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.