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Topic Title: Main bonding
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Created On: 15 November 2016 09:57 PM
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 17 November 2016 08:24 PM
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mapj1

Posts: 9716
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That's good, , at least we are allowed soft solder to gas pipes, unlike some of the states that insist that if you use copper tube it must be brazed - the idea being that soldered joints come undone in a fire.
Ah - perhaps the post AMD 3 consumer unit can have all-welded connections.

Cheers OMS - though I think the sort of MET that maybe used when its domestic and wires from 3 or more pipes converge, is more likely to be


-------------------------
regards Mike
 17 November 2016 08:42 PM
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UKPN

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I am wondering which part of the word "continuous" cannot be grasped?

Lets work it through, from the point of connection at the DNO service, the bonding lead, min 10sqmm, runs to the first service point of entry.
From there, unbroken, to the next and subsequent services.

Regards, UKPN.
 17 November 2016 08:51 PM
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Legh

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Originally posted by: UKPN

I am wondering which part of the word "continuous" cannot be grasped?

Lets work it through, from the point of connection at the DNO service, the bonding lead, min 10sqmm, runs to the first service point of entry.

From there, unbroken, to the next and subsequent services.

Regards, UKPN.


I think you have posted to the wrong person as page 39 from Guidance note 8 more or less states the same thing.

Legh

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http://www.leghrichardson.co.uk

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 17 November 2016 08:52 PM
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OMS

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Ahem - well yes - I was clearly back in heady days when my fee was based on the outurn cost - happy days

On the subject of solder we used to use different current rating for PILC based on jointing method

It was potentially designed for 60C if jointed with weak back ferrules and solder

If it was mechanically crimped you would run at really serious temperatures

There was a vague relationship derived from those temps that heavily influenced the short circuit assessment - the fear would be a big fault extending for several seconds would melt the solder - although I've never seen a solder joint fail under load or fault

OMS

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Let the wind blow you, across a big floor.
 17 November 2016 09:04 PM
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UKPN

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Guidance "note" ??? I dont read them. We have our own, as a matter of interest quoted on this forum frequently. Did the "notes" ever give a positive answer for unearthed steel fuseboards by the way?

Regards, UKPN
 17 November 2016 09:41 PM
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Legh

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Originally posted by: UKPN

Guidance "note" ??? I dont read them. We have our own, as a matter of interest quoted on this forum frequently. Did the "notes" ever give a positive answer for unearthed steel fuseboards by the way?

Regards, UKPN


1 of 8 guidance A4 books ; Guidance note 8: Earthing and Bonding supplementary guidance to BS7671
You may have heard of Guidance note 3: Inspection and testing, often quoted here is part of the same set of guidance notes.

Remember this is a forum for the wiring regulations to BS7671 not necessarily to any other set of regulations although they maybe relevant to electrical design and /or construction ......

I can't help you with 'unearthed metal fuseboards' unless it has something to do with IT earthing or SELV/PELV systems where a connection to earth generates a first fault alarm condition.

My understanding of exposed conductive parts under EEBADS or as it is now ADS which are part of BS7671 methods of safety against electric shock should be connected to the MET via either an earthing conductor, and/ or circuit protective conductor.

Legh

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http://www.leghrichardson.co.uk

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 18 November 2016 09:13 PM
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BurtonsElectricalLTD

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So from what i've read mostly by UKPN who seems very convincing, i'm not able to run a jointed cable of any sort and it has to be continuous
 18 November 2016 09:20 PM
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OMS

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Simply not true

OMS

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Let the wind blow you, across a big floor.
 18 November 2016 09:34 PM
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BurtonsElectricalLTD

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So i can run a jointed cable?

Edited: 18 November 2016 at 10:23 PM by BurtonsElectricalLTD
 18 November 2016 10:36 PM
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OMS

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Yes - make proper connections - crimps for example or a Henley block

OMS

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 18 November 2016 10:37 PM
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geoffsd

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Yes.

There is no doubt about it.
 18 November 2016 11:17 PM
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mapj1

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come on - it has to be possible to have joints, or how would you handle a complex building with multiple service entries for example one in each corner - The important requirement if you must have joints is to do them properly with adequate current carrying capacity.

Our colleague UKPN generally brings us a different perspective, being more professionally concerned with the stuff upstream of where we normally start, but the same house rules are not always going to apply - it is of course nice when they do join up but not always so.

-------------------------
regards Mike
 19 November 2016 01:51 AM
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geoffsd

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Originally posted by: UKPN
I am wondering which part of the word "continuous" cannot be grasped?

It's not the grasping of the meaning that is difficult but the spurious inclusion of it.
 19 November 2016 06:33 AM
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BurtonsElectricalLTD

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Thanks very much for clearing it up just wanted to be sure
 19 November 2016 09:45 AM
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sparkingchip

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Originally posted by: UKPN

"A common bonding conductor may be used to interconnect more

than one metallic service but the conductor must remain continuous

to ensure continuity in the event of alteration to connections along

the route of the conductor"





Regards, UKPN


That's what I was taught when I did the 16th edition course umpteen years ago.

Andy
 19 November 2016 10:08 AM
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mapj1

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And if a wire goes ten feet from the CU to the water pipe on a '951 clamp and then flies past to do the gas meter becasue its nearby, then that is indeed a very good idea. It ensures that taking the wire off the water pipe does not also unhook the gas - so far so good. Though I'd accept two wires in a suitably proportioned well crimped lug as equally secure.
But if two ten foot wires, one from each service in different places converge on one of those double screw earthing blocks I pictured earlier, again suitably secured to the wall and so forth, and then another wire goes a further 3 feet into the CU, that is also perfectly sensible, as you can still work on the water and leave the gas bonded or whatever.
The big thing to bear in mind is where the currents are likely to want to circulate to in a real fault - usually back to the company head in a TNC-s or TN-S system, so it is that path that must not be broken from where ever you are working at the moment, not, hopefully, currents coming in up the water pipe and going out down the gas main.

-------------------------
regards Mike
 19 November 2016 04:02 PM
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Legh

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Originally posted by: sparkingchip

Originally posted by: UKPN

"A common bonding conductor may be used to interconnect more

than one metallic service but the conductor must remain continuous

to ensure continuity in the event of alteration to connections along

the route of the conductor"

Regards, UKPN


That's what I was taught when I did the 16th edition course umpteen years ago.

Andy


Ditto - 15th ed.

Edit: We used to call it 'cross bonding' ......... the missing link ?

Legh

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http://www.leghrichardson.co.uk

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Edited: 19 November 2016 at 04:17 PM by Legh
 19 November 2016 04:37 PM
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geoffsd

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When using protective conductors allowed by 543.2.1 (v), (vi) and (vii), how would "continuos" be achieved?
 19 November 2016 05:31 PM
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Legh

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Originally posted by: geoffsd

When using protective conductors allowed by 543.2.1 (v), (vi) and (vii), how would "continuos" be achieved?


Well, I cross bond 10mm2 single core insulated conductors between service pipework by crimping two 10mm2 conductors together in a 10mm eyelet crimp with a 25mm2 conductor hole. It has worked for me and looks neat and tidy with either a green/yellow heat shrink sleeve or tape around the joint.
Anything larger needs to go to an earth marshalling bar - which is what Mike and OMS are referring to....

Suitably sized SWA when properly glanded (v) to metal trunking or adaptable boxes (vi) will provide a suitable bonding conductor.

Legh

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http://www.leghrichardson.co.uk

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 19 November 2016 05:49 PM
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geoffsd

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Yes, but that isn't "continuous", is it?

I am questioning those who say (wrongly) that the bonding conductor must be continuous.
IET » Wiring and the regulations » Main bonding

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