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Topic Title: Main earth bonding
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Created On: 26 October 2010 05:09 PM
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 26 October 2010 05:09 PM
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20Briggsy

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Having seen plenty of main earth bonding (or lack of) in recent months I have a query that needs a little clarification. I often seen the main earth bond for the water linked from the gas bond. I've been told that's perfectly fine so as long as it's the correct csa and it's within 600mm of where the service pipe enters the building. My gripe is, if future alterations where to take place and gas was no longer needed in the building as the service was removed and due to poor workmanship the water bond was left unconnected ou effectively loose your MEB to your water pipe!!

Any thoughts on this?
 26 October 2010 05:18 PM
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Legh

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I think the correct method of cross bonding is to provide a solid through connection (ie not cut)
There are several ways this can be achieved.
1/ strip back insulation but don't cut the copper and then wrap it round the terminal screw -
2/ Bend the stripped 10mm2 copper and push into a 35mm2 crimp, tape up the end -
3/ Cut the cable and crimp into 25mm2 crimp and tape up the end-

Legh


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 26 October 2010 05:23 PM
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OMS

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Yes - you wouldn't really expect a totally uncontrolled approach to managing electrical safety so it's not likley that the gas pipe will be removed without there being competent persons involved.

It's also why we have 514.13.1

Regards

OMS

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 26 October 2010 05:26 PM
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impvan

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All a bit hypothetical though isn't it? IF future alterations, AND service pipe removed, AND bad workmanship..

Why is it up to you to plan for this remote occurrence? You're a bleedin electrician, not a clairvoyant.

IMO, it's safe to assume that anyone skilled enough to be involved in gas main removal would understand the importance of retaining the two wires.

If you see it, and it concerns you, just crimp the two ends into one lug.
 26 October 2010 05:32 PM
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20Briggsy

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Fair point.
 26 October 2010 05:33 PM
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rocknroll

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All a bit hypothetical though isn't it?


Never take life seriously, nobody gets out alive anyway!

regards

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leave nothing but footprints!"
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 26 October 2010 05:45 PM
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Legh

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IMO, it's safe to assume that anyone skilled enough to be involved in gas main removal would understand the importance of retaining the two wires.


You would be amazed how many 'gas fitters' do not bother to connect the MPB after a refit

Legh

-------------------------
Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."
 26 October 2010 05:57 PM
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Grobbyman

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No I wouldn't.

 26 October 2010 06:15 PM
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John Peckham

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I know it is considered good practice to loop a protective bond from one pipe to another but can anyone provide a regulation to support this practice?

In the NICEIC Snags and Solutions book on Earthing and Bonding they put forward 528.3.3 but I think that is the deperate result of trying to find a Reg. to justify the folklaw.

I think terminating main protective bonds on to a clamp is a much better job if crimped lugs are used. I think lugs are a better job all round rather than trying to terminate an un cut bond under a clamp screw.

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 26 October 2010 06:25 PM
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OMS

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There is no specific regulation John - that's why we have 514.13.1 to warn people about the problem of removing those connections. We also have Reg 9 of EAWR to consider

I agree that 528.3.3 is just a pretty desperate attempt to bolster the preferences of the NICEIC. Given that 528.3.3 is under teh heading of " Proximity of Wiring Systems to Other Services" it can only be focused on potential damage - a cable being installed close to a steam line for example without adequate separation or thermal shielding

Regards

OMS

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 27 October 2010 01:28 PM
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AJJewsbury

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You would be amazed how many 'gas fitters' do not bother to connect the MPB after a refit

I think it's partly our fault - we put labels on them saying "do not remove". I found one where the gas pipework had been replaced but 6" of the original pipework remained - 3" each side of the clamp. Well, they hadn't removed it had they?

I know it is considered good practice to loop a protective bond from one pipe to another but can anyone provide a regulation to support this practice?

Code of practice, rather than "regulation", but I think it comes from BS 7430 ("Code of practice for Earthing") 21.4.

"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"

- Andy.
 27 October 2010 02:36 PM
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Jaymack

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Originally posted by: 20Briggsy
Having seen plenty of main earth bonding (or lack of) in recent months I have a query that needs a little clarification. I often seen the main earth bond for the water linked from the gas bond. I've been told that's perfectly fine so as long as it's the correct csa and it's within 600mm of where the service pipe enters the building. My gripe is, if future alterations where to take place and gas was no longer needed in the building as the service was removed and due to poor workmanship the water bond was left unconnected ou effectively loose your MEB to your water pipe!!

Any thoughts on this?


The OSG for the 16th edition had a picture of such an arrangement, as looping from the MET to the gas and water service pipes, it required to be a continuous unbroken length, so that the removal at any pipe could be carried out safely.
It's still allowed to the 17th as far as I know, done it myself where the services are adjacent, I don't see anything to the contrary although there is no picture of such an arrangement in the OSG for the 17th.

Regards
 31 October 2010 11:39 AM
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perspicacious

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GN 8, p39 may be useful.......

Regards

BOD
 31 October 2010 02:46 PM
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John Peckham

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BOD

Yes I ahve seen the advice/guidance in GN8 and other fine books but is it a regulation to have an uncut looped protective bond?

What should a contractor say to his/her assessor on their annual visit if they have a cut looped bond and they are marked down for this?

I understand the NICEIC assessors have to be able to state a BS7671 Regulation or EAWR regulation for a departure if challenged?

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http://www.astutetechnicalservices.co.uk/
 01 November 2010 11:11 AM
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perspicacious

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"Yes I ahve seen the advice/guidance in GN8 and other fine books but is it a regulation to have an uncut looped protective bond?"

As posted above, no.

"What should a contractor say to his/her assessor on their annual visit if they have a cut looped bond and they are marked down for this?"

I gather that the report has amongst other things, the facility to record both 1) non compliances with British Standards and 2) observations on where IET guidance has not been followed. What are you trying to convey by "marked down"? The tick in the box for insurance has been marked down I hope

I understand the NICEIC assessors have to be able to state a BS7671 Regulation or EAWR regulation for a departure if challenged?

What and where was actually written on the report John for this example you quote?

I've previously posted extracts fom old REC notes of guidance for PME where the "uncut" is their requirement which I'd imagine has led to the inclusion in GN8. To keep it topical for you John, London Electricity "A guide to the connection of customers to protective multiple earthed networks" 44 page booklet of ~1990 makes no mention of looped bonding that I can see but instead suggests the use of one bond per service...........

Regards

BOD
 01 November 2010 12:15 PM
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John Peckham

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BOD

I have not had this "departure" recorded on my assessment report as yet from the NICEIC after my annual "moongoose and snake" event.

I posted the question to verify if it was one of the myths and legends of installation that needed to be challenged.

I am waiting for my annual visit which is due any day now. In respect of my insurance I have updated this with the new company name and had to pay extra to add the word limited as I am now a humble employee of my own company so more likely to sue the company. The NICEIC also sent me a new certificate with the word "limited" added to my company name. I thought that was a nice service until I went to file the certificate and found an invoice for £56 in the envelope!

My old NICEIC AE has retired so I am expecting a "new broom" for the annual event so I need to be on my toes in preparation. Now should I take the cellophane off that big red book?

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 01 November 2010 01:25 PM
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AJJewsbury

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I see your point John, there's no reference to BS 7430 in section 544 of BS 7671.
- Andy.
 01 November 2010 01:41 PM
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OMS

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I posted the question to verify if it was one of the myths and legends of installation that needed to be challenged.


Like all of these things John, it's never that simple.

There is no specific regulation in BS 7671 that requires teh bond to be unbroken or looped if it serves more than one extraneous conductive part.

There is however lots of supporting documentation such as BS 7430 that suggests that it's good practice and tends to lead to these myths and legends

Like all of these things, assessors often feel a collective need to tell little white lies for the greater good. I can easily see an assessor telling a domestic installer that he shouldn't cut the cable and it should be unbroken - that same assessor however is not likley to raise the same "non conformance" with a competent engineer in a large contractor.

A classic case of don't do as I do - do as I tell you I guess, when the message is tailored to the level of the recipient

Regards

OMS

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 01 November 2010 01:46 PM
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ant1uk

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personally I dont see a problem looping a solid unbroken conductor between water and gas providing its the correct size. I don't do it myself but I do it for multiple water pipes.

Regards
 01 November 2010 01:53 PM
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John Peckham

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OMS

I think a crimped lug joint is better than a conductor under the screw head of a bonding clamp.

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John Peckham

http://www.astutetechnicalservices.co.uk/
IET » Wiring and the regulations » Main earth bonding

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