Does copper h/w cylinder need bonding?

[JohnW2]

Well, as you've pretty much covered, ecps may introduce a potential, which is usually local earth. However I suppose that means that you'd have to satisfy yourself that they really did have a good enough connection to local earth before any other connection. How about one supply sleeved in conduit eg gas tracpipe and the steel frame of the building well connected to local earth.

Very little is impossible, but I think you're scraping the barrel Whether or not the incoming pipe(s) have a good connection to earth is only part of the 'risk' one is considering. There also has to be a dangerous p.d. between the pipe and some other extraneous-c-p.

In any event, I think the scenario you are contemplating is so improbable as to be essentially moot. There surely cannot be many, if any, (used) buildings with gas and water supply pipes (or one of those and structural metal) but no electricity supply (even a 'de-energised' supply would normally leave the DNO earth connected) - so the requirement to bond would virtually always be there, anyway!

Kind Regards, John

 

[John D v2.0]

any event, I think the scenario you are contemplating is so improbable as to be essentially moot.

Ok let me rephrase my original point since you're hung up on the extreme example - bonding is not specifically related to the electrirical installation. Earthing is.

 

[EFLImpudence]

bonding is not specifically related to the electrirical installation. Earthing is.

Bonding - in the sense we use it - means 'joined electrically', so ...

As there is no MET in your premises without electricity, then you are not talking about main bonding.
That leaves supplementary bonding but there is no other bonding to which it can be supplementary - i.e. additional - so what is it and what is it doing?

Wouldn't the same apply to metal fence posts and similar things?

If you are worried about one of the pipes being made live somewhere else then all you would be doing is ensuring that both pipes became live.
If these pipes were connected somewhere in the premises at an appliance, then they would already be 'bonded'.

Also, of course, apart from you in your house, as there would be no electricians involved who would fit such 'bonding'?
The gas and water people are not going to bother.

 

[ban-all-sheds]

That is not the function of bonding. You therefore admit that your suggestion is supplementary (additional) earthing.


Why would the necessary immersion CPC not achieve that? Why would a second CPC be necessary?


Edit - see below.


Edit - Does the same not apply to the cylinder? So-
If not then the immersion CPC will do its job.
Please test the resistance/conductivity of the water in several meters (or one metre) of plastic pipe.

Even if it were metal, main bonding (as you suggested) is just not required and neither is supplementary bonding in the location.


The pipe is (in this case) plastic and cannot become live.


It should not worry you.

You are favouring protecting against an extremely unlikely scenario and introducing a much more likely hazard of touching an earthed object when getting a shock from a live conductor.
We cannot protect against everything so protecting against the more likely is accepted as the best compromise.

It is difficult not to ridicule your suggestions.

https://www.diynot.com/diy/threads/water-pipe-bonding.458276/page-3#post-3640655

 

[John D v2.0]

As there is no MET in your premises without electricity, then you are not talking about main bonding.

I don't think a MET needs bonding, that's just a standard central point according to the regs. I'm using logic rather than the regs here.

Wouldn't the same apply to metal fence posts and similar things?

It would if they were likely to introduce a potential into the zone.

If you are worried about one of the pipes being made live somewhere else then all you would be doing is ensuring that both pipes became live.

Indeed. You're basically describing the purpose of an equipotential zone

If these pipes were connected somewhere in the premises at an appliance, then they would already be 'bonded'.

Yes if they're already bonded with a low impedance then extra bonding wouldn't make a difference electrically.

Also, of course, apart from you in your house, as there would be no electricians involved who would fit such 'bonding'?

I never said it was someone's responsibility to do it, but my point is why does the addition of an existing supply require bonding when you can have as many other extraneous conductive parts as you like without bonding.
The only reason I can think is that there's a higher chance of a current flowing in a supplier earthing cable then in any other extraneous part.
At the end of the day, the supplier earth is simply an extraneous conductive part which may introduce a potential (supplier earth) into the zone.

 

[EFLImpudence]

I don't think a MET needs bonding, that's just a standard central point according to the regs. I'm using logic rather than the regs here.

The pipes need bonding to the MET because they and the MET may be at different potential.
If you don't have a MET, the problem does not arise.

It would if they were likely to introduce a potential into the zone.

Not if they are all the same, which they would be, with nothing else to be at a different potential.

Indeed. You're basically describing the purpose of an equipotential zone

Yes, but if they are not connected, there is no point making them both live.

Yes if they're already bonded with a low impedance then extra bonding wouldn't make a difference electrically.

No, it wouldn't make a difference - so no point, then.

I never said it was someone's responsibility to do it, but my point is why does the addition of an existing supply require bonding when you can have as many other extraneous conductive parts as you like without bonding.

Because it's the MET and the earthed parts which may be at a different potential.
If there isn't anything which may be at a different potential than your e-c-ps then there is nothing to bond - equalise potential.

The only reason I can think is that there's a higher chance of a current flowing in a supplier earthing cable then in any other extraneous part.
At the end of the day, the supplier earth is simply an extraneous conductive part which may introduce a potential (supplier earth) into the zone.

Exactly, so look at it the other way round if you wish, it is the MET (and all the earthed parts) which must be bonded to the e-c-ps.
So, if you haven't got a MET ...

 

[John D v2.0]

I think the difference is that you are assuming that all ecps will be at the same potential, I am saying is not guaranteed.
As per John w2s point above, it's incredibly unlikely that there would be a setup where there would be, but my point is if there was that setup, it wouldn't get bonded even if it were necessary. As per your point that an electrician wouldn't even be involved.

But anyway I think the problem is my explaining not my understanding

 

[ban-all-sheds]

Wouldn't the same apply to metal fence posts and similar things?

It would if they were likely to introduce a potential into the zone.

Are they bonded when they surround substations?

 

[JohnW2]

Bonding - in the sense we use it - means 'joined electrically'

Quite so.

... As there is no MET in your premises without electricity, then you are not talking about main bonding. .... That leaves supplementary bonding but there is no other bonding to which it can be supplementary - i.e. additional - so what is it and what is it doing? .... Wouldn't the same apply to metal fence posts and similar things?

Come and watch them fill my LPG tank, which is probably 40+ metres from any electrical installation, and isolated from my electrical installation by tens of metres of plastic pipe. During the delivery, they 'join electrically' their tanker and my tank - and I would think that qualifies as 'bonding', doesn't it?

If I recall correctly, the same is to be seen when petrol is delivered to filing stations, when aircraft are fuelled etc. In all those cases, there is no electrical installation in the equation, but they nevertheless utilise 'equipotential bonding', for good reason.

Kind Regards, John

 

[EFLImpudence]

Static sparks ?

 

[JohnW2]

Ok let me rephrase my original point since you're hung up on the extreme example - bonding is not specifically related to the electrirical installation. Earthing is.

Indeed. As I've just written, equipotential bonding does not necessarily have anything to do with anything electrical in the normal sense. In the situations I described, the danger which the equipotential bonding seeks to eliminate is generally due to static electricity, which is usually not a direct threat to human life (unless it's lightning!).

People engaged in work on static-sensitive electronic components will often utilise equipotential bonding between their bodies and the equipment they are working on.

For two or more extraneous-c-ps to introduce potentials of 'non-static' electricity into a building, whilst theoretically not impossible, is extremely improbable, so one would very very rarely have to contemplate equipotential bonding in the absence of an electrical installation.

'Earthing' at least in the sense we use the term, is, as you say only meaningful in the context of some sort of electrical installation which has (explicit or implicit) 'protective devices'.

Kind Regards, John

 

[JohnW2]

Static sparks ?

Exactly, but the concept of (and reason for) equipotential bonding is the same whether the electricity in question is 'static electricity' or 'conventional electricity' - see what I've just posted.

Kind Regards, John

 

[EFLImpudence]

I'm not sure what you are getting at.

Are you disagreeing with something I wrote?

 

[JohnW2]

I'm not sure what you are getting at. Are you disagreeing with something I wrote?

I was primarily agreeing with ('underlining') what you wrote ... namely that the purpose of equipotential bonding is to minimise the possible potential difference between two things (join electrically'), whether in relation to the sort of electricity you deal with or to static electricity.

If I was 'disagreeing' with (I would say 'commenting about'!) anything, it was probably your (I assumed essentially rhetorical) question about "metal fence posts and similar things". I would say that my LPG tank, or an aircraft, would qualify as one of those 'similar things' - in which cases equipotential bonding is essential if there is any possibility that something may approach (or touch) it at a different (static) potential .

Kind Regards, John

 

[EFLImpudence]

Yes, but that bonding, in your LPG example, is between the lorry, which may be staticallly charged, and an earthed tank to prevent a spark when the nozzle approaches.

Bonding the tank to anything else would not help.


As with a person receiving a shock when touching a car, it is the person that needs earthing.