Bonding gas/water yellow and blue

[DPG]

If you cannot prove it isn’t then yes.

Turn it on it’s head, would it be correct not to?

Ah but you originally (#17) said it's sometimes easier to bond it than to prove it, implying that you wouldn't bother testing.

 

[LeeH]

No, I was trying to imply that you can spend an age trying to prove isn’t and it can be quicker just to do it.

 

[telectrix]

I think you will find that it says "if the water / gas pipe enters the house is of plastic construction, and the rest of the pipework is copper, then this copper must be bonded, are we not getting our wires crossed with the > than 22Kohms refers to supplementary bonding, not main bonding, open for discussion?

no.the 22k ohms is to prove whether or not a piece of copper /metal pipe is extraneous or not.

 

[LeeH]

Or any other services, steel structure etc.

 

[Pete999]

no.the 22k ohms is to prove whether or not a piece of copper /metal pipe is extraneous or not.

Agree but is also used to prove that something is "extraneous" the pipework should be main bonded, but not bonded because it may be or maybe not classed as extraneous.

 

[Midwest]

In respect to your classic plastic incomer, sometimes it’s easier to bond it (the copper pipe work) than it is to prove it isn’t extraneous.

But then the situation could arise, as spinlondon stated in #9.

 

[Midwest]

I do find reg. 544.1.2 a bit confusing therefore, i.e. if the service is plastic the continuing internal metal does not need bonding argument? Or is the reg poorly worded and not drawing reference to extraneous or not.

 

[LeeH]

But then the situation could arise, as spinlondon stated in #9.

Yep that is a good point.

 

[Midwest]

On the other thread
Equipotential Bonding Explanation - https://www.electriciansforums.co.uk/threads/equipotential-bonding-explanation.136192/
if the metal pipework is not bonded, because the incoming service is plastic, when the kettle casing becomes live, the pipework may be not at the same PD, but could be earthed via parallel paths, so at the moment of the fault 'the touch voltage that may be experienced during a fault, i.e. for the 0.4s before the automatic disconnection occurs' (mentioned by RB) may be increased?

 

[Midwest]

And in this situation, if the service was plastic?
Equipotential Bonding - https://www.electriciansforums.co.uk/threads/equipotential-bonding.136204/#post-1355901

 

[Houndogg10]

So is this topic a grey area in general lol I can never find or hear a straight answer for it as I have also heard that bonding something that doesn’t need a bond will possibly start a not needed potential??

 

[Leesparkykent]

It's not a grey area. If it's an extraneous conductive part it needs bonding. If it's not an extraneous conductive part it doesn't need bonding. I always run a green and yellow in for gas and water on a new builds as I've had muppet meter fitters refusing to connect as no bonding, even though it didn't require bonding. If they moan I connect it then chop it off when the muppet has finished.

 

[Midwest]

Must admit, I'm still confusing myself over this. I understand the testing to conclude if a metal pipework after a plastic service is extraneous or not.

I take spinlondons point that bonding the above, under fault conditions may momentarily 'increase the number of conductive parts that will become live', but wouldn't these be earthed anyway by a circuit cpc?

The OSG recommends bonding of above, unless its been confirmed said pipework is not introducing Earth potential. It mentions pipework 'liable to introduce earth potential'. It doesn't mention testing to prove whether such pipes are extraneous, only gives examples, as in reg 411.3.1.2. Indeed the formulae for when doubt exists over effectiveness of extraneous or not, reg 415.2.2 is for supplementary bonding, something completely different. Reg 544.1.2 states where the consumers hard metal pipework should be bonded after insulating section or insert.

So I'm suggesting BS7671 recommends that unless you can physically confirm all such pipework is not liable to or not able to, then it should be bonded?

 

[LeeH]

That’s a sound conclusion.

 

[Deleted member 26818]

I don’t bother with the OSGs, as they contain so many errors.

Are you stating that the OSGs recommend bonding non-extraneous conductive-parts?

 

[Midwest]

I don’t bother with the OSGs, as they contain so many errors.

Are you stating that the OSGs recommend bonding non-extraneous conductive-parts?

But it does contain some pretty pictures for us plebs.

Have a shufty yourself, it talks about it on pages 44 & 46 in the yellow version.

 

[Deleted member 26818]

But it does contain some pretty pictures for us plebs.

Have a shufty yourself, it talks about it on pages 44 & 46 in the yellow version.

Unfortunately, that is not possible.
I only have a brown 16th and a red 17th someone gave me.
My point is however, BS7671 requires protective bonding for extraneous conductive-parts, not for non-extraneous conductive-parts.

 

[Midwest]

Unfortunately, that is not possible.
I only have a brown 16th and a red 17th someone gave me.
My point is however, BS7671 requires protective bonding for extraneous conductive-parts, not for non-extraneous conductive-parts.

Oohh ok, give me 5 mins, I'll type up what the OSG says. Might be 10, just sipping a G&T

 

[Midwest]

Yellow OSG Sec 4.5 'Main protective bonding of plastic services'. There's no shock here (excuse the pun), it says there's no requirement to bond plastic services.

Continuing on page 46; 'Where there is a plastic service and a metal installation within the premises, main bonding is recommended unless it has been confirmed that any metallic pipework within the building is not introducing Earth potential (see 4.3, (referencing to reg 411.3.1.2).

I have had a quick shufty through GN8, and can't seem to find specific mention of the above scenario.

What do you make of the definition of extraneous-conductive-part in BS7671?

 

[Midwest]

It goes onto say about internal metallic pipework which may be buried in the ground for convenience............but I'm not typing all that out for you