Question about ELI

[ricicle]

Ah riccle - It may be an NIC guideline, but it is also an obvious and staright forward assesment.

You cannot have an external loop impedance if one has not been DELIBERATELY constructed.

In that case why are they asking you to put down Zdb - this is the external impedance of a sub - board.Why would it apply to the only DB in a property that has no recognised earth system.
I'm going to ring the NIC and put them straight....

 

[Lectrician]

Where do you get the definition of Zdb from?

 

[Podooser]

With an earth loop tester at the DB

Sorry what I meant was where do you measure Zdb. Ze is measured between the supplied earth with main equipotential bonding disconnected and the incoming phase. Zdb between....

 

[ricicle]

Where do you get the definition of Zdb from?

Z(impedance) db(dis-board)

 

[Lectrician]

Yup, but where is the definition....and who created the definition?

At the end of the day, the Zdb is the EFL at the DB.

The Ze is the EXTERNAL impedance not just to the DB, but to the installation. If possible, this would be taken at the DNO terminals.........but generaly cannot be, and is done within the DB.


Remember you MUST test the Ze to the Main Earthing Conductor DISCONNECTED fromt he installation.


So, how are you going to record the Ze of the DB is YOU CANNOT DISCONNEC THE MAIN EARTHING CONDUCTOR......due to the fact there is not one? How have you removed parallel paths? You havn't! You are measuring them!

 

[ricicle]

Yup, but where is the definition....and who created the definition?

At the end of the day, the Zdb is the EFL at the DB.

The Ze is the EXTERNAL impedance not just to the DB, but to the installation. If possible, this would be taken at the DNO terminals.........but generaly cannot be, and is done within the DB.


Remember you MUST test the Ze to the Main Earthing Conductor DISCONNECTED fromt he installation.


So, how are you going to record the Ze of the DB is YOU CANNOT DISCONNEC THE MAIN EARTHING CONDUCTOR......due to the fact there is not one? How have you removed parallel paths? You havn't! You are measuring them!

Good point

 

[Podooser]

With an earth loop tester at the DB

Sorry what I meant was where do you measure Zdb? Ze is measured between the supplied earth with main equipotential bonding disconnected and the incoming phase. Zdb between....

Anyone?

 

[Lectrician]

The Ze is measured by disconnected the Main Earthing Conductor and conducting a test from Live to the disconnected Earth.

The Zdb is done in exactly the same way, but by leaving the MEC in place.

 

[Pensdown]

Good job I don't take much notice of NIC guidelines then - ah well.........................

One day you may have to.....Ricicle EI LTD?

 

[ricicle]

Good job I don't take much notice of NIC guidelines then - ah well.........................

One day you may have to.....Ricicle EI LTD?

I'm happy where I am....

 

[Pensdown]

Wise man....