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Topic Title: Extending earth bonding
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Created On: 19 April 2017 01:04 PM
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 19 April 2017 01:04 PM
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goldenboy1818

Posts: 802
Joined: 22 February 2011

Hi guys can i extend a earth bonding cable ? I know it has to be continuous but i assume a crimp joint will suffice ? Iv never had to extend one before. Thanks guys
 19 April 2017 01:32 PM
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dustydazzler

Posts: 992
Joined: 19 January 2016

I have used 30amp connector strip before


Tin hat on
 19 April 2017 01:41 PM
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geoffsd

Posts: 1523
Joined: 15 June 2010

Yes, you can. It does not have to be continuous.
You may even use other parts, except a gas pipe, as a bonding conductor.

On a semantic point, how would a crimp joint make it continuous?
 19 April 2017 02:08 PM
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mapj1

Posts: 8957
Joined: 22 July 2004

Bonding does not need to be mechanically continuous, just electrically so.
Crimp is often a good idea as less likely to be undone at some point, but screwed joints done well and accessible and standard label "Safety Electrical Connection - Do not remove" are fine.
Try to locate it in a dry location - you don't want water wicking back between copper and jacket and corroding the join, especially if mixed metals .

-------------------------
regards Mike
 19 April 2017 04:41 PM
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John Peckham

Posts: 8713
Joined: 23 April 2005

There is no reference in BS7671 concerning the joining of bonding conductors or them having to be continuous if looping from one bonding clamp to another contrary to common belief and folk law.

However in BS7430 is says.

"Where both main gas pipes and main water pipes enter a location, a common
bonding conductor may be used, but in such cases that conductor should be
continuous or should be permanently jointed (by soldering or crimping) in order
to preserve continuity. Such a bonding conductor may also be used in
association with other extraneous-conductive-parts".

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 19 April 2017 05:03 PM
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geoffsd

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What do you think is the justification for such a statement; both electrically and regulatory?

Plus, of course, noting the use of the word "should"

or are you just pointing out that "one person said this once"?
 19 April 2017 06:52 PM
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geoffsd

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Joined: 15 June 2010

I have found this in the same part of BS7430;

"The bonding connections to the water and gas pipes
should be made as near as possible to their point of
entry into the premises. If there is an insulating
section or insert at that point, the bonding
connection should be made to the metallic pipes on
the consumer's side of the section or insert."


Same poor practice as 544.1.2

It continues:

"The main equipotential bonding connections to the
main water pipes should normally be on the
consumer's side of the stop tap"


Why?

"but connection on the
Water Authority's side of the stop tap is acceptable,
as long as there is satisfactory electrical continuity
across the tap
."


It doesn't inspire confidence, does it?


Edit - From 1998 edition.

Edited: 19 April 2017 at 07:25 PM by geoffsd
 19 April 2017 09:22 PM
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spinlondon

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How does a code of practice become a British Standard?
 19 April 2017 10:11 PM
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AJJewsbury

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How does a code of practice become a British Standard?

By following the procedures specified in British Standard Zero (BS 0 ) "A standard for standards" - http://www.bsigroup.com/Documents/30342351.pdf
- Andy.
 20 April 2017 12:25 AM
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mapj1

Posts: 8957
Joined: 22 July 2004

Originally posted by: geoffsd

I have found this in the same part of BS7430;



"The bonding connections to the water and gas pipes

should be made as near as possible to their point of

entry into the premises. If there is an insulating

section or insert at that point, the bonding

connection should be made to the metallic pipes on

the consumer's side of the section or insert."




Same poor practice as 544.1.2



It continues:



"The main equipotential bonding connections to the

main water pipes should normally be on the

consumer's side of the stop tap"




Why?



"but connection on the

Water Authority's side of the stop tap is acceptable,

as long as there is satisfactory electrical continuity

across the tap
."




It doesn't inspire confidence, does it?





Edit - From 1998 edition.


Note of course that for buildings on PME supplies

ENA Engineering Recommendation G12 Issue 4
actually recommends such an insulating break for both gas pipes coming in on page 16, and outside taps going out on page 28.
I can't help wondering if in such cases, ditching the pretence of equipotential bonding to the stuff outdoors altogether, and just calling it earthing of the indoor piping, might be better.

-------------------------
regards Mike
 20 April 2017 01:04 AM
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geoffsd

Posts: 1523
Joined: 15 June 2010

Originally posted by: mapj1

Note of course that for buildings on PME supplies
(link)

The link states what, at present, is considered the lesser risk as we are required to bond extraneous-conductive-parts and not cater for lost neutrals.

actually recommends such an insulating break for both gas pipes coming in on page 16, and outside taps going out on page 28.

A good idea, but the bonding instructions, in 7430 and 544, if followed, leave the extraneous-conductive-part unbonded and the interior pipe, which is not an e-c-p, possibly unnecessarily earthed - that is earthed, not bonded.

I can't help wondering if in such cases, ditching the pretence of equipotential bonding to the stuff outdoors altogether, and just calling it earthing of the indoor piping, might be better.

Why is it a pretence? The indoor piping does not need earthing.

That is a different argument and an instruction to do that would be to earth possibly isolated parts, which do not require it, introducing hazards which were not present before - as the proverbial door knob.
 20 April 2017 01:38 AM
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mapj1

Posts: 8957
Joined: 22 July 2004

I think we are on the same page actually, though it may be that the insomnia, and a beer or two(*), is not helping the clarity - I agree, with an IJ in line there is precious little point in earthing the pipes specially back to the MET - after all any appliance connected to pipework within the building will have its own CPC, or be class II, and in any case a 10mmsq bond is then overkill for tripping the local breaker or RCD, now all that would be the most required.

The whole point was that without the IJ, assuming the pipes are electrically continuous and shared, then they bring it either the outside terra-firma potential via several, maybe many ohms in some cases, or nowadays more likely they bring in the integral of all the neighbour's neutral offset voltages via some tens to hundreds of milli-ohms if the road is on PME...

So the metal services are not really earthed, rather they are neutralled (avoiding using "neutralized" and "neutered" which may better describe the effects of the plastic mains and the relative the IJ on the slightly defunkt EEBADS concept.).

(* counting liberally, probably in decibels.+3 to +5 dBpints.)

-------------------------
regards Mike
 20 April 2017 05:17 PM
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geoffsd

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Joined: 15 June 2010

Yes, we are agreed but the important point about the instructions, for when an IJ is present, is not that the internal piping is unnecessarily earthed (not bonded) but that the external pipe is left unbonded.
 20 April 2017 06:53 PM
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weirdbeard

Posts: 3022
Joined: 26 September 2011

Originally posted by: geoffsd

Yes, you can. It does not have to be continuous.

You may even use other parts, except a gas pipe, as a bonding conductor.

On a semantic point, how would a crimp joint make it continuous?


Sorry to be more semantic, but with regards the OPs title, referencing BS7671, it would appear to be impossible to extend earth bonding.

-------------------------
:beer)
 20 April 2017 07:07 PM
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geoffsd

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I'm not certain exactly what you mean.

Are you querying the use of the term "earth bonding"?
 20 April 2017 07:22 PM
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weirdbeard

Posts: 3022
Joined: 26 September 2011

Originally posted by: geoffsd

I'm not certain exactly what you mean.


Who, me?

Are you querying the use of the term "earth bonding"?


Yes.

-------------------------
:beer)
 20 April 2017 07:28 PM
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geoffsd

Posts: 1523
Joined: 15 June 2010

I think it is just an unfortunate mistake for an abbreviation of "earthed equipotential bonding".
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