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Topic Title: 2 x6mm mpb cables in parallel to comply with pme regs.
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Created On: 02 February 2019 06:28 PM
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 02 February 2019 06:28 PM
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hertzal123

Posts: 503
Joined: 26 August 2007

As above,2 cables emerge from the wall,1 to gas and tother to water.Wondered if allowed to link both to gas and then loop to water in 10mm,subject to continuity test from mains and check cables run together in loft.I understand joints are allowed in bonding conductors.
Regards,Hz
 02 February 2019 06:50 PM
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daveparry1

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No problem there.
 02 February 2019 07:02 PM
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perspicacious

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I understand joints are allowed in bonding conductors

What type of joint?

Regards

BOD
 02 February 2019 07:15 PM
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chrispearson

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It's a bit unorthodox, but neither 411.3.1.2 nor 544.1 prohibits a joint.

Arguably, if there is one conductor from MET to pipe, any extension which is not continuous with the original cable is supplementary bonding.

I cannot see any advantage in connecting both 6 sqmm cables to one or other utility. A connexion of at least 4 sqmm between the main bonds achieves the same effect.

The risk is that either utility pipe could be changed, which would leave inadequate main protective bonding.
 02 February 2019 07:24 PM
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geoffsd

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Originally posted by: chrispearson
Arguably, if there is one conductor from MET to pipe, any extension which is not continuous with the original cable is supplementary bonding.

No it isn't. It will be the Main bonding conductor for the pipe to which it is extended and connected.
 02 February 2019 08:08 PM
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chrispearson

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Originally posted by: geoffsd

Originally posted by: chrispearson

Arguably, if there is one conductor from MET to pipe, any extension which is not continuous with the original cable is supplementary bonding.


No it isn't. It will be the Main bonding conductor for the pipe to which it is extended and connected.


A MPBC is connected to the MET (411.3.1.2) so if it isn't connected to the MET, it cannot be a MPBC.
 02 February 2019 09:06 PM
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geoffsd

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Connected electrically.
 02 February 2019 09:07 PM
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ebee

Posts: 6735
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Well you`ve ringed it from the MET so I see nothing wrong with that . Nice and effective and complies with 10.0 minimum

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 02 February 2019 10:19 PM
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mikejumper

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Originally posted by: ebee
Well you`ve ringed it from the MET so I see nothing wrong with that . Nice and effective and complies with 10.0 minimum

Now there's an idea; a main equipotential bonding ring.
CSA reduced to 6.0mm.
Why didn't anybody think of that before?
 02 February 2019 10:35 PM
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ebee

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Mike, it`s not something I`d suggest from the off.

However the OP has come up with a realistic way of converting an existing 6mm x 2 bonding for TNS to a seemingly compliant TNC-S (PME) setup with perhaps a minumum of disruption on some scenarios of conversion techniques.

I think it has its merits.

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 02 February 2019 11:33 PM
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sparkingchip

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Originally posted by: perspicacious

I understand joints are allowed in bonding conductors



What type of joint?



Regards



BOD


My understanding has always been that crimped connections are required, so in this situation a 12 mm to 10 mm reducing crimp seems to be required.
 02 February 2019 11:49 PM
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geoffsd

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Your understanding is misplaced.

Any electrically sound connection will be satisfactory.

In fact, other extraneous-c-ps may be used AS bonding conductors so obviously it does not have to be a continuous cable nor joined by crimps.
 03 February 2019 09:53 AM
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chrispearson

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Originally posted by: ebee

Well you`ve ringed it from the MET so I see nothing wrong with that . Nice and effective and complies with 10.0 minimum


Whilst it may be a pragmatic solution to the need to upgrade an existing installation, would anybody suggest that such an arrangement would be satisfactory in a new installation?
 03 February 2019 10:02 AM
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sparkingchip

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Originally posted by: geoffsd

Your understanding is misplaced.



Any electrically sound connection will be satisfactory.



In fact, other extraneous-c-ps may be used AS bonding conductors so obviously it does not have to be a continuous cable nor joined by crimps.


The folklore as told ten years ago.
 03 February 2019 10:07 AM
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sparkingchip

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John Peckham clarified the requirement on this forum April 2017.

Crimps or solder.

So solder the two 6 mm conductors to the 10 mm conductor.

Andy B.
 03 February 2019 10:29 AM
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ebee

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Could we all perhaps settle on - off course any joint need be both electrically and mechnically sound in such a way that it might be expected to remain so throughout its life - same as could be said for any other electrical connection to any item.

Might stop the crimps only folklore a tadd

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 03 February 2019 11:02 AM
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perspicacious

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Might stop the crimps only folklore a tadd

Has anything in GN8 changed in the last decade?

Regards

BOD

https://www2.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=30777&highlight_key=y&keyword1=gn8%20loop
 03 February 2019 12:01 PM
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ebee

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No Bod it`s still only guidance not a reg.



-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 03 February 2019 12:14 PM
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perspicacious

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The OP title is PME regs so I'd imagine the ESQCR take precedence over BS 7671

Regards

BOD
 03 February 2019 12:38 PM
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Weirdbeard2

Posts: 753
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Originally posted by: hertzal123

As above,2 cables emerge from the wall,1 to gas and tother to water.Wondered if allowed to link both to gas and then loop to water in 10mm,subject to continuity test from mains and check cables run together in loft.I understand joints are allowed in bonding conductors.

Regards,Hz


Hi Hz, why do you need to alter this, it sounds fine as is, or is there signs of overheating of the existing arrangement?
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