More on meters and 544.1.2

[JohnW2]

It could be a lead to copper adaptor meaning the bond should be connected to the copper pipe and not the lead.

I suppsoe so

Kind Regards, John

 

[RF Lighting]

 

[JohnW2]

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So where does the pipe disappearing into a wall go to?

As for the supply, that's obviously the classic case of what we're talking about. Electrically speaking, it definitely does not require main bonding. The debate is about what, if anything, the regs require.

I have to say that I've coming increasingly inclined to the view that, since there is no extraneous-c-p, one doesn't even have to look at 544.1.2, so one just sticks to the basic principle that something which is not an extraneous-c-p simply does not require main bonding. Full stop!

... now what about that other pipe?

Kind Regards, John

 

[RF Lighting]

It's a PRV pipe from a boiler going outside, but not into the ground.

Could it be argued though that the copper pipe work could still become extraneous through contact with damp walls, or even the water conducting across the plastic joint?

 

[JohnW2]

Could it be argued though that the copper pipe work could still become extraneous through contact with damp walls, or even the water conducting across the plastic joint?

I reckon that's one for Bernard! Personally, I very much doubt that a damp wall is ever going provide a low enough impedance path to earth to render anything 'extraneous' in the usual sense. If it did, then you surely would have an almost impossible nightmare scenario on your hands - since not only the pipework, but also any screw, nail or bolt that went into the walls, and anything metallic in contact with the walls, would also require main bonding, wouldn't they?

Kind Regards, John

 

[EFLImpudence]

But if the joint were metal, as it would have been until relatively recently , then, even if the lead pipe were slightly longer, it would be understandable and sensible that as "there is an insert the connection shall be made to the consumer's hard metal pipework and before any branch".

 

[JohnW2]

But if the joint were metal, as it would have been until relatively recently , then, even if the lead pipe were slightly longer, it would be understandable and sensible that as "there is an insert the connection shall be made to the consumer's hard metal pipework and before any branch".

That's another interesting idea, but are you suggesting that they are using 'hard' to distinguish between lead and copper/iron? If so, are you suggesting that they are saying that lead pipe shouldn't be bonded? Indeed, in what you say above, the 'insert' is fairly irrelevant, isn't it - wouldn't that argument be the same if the lead were soldered to the copper? What if there were a joint/coupler, with lead coming out of it (as well as into it), before it changed to copper a few more feet downstream - I doubt that you'd suggest that the bonding should be onto the copper, would you? Indeed, what if the entire plumbing system were copper (I'm sure there must be a few examples left ) - would you then not bond at all?

Conversely, as I think we probably agree, if RF's lead pipe were a foot or two long, then, at least theoretically, it would be that, not any copper, that needed bonding.

Kind Regards, John

 

[bernardgreen]

but also any screw, nail or bolt that went into the walls, and anything metallic in contact with the walls, would also require main bonding, wouldn't they?

In theory yes, in measured practise, also yes where the area of contact between metal item and damp wall is large. In normal conditions ( potential of PME earth close to true ground ) damp walls and metal in them will not be a significant hazard but in exceptional conditions where the PME "earth" is no longer at true ground potential the metal items in the walls will give a tingle of a shock.

The conductivity of original stone and rubble walls with lime mortar and no damp proof course is high enough to create a hazard.

 

[THRIPSTER]

Perhaps you need to consider case where water comes into house inplastic, copper iinstallation throughout house but extraneous due to metal drain pipes/feeds to outside toilets etc?

Regards

 

[EFLImpudence]

That's another interesting idea, but are you suggesting that they are using 'hard' to distinguish between lead and copper/iron? If so, are you suggesting that they are saying that lead pipe shouldn't be bonded? Indeed, in what you say above, the 'insert' is fairly irrelevant, isn't it - wouldn't that argument be the same if the lead were soldered to the copper? What if there were a joint/coupler, with lead coming out of it (as well as into it), before it changed to copper a few more feet downstream - I doubt that you'd suggest that the bonding should be onto the copper, would you? Indeed, what if the entire plumbing system were copper (I'm sure there must be a few examples left ) - would you then not bond at all?

Yes, but don't forget it says that the bonding should be connected at the point of entry and where there is an insert 'at that point' ...

 

[EFLImpudence]

Perhaps you need to consider case where water comes into house inplastic, copper iinstallation throughout house but extraneous due to metal drain pipes/feeds to outside toilets etc?

Then it would be those drain pies/feeds which would require bonding.

 

[JohnW2]

Yes, but don't forget it says that the bonding should be connected at the point of entry and where there is an insert 'at that point' ...

It does indeed. However, you now seem to be suggesting that 'hard pipework' means copper/iron, but not lead. As I said, if that were the case, then, if your (metal) 'insert' (pipe joint) was very close to the point of entry and what came out of that insert was lead, then you could end up bonding the service a long way from its entry, and would bond it nowhere in the rare case of all-lead pipework. I can't believe that's what it means.

I've never been quite sure what 'hard' was meant to mean, but suspect that it was probably merely intended to refer to metal, rather than plastic/rubber/whatever. I dont think that either of us believe that there was ever an intention to say that one shouldn't bond at a particular place because the pipe there was lead, do we?

Kind Regards, John

 

[EFLImpudence]

I've never been quite sure what 'hard' was meant to mean, but suspect that it was probably merely intended to refer to metal, rather than plastic/rubber/whatever. I dont think that either of us believe that there was ever an intention to say that one shouldn't bond at a particular place because the pipe there was lead, do we?

No. Oh, well.

 

[JohnW2]

Let's try turning this issue onto its head by temporarily forgetting about the regs and seeing if we can agree, in terms of electrical considerations, what should be done about main protective bonding. I would suggest the following:

1...If a service enters the premises in plastic, there is no extraneous-c-p. No need for any MPB.

2...If a service enters the premises in metal, and it is practicable, bond as close as possible to the point of entry.

3...If a service enters the premises in metal but then fairly quickly changes to plastic then, if it is practicable, bond the metal pipe as close as possibly to entry, per (2). If that is not practicable, then one simply can't. There is nothing else to bond.

4...The issue of a service which enters the premises in metal but soon encounters a short "insulation section or insert" (before turning back to metal) is really irrelevant. Once pipe has turned to plastic, there is no electrical need for MPB for any downstream pipework, even if it reverts to being metal. Therefore treat as (3) above.

4a...As discussed, I don't know if (some or all) meters represent 'insulating sections' or not. If there is no electrical continuity across a meter, one could proceed as per (4). However, if there is,or may be, electrical continuity and it is not practicable to bond prior to the meter (as close as possible to entry), then bond as close as practicable after the meter (and before any stopcocks or branches etc.). Given that meters get changed, the 'safe aproach' may be to assume that, even if at present 'insulating', a meter might get changed to one with electrical continuity (or the water supplier might install a 'strap') - so (when pre-meter bonding is not practicable) always bonding as close as practicable after the meter (in addition to bonding prior to the meter, if practicable - for times when the meter is insulating!) might be sensible.

That's about it. I think that, in terms of the electrical need for MBP, it is (or should be!) as simple and clear as that. The nearest to a 'messy' bit is that about the meter - but that's because of uncertainties (at least, in my mind) as to whether it is (or always will be) 'insulating' or not.

Any comments, agreements or disagreements?

However, having said all that, there is a practical consideration which may change all that, and make things considerably simpler. As I recently observed, although there are situations (3 & 4 above) in which there is no electrical requirement for MPB of the house's metal pipework, one may, in practice, want to install such bonding in order to ensure that the requirements for omitting supplementary bonding in bathrooms are always satisfied. As we've also discussed, although there is a theoretical argument that such 'unnecessary bonding' could (in certain circumstances) create a hazard, this is really moot because of the other incidental paths from pipework to MET which will almost certainly exist. If one wishes to take this approach, then the main bonding practice (which goes beyond the electrical MPB requirement) would simplify to just:

1...If a service enters the premises in metal, bond as close as practicable to the point of entry (if the metal pipe is too short/inaccessible to bond, then it simply can't be done). In addition bond the house's metal pipework after any 'insulating interruption'.

Any further comments?

Kind Regards, John

 

[THRIPSTER]

Good thread John. For all but new builds, then the liklihood is, that either/and/or the metal services (if these exist) are connected by supplementary bonding elsewhere in the house or have situations where metal pipes feed metal pipes connected to metal drain pipes or has a metal pipe running to an outbuilding etc. Any condideration of where/how to bond on customers side of the meter should take those possibilities into account (which is what I think you have done? ) and was the point of my earlier post EFLI.

Regards