3 Phase Board - Earthing

[Springerflame]

Guys

We (the school where I work), have just had our fixed wire testing completed for this year.  The installation has been classed as satisfactory, but has a C1 observation of:

There is no link cable between the two earth bars in the DB.

So, because the earth to both sides is being provided by the armour to the metal DB casing, why would someone make this observation !!  There are two earth bars, and neither are connected via a protective conductor.

They are quoting Regulation 411.3 (Chapter 54), but I don't see anything that says the earth bars have to be connected by a physical CPC conductor.

The DB has a measured Ze (Zdb) value

Each circuit has a measured Zs value

With that in mind, I am not sure that there is an issue with earth.

Any light that can be shed would be most helpful.

Thanks

Alan

PS.  This is my first post, so I hope this makes sense.

 

[Technician]

That reg. reference is the one about the requirements

for fault protection. 

There is a statement in this reg;

"Simultaneously accessible exposed conductive parts

shall be connected to the same earthing system individually,

in groups or collectively."

The one above it is about connecting exposed conductive parts to a protective conductor.

Why was it classed as satisfactory when a C1 is on it, a code used when there is immediate danger?

 

[steptoe]

Id suggest getting someone competent to do the testing next time.

as above, if there is a C1 it cannot be satisfactory, 

I dont see any code whatsoever, unless they have got mixed up with a removable gland plate with no fly-lead on it maybe,  :C

 

[Doc Hudson]

Guys

We (the school where I work), have just had our fixed wire testing completed for this year.  The installation has been classed as satisfactory, but has a C1 observation of:

Any light that can be shed would be most helpful.

Thanks

Alan

PS.  This is my first post, so I hope this makes sense.

Hello Alan, do you have access to a copy of BS7671 wiring regulations? page 398 gives the notes that should accompany an inspection report.  The inspection report you have received should also include these notes. Bullet point 7 states that if any observations have been given a code 1 or code 2 classification then the overall condition should be reported as Unsatisfactory.

So we have a contradiction; either they say it is satisfactory so there cannot be any code 1's or if they say there are any code 1's it cannot be Satisfactory. If someone cannot understand this bit of black and white guidance then the only conclusion is as Steptoe states they were not competent to undertake the inspection. If they are not competent then any observations they make and the validity of the whole inspection is brought into question. 

Doc H.

 

[Sidewinder]

As above really.

IIRC the Merlin Gerin Multi9 type B DB had two earth bars, and no link wire as designed, it meets all of the required standards.

So if it is one board with two earth bars then there is every chance that no link is needed.

If it is two separate metallic boards then the link could well be the containment, so that could be OK too.

I've not seen the installation, so can't say definitively.

However, Satisfactory and a C1 are mutually exclusive on an EICR, you can't have them both!

Sounds like you have an incompetent contractor with the info we have been given here.

 

[Steve3948]

Most earth bars on metal clad boards are bolted to frame of enclosure, but the gland plate is also normally bolted and cpc from bolt to bar.

As said above C1 is unsatisfactory, but sounds more like C3 to me if test results were good

 

[Springerflame]

Guys......................... Thank you.  

I was of the same mind as you all, but just wanted (for my own sanity) to catch up with some experienced thoughts.

Thanks again

Alan 

 

[Andy™]

even if there was no earth at all, its unlikely to be C1. it would be C2

sounds like r.b has done the work