I've got a copy of the 16th+AMD 1&2 (2004), and there's nothing like that in there AFAIK...
18th 544.1.2
- Thread starter EFLImpudence
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Perhaps as Bas intimated earlier in the thread, the 'bond everything' culture was never actually a requirement but the result of an inability to read correctly - as is apparently still the case.
That's certainly a possibility - as I said, what I know about 16th is limited, and I know nothing about earlier editions of the regs, other than what I occasionally read here. It would be interesting to hear from those (Secure?) who have access to earlier editions.
There was a time (a very long time ago) when I religiously installed 'cross-bonding' - regions like airing cupboards, bathrooms and the vicinity of boilers being absolutely strewn with G/Y cables (and it wasn't true 'supplementary bonding', since the G/Ys just connected pipes, with no connection to CPCs/MET) - and something must have 'taught' me to do that. Back then, I had no direct knowledge of the Wiring regs and relied upon reading many books and talking to people about 'how it should be done' - so, as I said, something amongst all that must have led me to believe that it was necessary and/or 'required'. If one doesn't think too deeply, the general concept of taking steps to ensure that all 'simultaneously touchable' metal is at the same potential does not sound unreasonable. It may be rather OTT with things that are already have 'metal-to-metal continuity' but, even back then, it was not unknown for rules/regulations to err on the side of 'over-caution' - so I could well have believed that such was what was 'required', even if it wasn't.
Kind Regards, John
What do you mean?
Supplementary bonding does not require a connection to the MET - and only to CPCs of (simultaneously accessible) items with exposed-c-ps (which might be achieved by a bonded pipe).
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As you might imagine, I mean essentially what you say (and SB seems of questionable necessity if there are no simultaneously-touchable exposed-c-ps, since the chances of two simultaneously touchable extraneous-c-ps {which, per your 'tests', would all have to have relatively low resistance/impedance paths to earth} being at dangerously different potentials are surely negligible).
However, 542.2.1 does say "The equipotential bonding system [which, in context, I take to mean the 'supplementary equipotential bonding' system, per first sentence of 542.2.1] shall be connected [which I take to mean 'explicitly connected', with G/.Y, not 'implicitly connected'] to the protective conductors of all equipment including those of socket-outlets". For that reason I am not sure that I would call the connection together of pipes etc. with G/Y, without any connection to the electrical installation (i.e. 'cross-bonding') 'supplementary equipotential bionding' in the BS7671 sense.
If you were faced with the (very common) situation of a bathroom with no exposed-c-ps which, for some reason, did not satisfy the requirements for omission of SB, would you feel that SB was required at all and, if you did, you connected all the extraneous-c-ps with G/Y, would you consider that to be compliant with regs if you did not also connect it to the electrical installation's earthing systems (i.e. CPCs or MET)?
Kind Regards, John
I would agree - and have often wondered if 415.2.1 which says - "simultaneously accessible exposed-cps and extraneous-c-ps" actually includes "simultaneously accessibe exposed-c-ps" and "simultaneously accessible extraneous-cps".
Either - 'No' - or - 'all' - I suppose.
You will note that 701.415.2 has slightly different wording which could decide this if we were certain the wording was intentional - probably not as it include ClassII items.
Typo? 415.2.1
Well, it is 'supplementary' by definition - additional. I don't think 'supplementary' has a separate electrical definition other than additional.
None of what you write means that it should be connected to the MET - by that I mean a direct conductor.
If there are no equipment or socket CPCs to connect to and you decide to bond extraneous-c-ps then no connection to the MET is required.
Yes it is compliant. The relevant factor is resistance between parts; the MET is irrelevant.
What would be the purpose or advantage in having a conductor to the MET if the resistance between the extraneous-c-ps is negligible?
Were that resistance negligible (or low enough - 50/Ia) without supplementary bonding then none would be required anyway, so why would a conductor to the MET be necessary?
Copy of relevant part of Wiring Matters magazine from which my qoute above was taken is:
supplementary-equipotential-bonding.pdf
That the writer of this publication did not understand the whole concept of earthing is hard to believe since it is written, and distributed, within a publication from the IEE, the compilers of the wiring regs.
One of the original documents I promised I would try to post last evening I will do as soon as possible but things have got bit complicated here.
One of the requirements for PME, which was really for-runner of combined neutral/earth contained words which implied, If I remember correctly was that if any metalwork in the property was earthed, or gave reasonable grounds to believe it was earthed shall be bonded to main earth terminal.
Gas pipes and water pipes within the dwelling meet this criteria since they are earthed via boiler/water heater/immersion heater wiring.
supplementary-equipotential-bonding.pdf
That the writer of this publication did not understand the whole concept of earthing is hard to believe since it is written, and distributed, within a publication from the IEE, the compilers of the wiring regs.
One of the original documents I promised I would try to post last evening I will do as soon as possible but things have got bit complicated here.
One of the requirements for PME, which was really for-runner of combined neutral/earth contained words which implied, If I remember correctly was that if any metalwork in the property was earthed, or gave reasonable grounds to believe it was earthed shall be bonded to main earth terminal.
Gas pipes and water pipes within the dwelling meet this criteria since they are earthed via boiler/water heater/immersion heater wiring.
You have moved to supplementary bonding now which is different than the main bonding which the thread was about originally.
Do you think the Government is made up of geniuses?
It is a botch caused by the supply companies not maintaining their TN-S cables which necessitated the connection of household CPCs (earthing) to the Neutral of the supply.
You refuse to accept that earthing is to cause disconnection of the supply in the event of a fault, and
bonding is to equalise potential between two items that you may touch during the fault. which earthing does not do.
You also refuse to accept the difference between earthing and bonding simply because the same colour wire is used for both. This is akin to people calling the black (or blue) wire attached to a light switch 'The Neutral'. It is NOT a neutral just because it is black (or blue).
It may be hard to believe but I am afraid that is the situation.
Do you think the Government is made up of geniuses?
PME was not a forerunner of anything.
It is a botch caused by the supply companies not maintaining their TN-S cables which necessitated the connection of household CPCs (earthing) to the Neutral of the supply.
Yes, but that has nothing to do with it.
Yes but that is nothing to do with the purpose of main or supplementary bonding.
You refuse to accept that earthing is to cause disconnection of the supply in the event of a fault, and
bonding is to equalise potential between two items that you may touch during the fault. which earthing does not do.
You also refuse to accept the difference between earthing and bonding simply because the same colour wire is used for both. This is akin to people calling the black (or blue) wire attached to a light switch 'The Neutral'. It is NOT a neutral just because it is black (or blue).
I think it was the 15th regs heres an article
https://electrical.theiet.org/media/1620/supplementary-equipotential-bonding.pdf
That is the same as posted by Alan.
It does not say bonding should be applied to parts which are not extraneous-c-ps.
It does not say bonding should be applied to parts which are not extraneous-c-ps.
It would appear that the bond everything era is a myth brought about by not reading the regulations properly.
Much the same as today -
if you ignore half the text then it does look like lots of things must be bonded.
Solution - Don't ignore half the text.
Much the same as today -
if you ignore half the text then it does look like lots of things must be bonded.
Solution - Don't ignore half the text.
Same as I posted earlier.
Yes just realised that he had posted it,sorry
Theres a clearer version of the same article here
https://www.voltimum.co.uk/articles/supplementary-equipotential-bonding
Theres a clearer version of the same article here
https://www.voltimum.co.uk/articles/supplementary-equipotential-bonding
I suppose that's what I am commenting on/asking - i.e. what is 415.2.1 actually 'requiring'? I think I have always assumed (almost subconsciously) that the whole point of SB (as sometimes required by the regs) was to avoid a situation in which there could be a significant pd between an extraneous-c-p and a simultaneously-touchable exposed-c-p - and that was achieved by bonding together all extraneous-c-ps and and all exposed-c-ps. As I previously said, it would seem incredibly unlikely that there would ever be a dangerous pd between two extraneous-c-ps (since, in practice, the voltage they are 'liable to introduce' will be the same in all cases) - so that makes me wonder whether the rather ambiguous wording of 415.2.1 perhaps is not trying to require that extraneous-c-ps be bionded together if there are no simultaneously-touchable exposed-c-ps (or, indeed, no exposed-c-ps at all in the location) that one could (or would need to) bond the extraneous ones to.
My goodness! Yes, a typo - but how my brain and/or tyuping fingers managed that one I haven't got a clue!
Yes, in a literal sense it is obviously 'supplementary' to main bonding. However, what I was talking aboiut was the SB as required by 415.2 (whatever that may be - as above).
I may have confused things by mentioning the MET. I was never suggesting that there should be a dedicated G/Y all the way back to the MET - I was talking about connecting to (approximately) 'MET potential' - achieved by connecting it to a local CPC.
That's what common sense says - so, again, I wonder whether 415.2.1 was intended to require SB when there are no exposed-c-ps in the location.
See above - it is clear that I really should not have let myself mention the MET. Please mentally substitute 'local CPC' or 'exposed-c-p whenever I wrote 'MET' - but, as above, it again begs the question as to whether the regs really are requiring SB in the absence of any exposed-c-ps (i.e. just joining extraneous-c-ps together with G/Ys, and to nothing else - aka 'cross-bonding'. As we have both said, there seems to be no point (ever), so maybe we have been misunderstanding the potential ambiguity ion 415.2.1?
Kind Regards, John
The 'bond everything' nonsense probably originated in a publication from one of the electrical organisations such as NICEIC, or more likely in some condensed guide type book published by an electrical union or similar organisation.
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