Earthing vs. (Supplementary) Bonding

[JohnW2]

As to supplementary bonding, as permitted by 544.2.4, a portion of extraneous conductor can be used as supplementary bonding as long as it meets the requirements of 543.2.6

One might actually say that 544.2.4 is redundant/unnecessary, since 543.2.6 (which appears to relate to protective conductors in general, including SB ones) already seems to allow (with conditions) an extraneous-c-p to be used as a protective conductor.

Interestingly, 'no-one' seems to feel or ever suggest that 543.2.6 applies to main bonding conductors - or else they would be attaching main bonding 'wherever was convenient', even if that was a long way from where the extraneous-c-p entered the property.

Kind Regards, John

 

[EFLImpudence]

One might actually say that 544.2.4 is redundant/unnecessary, since 543.2.6 (which appears to relate to protective conductors in general, including SB ones) already seems to allow (with conditions) an extraneous-c-p to be used as a protective conductor.

It's not redundant.
It merely states that items (i) to (iv) of 543.2.1. (conductors) shall be copper if less than 10mm² csa.

Interestingly, 'no-one' seems to feel or ever suggest that 543.2.6 applies to main bonding conductors - or else they would be attaching main bonding 'wherever was convenient', even if that was a long way from where the extraneous-c-p entered the property.

That would seem to suggest that a water pipe could be its own, and the gas pipe's, bond.
(Not vice versa as gas pipe prohibited from being used as such.)
This does not really make sense to me as it would lead to the conclusion that water supply pipes do not require main bonding.
(Its own (15mm tube) csa is 3½ times times that of 10mm².)

Does it fall foul of 543.2.6 (iii) and (iv)?



I would say that a water supply could be bonded to the metal frame of a metal-framed building or similar.

 

[JohnW2]

One might actually say that 544.2.4 is redundant/unnecessary, since 543.2.6 (which appears to relate to protective conductors in general, including SB ones) already seems to allow (with conditions) an extraneous-c-p to be used as a protective conductor.

It's not redundant. It merely states that items (i) to (iv) of 543.2.1. (conductors) shall be copper if less than 10mm² csa.

It took me a while to work out what you were going on about here, but I eventually twigged that you are presumably looking at 543.2.4, rather than 544.2.4

My point was simply that all of 543.2 would seem to apply to SB conductors (as well as other protective conductors), even if 544.2.4 didn't exist - which I reckon makes the latter pretty redundant!

Interestingly, 'no-one' seems to feel or ever suggest that 543.2.6 applies to main bonding conductors - or else they would be attaching main bonding 'wherever was convenient', even if that was a long way from where the extraneous-c-p entered the property.

That would seem to suggest that a water pipe could be its own, and the gas pipe's, bond.

Exactly my point (per the apparent word of the regs). I can find nothing that says that (all of) 534.2 doesn't apply to main bonding conductors just as much as it applies to any other protective conductors - can you?

This does not really make sense to me as it would lead to the conclusion that water supply pipes do not require main bonding. (Its own (15mm tube) csa is 3½ times times that of 10mm².)

They would still require main bonding, for the reasons we all know, but I can't see (in terms of the regs) why the actual MPB cable (connected to the MET) could not be attached to the pipe at a point remote from where it entered the premises - the pipe itself forming the 'protective conductor' (per 543.2.6) back to the point where the pipe entered the premises.

Does it fall foul of 543.2.6 (iii) and (iv)?

I've been waiting for someone to ask that in relation to SB, to which it applies just as much as it does to MPB! That reg is very vague - I'm not sure what would constitute "precautions against its removal". Frankly, I would think this was likely to be more of a concern in relation to SB than to MPB - since I would think it far more likely that people would play around with (perhaps even 'remove') bits of piping around a bathroom than they would be likely to 'remove' the main water supply pipe to their house! Of course, if they did totally 'remove' the water supply pipe, there would be nothing left that needed bonding, anyway!

Kind Regards, John

 

[EFLImpudence]

It took me a while to work out what you were going on about here, but I eventually twigged that you are presumably looking at 543.2.4, rather than 544.2.4

Oh I beg your pardon - then yes.

Exactly my point (per the apparent word of the regs). I can find nothing that says that (all of) 534.2 doesn't apply to main bonding conductors just as much as it applies to any other protective conductors - can you?

543.2 No, at least some definitely does.

They would still require main bonding, for the reasons we all know, but I can't see (in terms of the regs) why the actual MPB cable (connected to the MET) could not be attached to the pipe at a point remote from where it entered the premises - the pipe itself forming the 'protective conductor' (per 543.2.6) back to the point where the pipe entered the premises.

I have seen that proposed elsewhere, only to be shot down, but the regs. specifically say 'at the point of entry' - presumably to safeguard against any removal within, but as you say...

I've been waiting for someone to ask that in relation to SB, to which it applies just as much as it does to MPB! That reg is very vague - I'm not sure what would constitute "precautions against its removal". Frankly, I would think this was likely to be more of a concern in relation to SB than to MPB - since I would think it far more likely that people would play around with (perhaps even 'remove') bits of piping around a bathroom than they would be likely to 'remove' the main water supply pipe to their house!

Yes, but an insert of a piece of plastic pipe would leave the supply still requiring a main bond at point of entry but the same in the bathroom could leave a pipe isolated apart from the remaining SB.

 

[JohnW2]

Exactly my point (per the apparent word of the regs). I can find nothing that says that (all of) 534.2 doesn't apply to main bonding conductors just as much as it applies to any other protective conductors - can you?

543.2

damnit - I'm as bad as you - apologies! (at least I read the right reg, and merely mistyped it's number ).

No, at least some definitely does.

Quite so - but I'd say that it all applies to MPB conductors just as much as to any other type of protective conductor - I can see nothing that says otherwise, can you?

They would still require main bonding, for the reasons we all know, but I can't see (in terms of the regs) why the actual MPB cable (connected to the MET) could not be attached to the pipe at a point remote from where it entered the premises - the pipe itself forming the 'protective conductor' (per 543.2.6) back to the point where the pipe entered the premises.

I have seen that proposed elsewhere, only to be shot down, but the regs. specifically say 'at the point of entry' - presumably to safeguard against any removal within, ...

Yes, except that the regs also (seem to) say that, with certain conditions, the connection from MET to that 'point where the pipe entered the premises' could be partially achieved by the pipe itself.

....but as you say...

I've been waiting for someone to ask that in relation to SB, to which it applies just as much as it does to MPB! That reg is very vague - I'm not sure what would constitute "precautions against its removal". Frankly, I would think this was likely to be more of a concern in relation to SB than to MPB - since I would think it far more likely that people would play around with (perhaps even 'remove') bits of piping around a bathroom than they would be likely to 'remove' the main water supply pipe to their house!

Yes, but an insert of a piece of plastic pipe would leave the supply still requiring a main bond at point of entry but the same in the bathroom could leave a pipe isolated apart from the remaining SB.

Yes, I agree that the consequences of, say, inserting a piece of plastic pipe in the pipe run could have more serious (electrical) consequences in the case of MPB, as compared with SB, but the regs do not really to make a distinction. The regs seem to allow the pipe to be used as part of the bonding path in either case, provided only that 543.2.6(iii) is satisfied - and, as I said, that's a pretty vague requirement. What do you think would satisfy it - maybe a 'Do Not Remove' label attached every metre or so along the pipe's length?

Kind Regards, John

 

[EFLImpudence]

No, at least some definitely does.

Quite so - but I'd say that it all applies to MPB conductors just as much as to any other type of protective conductor - I can see nothing that says otherwise, can you?

No, that's what I meant.

Yes, except that the regs also (seem to) say that, with certain conditions, the connection from MET to that 'point where the pipe entered the premises' could be partially achieved by the pipe itself.

I agree that is the case in the present discussion BUT it is clearly stated that it must be applied at the point of entry.
Does that override and therefore rule out main bonding?

What do you think would satisfy it - maybe a 'Do Not Remove' label attached every metre or so along the pipe's length?

I don't know of anything which would actually prevent removal.

 

[JohnW2]

Yes, except that the regs also (seem to) say that, with certain conditions, the connection from MET to that 'point where the pipe entered the premises' could be partially achieved by the pipe itself.

I agree that is the case in the present discussion BUT it is clearly stated that it must be applied at the point of entry. Does that override and therefore rule out main bonding?

All it says is that the bonding must be applied at the point of entry - i.e. that's where the bonding conductor must connect to the extraneous-c-p. However, the regs all say that (with the provisos we've discussed, such as below), some or all of that bonding conductor may be the pipe itself.

What do you think would satisfy it - maybe a 'Do Not Remove' label attached every metre or so along the pipe's length?

I don't know of anything which would actually prevent removal.

Fortunately, 543.2.6(iii) doesn't actually require that something has to be done to 'prevent' removal - merely that "precautions shall be taken against removal" (presumably acknowledging that complete 'prevention' would be impossible). On that basis, I reckon that the labels I suggested would probably be about as good a 'precaution' as one could take, don't you think?

If anyone else notices this discussion, I suspect that we're in for some flak!

Kind Regards, John

 

[EFLImpudence]

I can think of nothing to contradict.
It just doesn't make sense.


Can of worms dept.

We can use a water pipe as a main bond for the gas supply - Yes?
Both supplies enter next to each other so G/Y from gas to water -
20m away, G/Y from water pipe to MET, one metre.

Gas satisfactorily bonded - Yes?
Water ???
R of 20m 15mm copper tube - 0.01Ω

 

[JohnW2]

I can think of nothing to contradict.
It just doesn't make sense. Can of worms dept.

Quite so - but I would say that it does really make (electrical) sense - provided only that one is confident that the water supply pipe is not going to be removed, or have bits of plastic inserted into it.

We can use a water pipe as a main bond for the gas supply - Yes? Both supplies enter next to each other so G/Y from gas to water - 20m away, G/Y from water pipe to MET, one metre. Gas satisfactorily bonded - Yes? Water ??? R of 20m 15mm copper tube - 0.01Ω

Indeed, that all seems to be correct and seemingly compliant in terms of the word of the regs - unless we are both missing something (and, as above, it also makes electrical sense {indeed, probably lower resistance connection to MET for both water and gas pipes than would be the case with 10mm² G/Y!} provided the pipe remains, and remains as a metal pipe).

So where are all these people who are (presumably!) going to start subjecting us to flak?

Kind Regards, John