Incoming Gas cross bonded off cold water

Discuss Incoming Gas cross bonded off cold water in the Electricians' Talk area at ElectriciansForums.net

H

highspark

Doing a CU change in a flat, concrete floors and ceilings, just been decorated in hallways and bedrooms. Basically kitchen fitters ripped units out today and the bonding to the main gas has been cross bonded to the water behind units. Water is bonded back to the MET. However incoming water is bonded in a cupboard next to CU (nowhere near kitchen). There is absolutely no way I can get 10mm bonding back to the board without smashing hell out of the place!

Do I need to get this back to the MET or can I note on cert it's cross bonded! Absolute nightmate!
 
Can you join the gas bond to the water bond with a through crimp so it is one continous cable from the MET to both and it is unbroken?
 
No, basically main water is bonded next to the front door - goes through a riser to each flat. The boiler (along with gas meter) is in the kitchen. 10mm bonding from gas pipe to the cold on the boiler.
 
If it's TNCS I'd say you have no choice but to bond the gas in 10mm back to the MET. TNS you might consider the current arrangement satisfactory assuming it tests OK,and write it as a departure. Your call on that,your name on the cert.
 
I would not be too concerned at all on this.Bear in mind, you did not install this bonding, so you are not initially verifiying it. You can only check / test it as you would an EICR.Use long lead test to confirm a sound connection between MET and the cold pipe you speak of. Ensure BS951 tags are present on earthing clamps. It is still effectively bonded just not exactly to what the non statutory document would like. Note on cert. No worries.
 
Problem is other spark/kitchen fitter is telling customer it needs to go back to CU! That's the problem here! I can't be bothered going back and forth with the other spark because ideally it should go back to CU! Customer wants me to do the work as she fears Kitchen fitters will over charge!
 
highspark said:
Problem is other spark/kitchen fitter is telling customer it needs to go back to CU! That's the problem here! I can't be bothered going back and forth with the other spark because ideally it should go back to CU! Customer wants me to do the work as she fears Kitchen fitters will over charge!
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If she's willing to pay crack on...
 
highspark said:
Problem is other spark/kitchen fitter is telling customer it needs to go back to CU! That's the problem here! I can't be bothered going back and forth with the other spark because ideally it should go back to CU! Customer wants me to do the work as she fears Kitchen fitters will over charge!
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Hell would freeze over before I ever took on board electrical advice from a kitchen fitter. Who is writing the cert, you or kitchen fitter?
 
I might be misreading the setup, but if the water bond is ok, then there is not a problem with through-crimping the existing bond and extending to the gas (as Leesparky has said)
 
I know what to do here. Install a bonding clamp on gas pipe with a short piece of 1mm connected to it. Tell kitchen fitter it is an aerial for your wireless bonding arrangement back to MET. He will definately believe you as he does not understand electrical type stuff thingys. Then tell customer it is free. Everyone will love you.
 
If there's 'negligable impedance' between the bonded cold water main near the CU and the cold feed in the kitchen [i.e. the same pipework with no plastic in between] then from a common sense point of view it will be absolutely fine. As TJ Anderson has said just note it on the certificate and hide that one from the assessor when he next turns up. :p
 
TJ Anderson said:
I know what to do here. Install a bonding clamp on gas pipe with a short piece of 1mm connected to it. Tell kitchen fitter it is an aerial for your wireless bonding arrangement back to MET. He will definately believe you as he does not understand electrical type stuff thingys. Then tell customer it is free. Everyone will love you.
Click to expand...

The main issue I have is this other "spark" being involved! Ideally I'd like the Gas to be bonded back to the MET but if he wasn't involved I'd quite happily have just noted on cert! If the units weren't removed I'd have never have known anyway as Clamp is present on incoming gas pipe and would have tested via a long lead!
 
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TJ Anderson said:
I know what to do here. Install a bonding clamp on gas pipe with a short piece of 1mm connected to it. Tell kitchen fitter it is an aerial for your wireless bonding arrangement back to MET. He will definately believe you as he does not understand electrical type stuff thingys. Then tell customer it is free. Everyone will love you.
Click to expand...

It will only work with a green/yellow aerial though !;)
 
highspark said:
The main issue I have is this other "spark" being involved! Ideally I'd like the Gas to be bonded back to the MET but if he wasn't involved I'd quite happily have just noted on cert! If the units weren't removed I'd have never have known anyway as Clamp is present on incoming gas pipe and would have tested via a long lead!
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Just to clarify, I was not serious about the RF bonding suggestion. (I want to patent it first before you lot start using it!)
 
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I dont have a regs book to hand so am working from memory here, but if it serves me correctly then:
If the cross sectional area of the copper of the water pipe is at least equal to the size required for a protective conductor (in this case a main bond) then it may be used as a protective conductor. But steps need to be taken to ensure that the pipe remains unbroken and electrical continuity be maintained if any alterations are carried out.
 
What Davesparks and TJ have said makes a lot of common sense, and I would agree with them, but the problem is, what happens when there is a leak in that pipe work and Tel's mates turn up with a length of plastic pipe to fix it??
 
davesparks said:
I dont have a regs book to hand so am working from memory here, but if it serves me correctly then:
If the cross sectional area of the copper of the water pipe is at least equal to the size required for a protective conductor (in this case a main bond) then it may be used as a protective conductor. But steps need to be taken to ensure that the pipe remains unbroken and electrical continuity be maintained if any alterations are carried out.
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I don't have a regs book handy either....but I am certain this applies to supplementary bonding only, not main bonding.
I still think this hinges on the type of earthing system. If it is TNCS, which unless I've missed something hasn't been stated, then no other option than a 10mm bond back to the MET is acceptable. It is quite possible on a TNCS system that bonding will result in a parallel path for return currents resulting in it carrying a significant load,a lashed up connection via a water pipe would create a hazard in those circumstances.
 
If we are talking about a loss of neutral (and therefore Earth on a TNCS system), most external gas supply pipes are plastic now anyway so isn't this a bit irrelevant?
 
sparksburnout said:
If we are talking about a loss of neutral (and therefore Earth on a TNCS system), most external gas supply pipes are plastic now anyway so isn't this a bit irrelevant?
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If conditions are as described in reg 528.3.4, then '(ii) fault protection shall be afforded in accordance with the requirements of Section 411.'

Then bonding of metal pipes with plastic service supply, may be required.
 
I completely agree mate. I would bond the internal copper even if it turned into plastic as it exited the building. However, I thought wire puller was getting at the suitability of the main gas bond to carry large fault currents, and presumably because he was stressing TNCS he meant if the neutral (and hence main earth) was lost the pipe route was not reliable, but if it's plastic outside it won't anyway will it?
 
sparksburnout said:
I completely agree mate. I would bond the internal copper even if it turned into plastic as it exited the building. However, I thought wire puller was getting at the suitability of the main gas bond to carry large fault currents, and presumably because he was stressing TNCS he meant if the neutral (and hence main earth) was lost the pipe route was not reliable, but if it's plastic outside it won't anyway will it?
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Apologies, did misinterpret your post.
 
Midwest said:
Apologies, did misinterpret your post.
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none required mate. Not sure if this is all worth getting worried about, as others have said. The pipe works all connected at the boiler anyway and any part of it in any installation could easily be disrupted by plumbing activity. How many people have ever seen or heard of a neutral being lost anyway??
 
In my own house the CU and boiler are in one cupboard, the gas meter in a separate cupboard on opposite side of kitchen and incoming water at other end of the room. On my last Elecsa assessment I asked if i could bond from MET to the gas at boiler and onto water at boiler and confirm continuity to incoming water and gas and the assessor said put note on cert and all would be fine.
 
colshaws said:
In my own house the CU and boiler are in one cupboard, the gas meter in a separate cupboard on opposite side of kitchen and incoming water at other end of the room. On my last Elecsa assessment I asked if i could bond from MET to the gas at boiler and onto water at boiler and confirm continuity to incoming water and gas and the assessor said put note on cert and all would be fine.
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seems logical to me
 
A protective earth conductor may be a number of things, trunking, SWA armour or even pipe work (excepting any pipe work which contains a flammable material or one belonging to a utility company).
 
sparksburnout said:
I completely agree mate. I would bond the internal copper even if it turned into plastic as it exited the building. However, I thought wire puller was getting at the suitability of the main gas bond to carry large fault currents, and presumably because he was stressing TNCS he meant if the neutral (and hence main earth) was lost the pipe route was not reliable, but if it's plastic outside it won't anyway will it?
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Nothing to do with fault currents,on a TNCS system the bonding conductors may carry a significant current under normal load conditions,thats why there is a requirement for 10mm.
 
wirepuller said:
Nothing to do with fault currents,on a TNCS system the bonding conductors may carry a significant current under normal load conditions,thats why there is a requirement for 10mm.
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come on then W/P, how under normal conditions can a TNCS system have "significant" current flowing through the EB?
 
sparksburnout said:
come on then W/P, how under normal conditions can a TNCS system have "significant" current flowing through the EB?
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Because main bonding is connected to a metallic service at or near earth potential, and is electrically connected to the neutral terminal. Therefore a parallel path is created through which a proportion of the neutral current may divert. Do you think the required CSA of TNCS/PME bonding conductors are increased over TT/TNS for fun?
 
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wirepuller said:
Because main bonding is connected to a metallic service at or near earth potential, and is electrically connected to the neutral terminal. Therefore a parallel path is created through which a proportion of the neutral current may divert. Do you think the required CSA of TNCS/PME bonding conductors are increased over TT/TNS for fun?
Click to expand...
A proportion yes, but I don't think the word significant is particularly apt under normal conditions?
 
sparksburnout said:
A proportion yes, but I don't think the word significant is particularly apt under normal conditions?
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Why not significant? If an old iron water main feeds a row of houses and each one has main bonding connecting that water main to the supply neutral then it will see a significant proportion of the neutral current
 
I'm not questioning your knowledge w/p, just trying to get this straight. I understand how some current will flow through the EP, obviously it is a parallel path, but under normal conditions, on an average (let's say domestic) installation, it's not going to be large, certainly no where near that requiring 10mm? For example I just tried my own installation - with the shower and other stuff running I have a current draw of 41A through the tails, 40mA through the water bond and *****all through the gas, which is not surprising as it is plastic outside.(maybe come back to that just thinking about it). Am I, therefore, incorrect in thinking that the increased EP bond for TNCS systems is nothing to do with fault conditions including possible loss of neutral then?
 
Due to the fact that the network neutral and earth are combined, any neutral current from the installation, will also be present in the earth conductors.
If incoming services are metallic and bonded, then diverted neutral currents from other installations that are bonded to the same services will also be present in the earth conductors.
A break in the Combined Neutral and Earth network conductor is another kettle of fish.
 
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spinlondon said:
Due to the fact that the network neutral and earth are combined, any neutral current from the installation, will also be present in the earth conductors.
If incoming services are metallic and bonded, then diverted neutral currents from other installations that are bonded to the same services will also be present in the earth conductors.
A break in the Cobined Neutral and Earth network conductor is another kettle of fish.
Click to expand...
cheers Spin, I wasn't thinking of the bigger picture here. Methinks I might get me a copy of GN7
 
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