Earthing Arrangements Explained + Photo's

[topquark]

To be quite honest gents I want other members to say things like what TC has said on this thread to expand it into a great source of information for everyone. Please continue with positive posts.

Why? Are you covering DC systems as well?

 

[Knobhead]

Why? Are you covering DC systems as well?

Do you want me to start on that?

 

[Knobhead]

Just a quick point as this is for training purposes Paul, on the drawn TT system someone may think that water and gas do not need earthing! I know it's a stupid point but someone will..................!

Edit:- As kindly pointed out to me it should read bonding not earthing!

Can't be doing with fussy cats

View attachment 13130

 

[Top Cat]

Can't be doing with fussy cats

View attachment 13130

Size of earth wires?

You'l wish soon you hadn't asked for criticism!

 

[Paul.M]

Let's just keep to domestic earthing systems for now lads. I know this is basic stuff but its somewhere that the learners can Google and learn more than in a book from us lot.

It's worth the effort IMHO.

 

[Air Conditioner]

Thanks for this thread its great to see some real life pictures, rather than just the pictures in books. One thing that took me by surprise in the transition from books to real life was that the main earthing terminal is sometimes in the CU in real life, rather than a totally separate earthing bar which how it is normally illustrated.

 

[telectrix]

that used to be the norm years agoo. it's only in the last 10-20 years that a separate MET has become more widespread.

 

[Air Conditioner]

Is there a reason for this? Is it easier to measure Ze? Or the manufacturing of cheaper CU's? Or is it just the way it is?

 

[Top Cat]

What are those yellow, blue and black things!:biggrin5:

You did say you liked what TC was doing! Lol

 

[Paul.M]

Air conditioner and Tel, these are the things that I'm on about. It's great learning from books to pass an exam but its a different world out there once you pick up your tool box and go to your first job.

Has any other members got main incomers photos? Post them up.

 

[Top Cat]

Air conditioner and Tel, these are the things that I'm on about. It's great learning from books to pass an exam but its a different world out there once you pick up your tool box and go to your first job.

Has any other members got main incomers photos? Post them up.

Hi Paul, sorry if i sounded flippant with my relies but it did have a serious message. If the first two diagrams have every detail on them, the third should also.

 

[Paul.M]

Hi Paul, sorry if i sounded flippant with my relies but it did have a serious message. If the first two diagrams have every detail on them, the third should also.

No offence taken mate. If I could find the osg diagram of a TT system on Google images I would have posted that instead. Seen as I do all my posting from a mobile phone (yes, over 3,800 atm) and I've spent over an hour today on this thread to give basic learning to others. If I can put the effort in, why can't the people that are learning the trade? Let's encourage them to better their knowledge. Well I'm still learning and I'm not a half bad sparky lol.

 

[JUD]

Here's mine at home...

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

Answers on a postcard :sifone:

 

[topquark]

It looks suspicously like TNCS but I'm going for TNS with that bit of GY lurking at the bottom of the head. I'm guessing you've put the REC in!

 

[Top Cat]

Here's mine at home...

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

Answers on a postcard :sifone:

The seals are missing, whats the problem!

 

[Air Conditioner]

Is the telephone cord you phoning the DNO for more seals?
Its a TNCS with a TNS thrown in for good measure. Just looking for an earthing rod!!!LOL

 

[JUD]

It looks suspicously like TNCS but I'm going for TNS with that bit of GY lurking at the bottom of the head. I'm guessing you've put the REC in!

Yep TN-S. Confused Elecsa guy a bit until I told him I got higher reading on PSCC. Yep I put the REC in for convenience when changing CU.

The seals are missing, whats the problem!

Never had a seal on it.

 

[Paul.M]

I've just shown this thread to my wife and she understands about earthing arrangements! Even Juds! Tomorrow we will step it up a notch I think.

 

[steveberry11]

Is it not the case that if a TNCS system has been given this is the primary source of earthing.

Just a thought
Would the DNO then leave in the TNS connection or connect the cable sheath to the TNCS terminal if the sheath earth is suspect in the area.

One word of caution in the first photo the TNS earth connection was made via an earth strap around the lead sheath. Beware of tightening these up if they become loose as the effect is to squeeze the lead sheath into the line and neutral conductors. End result BANG.
This also used to be common on SWA cables (not sure why). The outer sheath was striped back around 100mm from the gand and a earth strap fitted around the armour. While carrying out maintenancee or periodics the straps were found to be loose so were tightened up. After several rounds of this the armours were squeezed into the conductors BANG.

Obvious I know but beware.

 

[terminator]

Paul - It may be a way to remembers the 'S' as connected to Sheath (which of course it is) - but the important point is that it actually stand for 'Separated'.
i.e. Separate Neutral and Protective conductors throughout the system.

I know that you and experienced guys know that, but I think that guys learning the ropes ought to understand the importance of that. And how it differs from TN-C-S. (PEN conductors)
T = Terra (earth)
S = Separate
C = Combined

Apologies if I've opened a can of worms. But good thread. I think that Earthing is one of the most misunderstood subjects in the trade.
Thanks anyway Paul.