earthing system(UK)

Sergeant · 1 Dec 2010

Can anyone tell me that is there any connections with the earthing system between substations and consumers?

Such as the substation use TT system, the consumers use TN-C-S, or TN-S, or TT. Is there any imperative rules to define that in 17th?

holmslaw · 1 Dec 2010

ricicle · 1 Dec 2010

Didn't expect to see that on here, someone from Zaire talking to someone from China about the UK distribution system

ricicle · 1 Dec 2010

Duplicate post

Sergeant · 1 Dec 2010

holmslaw said:
Sub stations will be earthed via earth rods/mats and the incoming HV cables.

The 17th edition does not apply to the uk distribution system.

BS7671 is also from IEE Wiring Regulation 17th

So，that is, the earthing system of consumers is nothing with that of substations?

Sergeant · 1 Dec 2010

ricicle said:
Didn't expect to see that on here, someone from Zaire talking to someone from China about the UK distribution system

Is that cool?

Big earth, small internet!

Spark123 · 1 Dec 2010

A substation is not a TT system, a substation with a star point transformer which is tied down to earth provides the means of earthing for the system i.e. the initial "T" (terra) for 'T'T, 'T'N-S or 'T'N-CS systems.
More info here:
http://en.wikipedia.org/wiki/Earthing_system

Sergeant · 2 Dec 2010

Spark123 said:
A substation is not a TT system, a substation with a star point transformer which is tied down to earth provides the means of earthing for the system i.e. the initial "T" (terra) for 'T'T, 'T'N-S or 'T'N-CS systems.
More info here:
http://en.wikipedia.org/wiki/Earthing_system[/QUOTE]

You mean that the substation do not have the conception of TT or TN system and it's nothing with the consumer's earthing system?

ricicle · 2 Dec 2010

Sergeant said:
You mean that the substation do not have the conception of TT or TN system and it's nothing with the consumer's earthing system?

The substation or pole mounted transformer will have the secondary side's star point earthed to ground via a rod, tape etc. This will generally be the same for all HV to LV transformers. (The star point also forms the Neutral)
As Spark123 pointed out this is what makes the first part of an earthing system description ie T(T), T(NS), or T(NCS).
The differences occur by the means in which the earth is distributes to the consumers either via ground (TT), cable sheath (TNS) or combined with the Neutral up to the service head (TNCS).

efiste2 · 2 Dec 2010

Hope you dont mind the pics, heres a Delta/Star configured 500Kva 11000/415v Transformer with the LV star point/Neutral fixed to earth at the Distribution board(lower pic). Its covered by the Electricity supply regs if i remember correctly.

holmslaw · 2 Dec 2010

Sergeant · 3 Dec 2010

ricicle said:
Sergeant said:

You mean that the substation do not have the conception of TT or TN system and it's nothing with the consumer's earthing system?

Click to expand...

The substation or pole mounted transformer will have the secondary side's star point earthed to ground via a rod, tape etc. This will generally be the same for all HV to LV transformers. (The star point also forms the Neutral)
As Spark123 pointed out this is what makes the first part of an earthing system description ie T(T), T(NS), or T(NCS).
The differences occur by the means in which the earth is distributes to the consumers either via ground (TT), cable sheath (TNS) or combined with the Neutral up to the service head (TNCS).

Thanks， it's clear to me!

and can you tell me does the lighting need RCDs protection in TT system， we all know that sockets outlets need RCDs protection in TT system. But for lighting, I don't find any British or IEC standard to clarify this issue.
So, what's the principle to definite a loop need the protection by RCDs in TT system. How to calculate?

I don't know whether do i express it clearly.

ricicle · 3 Dec 2010

An RCD is the prefered method for ADS in a TT system for BS7671.
Under the most recent update all unprotected (earthed metallic protection) cables buried less than 50mm deep require RCD protection at 30mA anyway as do all general use sockets, regardless of the type of earthing system.

ban-all-sheds · 3 Dec 2010

holmslaw said:
efiste2 said:

heres a Delta/Star configured 500Kva 11000/415v Transformer with the LV star point/Neutral fixed to earth at the Distribution board(lower pic).

Click to expand...

I can't see any star point connection, could you be more specific.

It'll be here, no?

efiste2 · 3 Dec 2010

Spot on mate, i should have circled it myself. The star point/Neutral of the TX is carried via a busbar to the lv board and is earthed where the circle is

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earthing system(UK)

holmslaw

holmslaw

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