Earth fault loop impedance, initial verification, multiple DB

[Gary Tollison]

Hello.
Not sure if this is the correct forum to post this in (still trying to work out where the trainee section is).

Just been doing some practice fault-finding online.
Found this scenario:

After doing initial verification on an outbuilding with its own DB, which is supplied from the main DB in another building, the EFLI on a DB in another building also supplied from the main DB is poor as a result of the I.V.

I’ve been scratching my head trying to suss out a cause.
The only one I can come up with is when EFLI was tested during I.V, the main earthing conductor would have to be disconnected to do the test, and then reconnected afterward. The connection wasn’t tightened, resulting in high resistance, yes?

Thanks in advance
And btw, any help in how/where to join the trainee section?

Gary

 

[Octopus]

Readings ?

Supply type?

 

[haptism]

Dont see how a poor loop reading can be the result of an initial verification per se. whatever is causing a high loop reading could be anything from, ccc too small, high resistance (loose) connections, suppliers earthing system at fault maybe, earth rod problems, ect ect. The question does not give enough information imo

 

[Ian1981]

Hello.
Not sure if this is the correct forum to post this in (still trying to work out where the trainee section is).

Just been doing some practice fault-finding online.
Found this scenario:

After doing initial verification on an outbuilding with its own DB, which is supplied from the main DB in another building, the EFLI on a DB in another building also supplied from the main DB is poor as a result of the I.V.

I’ve been scratching my head trying to suss out a cause.
The only one I can come up with is when EFLI was tested during I.V, the main earthing conductor would have to be disconnected to do the test, and then reconnected afterward. The connection wasn’t tightened, resulting in high resistance, yes?

Thanks in advance
And btw, any help in how/where to join the trainee section?

Gary

Click on the ‘forums’heading at the top of the page , scroll down the page and they will be an option to join the trainee section.
You just need to fill out a few details etc

 

[Gary Tollison]

Thanks Ian
As to my scenario, I misread it in my usual fashion!
The I.V was on the entire installation, not on just one sub DB.
So it’s most likely damaged cable,or too small.
Example didn’t give readings, just said what would be the likely cause.
Thanks for the comments