EICR and Supplementary Bonding.

[rattlehead85]

I have noticed recently on the forums various opinions on what does and doesn't warrant observation regarding bathroom bonding to previous 16th regulations,
Would be interested to gather opinion on the following scenario.....

2 Bed 6th floor flat wired in PVC singles through in-situ pvc conduit through building fabric. Consumer unit is a 16th edition unit consisting of BS 3871 type 2 MCB's with no existing RCD protection on circuits covering the bathroom. There is 10mm2 main protective bonding to both gas and water services to the premises and the Zs values of the circuitry within the location are compliant.

The bathroom has a class 1 sufficiently i.p rated light on a 5A MCB and a downflow heater circuit located outside zones protected by a 15a MCB.
There are no visual signs of 4mm2 earth or bs951 clamps to either the pipework or run to circuits, howerver, a continuity test gives the following results.
Between all extraneous pipework within the location 0.00ohms

Between pipework and metal light carcass 0.44ohms

Between pipework and downflow heater circuit cpc 0.26ohms.

Taking all the above into account would this therefore warrant
1/ A C2 departure as there is no RCD and no visual signs of bonding......or

2/ A C3 departure as No RCD protection present but bonding confirmed as adequate by continuity tests using the formula R<_ 50v/ Ia.

Thoughts and reasons for your answers would be interesting, and no this isn't somebody looking for an answer to an exam question!!

 

[Geoffsd]

I think you can only give it a C3.
Modern thinking would recommend the improvement to RCD protection.

I don't think you can class it as unacceptable.

 

[Guest55]

not so fast gents
unfortunately the ESC eicr reporting guide does not agree.

no rcds + no local supp. bonding for bathrooms = C2

and theres no using a maths formula to get around it either , so option 2 is no dice.

and for visually unverifed conductor runs they allow only 0.05 ohms max , which blows out 2 of your exposed items values straight away.

C2 im afraid.

 

[Geoffsd]

I don't know what the ESC agrees with (aren't they NIC and so...?).

According to the BGB, the supplementary bonding has been shown, by the OP, to be satisfactory and therefore 'acceptable' - i.e. not 'unacceptable' and so does not require a C1 or C2.

The only thing is lack of RCDs because of age.
Regs. are not retrospective so all that can be done is 'recommend improvement' - C3.

 

[rattlehead85]

If the values obtained during the tests carried out exceeded the maximum for the protective devices used for the circuitry within the location (which in this case are 1.42 ohms and 0.47 ohms respectively) then there is no argument that supplementary bonding to the effect of running back to each circuit and between pipework would be needed to ensure the touch voltage does not exceed 50v under any circumstances. Or is this theory wrong?

 

[Guest55]

I don't know what the ESC agrees with (aren't they NIC and so...?).

According to the BGB, the supplementary bonding has been shown, by the OP, to be satisfactory and therefore 'acceptable' - i.e. not 'unacceptable' and so does not require a C1 or C2.

The only thing is lack of RCDs because of age.
Regs. are not retrospective so all that can be done is 'recommend improvement' - C3.

where in bs 7671 does it even mention defect codes ?

and as to what the OP has shown ? well thats diddly squat as he found no evidence of local bonding whatsoever ??


meh , do as you wish , but i'd rather make the installation owner go at least some way to improving that set-up if just for his own safety , hence a C2 imo.

 

[rattlehead85]

The arguement against the above is that under the previous 16th edition regulation 601.4 asks for bonding to be applied connecting terminals of class 1 & 2 equipment together in all zones and to extraneous pipework. Surely this still stands under current 17th edition where RCD protection is not provided even though bathroom zoning has been ammended.

 

[Geoffsd]

where in bs 7671 does it even mention defect codes ?

Appendix 6.

and as to what the OP has shown ? well thats diddly squat as he found no evidence of local bonding whatsoever ??

If those values are the resistances of the pipes and cpcs themselves then none would be required.

do as you wish , but i'd rather make the installation owner go at least some way to improving that set-up , hence a C2 imo.

Fair enough.

 

[rattlehead85]

where in bs 7671 does it even mention defect codes ?

and as to what the OP has shown ? well thats diddly squat as he found no evidence of local bonding whatsoever ??


meh , do as you wish , but i'd rather make the installation owner go at least some way to improving that set-up if just for his own safety , hence a C2 imo.

Good opinion there Biff. If you recommend improvement then surely C3 code is used. C2 if potentially dangerous, in this instance can it be said that the scenario given is potentially dangerous??

Test results have shown that under fault conditions there will not be a potential difference between pipework or circuitry above 50v within the location.

 

[rattlehead85]

Would be interesting to gather opinions from members such as Tel and MDJ on this as they usually offer very good advice.

 

[Badged01]

Would be interesting to gather opinions from members such as Tel and MDJ on this as they usually offer very good advice.

Im not in the same league as Tel and MDJ on electrical knowledge, being an electrical guy from an industrial background, and my advice isnt always good (take it at your own peril) but my view would be to support what Biff55 has already stated. Assuming the question is raised as to EICRing in a bathroom location .....

If there is no compliant supplementary bonding and there is no RCD protection either then you have a shortfall against the requirements of BS7671 17th Edn, so it needs to be raised and coded -- C2 or C3 I would suggest, but you the inspector decide.

However, advice from the ESC says it should be a C2 code so I would further suggest you follow this guidance and code C2 and not C3. Why? Because the ESC are supported by the IET (who produce BS7671) and the large electrical organisations (NECIEC/ECA etc .. ) who are the 'voice' of the industry. If you decide to go against their professional electrical recommendation/advice/judgement they you better have a good reason why if you end up in a court of law .....

 

[D Skelton]

C3, I'm with Geoff.

Just because there is no visual sign of supplementary bonding doesn't mean it isn't there. There is no requirement for the terminations to be accessible or visible, therefore an assumption can be made that supplementary bonding is present and adequate if R≤50V/Ia. The lack of RCD makes for a C3 only.

 

[Badged01]

.... but bonding confirmed as adequate by continuity tests using the formula R<_ 50v/ Ia.

Be careful how you apply this equation! It is used to confirm the resistance between 'extraneous parts' is adequate for protection when you have doubts about the effectiveness off the 'supp' bonding. I dont take it as being an alternative mathematical solution to confirming 'supp' is physically present by use of the mark 1 eyeball.

If all the water/gas pipework is already bonded then you will get continuity if no supplementary bonding is present as everything is tagged back to the MET? (assuming no plastic pipework!). If the 'supp' is physically there and you loose one of the main bonds to water/gas then the additional protection is still provided. For me this is what the regulation is about, ensuring the additional protection is there by physical bonding between all the "extraneous" parts.

However, I have been known to be wildly wrong in the past with my understanding and interpretation of regs ..... but if in doubt, ESC guidance is safe bet!

 

[Flanders]

The OPs reading to be suggest there is no supplementary bonding as the values look like they are the resistance of the CPC + the resistance of the main bonding and copper pipe work , I was always guided to give this case a code 2 when we were working to the 16th addition but always thought it was a bit over the top and a pain to rectify + I vary rarely came across site were the supplementary bonding was done the most I would see is cross bonding in the airing cupboard or the pointless cross bonding of the pipe at the bottom of a combi boiler

 

[Geoffsd]

The OPs reading to be suggest there is no supplementary bonding as the values look like they are the resistance of the CPC + the resistance of the main bonding and copper pipe work ,

Yes, but that doesn't matter.
If the resistances are below 50/Ia - in this case 50/75 = 0.66 - then supplementary bonding is not required.

I was always guided to give this case a code 2 when we were working to the 16th addition but always thought it was a bit over the top and a pain to rectify

You are giving a code 2 to an installation which is compliant - why?
In this case there is nothing to rectify.

+ I vary rarely came across site were the supplementary bonding was done

Either it was not done or it was not required.
There is a huge difference between these two situations even though they look the same.

the most I would see is cross bonding in the airing cupboard

Why do you use the term 'cross bonding'?
It was probably supplementary bonding correctly applied.
Whilst e-c-ps in the bathroom may require supplementary bonding it does not have to be applied in the bathroom.

or the pointless cross bonding of the pipe at the bottom of a combi boiler

Plumbers like this for some reason or they refuse to commission the boiler.

 

[Geoffsd]

Be careful how you apply this equation! It is used to confirm the resistance between 'extraneous parts' is adequate for protection when you have doubts about the effectiveness off the 'supp' bonding. I dont take it as being an alternative mathematical solution to confirming 'supp' is physically present by use of the mark 1 eyeball.

The equation is used to determine whether supplementary bonding is required.
You cannot tell by looking at some pipes.

If all the water/gas pipework is already bonded then you will get continuity if no supplementary bonding is present as everything is tagged back to the MET? (assuming no plastic pipework!).

If those values are below 50/Ia then all is well.

If the 'supp' is physically there and you loose one of the main bonds to water/gas then the additional protection is still provided. For me this is what the regulation is about,

But it isn't.

ensuring the additional protection is there by physical bonding between all the "extraneous" parts.

You seem to be confused by the meaning of 'supplementary'.

1. Something added to complete a thing, make up for a deficiency, or extend or strengthen the whole.

So, if complete, not deficient, strong enough or whole already then not required.

 

[Badged01]

You seem to be confused by the meaning of 'supplementary'.

1. Something added to complete a thing, make up for a deficiency, or extend or strengthen the whole.

Not at all, I think im quite clear in my understanding but without wanting to get into another long thread of back and forth arguements, I'll agree to disagree with you on our intepretation of the regs.

However, you may also want to check the closest definition to supplementary that counts --- in the BGB definitions -- not exactly supplementary bonding but gives a flavour. Also the ECS recommendations around what constitutes supplementary bonding and its application gives a further indication as to what supplementary bonding is about -- bearing in mind that the ECS is supported in its statements by the IET (owners of BS7671) and the large electrical bodies that speak for the industry (NICEIC/ECA etc ....)

But hey, each to their own as they say in their interpretation of the regs. The only time you really need to justify it is in a court of law ......

 

[wozz]

I like following what the ECS says so i would.

But I cant really understand the thinking behind it, as far as I can make out the exposed and extraneous parts are electrically connected. If they are not I would think C2, as they are C3.

Have you got a link to the ECS lit badged?

 

[Badged01]

.... I cant really understand the thinking behind it, as far as I can make out the exposed and extraneous parts are electrically connected.

You need to convince yourself one way or the other as to whether physical conformation of supplementary equipotential bonding is required in the bathroom (in addition to the existing main protective equipotential bonding to water/gas) by having a read of section 701 on supp bonding, looking at the pretty pictures in GN8 which show the supp bonding connections (note the dead give away as to whether supp bonding is present in the bathroom by there being a connection at the light fitting!) and the ESC publications which further expands on both of the former. (Havent got a link to the ESC website publication but a quick internet search will lead you there).

Ultimately all these documents are there for "guidance" and you have to make the decision on the need to confirm supp bonding or not based on your interpretation of the regs requirements. And you can see from the thread views on YES/NO, no-one is truely in agreement so good luck!!

 

[Geoffsd]

You don't need to convince yourself of anything other than doing it properly.


The problem in this thread leading to what is being termed 'different views' is that the ESC document is not considering the situation where supplementary bonding is NOT REQUIRED because the impedance of the parts is low enough in itself to limit any touch voltage to the safe amount.

You cannot tell by looking at the parts whether supplementary bonding is missing or not required.

There is, of course, another option where no supplementary bonding is visible; that the parts are not extraneous anyway and bonding would introduce hazards.

 

[Badged01]

….. is not considering the situation where supplementary bonding is NOT REQUIRED because the impedance of the parts is low enough in itself to limit any touch voltage to the safe amount…….

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.

 

[Badged01]

There is no requirement for the terminations to be accessible or visible.

Sorry for the delay, missed this point first time round.

How will you check/ensure conform with 514.13.1 (ii) regarding warning labels if you cannot access to inspect? Just grade it code C3 as not being there regardless (safe bet!), or assume there must be one there if you are getting a reading and ignore it?

 

[D Skelton]

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.

I'm sure Geoff doesn't need me to spring to his defence but I don't think he is 'off course' in his understanding of the requirements for supplementary bonding at all.

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.

Neither of us have said this^^^, what we have said is that supplementary bonding would not be required between non-extraneous conductive parts, and just looking at pipes isn't going to tell you whether they're extraneous or not.

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.

And you'd be completely and utterly right if we were referring to a new installation and supplementary bonding couldn't be ommitted as per 701.415.2, but we're not. We're talking about periodic inspection where depending on the installation a few assumptions are going to have to be made.

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.)

No, supplementary bonding is applied for additional protection only, not fault protection.

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.

And how do you propose to do this on a periodic inspection? There is no requirement for supplementary bonding connections to be visible or accessible. Are you going to start ripping apart the floors, walls and ceilings just to see? If it's not visible, then the application of R≤50V/Ia is good enough to be able to assume that supplementary bonding is in place and is effective.

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.)

If you want to apply your way of thinking then the best you could do when confirming the presence of supplementary bonding is to LIM it if you can't see it.

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?

No, but you can make an assumption that it is there by applying the appropriate test. If that test is there to confirm the effectiveness of supplementary bonding, then if the results show that it is effective, then it says to me that it is there or as good as there.

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??

As above^. And I say again, supp bonding is not there for fault protection, it is additional protection only.

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.

Aren't we all, but maybe seeking understanding from the ESC and thier interpretation of the regs book, which in itself is riddled with flaws, isn't best practice

Use your own head mate, if you can't see something but evidence suggests that it is there or at least as good as being there, then what's the issue?

 

[D Skelton]

Sorry for the delay, missed this point first time round.

How will you check/ensure conform with 514.13.1 (ii) regarding warning labels if you cannot access to inspect? Just grade it code C3 as not being there regardless (safe bet!), or assume there must be one there if you are getting a reading and ignore it?

By making sure that it is visible when access is gained to the extraneous conductive part in question. That regulation I believe was only meant to apply to main protective bonding conductors anyway.

 

[Badged01]

Neither of us have said this^^^, what we have said is that supplementary bonding would not be required between non-extraneous conductive parts, and just looking at pipes isn't going to tell you whether they're extraneous or not.

Absolutely, but thats not what Im saying. If they are extraneous, which is what im being led to believe they are, then they must be supp bonded. My arguement then is that the only way to tell if they are bonded to start with is is to see if the bonding is physically there! It doesnt mean its complete, it could be broken. But if it is there then testing confirms the adequacy of said bonding, not that the bonding is there in the first place.

And you'd be completely and utterly right if we were referring to a new installation and supplementary bonding couldn't be ommitted as per 701.415.2, but we're not. We're talking about periodic inspection where depending on the installation a few assumptions are going to have to be made.

No, if doing an EICR you do it to the latest regulations and record your deviances as such -- no bonding is a deviation-- you dont inspect to what previous regs may have allowed or not. What you have is an caveat in the regs that because it was to a previous reg it doesnt make it unsafe, you as the inspector make that call. (I'm not that old but hasnt supp bonding always been a requirement under previous regs??). My arguement is that the "governing bodies" have deemed it unsafe not to have it without RCD top cover but whether you hold to this is entirely your choice as the inspector. Only you answer for your decisions on how you code it!

No, supplementary bonding is applied for additional protection only, not fault protection

Wrong, you seriously believe additional protection is not for fault protection?. (Check 415.2 note 1). If not for fault what do you actually believe it is there for?

And how do you propose to do this on a periodic inspection? ...... If it's not visible, then the application of R≤50V/Ia is good enough to be able to assume that supplementary bonding is in place and is effective.

Thats my arguement, the equation is flawed unless you have disconnect all other bonding as you will get a reading and assume it is present even if it isnt? If you cant disconnect all other bonding (cos you dont know what other bonding may be hidden?) the only failsure method to prove supp may be there is to see it. To prove it is effective you test -- not the other way around. Your right though, I wont be ripping up floor boards. If I cant see any signs of supp bonding I assume its not there and code -- I wont rely on a test between part to prove supp bonding is present.

If you want to apply your way of thinking then the best you could do when confirming the presence of supplementary bonding is to LIM it if you can't see it.

Valid point, you could exclude from the EICR. Personally I wont.

No, but you can make an assumption that it is there by applying the appropriate test. If that test is there to confirm the effectiveness of supplementary bonding, then if the results show that it is effective, then it says to me that it is there or as good as there.

Not necesarily, if you have parallel paths due to other bonding elsewhere in the premises you will always get a reading. Only if you can remove every possible parallel path would this method be effective. (Have I just convinced myself of a possible method to use this for proving the presence of supp bonding?)

.....I say again, supp bonding is not there for fault protection, it is additional protection only.

And what do you believe additional protection is for if not to protect against a fault?

.... ESC and thier interpretation of the regs book, which in itself is riddled with flaws, isn't best practice

I'll leave that one with you to argue! I in no way consider myself of sufficient knowledge and experience to challenge the 'big boys' and their technical 'experts' -- plus on their interpretation and guidance I actually think they are right!

Use your own head mate, if you can't see something but evidence suggests that it is there or at least as good as being there, then what's the issue?

In agreement with you there if the evidence supports the probability. But my disagreement on this particualr issue with supp bonding is that not being able to see it I wont rely on a test to convince me (evidence) that it is there. I am risk adverse, numerous kickings for assumptions at work have made me that way, so always err on the side of caution. The receiver of the EICR can ignore what I state if they want, its my perogative as the inspector to make my assessment and its the perogative of the client to ignore it. I just like knowing my butt is covered should the sh8t hit the fan!

p.s. I have no personal disagreement with anyone, im just exploring the technicalities of supp bonding

 

[Badged01]

By making sure that it is visible when access is gained to the extraneous conductive part in question.

But the discussion so far is that it isnt accesible ..... hence using the "equation"

That regulation I believe was only meant to apply to main protective bonding conductors anyway.

Nope, "every protective bonding conductor" --- you may interpret it that way but for me it means what it says on the tin!


Edited: Forgot to add that unless the connection to the pipework is 'permanently made' it should be accessible for inspection, testing & maintenance (526.3), Again I dont think this requirement is just a 17th edition update?

 

[Geoffsd]

Supplementary bonding is not for fault protection, that is earthing - fact, but to equalise, or reduce to an acceptable level, potential difference between two (or more) parts in the event of a fault.

That is, to reduce the impedance between these parts in order to minimise volt drop when a fault occurs causing current to flow between these parts until the opd operates.

The accepted safe voltage is 50V therefore this impedance must be below 50/Ia. See 415.2.2
If the impedance between the parts is greater than this value then supplementary bonding is required to reduce that impedance.
However, if this impedance is already below 50/Ia because the runs (from main bonding and consumer unit) are short enough or connections elsewhere then supplementary bonding is not required because the conditions are already met.

For example a small flat: the water service entry, hence main bonding, DHW cylinder and the consumer unit are all on the other side of the bathroom wall.
The maximum run, from the bathroom, of pipes to main bond and cpcs to consumer unit is three metres.
The only circuit in the bathroom is the lighting.
As it is allowed to use a pipe as a supplementary bond the conditions are satisfied by the pipes themselves.
The pipes are then effectively connected to the MET and cpcs by the main bond itself.


So, If the measurements are within the acceptable limit it does not matter (for EICR) if the reason for this is satisfactory supplementary bonding out of sight (SB does not have to be IN the location), connection between the parts elsewhere or the low impedance of the parts themselves.

Saying that supplementary bond shall be applied is true but it only if required.

 

[D Skelton]

Absolutely, but thats not what Im saying. If they are extraneous, which is what im being led to believe they are, then they must be supp bonded. My arguement then is that the only way to tell if they are bonded to start with is is to see if the bonding is physically there! It doesnt mean its complete, it could be broken. But if it is there then testing confirms the adequacy of said bonding, not that the bonding is there in the first place.

Ideally you're right, but with periodic inspection we are not dealing with ideals, we're dealing with limitations.

No, if doing an EICR you do it to the latest regulations and record your deviances as such -- no bonding is a deviation-- you dont inspect to what previous regs may have allowed or not. What you have is an caveat in the regs that because it was to a previous reg it doesnt make it unsafe, you as the inspector make that call. (I'm not that old but hasnt supp bonding always been a requirement under previous regs??). My arguement is that the "governing bodies" have deemed it unsafe not to have it without RCD top cover but whether you hold to this is entirely your choice as the inspector. Only you answer for your decisions on how you code it!

You misunderstand me. I wasn't referring to a 'new' installation in terms of its compliance with current regs, I was referring to a new installation in general. If you were wiring from scratch and supplementary bonding was needed then you'd have to fit it and then test it to confirm its effectiveness, but when carrying out periodic inspection then you are making assumptions as to its suitability for continued use. If a test indicates that supplementary bonding is there or is as good as there then you can assume that it is.

Wrong, you seriously believe additional protection is not for fault protection?. (Check 415.2 note 1). If not for fault what do you actually believe it is there for?

No, it is an addition to fault protection, it is not used for fault protection. See 415.2 note 2.

If you cant disconnect all other bonding (cos you dont know what other bonding may be hidden?) the only failsure method to prove supp may be there is to see it.

I agree

To prove it is effective you test

I agree

not the other way around.

I agree, with a 'but'.

Thats my arguement, the equation is flawed unless you have disconnect all other bonding as you will get a reading and assume it is present even if it isnt?

Your right though, I wont be ripping up floor boards. If I cant see any signs of supp bonding I assume its not there and code -- I wont rely on a test between part to prove supp bonding is present.

But you rely on an R1+R2 test to prove that a cpc is there don't you??? No. Think about it, unless you are carrying out initial verification there is not a single continuity test you can carry out without risk of parallel paths being present. You are carrying out an EICR, you are not there to 'prove' anything, you can however use your test results to suggest that it is there.

Valid point, you could exclude from the EICR. Personally I wont.

I wouldn't exclude, I would say that although I cannot see any sign of supplementary bonding, my test results suggest that it is there.

Not necesarily, if you have parallel paths due to other bonding elsewhere in the premises you will always get a reading. Only if you can remove every possible parallel path would this method be effective. (Have I just convinced myself of a possible method to use this for proving the presence of supp bonding?)

As above, do you ensure the removal of every parallel path when conducting an R1+R2 test during an EICR?

And what do you believe additional protection is for if not to protect against a fault?

As above, it is in addition to...

I'll leave that one with you to argue! I in no way consider myself of sufficient knowledge and experience to challenge the 'big boys' and their technical 'experts' -- plus on their interpretation and guidance I actually think they are right!

Big boys??? No mate, suits, nothing more, many of which with little experience of the practical application of the regulations. Could I challenge them on the whole regs book? No, certainly not. But I could certainly challenge them on certain sections!

In agreement with you there if the evidence supports the probability. But my disagreement on this particualr issue with supp bonding is that not being able to see it I wont rely on a test to convince me (evidence) that it is there. I am risk adverse, numerous kickings for assumptions at work have made me that way, so always err on the side of caution. The receiver of the EICR can ignore what I state if they want, its my perogative as the inspector to make my assessment and its the perogative of the client to ignore it. I just like knowing my butt is covered should the sh8t hit the fan!

Again, when carrying out an EICR you're working with what you have and what you can see and test. It is a report, not a certificate, therefore you can say whatever you want really! If you wanted to give everything a C1 regardless of its severity then that's your prerogative (although evidently you wouldn't make a very good inspector), and you still remain responsible for nowt! Every inspection you carry out and every test result you gain is nothing more than a suggestion as to the current safety of the installation. I reiterate, periodic inspection and initial verification are two completely different ball games.

p.s. I have no personal disagreement with anyone, im just exploring the technicalities of supp bonding

Neither do I, but the vagueness of the regulations gives rise to threads such as this occuring highlighting the relevance of my comment regarding challenging the suits up at the IET!

 

[D Skelton]

Nope, "every protective bonding conductor" --- you may interpret it that way but for me it means what it says on the tin!

A supplementary bonding conductor is not a protective bonding conductor.

 

[Badged01]

Supplementary bonding is not for fault protection, that is earthing - fact, but to equalise, or reduce to an acceptable level, potential difference between two (or more) parts in the event of a fault.

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)

[/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

If the impedance between the parts is greater than this value then supplementary bonding is required to reduce that impedance.

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?

However, if this impedance is already below 50/Ia because the runs (from main bonding and consumer unit) are short enough or connections elsewhere then supplementary bonding is not required because the conditions are already met.

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

For example a small flat: the water service entry, hence main bonding, DHW cylinder and the consumer unit are all on the other side of the bathroom wall. The maximum run, from the bathroom, of pipes to main bond and cpcs to consumer unit is three metres. The only circuit in the bathroom is the lighting.

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!.

As it is allowed to use a pipe as a supplementary bond the conditions are satisfied by the pipes themselves.

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?

The pipes are then effectively connected to the MET and cpcs by the main bond itself.

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

So, If the measurements are within the acceptable limit it does not matter (for EICR) if the reason for this is satisfactory supplementary bonding out of sight (SB does not have to be IN the location), connection between the parts elsewhere or the low impedance of the parts themselves.

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.

Saying that supplementary bond shall be applied is true but it only if required.

No arguement from me there. Totally correct statement!

 

[Badged01]

A supplementary bonding conductor is not a protective bonding conductor.

A protective bonding conductor is a conductor for protective equipotential bonding --- what would you define additional supp bonding as?

I stand by 701.415 -- Additional protection -- equipotential bonding. Hence i interpret it as being a protective bonding conductor.

 

[D Skelton]

A protective bonding conductor is a conductor for protective equipotential bonding --- what would you define additional supp bonding as?

I'd define a supplementary bonding conductor as what it is; a supplementary bonding conductor.

 

[Badged01]

I'd define a supplementary bonding conductor as what it is; a supplementary bonding conductor.

Fair point thats your definition.

I was just intrigued as to whether you had some technical definition to support it not being a protective bonding conductor.

 

[D Skelton]

Fair point thats your definition.

I was just intrigued as to whether you had some technical definition to support it not being a protective bonding conductor.

The technical definition is in it's title! Lol

It is not a protective bonding conductor because it is not protective, it is supplementary!

It is not there to equalise the potential between exposed and extraneous conductive parts in the event of a fault, it is there to supplement the main protective bonding in its duty of equalising the potential between parts.

 

[dazza1981]

Im relatively new in the game and learning all the time but when it comes to exporting earths and supplementary bonding etc etc there are so many different views i can never get my head to understand it all. Interesting reading all the views though!!

 

[Badged01]

The technical definition is in it's title! Lol

It is not a protective bonding conductor because it is not protective, it is supplementary!

It is not there to equalise the potential between exposed and extraneous conductive parts in the event of a fault, it is there to supplement the main protective bonding in its duty of equalising the potential between parts.

Thats why Im intrigued as to my interpretation of BS7671 defining it as protective but you dont? Should the main bonding fail (e.g. the plumber has disconnected the one to the water pipe) then the 'supplementary' bonding provides the 'protection' that the main bonding would have? Or are you suggesting that because it called supplementary it is not at the same level as the main bonding and it wont provide the same protection?

 

[D Skelton]

Thats why Im intrigued as to my interpretation of BS7671 defining it as protective but you dont? Should the main bonding fail (e.g. the plumber has disconnected the one to the water pipe) then the 'supplementary' bonding provides the 'protection' that the main bonding would have? Or are you suggesting that because it called supplementary it is not at the same level as the main bonding and it wont provide the same protection?

BS7671 doesn't define a supplementary bonding conductor as protective, because it isn't! Lol

I think this is where the flaws in your understanding of its purpose stems from.

Should the main bonding fail then the main bonding fails! The supplementary bonding is not there to make up for a lack of main bonding, it is there to supplement it!

Argh!

- - - Updated - - -

Thats why Im intrigued as to my interpretation of BS7671 defining it as protective but you dont? Should the main bonding fail (e.g. the plumber has disconnected the one to the water pipe) then the 'supplementary' bonding provides the 'protection' that the main bonding would have? Or are you suggesting that because it called supplementary it is not at the same level as the main bonding and it wont provide the same protection?

BS7671 doesn't define a supplementary bonding conductor as protective, because it isn't! Lol

I think this is where the flaws in your understanding of its purpose stems from.

Should the main bonding fail then the main bonding fails! The supplementary bonding is not there to make up for a lack of main bonding, it is there to supplement it!

Argh!

 

[Badged01]

BS7671 doesn't define a supplementary bonding conductor as protective, because it isn't! Lol I think this is where the flaws in your understanding of its purpose stems from.

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?

 

[spark 68]

Fascinating discussion chaps.

The problem (as I see it), is that the earlier editions of the regs state that Supplementary bonding must be fitted in a location containing a fixed bath or shower, no exclusions until the 17th (RCD/MPB/disconnection times met blah blah) were permitted.

The regs and methods of applying supplementary bonding even change within the same edition via various amendments, it seems even the IEE/IET could not agree amongst themselves the best way of doing it.

In one early edition/amd of the 16th all SB had to be connected back to the MET, then it was realised this didn't provide local equipotential bonding and so this practice was discontinued and the more common method of tying everything together was introduced.



I have the first 15th ed, and 16th ed amd 1 & 2 books here the 15th just says it (SB) should be applied, the 16th introduces zones and in the amd1 book the only exception is for Selv supplies, 16th amd 2 adds more information giving examples of what should be bonded.

It would suggest that no one is right or wrong here, as the installation may conform to one or other method of an earlier edition/amd which was correct at the time, so only attract a C3, the most sensible way forward would be to test as Geoff suggested, not ideal but unless you had every edition of the earlier regs to check.

 

[telectrix]

think i'll move my bath to the back yard. i'll need to sink a few rods and connect them to the feet of the bath. supplementary bonding connected to the caravan, car charger, and the barbed wire fence. the waste will be plastic, so the bonding will be attached with a lazzy band.

 

[Badged01]

think i'll move my bath to the back yard. i'll need to sink a few rods and connect them to the feet of the bath. supplementary bonding connected to the caravan, car charger, and the barbed wire fence. the waste will be plastic, so the bonding will be attached with a lazzy band.

Sounds like a cunning plan but dont use a lazzy band incase you introduce any eddy currents as water flows down the pipe!

 

[Badged01]

It would suggest that no one is right or wrong here ......

Man up, jump off the fence and make a decision .....

 

[spark 68]

Have a look at this:

 

[Badged01]

You are going to make a fine politician

 

[telectrix]

that's a contradiction in terms. like saying intelligent plumber.

 

[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.