ZS AT DB

[Deleted member 138473]

Hi

When filling in an Schedule Of Test Results, the top left box asks for ZS at DB.

On an installation with only one DB will the ZS at DB recorded as the same value as ZE.

After performing a ZE test can you reconnect the Earthing conductor and test for ZS and use that value.

Parallel paths will occur ?

Thanks

 

[Wilko]

I use Ze

 

[ipf]

I think you'll find 'Zs at DB' is for any sub boards (CU's) and won't be needed for the main one, as a rule.

 

[buzzlightyear]

When filling in an Schedule Of Test Results, the top left box asks for ZS at DB

me zeeeeeeeeeee.

 

[Deleted member 138473]

Yes Zdb for any additional DB after the origin.

 

[Deleted member 138473]

Can you perform a ZS at the DB and record that value?

 

[buzzlightyear]

 

[Vortigern]

The PFC is usually highest at the origin of the circuit/supply. Hence Ze is used to calculate this. I would not be putting Zs at DB for the origin CU. I noticed that my iCertifi has also changed this from Ze to Zs which has puzzled me. Has something changed in regs? Am I missing something?

 

[Mike Johnson]

I think you'll find 'Zs at DB' is for any sub boards (CU's) and won't be needed for the main one, as a rule.

If that was the case would it not say "Zs at DB2"?

One of the downloaded forms I have, at the top of the test sheet says "Zs at this board"

Downloaded from here: Electrical Installation Condition Report - http://www.electricaltestcertificates.co.uk/Electrical_Installation_Condition_Report_Amendment3.html

 

[Mike Johnson]

Ze is the external fault loop impedance of the supply characteristics carried out with the main earth disconnected.

Zs is the internal fault loop impedance and external fault loop impedance combined with the main earth connected, I don't see how you can transpose one with the other, they are two entirely independent measurements. Or am I missing something?

 

[Mike Johnson]

Did not think I would ever disagree with JW, but in his video above at 29:21 he states that the Zs at DB on the test sheet is for an additional board not the main board as detailed previously on a different page, yes you have repeated the information, but it allows the test sheet to stand on its own, the point is it's the main board test sheet not a supplementary board, IMO you append an additional test sheet with the full details of DB2 under "DB reference no" if needed.

 

[ipf]

It could be a case of differing interpretation.
I generally don't have the time or patience to watch such a video ....for three quarters of an hour. Looking at that particular certificate at the half hour point, as you say, It does look that way (he knows his stuff but he ain't half boring).
However, with NICEIC certs, there is the 'only if connected directly to the origin' factor, a good point, I feel.