OK this all should be incorporated now, or at least when it gets willing to save the new draft. I've clarified the bit about keeping portable appliances out of zone 2 in there too. Cheers.
Yes, but I think you are misinterpreting the sense of "required" to mean something that building regs or some other authority say you must do now.
The "requirement" is a technical one from BS7671. There is no *legal* obligation to install missing bonding (unless you a changing something electrical in the room anyway, when one might argue that part P would make it so).
However, to wire or alter a room containing bath or shower then one
*may* be required (for reasons of complying with BS7671 and for best practice / good workmanship) to install or upgrade bonding. I use the word "may" since the 17th edition is the first version in recent times to offer an alternative to installing bonding.
Sounds like we agree on the principle, but differ on the wording. I wanted to try and clarify it in the article as its a much misunderstood area, and many people sent into a tailspin over nothing, or paying out for work that doesn't need doing.
So in short there is no real world requirement for such bonding to be retrofitted to existing wiring unless electrical work is being carried out, in which case the end result should be regs compliant.
I propose adding a sentence to explain that, probably much further up in the article since it affects most of it.
Sounds like we agree on the principle, but differ on the wording. I wanted to try and clarify it in the article as its a much misunderstood area, and many people sent into a tailspin over nothing, or paying out for work that doesn't need doing.
So in short there is no real world requirement for such bonding to be retrofitted to existing wiring unless electrical work is being carried out, in which case the end result should be regs compliant.
I propose adding a sentence to explain that, probably much further up in the article since it affects most of it.
NT
Hi
The lack of supplementary bonding would be flagged up on a PIR if the wiring was to the 16th edition. However the lack of RCD protection for cables behind plaster would also be flagged if the system was installed to the 16th edition.
The main difference is that the the lack of supplementary bonding would be code 1 (requires immediate attention) and the lack of RCD protection for the cables would be code 4 (does not comply with BS17671:2008).
I would suggest that supplementary bonding "when required but not present" should be installed ASAP regardless of any proposed electrical installation. As John pointed out, any installations are part P governed and so would need the supplementary bonding to be installed.
The other point to note is that any alterations to bathroom or kitchen electrics also need the main equipotential bonding to be brought up to current standards when the work is carried out.
A mixture of RCD protected and non RCD protected bathroom electrics still need supplementary bonding. eg a split load 16th edition install with the bathroom lights non RCD protected and then an electric shower is added to the RCD side. Supplementary bonding must be fitted between the lighting and the shower.
So if I understand you correctly you also think equi bonding only need be installed if and when electrical work is done. Note I say 'need be', not 'is an option'.
So if I understand you correctly you also think equi bonding only need be installed if and when electrical work is done. Note I say 'need be', not 'is an option'.
NT
I would consider an electrical inspection (diy or professional) to be electrical work. If the supplementary bonding is found to be missing (and is needed because it is not a 17th edition installation) then the house electrics are not up to standard and the bonding should be installed ASAP.
However I do not think that any authority can cut a supply to a house due to a lack of supplementary bonding and people cannot be made to add the bonding just because it is missing.
Whether it ought to be fitted is another matter, one of opinion, and the job is one which most households arent concerned about doing. Given the near zero safety benefit I'd personally agree with them.
One is semantics - yes you could argue that if you are changing nothing, then installing bonding is not "required". However, if no change is being made or contemplated, why refer an article on bathroom electrics in the first place? Chances are if you are looking for information on this, then you plan to make some alterations, at which point this work becomes required. Also if we are addressing competent DIYers seeking to improve bad things on their electrical system, then encouraging them to add bonding when its required but missing, is a "good thing" IMHO. Its cheap, easy to do, and depending on the circumstances can make a life or death difference should you be unlucky enough to have something go bang unexpectedly.
Secondly, there is the issue of severity. I expect based on comments you have made in the past that you don't consider the lack of "required" bonding to be of particular concern. However as I see it (and as Adam highlights, as any form of proper inspection would see it), it is classed as a fairly severe fault.
Which only demonstrates that many of them are poorly informed about these things.
I am not sure why you consider this to be of "near zero safety" benefit.
It is equal I would say to having no RCD protection on a outdoor power feed. It is after all the greatly increased risk of severe shock imposed by the surroundings that make the RCD protected supply desirable. Same applies in a bathroom.
One could certainly argue that. But I think the average householder is well aware that on their list of priorities its extremely low, and in safety terms theyre quite correct on that point.
The near zero number of resulting deaths. When you compare the spend per benefit of equi bonding to many other measures one can take, it simply ceases to be a path worth pursuing unless one is for some reason obliged to do so.
Unless I'm mistaken, the level of fatalities don't agree with that claim.
But that is an incorrect way to assess safety. There is no end of things that could happen, what matters is which ones do and how often.
:
Thats a true fact, not semantics :)
Many times people get a PIR done that says you need to fit equi bonding, and they mistakenly believe it to be so. Our article should tell them the truth, that there is no requirement to fit it unless youre carrying out electrical work.
Theres nothing wrong with also adding a section of whether we think you should, but I dont think we ought to tell porkies by saying yes you're required to do it.
So opinion is mixed. If, as we did once before, guess the average cost of installing it, multiply by the number of houses, and divide by the number of lives it saves per year it works out at a phenonmenally high price per life, when many other simple domestic works for the same money/time would yield far greater safety improvement. It just isnt warranted on safety grounds.
Why not...
Lets say install cost =A320 materials, 4 hours labour for a diying novice, including going and getting the bits. Total cost =A320 + 4x7-15, perhaps =A340 as a balpark figure =3D =A360 total
x20 million houses =3D =A31.2 billion
If this saves one life every 5 years, thats a cost of 6 billion per life saved, which is orders of magnitude higher than a whole swathe of more practical constructive measures one can take.
That only shows a recognised flaw in such testing, namely that the results given are sometimes entirely unrealistic and to encourage needless spending.
I took the bonding off the metal bath when I re-plumbed, as there's no metal to/from the bath at all. The shower's on a RCD (nominally 30mA but goes between 20 - 25mA) and if the shower were to become live there's no path to earth anyway. If a fault develops and the RCD fails, I'd rather not be the link beween 240V and a bonded earth!
One could certainly argue that. But I think the average householder is well aware that on their list of priorities its extremely low, and in safety terms theyre quite correct on that point.
The near zero number of resulting deaths. When you compare the spend per benefit of equi bonding to many other measures one can take, it simply ceases to be a path worth pursuing unless one is for some reason obliged to do so.
Unless I'm mistaken, the level of fatalities don't agree with that claim.
But that is an incorrect way to assess safety. There is no end of things that could happen, what matters is which ones do and how often.
Thats a true fact, not semantics :)
Many times people get a PIR done that says you need to fit equi bonding, and they mistakenly believe it to be so. Our article should tell them the truth, that there is no requirement to fit it unless youre carrying out electrical work.
Theres nothing wrong with also adding a section of whether we think you should, but I dont think we ought to tell porkies by saying yes you're required to do it.
So opinion is mixed. If, as we did once before, guess the average cost of installing it, multiply by the number of houses, and divide by the number of lives it saves per year it works out at a phenonmenally high price per life, when many other simple domestic works for the same money/time would yield far greater safety improvement. It just isnt warranted on safety grounds.
Why not...
Lets say install cost £20 materials, 4 hours labour for a diying novice, including going and getting the bits. Total cost £20 + 4x7-15, perhaps £40 as a balpark figure = £60 total
x20 million houses = £1.2 billion
If this saves one life every 5 years, thats a cost of 6 billion per life saved, which is orders of magnitude higher than a whole swathe of more practical constructive measures one can take.
That only shows a recognised flaw in such testing, namely that the results given are sometimes entirely unrealistic and to encourage needless spending.
NT
Hi
I do not accept that there is a flaw in a test procedure that correctly identifies a fault an electrical installation.
The Wiki article on bathroom electrics does have a link to supplementary bonding requirements and that is good.
Maybe the words
"Unless an installation complies with the latest requirements of the 17th edition then supplementary equipotential bonding is required."
could read
"Unless an installation complies with the latest requirements of the 17th edition then supplementary equipotential bonding should be installed to BS7671 regulations if you ever want a pass certificate on your house electrics when you want to sell your house and do not want the buyer to start knocking money off if the buyer is looking for faults"
or
"Unless an installation complies with the latest requirements of the 17th edition then supplementary equipotential bonding should be installed to BS7671 regulations"
For some reason there seems to be far much trouble caused by using the word "required".
Not really - the wiring regs still say its required. The fact that there is no legal compulsion to update the exiting install to follow those requirements does not make the requirement go away.
We could include extra verbage at the top that highlights what is meant by "required" etc, but then why single out this article? Few of the others contain similar. Its not as if this one is focussed on specific advice on a task like changing a CU or installing outside power feeds. Its just an overview of the right things to do in bathrooms and a heads up as to why they are different from other rooms.
PIRs don't include an in depth analysis of the implications of things like missing bonding. In some cases you could argue that a particular installation has very few if any failure modes where EQ bonding would mitigate. Equally however, there may be some that make it very well worth having.
By all means tell em that they are not legally obliged to carry out the work; but if the PIR has highlighted a fault that should be fixed, unless they are in a position to carry out enough analysis to say if there is a better cost benefit trade off to be had elsewhere, they ought to carry out the fix. Any other advice would be reckless.
A couple of example scenarios:
e.g.
1) 16th edition PMR head end, small shower room, plastic pipes everywhere and the only electrical circuits in use are the lighting one, and a spur from a upstairs ring circuit to feed a towel rail. The lights are SELV downlighters. The actual risk of serious shock in this circumstance is negligible. Since mains never manifests in the room anywhere other than the towel rail, and there are no other extraneous conductive paths (the CPC of the lighting circuit does not present in the room - the metalwork of the down lighters is floating, the switch is non conductive and out of reach on a string). According to to the Regs Bonding is still required, however the implications of ignoring the requirement are to all intents nil as things stand.
2) 15th edition install, re-wireable fuses, TT head end (overhead wire supply), no bonding at all (main or supplementary), a VO ELCB is connected inline with the main earth provided by a gas pipe. There are a number of borrowed neutrals and neutral earth faults. a 13A socket is installed beside the sink to allow a hairdrier etc be plugged in. Bathroom has CH piped towel radiator, metal pipes to all taps and cistern, and an electric shower, plus fan heater, and some class 1 luminaries on a low ish ceiling controlled by a nice polished chrome wall switch next to the shower. In this case there are any number of fault scenarios that could present serious and life threatening shock hazards i.e. faults that could leave high touch voltages on metal surfaces for extended periods, with ready access to an independent earth close to hand. Now obviously a PIR would highlight all manner of shortcomings here. The long term solution would probably be a package of measures including a re-wire or at least a new head end. However installing main and supplementary bonding PDQ would be cheap and effective way to lower the rooms status from "death trap" to something more acceptable.
Depends on your interpretation of required. See comments above.
Statistical exercises like this can be useful for setting government policy[1]. However we are not really concerned with overall impacts, targets, costs to the nation etc, and are focussing on one electrical installation. What is best for the majority has no bearing on what is best for Joe Internet Searcher, 32 Acacia Avenue who has just moved into a place and had a PIR throw up reams of faults that he does not understand; missing bonding being one of them. The only sensible advice we can give in a general purpose guidance article is to say you need to be lead by the professional opinion of the people you have paid for advice and here is what the bonding does and how it works if you want to know. The implications of it not being there may be trivial, or may be very serious, we can't tell you from here.
(Note also this is partly a circular argument. We have very safe electrics in the UK as a general rule - both fixed, and appliances (the former more so than the latter). Deaths are very rare, and injury relatively rare. Part of the reason for this is that we do specify and install safety measures like EQ bonding, RCD protection and a host of other measures. Its almost impossible to say how many extra injuries etc we would have had without these measures, other than a casual observation that numbers of deaths etc have been falling for years (at least until the intro of part p anyway), and electrical installations as a whole have been getting better as more are updated and rewired to current standards).
So the question that matters to me is, could that £60 save the life of someone in the family should something go wrong? The answer is usually yes.
So the next question is, how likely is it that something will go wrong in a dangerous way, with my particular installation, that means I would get to "use" that £60s worth of investment and hence make it worth spending here and not on mitigating some other risk. If the answer is "high to moderate" then you spend the £60. If the answer is "I don't know" the next question is can I get sufficient expert analysis at less cost, that would tell me if its going to make a difference. If the answer is no, then you spend the £60. If the answer is yes then you spend the money on that instead, and then possibly spend the £60 afterwards as well depending on the outcome.
We are not talking about spending billions, since we are not writing an article to advice policy makers. We are talking to the individual ones looking at your £60 bill.
Its a flaw in the process that one accepts since it controls the cost of such testing. A PIR plus the cost of remedial action is in many many cases going to be significantly less that the cost of a test with a detailed analysis and risk assessment to go along with it. Also doing the work once often saves repeating the exercise later to justify that something non standard is actually ok in this circumstance.
Agreed; and sometimes the results will be highly realistic, and encourage spending on something that needs doing as a matter of urgency.
How do you differentiate without detailed technical knowledge?
Perhaps there is a whole new article there; "My PIR said X, how much notice should I take?".
[1] although following the logic, part P would never have been introduced - which shows up the disparity between stated and real agenda.
They don't help matters when the experts start spouting confusing and incorrect terminology:
Jonathan Keane, an electrical expert, told the inquest in Truro, Cornwall, that the home hadn't been rewired or inspected electrically since 1981.
He said: "The combination of the lack of *earth bonding* and the faulty heater created a lethal charge to the taps - killing Thirza when she touched them."
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