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Gas and Water Bonding - part 2
Question
Three weeks ago I asked about Bonding Gas & Water pipes and whether it was acceptable/permissible for the earth bonding conductor to be a single 10 mm² green/yellow from the consumer unit to go to say the water 351 earth clamp, looped around the screw and then to the gas 351 without cutting the cable, so that it is one continuous length. (Or if not looped around the crew, for a bare section to be opened up 3 strands and 4 strands and the screw fitted between?) https://communities.theiet.org/discussions/viewtopic/1037/28142?post_id=160255#p160255

Since then, I have been involved in the splitting of the water supply to replace lead pipe through the common meter to the two properties.

The original property was basically a village hall with an attached house for a caretaker. The water supply, via a single meter in lead pipe came into the village hall (at the front) and beneath the floor was split. One section went to the rear of the building where it entered as a lead riser to the stop tap where it became copper. A 351 on the 15mm copper is connected via 10 mm² green/yellow to the earth block in the meter cupboard. Three phase TNS with a conductor from the PILC to the earth block. A second 10 mm² green/yellow from the copper gas pipe at the meter outlet is connected to the earth block.

A new MDPE water pipe has been installed which comes up outside to be connected to the existing meter and to the existing 15mm copper water pipe which is located near to the gas meter and 351.
Similarly, for the caretaker's house, a new MDPE water pipe has been moled in to connect to an internal cold 15mm water pipe adjacent to the combi boiler. Currently there is a 10 mm² green/yellow between the house earth block adjacent to the house incoming PILC cable and the gas meter outlet pipe which is the other side of the wall to the combi boiler. This 10 mm² green/yellow is quite slack and my intention is to cut a section of g/y insulation off this cable and connect to a 351 where the MDPE connects.
The existing water supply into the house is at the other end of the lead pipe which beneath the village hall floor. Again at the stop tap there is a 351 with10 mm² green/yellow to the house earth block.

So, a couple of questions if I may.

1. There is insufficient slack on the village hall 10 mm² green/yellow to the 351 on the gas pipe to reach a 351 located on the nearby 15mm copper water pipe. Can the existing 10 mm² green/yellow to the gas pipe be connected into a 4-way earth block such as a https://www.screwfix.com/p/4-way-earth-block/12386 and the two 351s connected to this earth block using two 10 mm²?

I am a little wary, since a NAPIT registered friend, tells me that there HAS to be separate 10 mm² green/yellows for the gas and water pipes.

2. Can the original G/Y and 351 remain on the existing incoming water pipes in village hall and house?

Many thanks.
Clive
 
23 Replies
UKPN
218 Posts
Its a PILC cable sheath earth, DNO/PME rules dont apply. You can run two separate 10mmsqs.

Regards, UKPN
Good Morning Clive.
BS7671 has nothing to say about how bonding conductors are arranged, just the connectivity. There is no reason at all why cables cannot travel to several places, or be joined, although my preferred method would be a proper 10mm (or whatever size for larger installations) crimp, which then does not have to be visible. The BS951 clamps for pipes (351?) again may be connected as you say, but again my preferred method is suitable solid crimp tags as required under the screw, as this is infinitely more reliable than the cable conductors by themselves. The NAPIT man is simply wrong (and therefore should be prevented from carrying out any certification or EICR work), the feature from BS7671 is only the connectivity. Strangely this is not an unknown requirement of certain Electricians, I would like to know why they have this idea, maybe some throwback from the 15th edition?
As you now have a plastic supply pipe you may like to consider if main bonding is a good idea, or required, and whether whatever exists is useful or satisfactory.

Regards
David
mapj1
3555 Posts
There is nothing in BS7671 to say that the bonds need to be together or distinct, or unbroken,
It is a good idea not to use joints of the kind that come undone and get forgotten to be re-tightened after the plumber has done somthing, but there is certainly no compulsion in the regulations
Mike.

PS cross post with DZs fuller answer wich I agree with. I take a long time between composing and posting sometimes.
Zoomup
2916 Posts
411.3.1.2  Protective Equipotential Bonding.

Main equipotential bonding is only required on EXTRANEOUS CONDUCTIVE PARTS, like underground metal service pipes...water/gas/oil, that enter a building or introduce an Earth potential. Metal pipes that have an insulating section at the point of entry to a building do NOT need to be main bonded.

Z.

 
AJJewsbury
2580 Posts
If the water is now coming out of the ground in MDPE it probably doesn't need bonding anyway (other than if the metal pipework elsewhere then goes outside again or into a different installation - in which case there may be a more appropriate location for the bond).

It's nonsense to say gas and water have to have separate bonding conductors - even the BS code of practice for Earthing specifically says that one bond may serve both (but does have a recommendation that the conductor is not cut at the intermediate clamp).

  -  Andy.
Sparkingchip
4103 Posts
IET GN 8 Earthing and Bonding.  BS7671:2008.

I do not have the later editions. 



 
Sparkingchip
4103 Posts
davezawadi (David Stone):
 The NAPIT man is simply wrong (and therefore should be prevented from carrying out any certification or EICR work)

Regards
David


That's a bit harsh, he may have got over 99% of the questions in the Wiring Regulations exam correct. 😉

Sparkingchip
4103 Posts

528.3.3 requires a common main protective bonding conductor to be continuous, so that is a pipe clamp or the like is removed the conductor remains as a single length of cable. 
mapj1
3555 Posts

You could interpret that in more than one way, I do not read it as meaning  the wires have to be continuous,  -  presumably a 'Tee'  tap crimp or even a suitably supported in-line solder joint to a short flyer to the water pipe or whatever as the main bond sails past to an other destination  would also meet that requirement to the letter.
After all there are far more 'mission critical'  situations where  a sleeved solder joint in that style would be accepted....
I would like to say that in terms of the physics of connections we are not on an island, but strictly that is not true..

AJJewsbury
2580 Posts
I hadn't thought of 528.3.3 as being the source of the unbroken requirement - mainly as neither spacing nor shielding would achieve much.

I think the guidance for an unbroken conductor when looping multiple clamps comes more directly from BS 7430 (The code of practice for Earthing):
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.
- Andy.
Chris Pearson
2574 Posts
Sparkingchip:
528.3.3 requires a common main protective bonding conductor to be continuous, so that is a pipe clamp or the like is removed the conductor remains as a single length of cable. 

I think that has been taken out of context. 528.3 is all about protecting the wiring from water, heat, fumes; plumbers, and gas fitters.

Bonding is not in proximity to other services; it is in contact with them.

 

Sparkingchip
4103 Posts
Protecting the wiring from plumbers and gas fitters.

That’s bang on isn’t it?
wallywombat
454 Posts
I wonder if there has ever been a recorded incident of a plumber seeing a warning sign stating "safety electrical connection - do not remove" and coming to the conclusion that the connection should be left?
Sparkingchip
4103 Posts
I went into a house where the water pipe earthing clamp had been removed and asked the home owner why? He said it does not matter, so I asked why they had labels on them saying do not remove, I did not get an answer to that question.
Zoomup
2916 Posts
Sparkingchip:
I went into a house where the water pipe earthing clamp had been removed and asked the home owner why? He said it does not matter, so I asked why they had labels on them saying do not remove, I did not get an answer to that question.

House owners eh? Some just don't know what they don't know.

Z.

ebee
1166 Posts
Zoom,
quite a few plumbers think that  "Do not remove" means remove/disconnect from pipework and do not reconnect once pipeworks finished!
I think we have probably slagged off plumbers sufficiently! How about all the electricians who fit bonding to plastic pipes, or any of the other idiotic things they do?

It seems that my comment above about someone who has insufficient knowledge to use the regulations properly, should not offer certificates or reports, does not go down well. The truth often hurts, how can one responsibly do either of these things if they bear no relation to BS7671? That is the fundamental problem with the Electrical industry as a whole. Unfortunately, it is also very difficult to fix, because many "vested interests" do not see it as a problem that concerns them, as it might reduce income streams, and anyway, proper training is both time consuming and expensive, and there are very few informed trainers!.
geoffsd
208 Posts

Bonding conductors obviously do not have to be continuous as other parts (except gas pipes) may themselves be used as a bonding conductor.

 
AJJewsbury
2580 Posts
wallywombat:
I wonder if there has ever been a recorded incident of a plumber seeing a warning sign stating "safety electrical connection - do not remove" and coming to the conclusion that the connection should be left?

Well I know of one - main gas pipe after the meter had clearly been replaced - 6" of the original was still there supported by the bonding conductor... So it seems they had read the notice and done exactly what they were told ... just not what was really wanted.

  - Andy.

Chris Pearson
2574 Posts
AJJewsbury:
wallywombat:
I wonder if there has ever been a recorded incident of a plumber seeing a warning sign stating "safety electrical connection - do not remove" and coming to the conclusion that the connection should be left?

Well I know of one - main gas pipe after the meter had clearly been replaced - 6" of the original was still there supported by the bonding conductor... So it seems they had read the notice and done exactly what they were told ... just not what was really wanted.

That might be slightly on the autistic spectrum, but it is entirely correct in a literal sense.

You could imagine the same with a bit of supplementary bonding - two pipes to a wash-hand basin joined forever. 😁

Zoomup
2916 Posts
I have just renewed a small consumer unit. Upon checking the main bonding I found a card on top of the gas meter, which had recently been renewed. It said that as P.M.E. earthing was present it was important to main bond the gas pipes. No evidence was visible that bonding was present on the gas pipes. The householder claims that they were not told of this matter. Who searches into the dark spider world cupboard where the gas meter lurks to read unannounced notices. The gas meter had a nice new stainless steel flexible pipe with a notice saying keep flux away from the pipe, and a length of lead pipe which converted to steel as it disappeared into the floor. Just enough steel pipe to get a clamp onto.

Z.
hertzal123
72 Posts
If bonding conductors had to be continuous  ,bonding cables could not be run from a board at the end of a sub main?
                     hz.
Clearly. That is one reason why they don't!

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