Zdb before dead tests.

[swaley]

Hi guys got my assesment in 3 weeks and want to get my testing spot on. Little confused whether to test Zdb on 2 way CU before dead tests?? Or do I jump straight into continuity? Thanks in advance.

 

[Nigel]

Zdb is perfectly acceptable to use.

 

[westward10]

In what context.

 

[Strima]

I agree but not a abbreviation I ever quote. I believe it has been adopted where a true value of Ze cannot be established due to operational restrictions and the value is often referred to as Zdb which although often quoted is not a recognised abbreviation.

I have always taken Zdb as the measured EFLI at a DB to avoid confusion between Ze and Zs.

Ze would always Be Ze whether tested with the main earth disconnected or with parallel paths in place.

Although not a recognised abbreviation I've found it can save a lot of confusion. Especially handy when dealing with several DBs in an installation. If there was only one DB then there would only be Ze and Zs.

 

[westward10]

Yes I know that I was just wondering in what context if any it would be used in a technical report/document. My initial comment on it being the OP shouldn't really use a non recognised abbreviation on an assessment.

 

[Nigel]

Zdb is perfectly acceptable to use.

In what context.

In the context of having a professional conversation with another professional.

 

[westward10]

Outside my scope of expertise then

 

[Wilko]

Errr, when bein skooled for a Cooking & Gardening qual, this was the term used for that 2nd (or 22nd) board from the origin.

 

[Pete999]

Outside my scope of expertise then

Your words

 

[Risteard]

As westward points out it is the Zs of the distribution circuit. There is no BS7671-defined term "Zdb" so I would agree that it shouldn't be used.

 

[Octopus]

I think common sense is called for here. ............. its distinctly lacking in BS 7671

If you refer to a Zs - its the end of a circuit
If you refer to a Zbd - its obvious its at a sub board

So maybe it should be called a ZeZdb

 

[Deleted member 26818]

As westward points out it is the Zs of the distribution circuit. There is no BS7671-defined term "Zdb" so I would agree that it shouldn't be used.

How does that work say for a garden shed that you intend to TT?

 

[Pete999]

I think common sense is called for here. ............. its distinctly lacking in BS 7671

If you refer to a Zs - its the end of a circuit
If you refer to a Zbd - its obvious its at a sub board

So maybe it should be called a ZeZdb

Or Impedance at the DB Or more sensibly Zdb, what on earth is the argument for, after all it may not be a regulation but Z db makes sense to me

 

[westward10]

Zskt = Zs at socket outlet.
Zltg = Zs at light fitting.

 

[westward10]

I think common sense is called for here. ............. its distinctly lacking in BS 7671

If you refer to a Zs - its the end of a circuit
If you refer to a Zbd - its obvious its at a sub board

So maybe it should be called a ZeZdb

No Zs.

 

[Octopus]

Zdb = Zs at door bell!