I agree, and there are no bonded picture hooks, door handles, or towel rails bonded - bonding those would just be unnecessary, and extreme, but the main items which are touchable, and might potentially become live, are bonded.
Equipotential bonding required for new boiler?
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I agree, and there are no bonded picture hooks, door handles, or towel rails bonded - bonding those would just be unnecessary, and extreme, but the main items which are touchable, and might potentially become live, are bonded.
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Anything connected to the supply earth can potentially become live so if it doesn't need to be earthed, it shouldn't be. Bonding is designed to mitigate in that scenario, whereas being isolated from earth eliminates that risk.
My goodness
Is each radiator also connected by G/Y cables) to all exposed-c-ps and other extraneous-c-ps in the location? If not, then it is presumably 'earthing', not supplementary bonding.
My goodness
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Exactly.
Quite so. A picture hook is so small, and quite probably not very easily touchable, that even those who are obsessed with such things might not feel that they "want or need" to earth or bond it. However, it's just as likely that a screw could penetrate a buried cable when it is attaching something much larger and touchable, like a wall-hung metal cabinet, shelving or whatever.
Yes you need to balance the credible to the incredible and . as I eluded to, that balance might change to one or the other in a very small number of very limited cases. If you are aware of such peculiarities then you might decide on this one rare occasion you could "flip the choice" but usually you would categorise one way or the another accordingly.
Lets say you test resistance (impedance) of something to determine whether extraneous or not and you get a reading very near the boundary of one reading or another and you know that their is a realistic chance that it will go one way or the other and you are pretty sure the outcome is more likely than not then you might flip choice if you have carefully considered all scenarios with best of intent, the good. but the prime endevour must always to be to class it one way or the other and justify a choice once made. I am not suggesting there are many borderline cases because the are quite rare, however just sometimes it can be a choice that requires good thought, but only rarely, it is usually quite clear cut.
Lets say you test resistance (impedance) of something to determine whether extraneous or not and you get a reading very near the boundary of one reading or another and you know that their is a realistic chance that it will go one way or the other and you are pretty sure the outcome is more likely than not then you might flip choice if you have carefully considered all scenarios with best of intent, the good. but the prime endevour must always to be to class it one way or the other and justify a choice once made. I am not suggesting there are many borderline cases because the are quite rare, however just sometimes it can be a choice that requires good thought, but only rarely, it is usually quite clear cut.
That is all correct ebee but it has nothing to do with those who want to earth a radiator (yet call it bonding) in case one of its fixing screws contacts a buried live conductor.
As I said, after such superfluous earthing the said radiator might then require bonding.
As I said, after such superfluous earthing the said radiator might then require bonding.
Almost nonsense! When I fix something to a wall, I always assess the likelihood of there being cables or pipes where I intend to fix. If I have doubts, then I investigate further. That contrasts with pipes, feeding baths, sinks, wash-basins, showers, and radiators - pipes which are hidden under the floor, often in close-proximity with numerous live cables.
Chances of one of those pipes, expanding and contracting, eventually abrading it's way to making contact with a live conductor, are much higher than my accidentally drilling a cable buried in the wall, to fix a hook. Risk to me, or any one in my home, should any pipe become live - zero, because everything in bonded. Also, don't forget, and I agree - chances of drilling a cable, hitting the live, but not also hitting the earth are minimal.
Sorry, but you have failed to convince me that bonding all substantial bit of metal, is not the safest idea.
FFS - You are talking about EARTHING.
In this case, we're really talking about 'balancing' (assessing the relative probabilities of) twop scenarios, both of which are 'credible' (not impossible), but both of which are extremely small.
Consider the vacuum cleaner with a damaged cable exposing a small bit of the L conductor, being used in a room with a metal bath. Bernard seems to feel that it is more likely that the small bit of exposed L will come into contact with the bath, whereas I feel it's probably more likely that it will come in contact with the person using the cleaner. Goodness knows which of us is 'right'. A more pragmatic view would probably say that both probabilities are so exceeding small that it is not really worth wasting time thinking about or discussing them!
Sure - but, as above, it would seem very unlikley that one would usually have enough 'information to know that the particular circumstances impacted on that decision.
That' can be rather different. I'm often cited the case of the underground LPG pipe entering my house, travelling through a deep pile of gravel. Measured under 'dry' conditions, the impedance is well high enough to NOT be considered an extraneous-c-p, but when conditions are very wet, it can fall to levels that definitely render it an extraneous-c-p. One still has to make a decision, but in that sort of situation one at least knows that both scenarios are likely to apply at different points in time..
In that case, my decision was fairly easy. Since the pipe was already going to be earthed/bonded at the boiler, I had no difficulty in deciding to main bond the pipe where it entered the house.
Needless to say, I don't think that I am the one talking "nonsense"!
I'm glad to hear that - but it doesn't alter the fact that it was you who introduced the idea of a screw fixing the radiator bracket to the wall that might penetrate aa cable (and miss the CPC), seemingly as a justification for the need to earth the radiator.
I'm not really sure of the relevance of all that. Apart from anything else, I have in my time come across a good few cables that have been 'wrapped around' hot water pipes for decades, but never have seen a case in which that resulted in a live conductor coming in contact with the pipe.
No need to apologise, since that's your prerogative, but our view on this clearly differ. It's often unavoidable but if a substantial bit of touchable metal in my house is not earthed (by some process), I am personally far more comfortable to leave it 'not earthed'.
Furthermore, as we keep saying, it is still not clear as to whether you really are talking about 'bonding', rather than just 'earthing'. You've told us that (rather amazingly!) each of your radiators are connected to your installation's CU/MET, but not whether they are also connected, locally, to all the other extraneous- and exposed-c-ps in the location. If not, it is earthing, not supplementary bonding.
I think it could be either. As I've just written, Harry has yet to answer my question about exactly what is connected to what./
Actually, I did. All are connected together, and to the earth terminal at the CU. Your large lumps of metal, not earthed/bonded, are fine, providing you can absolutely guarantee that they are isolated, from absolutely any chance of becoming live - for everything else....
I presume therefore that you must also earth all Class II appliances.
Yes Agreed and that is what I was attempting to point out, if it`s in the realm of 55/50 yes or no you make a choice (I`d usually do the same as you suggest) but if you have particular info of one way or another becoming more likely (including in the future) then you might, just might decide the opposite. It would only be after a lifetime and with all results permanently monitored that you would know that you selected the correct choice. You make your best guess and decide yes or no. If some quirk drives you harder one way or the other then you might, just might decide to modify that choice.
Why did "Home Office" Skirts appear on batten lampholders for bathrooms? Was it to decrease the danger by someone standing hot, naked, sweaty in a bath full of water and reaching over arms outstretched to change a lightbulb whilst it`s switched on? They`d be stark raving mad but some folk would do it!
Charlie Darwin might enter the fray on that one!
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