supplementary bonding

[EFLImpudence]

I don't know what to say, then.

Further confusion:
There is a diagram in GN8 Fig.8.5 which shows a bathroom with all plastic plumbing in which SB is only applied between:
Shower, Shaver socket (isolated?), above sink luminaire and FCU for electric bar heater; not the ceiling light and pull switch because:

Fig,8.4 shows a normal bathroom where fittings (light and pull-switch) are not bonded because they are outside the zones which still include an area of zone 3 although it is not named as such.

 

[JohnW2]

I don't know what to say, then.

Nor do I. As I said, I find the regs to be anything but clear, and was hoping that you (or someone) could help me to understand exactly what they are meant to mean (and, if necessary, why?)!

Further confusion: There is a diagram in GN8 Fig.8.5 which shows a bathroom with all plastic plumbing in which SB is only applied between: Shower, Shaver socket (isolated?), above sink luminaire and FCU for electric bar heater; ...

I'm not sure what you are saying here. If the shaver socket were plastic and the luminaire Class II (and the plumbing all plastic), exactly what was being 'bonded' - are you just saying that the CPCs of all the items you mentioned are joined together with a bonding conductor, in the absence of any extraneous-c-ps or exposed-c-ps? (if one undertook your tests, one would quite possibly find that the resistance/impedance between those CPCs was already 'low enough'). If something other than CPCs, exactly what is being 'bonded'?

... not the ceiling light and pull switch because: Fig,8.4 shows a normal bathroom where fittings (light and pull-switch) are not bonded because they are outside the zones which still include an area of zone 3 although it is not named as such.

I don't really get that one, either. 701.415.2 of the BGB says nothing about zones - it seems to imply (by not saying anything else!) that if anything does need SB, that has to be connected to the CPCs of all circuits which supply equipment in the room.

Reading that first paragraph of 701.415.2 again, it says that (for SB) CPCs of all circuits supplying equipment (presumably 'in the room') should be "connected together ... to the extraneous-cp-s". Apart from that being grammatical nonsense, do you think they might be saying that the CPCs of all circuits should be connected together (in the name of SB) even if there are no extraneous-c-ps (which would seemingly be consistent with the GN8 Fig 8.5 you mention) ?

Kind Regards, John

 

[EFLImpudence]

Further confusion: There is a diagram in GN8 Fig.8.5 which shows a bathroom with all plastic plumbing in which SB is only applied between: Shower, Shaver socket (isolated?), above sink luminaire and FCU for electric bar heater; ...

I'm not sure what you are saying here. If the shaver socket were plastic and the luminaire Class II (and the plumbing all plastic), exactly what was being 'bonded' - are you just saying that the CPCs of all the items you mentioned are joined together with a bonding conductor, in the absence of any extraneous-c-ps or exposed-c-ps? (if one undertook your tests, one would quite possibly find that the resistance/impedance between those CPCs was already 'low enough'). If something other than CPCs, exactly what is being 'bonded'?

Yes, leaving aside 'my tests' just the CPCs of (possibly exposed-c-p free) appliances are bonded.
No exposed-c-ps to touch and no extraneous parts in the room.

... not the ceiling light and pull switch because: Fig,8.4 shows a normal bathroom where fittings (light and pull-switch) are not bonded because they are outside the zones which still include an area of zone 3 although it is not named as such.

I don't really get that one, either. 701.415.2 of the BGB says nothing about zones - it seems to imply (by not saying anything else!) that if anything does need SB, that has to be connected to the CPCs of all circuits which supply equipment in the room.

I agree that that is what it says.

Reading that first paragraph of 701.415.2 again, it says that (for SB) CPCs of all circuits supplying equipment (presumably 'in the room') should be "connected together ... to the extraneous-cp-s". Apart from that being grammatical nonsense, do you think they might be saying that the CPCs of all circuits should be connected together (in the name of SB) even if there are no extraneous-c-ps (which would seemingly be consistent with the GN8 Fig 8.5 you mention) ?

I can't tell.
It says that SB "shall be established connecting together the terminals of the CPC of each circuit...to the accessible extraneous-c-ps"
Should the 'to' be an 'and'?

Does your proposal that - if there are no exposed-c-ps then bonding extraneous-c-ps is not required - work the other way round?
I.e. if there are no extraneous-c-ps do the exposed-c-ps require bonding (as in Fig.8.5).



I would still refer to 415.2 which - logically - implies, by stating the opposite, that if parts are NOT: simultaneously accessible, exposed or extraneous then they do not require SB.
This definitely does apply to parts which are not extraneous so how/why can it not apply to the others?

 

[JohnW2]

Yes, leaving aside 'my tests' just the CPCs of (possibly exposed-c-p free) appliances are bonded.
No exposed-c-ps to touch and no extraneous parts in the room.

Interesting. If that's in GN8, I guess a lot of people must have been doing it. I think I've only ever heard of SB in the presence of extraneous-c-ps (and it's always 'bonding the pipes' that people ask questions about).

701.415.2 of the BGB says nothing about zones - it seems to imply (by not saying anything else!) that if anything does need SB, that has to be connected to the CPCs of all circuits which supply equipment in the room.

I agree that that is what it says.

So much for GN8, then? (is your GN8 up-to-date?)

... Apart from that being grammatical nonsense, do you think they might be saying that the CPCs of all circuits should be connected together (in the name of SB) even if there are no extraneous-c-ps (which would seemingly be consistent with the GN8 Fig 8.5 you mention) ?

I can't tell. It says that SB "shall be established connecting together the terminals of the CPC of each circuit...to the accessible extraneous-c-ps" ... Should the 'to' be an 'and'?

I can't tell, either - as I said, all these bits of the regs appear as clear as mud! Changing "to" to "and" would sort out the grammar - and might be what they intended to write

Does your proposal that - if there are no exposed-c-ps then bonding extraneous-c-ps is not required - work the other way round? I.e. if there are no extraneous-c-ps do the exposed-c-ps require bonding (as in Fig.8.5).

If the possible interpretation I've been suggesting were correct, then, yes, I would think it would work both ways around (and, as I said above, I think I've only heard of SB when there were extraneous-c-ps). However, you seem to be indicating that GN8 disagrees!

I would still refer to 415.2 which - logically - implies, by stating the opposite, that if parts are NOT: simultaneously accessible, exposed or extraneous then they do not require SB. ... This definitely does apply to parts which are not extraneous so how/why can it not apply to the others?

I would agree - but there appears to be this alternative interpretation which leads to GN8 showing SB when there are no extraneous-c-ps and no exposed-c-ps - with them merely 'bonding' CPCs together!

Kind Regards, John

 

[EFLImpudence]

So much for GN8, then? (is your GN8 up-to-date?)

Yes, 2011.

I would agree - but there appears to be this alternative interpretation which leads to GN8 showing SB when there are no extraneous-c-ps and no exposed-c-ps - with them merely 'bonding' CPCs together!

It does but I would rather follow the regulations (if decipherable) than any interpretation from a guide.

To be fair, I have just noticed that it states that Class II items should be bonded in case they are swapped for Class I in the future.
I don't think this is stated in 7671.
It does not say the same about items that have no exposed-cps.
So, anyone purposefully choosing such parts would still, apparently by GN8, be required to bond them.


Anyway, without exposed-c-ps or indeed any items, would you not still consider bonding the pipework?
Might it not be advantageous regarding something like the recent 'tingles' thread?

 

[JohnW2]

I would agree - but there appears to be this alternative interpretation which leads to GN8 showing SB when there are no extraneous-c-ps and no exposed-c-ps - with them merely 'bonding' CPCs together!

It does but I would rather follow the regulations (if decipherable) than any interpretation from a guide.

So would I - but, as I've been saying I don't think that the regs actually are 'decipherable'. GN8 is simply adopting one of the possible interpretations of the regs.

To be fair, I have just noticed that it states that Class II items should be bonded in case they are swapped for Class I in the future. I don't think this is stated in 7671.

What is one meant to actually 'bond' in a Class II item? Are we simply back to 'connecting CPCs together' again?

It does not say the same about items that have no exposed-cps.

Eh? - so what were you talking about in that previous comment - Class II items do not usually have exposed-c-ps!

Anyway, without exposed-c-ps or indeed any items, would you not still consider bonding the pipework? Might it not be advantageous regarding something like the recent 'tingles' thread?

As I said before, I can see the sense in connecting all extraneous-c-ps to one another (technically, they could be 'liable to introduce' different potentials!) - but, if there are no exposed-c-ps, I struggle to see the point in also joining the pipework to the CPCs. In terms of the 'tingling' thread, where one can but presume that, if it were real, capacitive pickup was at work, connecting pipework to CPCs is probably as likely to do harm as good!

Kind Regards, John

 

[EFLImpudence]

It does not say the same about items that have no exposed-cps.

Eh? - so what were you talking about in that previous comment - Class II items do not usually have exposed-c-ps!

I meant plastic items which are not actually classed as Class II - shower ?

As I said before, I can see the sense in connecting all extraneous-c-ps to one another (technically, they could be 'liable to introduce' different potentials!) - but, if there are no exposed-c-ps, I struggle to see the point in also joining the pipework to the CPCs.

I never meant connecting them to the CPCs as well.
Is that where we were confused earlier?

 

[JohnW2]

It does not say the same about items that have no exposed-cps.

Eh? - so what were you talking about in that previous comment - Class II items do not usually have exposed-c-ps!

I meant plastic items which are not actually classed as Class II - shower ?

I see! Are showers not Class II? I'd always assumed that their casings counted as 'reinforced', therefore qualifying them as Class II. Whatever, my previous question remains. If you want to 'bond' a shower with no exposed-c-ps, exactly what do you 'bond' - as I asked, are you simply talking about 'connecting CPCs together', or what?

As I said before, I can see the sense in connecting all extraneous-c-ps to one another (technically, they could be 'liable to introduce' different potentials!) - but, if there are no exposed-c-ps, I struggle to see the point in also joining the pipework to the CPCs.

I never meant connecting them to the CPCs as well. Is that where we were confused earlier?

I don't know whether you were confused - I've made the point several times about the seemingly unnecessary connection of SB to CPCs if there are no exposed-c-ps. The point surely is that 701.415.2 gives no option (in a bathroom) - it requires that SB is connected to the CPCs of all circuits, whether one likes it or not.

Kind REgards, John

 

[EFLImpudence]

I see! Are showers not Class II? I'd always assumed that their casings counted as 'reinforced', therefore qualifying them as Class II.

No. They are earthed and I would not class the cover as reinforced.

Whatever, my previous question remains. If you want to 'bond' a shower with no exposed-c-ps, exactly what do you 'bond' - as I asked, are you simply talking about 'connecting CPCs together', or what?

Not if there are no exposed-c-ps.

As I said before, I can see the sense in connecting all extraneous-c-ps to one another (technically, they could be 'liable to introduce' different potentials!) - but, if there are no exposed-c-ps, I struggle to see the point in also joining the pipework to the CPCs.

No, I have only been saying that the extraneous-c-ps should still be bonded.

The point surely is that 701.415.2 gives no option (in a bathroom) - it requires that SB is connected to the CPCs of all circuits, whether one likes it or not.

Only if you discount the rider regarding 415.2.
The same as 701.415.2(i) regarding metal pipes; it does not apply if they are not extraneous.

 

[JohnW2]

As I said before, I can see the sense in connecting all extraneous-c-ps to one another (technically, they could be 'liable to introduce' different potentials!) - but, if there are no exposed-c-ps, I struggle to see the point in also joining the pipework to the CPCs.

No, I have only been saying that the extraneous-c-ps should still be bonded.

Do I take it that when you say 'bonded' you mean 'joined together, but not to anything else' (i.e. as in plumbers' 'cross-bonding')? If so, in electrical terms we're agreed about that - even if we are struggling to determine what the regs 'require'.

The point surely is that 701.415.2 gives no option (in a bathroom) - it requires that SB is connected to the CPCs of all circuits, whether one likes it or not.

Only if you discount the rider regarding 415.2. The same as 701.415.2(i) regarding metal pipes; it does not apply if they are not extraneous.

I can't really see how that 'rider' can over-ride/negate the requirement of 701.415.2 itself that SB (if it is required) has to be connected to the CPCs.

Kind Regards, John

 

[EFLImpudence]

Do I take it that when you say 'bonded' you mean 'joined together, but not to anything else' (i.e. as in plumbers' 'cross-bonding')? If so, in electrical terms we're agreed about that - even if we are struggling to determine what the regs 'require'.

Yes, to bring down the impedance between them if required.

I can't really see how that 'rider' can over-ride/negate the requirement of 701.415.2 itself that SB (if it is required) has to be connected to the CPCs.

Because it (415.2) states extraneous and exposed-c-ps.

I presume you don't think non-extraneous pipes should be bonded even though 701.415.2(i) does not mention the extraneous part but just metal pipes.

 

[JohnW2]

Do I take it that when you say 'bonded' you mean 'joined together, but not to anything else' (i.e. as in plumbers' 'cross-bonding')? If so, in electrical terms we're agreed about that - even if we are struggling to determine what the regs 'require'.

Yes, to bring down the impedance between them if required.

OK - so we're agreed on that, electrically.

I can't really see how that 'rider' can over-ride/negate the requirement of 701.415.2 itself that SB (if it is required) has to be connected to the CPCs.

Because it (415.2) states extraneous and exposed-c-ps.

You've rather lost me. When do you think that the requirement of 710.415.2 that SB has to be connected to CPCs does apply, then? Is this somehow related to the GN8 Figure you referred to in which CPCs (I presume) were all joined together, despite the absence of either extraneous or exposed cps?

Kind Regards, John

 

[MrCox1963]

and I'm lead to believe even with plastic supply as above the water pipes need bonding too.

No, as long as none of the copper pipes reenters the ground.

I was told even though the water pipes will not provide a route to earth due to the plastic entry, if due to fault the water pipes became live, and for instance I touch the tap and metal shaver socket then I create a link between the shavers earth and the live water pipes.. is that in any way possible or am I being fed a load of rubbish? ( if it is and i don't need any sup.bonding please answer the rest of my questions anyway for educational purposes if nothing)

assuming the above is incorrect and supp. bonding of water pipes is not needed then am I right in thinking I should remove the water pipes main bond I installed as this is providing the pipes with a route to earth eliminating the protection of the plastic supply pipe?

so I want to bond the basin h&c to the radiator pipe (or does it need to be both radiator pipes? can't be rad as its a towel rail rad)

You do not bond the radiator but the pipes.

what i meant here was can I take the bond to just one of the pipes feeding rad. or does it need to be both pipes?

Finally I'm planning to use 4mm2 does the supplementary bond have to be unbroken.

by this I meant does the sup. bond need to be one continuous wire or can it be a small peice just from hot to cold pipe and the a separate peice of wire connecting shavers CPC to cold water pipe... and so on?

It only has to connect the parts; it does not have to go to the CU.
Also, the pipes and CPCs(earth wires) themselves may be used as the bond.
This means that connecting two pipes, for example, may in actual fact connect them all

so.. though the CPCs of both circuits (light & shaver unit) are in effect acting as a bond via the CU,but to reduce resistance in the event of a fault I should take a sup. bond wire from shaver units CPC to the light rose CPC then to the nearest water pipe.
then with a separate piece of bond wire I can connect the basin H&C (which in effect connects the showers H&C) to one of the radiator pipes, and this would complete the sup. bond?

thanks again I appreciate your help
Rob

 

[Chris61]

Just to clear up the shower Class I/II thing...

Showers are usually Class I with Class II construction. There has to be double or reinforced insulation between live parts and the accessible plastic cover. This is usually provided by the cover itself, the air between the cover and the live parts or a combination of the two.

 

[JohnW2]

The OP may have unwittingly raised a question which has never occurred to me before, and which I don't recall having previously been discussed here.

As we know, the second part of 701.415.2 allows that supplementary bonding in a bathroom may be omitted if various conditions are all satisfied. Two of those conditions are that the building has a "protective equipotential bonding system" (i.e. 'main bonding') and that the extraneous-conductive-parts (essentially pipework and things attached thereto) are effectively connected to that protective equipotential bonding.

So what if, as in the OP's case, there is no requirement for main bonding because the water service enters the property in plastic (and, for the purpose of argument, let's say there is no gas supply)? If, since it's not required, one does not main bond the water pipework, there is then no "protective equipotential bonding system", so is it possible for the conditions for omission of supplementary bonding in the bathroom to be satisfied?

Kind Regards, John