Earthing Arrangement- confused

[spinlondon]

WTF? No they are not.

I think you need to look in BS7671. Page 33 of the 17th edition:

"This type of distribution system is known also as protective multiple earthing."

 

[PBC_1966]

I actually mean either, as they are the same.

Not quite. You could have a TN-C-S arrangement without the distribution system being PME (not permitted by the supply authorities in the U.K., but technically possible).

And you can have a PME distribution network without every installation fed from it being TN-C-S (as in the rural area where I live - local LV network is all PME now, but many installations are still TT).

 

[Andy™]

TNCS is not always PME - it can be CNE (although this is not generally used for distribution)

 

[ianmacd]

I think you need to look in BS7671. Page 33 of the 17th edition:"This type of distribution system is known also as protective multiple earthing."

You are mixing distribution network with earthing type.

 

[spinlondon]

You are mixing distribution network with earthing type.

Not me, must be BS7671.

As I live and work in the UK, I adhere to the British Standard.

The British Standard states that TN-C-S is also known as PME.

If you don't agree, please feel free to take it up with the BSI and the IET. I'm sure they'll take on board your opinions. However, untill such time as they change their definitions, I will continue to refer to Tn-C-S as PME.

 

[Lurch]

However, untill such time as they change their definitions, I will continue to refer to Tn-C-S as PME.

Even though it's not?

 

[Andy™]

PME is protective multiple earthing (which we all know)

CNE is combined neutral and earth.

TNCS can be either of these.

PME & CNE are very different from each other

 

[ianmacd]

Not me, must be BS7671.As I live and work in the UK, I adhere to the British Standard.

The British Standard states that TN-C-S is also known as PME.

If you don't agree, please feel free to take it up with the BSI and the IET. I'm sure they'll take on board your opinions. However, untill such time as they change their definitions, I will continue to refer to Tn-C-S as PME.

WTF? You even quoted it as Distribution and you still think they are wrong?

 

[spinlondon]

Even though it's not?

You say it's not, BS7671 says it is.

Who should I take note of, you or BS7671?

 

[ianmacd]

You say it's not, BS7671 says it is.Who should I take note of, you or BS7671?

Both as they are saying the same thing you just are not understanding what you are reading.

 

[spinlondon]

WTF? You even quoted it as Distribution and you still think they are wrong?

I really think you should read your posts before posting.

I quoted BS7671, and I think their wrong???

No I quoted BS7671, and I think they're correct.

If you are not happy with what is stated in BS7671, get in touch with BSI and the IET.

 

[ianmacd]

I really think you should read your posts before posting.I quoted BS7671, and I think their wrong???

No I quoted BS7671, and I think they're correct.

If you are not happy with what is satated in BS7671, get in touch with BSI and the IET.

I need to read MY posts? Back at you babe.

Suggest you read all of that section then come back when you still don't understand it.

 

[PBC_1966]

I think the problem here is with the casual use of terms in other than their purest senses with the developmental history involved.

In basic meaning, TN-C-S and PME are not the same thing. But because historically a TN-C-S installation has been permitted only where the distribution system is PME, the widepsread adoption of the TN-S/TN-C-S/TT terms in the early 1980's led to the association between them.

As for BS7671 definitions, there is one in there which is fundamentally wrong and has been there for decades, long before the Wiring Regs. ever became an official British Standard. I'm talking about the definition of "neutral."

But when it comes to the Regs./BS7671, especially when you get to things like the change in definition of a "live" conductor, or the fact that 415V was once classed as medium voltage but is now classed as low voltage, it really seems to be the Alice In Wonderland case that "a word means whatever I want it to mean, no more, no less."

 

[Lurch]

You say it's not, BS7671 says it is.Who should I take note of, you or BS7671?

It doesn;t matter who you take note of. If you knew the difference between TN-C-S and PME you wouldn;t need to take note of either me or BS7671.

 

[spinlondon]

I need to read MY posts? Back at you babe.Suggest you read all of that section then come back when you still don't understand it.

Please explain your post.

WTF? You even quoted it as Distribution and you still think they are wrong?

Who are you stating I still think are wrong, BS7671, Lurch or Paul?

 

[spinlondon]

Whether or not you can have a TN-C-S sytem that is not PME, is irrelevant.

We have been discussing a PME system.

By the simple fact of installing a rod at the premises, we would change a single earth source TN-C-S sytem into PME.

 

[ianmacd]

Again Wrong. I suggest you go read up on Distribution systems and then come back. Only the DNO can make a system TN-C-S and only if the network is PME. 'Installing a rod' does not make the network PME.

 

[ianmacd]

Who are you stating I still think are wrong, BS7671, Lurch or Paul?

You.

 

[spinlondon]

You.

This is a discussion forum, if you have something to discuss, a point to make, something to impart then please do so.

The posts you have been making are mostly statements, they are often unclear, and often as in the case of the one I have quoted above nonsense.

From what I can read of your posts, you appear to be stating that a TN-C-S distribution system, and a PME network, are separate and distinct?

I don't know why you just can't say this, instead of making cryptic and unclear comments.

To my mind, distribution system and network are just different ways to describe the same thing.

 

[ianmacd]

This is a discussion forum, if you have something to discuss, a point to make, something to impart then please do so.The posts you have been making are mostly statements, they are often unclear, and often as in the case of the one I have quoted above nonsense.

From what I can read of your posts, you appear to be stating that a TN-C-S distribution system, and a PME network, are separate and distinct?

I don't know why you just can't say this, instead of making cryptic and unclear comments.

To my mind, distribution system and network are just different ways to describe the same thing.

Well maybe if you understood the difference ALL the people who have said your understanding is wrong may not have resourted so short replys as there are no other ways to say what we have been saying for a number of posts now.

I now understand why steps gets stressed with people on here when he is trying to make a point.

TN-C-S you are describing in BS7671 is NOT a distribution system but an earthing system. The distribution system or network are PME or (as Lurchie pointed out above) CNE.