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Thanks - really helpful.

In terms of the gas bonding, the green/yellow cable goes from the CU CPC busbar direct to the Gas meter (adjacent pipework). The same busbar that has all the CPC and the green/yellow cable to the main earth stake and then onto the bathroom incoming water supply.
 
Thanks - really helpful. In terms of the gas bonding, the green/yellow cable goes from the CU CPC busbar direct to the Gas meter (adjacent pipework).
You're welcome, and fair enough. If you wanted to bring it up to compliance with regs (even if it makes little sense), you would merely have to move the connection from the supply side to your side of the gas meter.
The same busbar that has all the CPC and the green/yellow cable to the main earth stake and then onto the bathroom incoming water supply.
Do I take it that those are two separate G/Y cables - i.e. one from CU to earth stake and the other from earth stake to incoming water supply? (rather than a single continuous cable that is not broken at the earth stake). If so, as I've said, ideally the cable from water supply should be re-routed to the CU/'MET'. If it were a single continuous cable (probably unlikely), that would not really be necessary.

Kind Regards, John
 
What difference does the 'continuousness' of the cable make?
I know the usual arguments but it is not required, is it?

We do not know the orientation of the bonded items.
Anyway, in a TT installation would bonding to or via the electrode not achieve the desired result?
 
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What difference does the 'continuousness' of the cable make? I know the usual arguments but it is not required, is it?
This is a bit different from the "usual argument". As you say, there is certainly no regulatory requirements for continuous bonding conductors, and I personally wouldn't be at all concerned about a few joints in such a conductor (after all, there are inevitably several joints in the path between extraneous-c-ps and exposed-c-ps, even if the bonding conductor itself is continuous).

However, the OP's situation is different. The bonding conductor is taken to the earth spike, rather than the CU/met - which means that if the earthing conductor (from CU to earth spike) (if 'separate') were to become disconnected or broken, there would be no bonding path between extraneous-c-ps and exposed-c-ps - particularly dangerous since the loss of the earthing conductor would mean that the cpcs, hence exposed-c-ps would rise to near line potential in the case of an L-cpc fault. However, if the cable from water to supply pipe (via earth spike) were 'continuous', that risk would not exist, and it would be no different from a conventional, 'dedicated', main bonding conductor directly from water supply pipe to CU/MET.
Anyway, in a TT installation would bonding to or via the electrode not achieve the desired result?
See above. If the ('separate') connection between CU/MET and earth spike were lost, that could theoretically result in a potentially lethal situation (although not in OP's case - see below). You are perhaps thinking that incidental 'parallel' paths would connect any metal water pipework to the CU/MET - but one obviously should not rely on that.

In any event, this is all totally moot in the OP's case, since, AIUI, all of his internal water pipework downstream of the stopcock is plastic - so the quality of the bonding to the (presumably very short) length of metal pipe upstream of the stopcock is really neither here nor there!

Kind Regards, John
 
However, the OP's situation is different. The bonding conductor is taken to the earth spike, rather than the CU/met - which means that if the earthing conductor (from CU to earth spike) (if 'separate') were to become disconnected or broken, there would be no bonding path between extraneous-c-ps and exposed-c-ps - particularly dangerous since the loss of the earthing conductor would mean that the cpcs, hence exposed-c-ps would rise to near line potential in the case of an L-cpc fault. However, if the cable from water to supply pipe (via earth spike) were 'continuous', that risk would not exist, and it would be no different from a conventional, 'dedicated', main bonding conductor directly from water supply pipe to CU/MET.
I'm a bit confused; did you make a typo and a mistake?

Surely if the earthing conductor between the CU and spike were broken (disconnected would imply intentionally so not really applicable) what difference would it make if it were continuous to the water pipe or joined at the spike?

Also, for this to happen (unearthed installation) at the same time as a fault L-cpc is just thinking up implausible reasons.
 
I'm a bit confused; did you make a typo and a mistake?
I don't believe I made either!
Surely if the earthing conductor between the CU and spike were broken (disconnected would imply intentionally so not really applicable) what difference would it make if it were continuous to the water pipe or joined at the spike?
By 'disconnected', I was referring to an iffy (or even 'fallen out') connection at one of the ends of the earthing conductor. If that happened, then the water pipe would end up bonded to nothing (other than a disconnected earth spike) - which, as I said is theoretically a "doubly dangerous situation" (firstly, lost connection between cps and earth; secondly, lost bonding of extraneous-c-p to cpcs)
IAlso, for this to happen (unearthed installation) at the same time as a fault L-cpc is just thinking up implausible reasons.
It doesn't have to be 'at the same time'. A broken earthing conductor could have been present, unnoticed, for years before the L-cpc fault arose. ... you might just as well say that you wouldn't worry/comment about a broken main bonding conductor, since it would be 'implausible' that an L-cpc fault 'would arise at the same time'!

However, as I said, this discussion is irrelevant to the OP's situation if, as he seems to have indicated, virtually all of his interior water pipework is plastic.

As a matter of interest, are you implying that if you were undertaking an EICR, you wouldn't even comment on, let alone code, the fact that a main bonding conductor was connected (separately) to an earth electrode rather than to the MET?

Kind Regards, John
 
It doesn't have to be 'at the same time'. A broken earthing conductor could have been present, unnoticed, for years before the L-cpc fault arose. ... you might just as well say that you wouldn't worry/comment about a broken main bonding conductor, since it would be 'implausible' that an L-cpc fault 'would arise at the same time'!
That's stretching it a bit.
None of the conductors should be disconnected. What if {all sorts of things}?

As a matter of interest, are you implying that if you were undertaking an EICR, you wouldn't even comment on, let alone code, the fact that a main bonding conductor was connected (separately) to an earth electrode rather than to the MET?
But it is connected to the MET.
Can the top of the spike be the MET?

Is an earthing conductor allowed to be used as a bonding conductor or vice versa?
 
It doesn't have to be 'at the same time'. A broken earthing conductor could have been present, unnoticed, for years before the L-cpc fault arose. ... you might just as well say that you wouldn't worry/comment about a broken main bonding conductor, since it would be 'implausible' that an L-cpc fault 'would arise at the same time'!
That's stretching it a bit. None of the conductors should be disconnected. What if {all sorts of things}?
You seem to be attempting to draw me into a discussion/argument that I never intended. Right at the start of this thread, I told the OP that I did not regard this as a 'real concern' - and that was even before I knew that he had virtually no internal metal water pipework! My view remains unchanged. It was securespark, not me, who raised concerns about the bonding conductor from the water supply pipe going to the earth electrode, rather than 'directly to the CU.

As I've said, I can sympathise with secure's concerns, even though I personally do not regard the risks as significant. We all know that the (one and only) purpose of main bonding is to minimise any possible potential differences between exposed-c-ps (hence cpcs) and extraneous-c-ps (under very rare "what if?" circumstances) - i.e. to maintain an equipotential zone within the building under (very rare) fault conditions. As such, the surest way of achieving that is to have a conductor within the building which directly connects the extraneous-c-p to the MET (hence cpcs and exposed-c-ps).
As a matter of interest, are you implying that if you were undertaking an EICR, you wouldn't even comment on, let alone code, the fact that a main bonding conductor was connected (separately) to an earth electrode rather than to the MET?
But it is connected to the MET. Can the top of the spike be the MET? Is an earthing conductor allowed to be used as a bonding conductor or vice versa?
Again, this isn't really 'my argument', but ... I presume that the top of the earth spike could be defined as the MET, but I imagine that there would be a requirement for an 'outdoor MET' to be adequately protected from 'the elements'. Although probably not stated as such in the regs, I think that most people probably believe that there should only be one 'MET' (hence the "M") and that all main bonding conductors should be connected "directly" to that single MET. For those who adopt that interpretation, the bond to the gas pipework would presumably have to be re-routed to the earth spike? ... or do you feel it's OK to have two or more 'METs', provided they are joined electrically?

I have to say again that this is all irrelevant to the OP's situation (hence this thread), given his plastic plumbing.

Kind Regards, John
 
it may be irrelevant to the OP but the general question was introduced.

You can have a MET and an earth-marshalling point but there can only be one MET, as such, but it can be any connection point so if you ( I ) consider the top of the spike to be the MET then I presume the same arguments will be forthcoming regarding the gas and cpcs.
However, they are all connected so which point you regard as the MET and which conductors are what (if all the same csa) is questionable (much like which is the radial and which are the spurs).

With regard to the OP situation, as I said, we do not know the location of the items.
Perhaps the water and spike are close together and the gas and cu at the other side of the house, or -

it is an installation for which the water used to be the earth and now it is not allowed, someone has placed a spike near the water for a compliant but inferior earth.
 
it may be irrelevant to the OP but the general question was introduced.
Indeed - but, as I said, it's really secure you should be arguing/debating with, not me!
You can have a MET and an earth-marshalling point but there can only be one MET, as such, but it can be any connection point so if you ( I ) consider the top of the spike to be the MET then I presume the same arguments will be forthcoming regarding the gas and cpcs. However, they are all connected so which point you regard as the MET and which conductors are what (if all the same csa) is questionable ...
Indeed, it almost becomes semantic. Once one has accepted that any of the conductors concerned may have 'joints' (i.e. don't have to be 'continuous') (about which I think you and I are agreed), all that matters electrically is that the MET, earth electrode (or DNO-supplied earth terminal), CU earth bar and any extraneous-c-ps be joined together with cables of adequate CSA - and which point/object one chooses to define as the 'MET' is essentially arbitrary. Looked at like that, if there is any issue at all it would presumably relate only to whether one can/should consider an outdoor joint to be as reliable as an indoor one.
With regard to the OP situation, as I said, we do not know the location of the items. Perhaps the water and spike are close together and the gas and cu at the other side of the house, or - ...
Yes, I have been rather assuming that there is probably a practical/convenience issue such as that to explain the (unusual) arrangement the OP appears to have. If it is like that, there presumably is a fairly long conductor which is doubling as an earthing conductor and a main bonding conductor (for either gas or water, depending upon where one defines the MET as being) - but I don't think there is any regulation which precludes such a dual function conductor.
it is an installation for which the water used to be the earth and now it is not allowed, someone has placed a spike near the water for a compliant but inferior earth.
Indeed - another possibility. In that case, of course, the 'bonding conductor' between spike and water supply would actually mean that the installation would continue to enjoy the (very probably better) earth afforded by the water pipe - and, given an adequate connection (again a 'dual function' one) to the CU would more-or-less preclude any appreciable pd arising between extraneous-cps and the cpcs (hence exposed-c-ps) of the installation.

Kind Regards, John
 
Looks like I have started an interesting technical discussion here!

For further information, the earth spike is under the kitchen floor (accessed via small hatch in floorboards). The spike is closer to the incoming water (in bathroom at rear of kitchen) than it is to the CU or Gas Meter. The Gas Meter is adjacent to the CU. I guess it was done like this to save on copper wire!. Not sure if it is continuous or not, will have to check!

Also the stake has some bonding attached from the adjacent boiler pipework.
 

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