EICR and Supplementary Bonding.

[Chr!s]

I think this one with regards to terminology is pretty straight forward.

Chapter 54 Earthing Arrangements and Protective Conductors Page 157

Sub Headings

Protective Bonding Conductors:

Main Protective Bonding Conductors
Supplementary Bonding Conductors


Chris

 

[Badged01]

Chapter 54 Earthing Arrangements and Protective Bonding Conductors Page 157

Damn ....... You've just played my trump card

 

[Chr!s]

Damn ....... You've just played my trump card

 

[Geoffsd]

Oh this has got a bit long.

If that isnt fault protection (shock) what is it? Protection against thermal effects, overcurrent, voltage or electromagnetic disturbances? Or is there some other protection for safety in the BGB that supp bonding is and I've missed? (415.2 note 1 also mentions supp bonding being an addition to fault protection)

Well, that's just the definitions.
OPDs protect against faults by disconnection. SB protects a person until disconnection but does not and cannot clear the fault.

[/QUOTE]The accepted safe voltage is 50V therefore this impedance must be below 50/Ia. See 415.2.2
No problem with that, reg 415.2.2 as you state[/QUOTE]
But you are arguing that this is not good enough and the 'below 50/Ia' must be reduced by more bonding.

Is that a direct quote from the BGB? -- if so please point me to the reg as the only regs I can find are in 701 stating supp bonding must be in place and 415 where it states what must be supp bonded and how you can use the 'equation' to confirm the effectiveness of this supp bonding when in place. I cant find anything that states that if the 'equation' value is greater then only then, and then only, must supp bonding be installed?

It states that the value must be below 50/Ia so if it is higher SB is required, if it is lower it is already ok.
E.g. you cannot 'see' any SB between two pipes but the measurement is 0.05, are you going to add SB so that it is 0.01 even though 200A x 0.05Ω = 10V.

Totally disagree, supp bonding is a requirement under 701/415 regardless of readings.

No, the readings are the determining factor. <=50/Ia is satisfactory.
What is the point of the measurement if you had to ensure 0.05Ω

The regs allow supp bonding to be either in the bathroom or close to where the 'extraneous' parts enter the bathroom. Whether you can combine supp bonding and main bonding as the same thing just outside the bathroom sounds like another thread to discuss! Ive never thought of it like that but I can see its merits!.

Would you demand two conductors in parallel?
What would be the point?
The main bond does not need (require) supplementing.

New one on me! I know you can use the CPC of attached equipment as a bond (544.2.5) but didnt know a pipe was an acceptable conductor alternative. Where is this pipe as a bonding conductor defined?

543.2.1(vii)

Thats not the point of supp bonding -- to connect to the MET. Its to connect all the 'extraneous parts', 'protective conductors' etc ... together in the bathroom to form I guess a faraday cage? But you raised an interesting point before, can the supp bonding and main bonding be one of the same thing when just outside the bathroom

No, but the extraneous parts must be 'effectively connected to the MET'

I think it does matter what is causing the reading ..... the definition is in 701 that supp bonding must be in bathroom (or close by) and 415 which defines a physical connection between all the bits, the effectiveness of this connection being proved by the 'equation'. Again if there is a reg that over rides these requirement then please quote. Or if my interpretation of what the regs state is clearly wrong please define which part supports your arguement.

What do you mean 'if there is a reg that over rides these requirement then please quote'?
That is what I have been saying all along.
You are again forgetting the 'if required bit'.
If the measurements are within the safe limit (50/Ia) then the parts are proved to be effectively connected.

No arguement from me there. Totally correct statement!

But you have been arguing that it is necessary whether required or not.

 

[D Skelton]

Ive tried to show you my logic from BS7671 as to why it is a protective conductor but your not giving me anything back to challenge this. Other than your own definition of supplementary?

It's not my definition of supplementary though is it? It's the definition of supplementary, which is: In addition to. The regs don't define them as protective conductors, only group them in the same section as protective bonding conductors.

The application of a supplementary bonding conductor is to add to the protection given by a main bonding conductor, a supplementary bonding conductor on it's own has no application whatsoever.

 

[Badged01]

And we go round in circles! OK, I have my view and you have your view and there is enough information in the thread for a 3rd party to draw there own conclusions.

Stumps drawn, Im taking my bat & ball home .........

 

[Des 56]

Has this thread discussion concluded so soon ?

For anyone who wants to read IET guidance and history, in order to wade in to this subject
Its from past editions and gives the timeline of change and requirements


Click on the item in issue 27 summer 2008
Wiring Matters - 2008 issues - IET Electrical

413-7 is interesting regarding some of the views posted in this thread

 

[rattlehead85]

I didn’t want to end up with a lengthy and boring to and fro thread but feel you are completely off course in your interpretation/understanding of the application and need for supplementary equipotential bonding. Nowhere can I find anything that states supp bonding is not required if the impedances are low enough to limit meet the touch voltage requirement.

Section 701 states additional protection in the form of supp bonding SHALL be established connecting protective conductors to accessible extraneous-conductive parts in the location. My interpretation is there has to be a physical connection to achieve this in the location and this is supported by the advice/pictures/drawings in GN8 and the ESC publications.

Change the word “insulation” for “bonding” in the definition of Supplementary in the BGB. This I believe gives a further intent as to application of supplementary. That is supp bonding is applied in addition to main bonding for fault protection. (“applied” I interpret as meaning a physical connection as with main bonding.)

If main bonding is fitted you will always get a reading in the bathroom to showing continuity and 90% of the time it will meet touch voltages (assuming continuity of metalwork). Hence a reading alone will not prove supplementary bonding is physically present. You need to see it to confirm its presence.

Once you can see supp bonding, if you have any doubt as to the “effectiveness” of that supp bonding then you can test as per 415.2 using said touch voltage equation. No where in the regulations can I see anything that suggests this test alone is a substitute for confirming sup bonding is present, just “effective”. Its application is purely as a test if not sure that the supp bonding is “effective” in providing additional protection. (i.e. you’ve seen it and now want to test to confirm compliance.)

Even to apply this equation in practice, for me you have to be able to physically disconnect an end of the sup bonding and test, because if you have any bonding elsewhere in the premises your results will be effected by parallel paths. So if sup bonding isn’t there in the first place you cant prove its effectiveness just by using the equation?

At the end of the day sup bonding is there as an additional fault protection method and if you cant confirm its presence (not effectiveness) by the good old mark one eye-ball then no testing to an equation will convince me it is, just hidden somewhere. Lack of sup bonding can have serious implications in a fault situation should for example main bonding be lost, hence why the ESC consider lack of its presence being a C2 without an RCD fitted??

If there is anything in the regulations that Ive missed or goes against anything Ive stated then please advise and correct me. I am always learning and seeking new knowledge and understanding.

This is a very good opinion offered and makes good sense.

 

[Geoffsd]

Unfortunately it is fundamentally flawed and

contradicts your original question which, without option 1, was entirely correct.

 

[rattlehead85]

Flawed.... it's his interpretation and i can see his point. I still see a valid argument for both sides but to be honest the regs and GN both clearly define Supp bonding as being required in a room containing a bath or shower...not as required only if a test to confirm r<50v/Ia is not met which indicates that the test to verify r<50v/Ia is only used to confirm if the bonding required is effective.

 

[rattlehead85]

So....interpreting the regs in this way the scenario i originally put forward would clearly warrant a code 2 departure as there is no RCD, no required bonding in the location as stated by 7671 section 7 and therefore the test i applied cannot be classed as valid because there was no evident supplementary bonding in place to apply the test to.

 

[Guest55]

So....interpreting the regs in this way the scenario i originally put forward would clearly warrant a code 2 departure as there is no RCD, no required bonding in the location as stated by 7671 section 7 and therefore the test i applied cannot be classed as valid because there was no evident supplementary bonding in place to apply the test to.

yep pretty much what i said in my first post many pages ago , but some folk just wanna talk & argue in circles for the sheer sake of it.

 

[telectrix]

still better than discussing fans on showers and RCDs in series.

 

[Geoffsd]

Alright, last post - but just make sure it IS extraneous before applying unnecessary bonding.

So....interpreting the regs in this way the scenario i originally put forward would clearly warrant a code 2 departure as there is no RCD, no required bonding in the location as stated by 7671 section 7 and therefore the test i applied cannot be classed as valid because there was no evident supplementary bonding in place to apply the test to.

You have said 'required' so what if it is not required?

Flawed....

Yes.

it's his interpretation and i can see his point. I still see a valid argument for both sides but to be honest the regs and GN both clearly define Supp bonding as being required in a room containing a bath or shower...not as required only if a test to confirm r<50v/Ia is not met which indicates that the test to verify r<50v/Ia is only used to confirm if the bonding required is effective.

But that is the same thing.

415.2.2 states Where doubt exists regarding the effectiveness of supplementary bonding, it shall be confirmed that the resistance R between simultaneously exposed-conductive-parts and extraneous-conductive-parts fulfils the following condition: R ≤ 50/Ia (or I∆n)

Presumably if visible, doubt does not exist,

So, ≤ 50/Ia means the SB is effective where doubt exists.

Therefore, if the parts themselves give a reading of ≤ 50/Ia then do you not still agree, as you stated in your first post, that supplementary bonding is not required.




It's the same as applying another CPC to a circuit because you cannot see where the conduit goes even though the Zs is satisfactory.

 

[Chr!s]

Its simple, no RCD, then Supplementary bonding required between exposed and extraneous.

Chris