith]

How's the earth actually made, and where does it join neutral (if at all).

I'm comparing with our supply, which is the same type of pole mounted 11kV transformer but in our case we're connected by underground split concentric to provide TN-S (DNO called this CEW as well). As explained by the DNO our transformer's neutral on the LV side is connected to an earth cable/rod/spike or something at the foot of the pole.

A previous house, served by overhead 240V, only had L and N overhead with a locally provided earth.

In this case, are they really providing Earth on an overhead cable?

 

[Silly Sausage]

I found this comment on the IET forum (thanks Archy S): "Up in Scotland as one of the DNOs, CEW or (SEN) is a Continuos earth wire earthing system given to consumers who have an earth loop higher than 0.35 ohms. ie 3 wire single phase system consisting of a phase, neutral and a separate earth. If PME they'd just get a phase and a combined earth/neutral."

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

 

[aesmith]

"Up in Scotland as one of the DNOs, CEW or (SEN) is a Continuos earth wire earthing system given to consumers who have an earth loop higher than 0.35 ohms."

I'm not sure if it's the same thing he was meaning, but SSE publishes a target of max 0.35 ohms for TNCS, but up to 0.80 for TNS. It doesn't necessarily mean that TNS will be over 0.35 though, ours is 0.29.

 

[Hohmage]

How's the earth actually made, and where does it join neutral (if at all).

I'm comparing with our supply, which is the same type of pole mounted 11kV transformer but in our case we're connected by underground split concentric to provide TN-S (DNO called this CEW as well). As explained by the DNO our transformer's neutral on the LV side is connected to an earth cable/rod/spike or something at the foot of the pole.

A previous house, served by overhead 240V, only had L and N overhead with a locally provided earth.

In this case, are they really providing Earth on an overhead cable?

Hi aesmith, thank you for replies. I am only versed in basic electrics. Can you tell me were I should b looking to answer your question "how's earth made, and whre does it join neutral". I have a basic understanding of the more obvious systems TN-S etc. I could take more pics.

I have been told that this overhead earth is still common up here. I had a response on another forum about split concentric: "It looks like an old TN-S to me. Separate overhead earth (no longer done). You could report lack of earthing and see if they will replace your aged supply with a SPLIT concentric drop (TN-S)". I decided to post on this thread because it was specifically targeting earthing systems. I did try to get the chap from SSE to explain more to me, but he seemed unwilling.

 

[Hohmage]

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

I am going to join you on that stuff right now! The electrics in this house are doing my head in!

 

[Hohmage]

"Up in Scotland as one of the DNOs, CEW or (SEN) is a Continuos earth wire earthing system given to consumers who have an earth loop higher than 0.35 ohms."

I'm not sure if it's the same thing he was meaning, but SSE publishes a target of max 0.35 ohms for TNCS, but up to 0.80 for TNS. It doesn't necessarily mean that TNS will be over 0.35 though, ours is 0.29.

This is interesting, thanks. I was hasty in my response about the resistance and the thought of TT, best to be quick whilst kind folk are in the process of helping you out!

 

[aesmith]

Hi aesmith, thank you for replies. I am only versed in basic electrics. Can you tell me were I should b looking to answer your question "how's earth made, and whre does it join neutral". I have a basic understanding of the more obvious systems TN-S etc. I could take more pics.

You may be misunderstanding me, I'm not an electrician but I have taken a keen interest in our earthing arrangements because of the need to take supplies out to some outbuildings with a lot of extraneous metalwork so I made it my business to get a definitive answer.

I see you're supplied by SSE as well, but I guess there are regional differences. I contacted them ([email protected]) to ask what sort of earth they provided. Their first response was that I should get it checked by an electrician, but they also said they were installing PME and could check whether we could be "upgraded". When I asked to follow that up they arranged for their guy to come to site, who clarified the system and also took the Ze reading. I think you have to be a bit persistent, you're probably dealing with someone non technical in the first instance, so you need to give them a reason to pass your question onto the technical team. Are you concerned about the safety of your supply from an earthing point of view?