Equipontal Bonding - Water

[RF Lighting]

They don't.

If you can prove that the gas supply is not extraneous then it doesn't require bonding. As plastic gas pipes are not allowed to enter into properties virtually all gas supplies will be extraneous.

I don't get what you're on about with your gas / water thing.

If the metallic parts of the gas pipe are wholelly contained within the equipotential zone of the property then it doesn't matter what is or isn't connected to it, it can not become extraneous in it's own right.

 

[EFLImpudence]

If the metallic parts of the gas pipe are wholelly contained within the equipotential zone of the property then it doesn't matter what is or isn't connected to it, it can not become extraneous in it's own right.

Not in its own right but connected to unbonded extraneous parts it could become so.

I am trying to discover why the regulations state that the gas supply should be main bonded even though it is supplied in plastic and so is not extraneous.

I should have said 'with insulating section' rather than 'supplied in plastic'.

544.1.2

Do you know the reason?

 

[ban-all-sheds]

Not in its own right but connected to unbonded extraneous parts it could become so.

Don't connect it to unbonded extraneous parts then.

Simples.

 

[EFLImpudence]

Not in its own right but connected to unbonded extraneous parts it could become so.

Don't connect it to unbonded extraneous parts then.

Simples.

Indeed, but is that the reason for the requirement of 544.1.2 to main bond insulated metalwork which will be connected to extraneous c-ps (which, obviously, should be bonded).

 

[chapeau]

... reason for the requirement of 544.1.2 to main bond insulated metalwork which will be connected to extraneous c-ps (which, obviously, should be bonded).

Assuming the reg is properly written (hard to believe).....

The only possible logical electrical explanation is that they are thinking the actual water in an insulating pipe forms an electrical connection between the outside and inside of the equipotentional zone. By bonding the metal on the consumer side of the plastic you are in effect bringing the incoming potential to the same as the MET.

I don't like that explanation as tap water is quite a good insulator, but it is the best of a bad bunch.

If there is any metal entering the house, even only 5cm, which then becomes plastic, and then becomes metal again you should bond the 5cm length of metal. That is the only answer which makes sense if you understand how electricity works.

 

[seasickstevie]

...if you understand how electricity works.

That'll be none of us

 

[JohnW2]

I don't really understand. The gas pipe is a separate issue. If, as is almost always the case, it enters the premises as an extraneous-c-p, then it needs main bonding in its own right, even if the premises doesn't have a water supply! Perhaps I'm missing something.

Nope that sounds correct to me.

Goodness - is this agreement?

No. It's still bonding - i.e. to equalise potential - not to ensure operation of the cpd.

Equalise the potential between what and what, and why?

Between the suppliers earth / MET and anything extraneous as a PD could exist between these two points especially under fault conditions.

Before I can get into that one, I think I need to know what you mean/understand by 'extraneous' in that context.

In any event, I'm again confused. Even if one did have a gas supply which was not an extraneous-c-p (which, as above, I would think would be extremely rare), why would connecting it to a boiler (hence other pipework) suddenly make it an extraneous-c-p?

It wouldn't

As I thought - which is why I was (and still am) confused by the statement to which I was responding!

Kind Regards, John.

 

[JohnW2]

I don't get what you're on about with your gas / water thing. If the metallic parts of the gas pipe are wholelly contained within the equipotential zone of the property then it doesn't matter what is or isn't connected to it, it can not become extraneous in it's own right.

Quite so. I don't really understand what he's getting at, either. Indeed, as I said before, I don't even understand why discussion about gas pipes got into this thread at all!

Kind Regards, John.

 

[JohnW2]

Indeed, but is that the reason for the requirement of 544.1.2 to main bond insulated metalwork which will be connected to extraneous c-ps (which, obviously, should be bonded).

This seems to be getting all very confused/confusing.

I don't think there is any requirement to main bond anything which is not, in itself, extraneous (to the premises). For example, if the 'gas supply' came from an LPG cylinder which was wholly within the premises (which may or may not be allowed, gas-wise!), and the associated gas pipework was also wholly within the premises, then I don't see that there would be any requirement to main bond the gas supply or any part of the gas installation.

Sure, the gas pipework is probably going to be connected to (hopefully main bonded) water pipework, but that doesn't alter what I've just said - and, in fact, merely helps to ensure that all pipework, of whatever nature, within the premises is equipotential.

Kind Regards, John.

 

[JohnW2]

]Equalise the potential between what and what, and why?

Well, the MET and true earth and between other metalwork.

Well, for a start, main bonding is about minimising PDs between the MET and metalwork which may be introducing 'true earth' potential into the premises (i.e. an extraneous conductive part, which enters the premises). The way I've been brought up, anything with a purpose other than that is not main bonding. You may say think that is a semantic issue, but I think it's an important conceptual/functional one and, in practical terms, could have a major impact on the required CSA of the conductor concerned.

When you speak more generally of equalising the potential between MET and 'other metalwork', aren't you at risk of sliding down the path of metal baths, door knobs and spoons?

Kind Regards, John.

 

[EFLImpudence]

I don't think there is any requirement to main bond anything which is not, in itself, extraneous (to the premises).

But there is - 544.1.2

This states that even if the supply has an insulated section on/after entering the property it shall still be main bonded on the consumer side, i.e. the side that is not extraneous.
No mention is made of the part which actually is extraneous.

I am trying to discover a reason for this.
The only one I can think of is that (even though it is not extraneous (in its own right)) it is connected to extraneous parts by the boiler and
it is 'belt and braces thinking just in case'.

With regard to your query about whether it is main bonding and whether it would affect conductor sizing, 544.1.2 is under the 'main bonding' heading.

When you speak more generally of equalising the potential between MET and 'other metalwork', aren't you at risk of sliding down the path of metal baths, door knobs and spoons?

You know that isn't true for me but 544.1.2 could be on that path.

 

[JohnW2]

I don't think there is any requirement to main bond anything which is not, in itself, extraneous (to the premises).

But there is - 544.1.2 .... This states that even if the supply has an insulated section on/after entering the property it shall still be main bonded on the consumer side, i.e. the side that is not extraneous. No mention is made of the part which actually is extraneous.

In my opinion, most people are misunderstanding ('not reading properly'?) 544.1.2. As I read it, this is the section on main bonding conductors, and indicates the required CSA and 'points of connection' (to bonded parts) of main bonding conductors when they are required. To my mind, 544.1.2, per se, is (or should be!) saying nothing about what things do need main protective bonding.

It is 411.3.1.2 which indicates what 'parts' require main protective bonding (using conductors per 544.1.2). It starts by saying that the MET should be connected by MPB to extraneous-conductive parts, and then adds "including....." with a list of five 'parts', including water and gas installation pipes. Maybe I'm wrong, but I've always regarded the 'extraneous conductive parts' at the start of that as being the over-riding consderation, with (i)-(v) merely being examples of things which may (or may not) be extraneous-conductive parts. In other words, just because something appears in (i)-(v) that doesn't mean that it is necessarily an extraneous-c-p and, if it's not, then my interpretation has always been than MPB is then not required. Is that not precisely how most people interpret (iv) in the list ("Central heating and air conditioning systems") - which, in domestic situations, will almost never be extraneous-c-ps and therefore are not normally main bonded?

I am trying to discover a reason for this. The only one I can think of is that (even though it is not extraneous (in its own right)) it is connected to extraneous parts by the boiler and it is 'belt and braces thinking just in case'.

As above, I have never believed that either 544.1.2 or 411.3.1.2 imposes a requirement to main bond anything which is not an extraneous-conductive part, not the least becasue that would be inconsistent with what I understand as the concept of main protective bonding. However, I agree with you in the sense that I have always regarded it as a confusing anomoly that 544.1.2 should talk about connections to something which is not an extraneous-conductive part in a section on MPB conductors (and which would therefore probably not count as main bonding per 433.3.1.2!)!

Do others not interpret the regs in the same way as me?

Kind Regards, John.

 

[tebreak]

or if that can not be done where practical and the location noted down on the test certificate.
But we have touched on this before but you don't seem to acknowledge this.
//www.diynot.com/forums/electrics/flippin-lost-off-with-bonding-earthing-etc.322565/[/QUOTE]

AAAhh! THAT'S where it went.