Earhing for Distribution Board

[masalah]

A distribution board (DB) in the ground floor located inside an electrical room, is fed from a Sub main distribution board (SMDB) which is located in the same room.

In the earthing schematic diagram submitted, there is no earthing cable from the earth bar installed on the wall to the earth terminaion network.
There is an earthing cable from the SMDB to this earth bar, and there is a cable from the SMDB to the earth termination network.

Don't we need an earthing cable from the earth bar to the earth termination network??

The earthing system is TN-S.

Thank you in advance.

 

[Kiribanda]

masalah,
It looks like you are from IEC world. Could you please upload a sketch showing the earthing arrangement?

 

[masalah]

Dear Kiribanda,

Here is the CAD earthing schematic diagram drawing.

The question is why there isn't a connection from the earth bar in the electrical room (as per the typical attached schematic diagram) just as the connection from the earth bar within the Telecomm. room.

Thank you.

 

[Kiribanda]

masalah,
Eventhough I had a look on your earthing dwg, sorry to say that I am still unable to understand your question. It looks like you are using non standard terms in earthing. What you mean by earth termination network? Is it not possible to use IEE 17th Edition or IEC 60364 terms? May be some other member can give you an answer.

 

[masalah]

Thank you Kiribanda for your persistence in trying to help me

Earth termination network is the earthing grid dipped under ground soil.

 

[karls2]

masalah,
what I understand, the first lv board is already connect to the earth bar.
If the second lv board is connect to the first lv board by TNS so there's a cable with at least phases wire neutral wire and PE wire (yellow green). This yellow green wire will be connected to the internal earth bar inside the panels on both side. So the earthing will be done trough this wire and his connection, and it will be not necessary to add an external earth wire.
You can add an external wire more for improve the equipotential than for the fault current.

 

[ScottyUK]

At a guess the power earths probably return to the switch house earth bars which will in turn be connected to the earth electrode, whereas the telecom earth is a dedicated separate earth electrode. What does the drawing of the the end of the conenctions? Have a look at the detail for the switch house earth bars which are just shown at a very simplistic level on the drawing you uploaded.