Is this really correct?

[Sparky83]

Hi guys,

On a forum i often go on someone was asking about the MEB to there gas pipe as the gas engineer had pointed out that there was bonding to both side of the gas meter.

Someone asked this question...

Aren't gas mains plastic too? What is the earthing for, to protect those inside the property from an issue that causes the pipework to become live?


Somebody whom says they are an electrician said the following...

its to stop external influences affecting your metal work essentially, nowadays most incoming gas/water bonds are plastic and don't need the equipotential bonding to them but most sparkies do it anyway, just disconnect the before clamp wire and put it in the post clamp terminal, easy job and should take 2 mins. nothing will happen when you remove it, just make sure its tight enough not to pull out and the clamp should not spin on the pipe either

Now is this correct? As im pretty sure that you always need the MEB to be in place?

I did question this with him and his reply about did he mean supps was...

main bonds too, i know it seems crazy to me too, it come up on my last nic inspection i went to.

he asked why i bonded main earth and water when they was plastic incoming. if its not metal incoming into the property the the metal work is inside is classed as supplementary, (not required now) he then proceeded to ask me how i would get a shock from metal work if it wasn't even connected to the "installation" with so many instances where continuity cannot be obtained on all pipe work then there should never be a potential difference between materials. hence no bonds no difference. obviously all circuits in said install have to be 30ma rcd protected

(again im no lecturer but those who have niceic inspections know how ---- they can be, so only going on what im told)

Hope it makes sense, Any thoughts on the above?

 

[pjcomp]

Some older properties had (still have) the gas and/or water pipe as the main earth. As these supply pipes are being converted to plastic they are failing to provide earthing to the property.

PJ

 

[Darkwood]

Because of incoming plastic service supplies - the need for equipotential Bonding is a must, this is because the metal pipework within the installation is effectively isolated from ground. If no bonding was present then a fault Live - earth (gas/water pipes) would create a 230v potential between all the metal pipework, sinks etc etc and anything connected to earth like appliances the floor itself thus been in contact with both item would see you become part of the fault circuit EEEK!.
Before plastic incoming pipes they were brought in in lead,steel, iron etc etc which because its conductive and was buried in the ground gave natural earth bonding, this is why older installation may have no bonding at all, and in some cases earthing was pinched off the pipework if needed for a light etc.
The muppet on said other site is a dangerous mouth and if you could just PM him and send him to this site maybe he may learn a thing or 2 before he puts someone in danger.

 

[roukel01]

Its the first time I have had a look at my new green onsite guide. However, pages 40,41,42 seem to verify what you were saying about not installing main bond to plastic incoming services. The HOWEVER is that you have to confirm that any metallic pipework within the building is not introducing earth potential.

 

[malcolmsanford]

Because of incoming plastic service supplies - the need for equipotential Bonding is a must, this is because the metal pipework within the installation is effectively isolated from ground. If no bonding was present then a fault Live - earth (gas/water pipes) would create a 230v potential between all the metal pipework, sinks etc etc and anything connected to earth like appliances the floor itself thus been in contact with both item would see you become part of the fault circuit EEEK!.
Before plastic incoming pipes they were brought in in lead,steel, iron etc etc which because its conductive and was buried in the ground gave natural earth bonding, this is why older installation may have no bonding at all, and in some cases earthing was pinched off the pipework if needed for a light etc.
The muppet on said other site is a dangerous mouth and if you could just PM him and send him to this site maybe he may learn a thing or 2 before he puts someone in danger.

Really DW?

I would say that if your start bonding metal work that wasn't an extraneous conductive part then you more likely to make that piece of metal live during a fault. We after all don't bond metal door frames, windows etc, as they have no contact with earth, and so bonding a metal pipe within an installation, that as no connection with earth, ie main pipe coming in plastic, but internal installation is copper, is IMO not needed.

Of course it is always best to check if the pipe is an extraneous conductive part, but if it isn't it don't need bonding

 

[Amp David]

There is one good way to see if something actually requires bonding and that's to test it, isn't it?

 

[RWJ]

Sounds similar to a job we recently did where all the plumbing was plastic and the plumber wanted each tap bonding

 

[SPARTYKUS]

Hi guys,

On a forum i often go on someone was asking about the MEB to there gas pipe as the gas engineer had pointed out that there was bonding to both side of the gas meter.

Someone asked this question...

Aren't gas mains plastic too? What is the earthing for, to protect those inside the property from an issue that causes the pipework to become live?


Somebody whom says they are an electrician said the following...

its to stop external influences affecting your metal work essentially, nowadays most incoming gas/water bonds are plastic and don't need the equipotential bonding to them but most sparkies do it anyway, just disconnect the before clamp wire and put it in the post clamp terminal, easy job and should take 2 mins. nothing will happen when you remove it, just make sure its tight enough not to pull out and the clamp should not spin on the pipe either

Now is this correct? As im pretty sure that you always need the MEB to be in place?

I did question this with him and his reply about did he mean supps was...

main bonds too, i know it seems crazy to me too, it come up on my last nic inspection i went to.

he asked why i bonded main earth and water when they was plastic incoming. if its not metal incoming into the property the the metal work is inside is classed as supplementary, (not required now) he then proceeded to ask me how i would get a shock from metal work if it wasn't even connected to the "installation" with so many instances where continuity cannot be obtained on all pipe work then there should never be a potential difference between materials. hence no bonds no difference. obviously all circuits in said install have to be 30ma rcd protected

(again im no lecturer but those who have niceic inspections know how ---- they can be, so only going on what im told)

Hope it makes sense,Any thoughts on the above?

Hi
sparky83

Wrt the mention of supp bonding not required now, this tends to be a blanket statement and is not nec. True. It depends. Not every circuit in a house, even under the 17th, amended, HAS to be on an RCD. This another blanket belief. In fact I have a socket in my garage that has no RCD PROTECTION!

 

[Des 56]

There is always conflict of opinion on the forum for necessity for main bonding

I posted a link in another tread to an article by Paul Cook of the Iet
It is worth reading because its a simple outline of why and what requires to be bonded,given the various combinations of internal and supply service materials

Please note the following,quoted from the article

It is important to note that the reference above is always to metal pipes. If the pipes
are made of plastic, they do not need to be main bonded.

If the incoming pipes are made of plastic, but the pipes within the electrical
installation are made of metal, the main bonding must be carried out

In the link there is also a chart that details combinations of materials in a bathroom where supplementary bonding can be assessed

Here is that link
http://www.plasticpipesgroup.com/pdfs/earthbonding.pdf

 

[Sparky83]

There is always conflict of opinion on the forum for necessity for main bonding

I posted a link in another tread to an article by Paul Cook of the Iet
It is worth reading because its a simple outline of why and what requires to be bonded,given the various combinations of internal and supply service materials

Please note the following,quoted from the article

It is important to note that the reference above is always to metal pipes. If the pipes
are made of plastic, they do not need to be main bonded.

If the incoming pipes are made of plastic, but the pipes within the electrical
installation are made of metal, the main bonding must be carried out

In the link there is also a chart that details combinations of materials in a bathroom where supplementary bonding can be assessed

Here is that link
http://www.plasticpipesgroup.com/pdfs/earthbonding.pdf

Thanks for the replies guys, i understand not bonding the plastic pipes, but thought you would need to bond them where the plastic meets the metal pipe, and having read the link above it would seem this is the case.

Thanks again.

 

[malcolmsanford]

What a wonderful thing our industry is there is someone. Paul Cook regarded as an authority claiming that if incoming is plastic but installation is metal .........off we go and bond away, regardless of whether that metal is an extraneous conductive part

or in our OSG guide section 4.5 we have

"Where there is a plastic incoming service and a metal installation within the premises, main bonding is recommended"

So it would seem My Cook is right, ahhhhhhhhhhhh hold on though , OSG continues

"​unless it has been confirmed that any metallic pipework within the building is not introducing earth potential (see4.3)"


So what do we do, bond away anything that is metal or a pipe in case it introduces a potential, or do our jobs. If I found plastic incoming services gas/water, but metal pipework in the installation, before I start bonding everything in sight I might, just might check to see if that metalwork is in fact an extraneous conductive part.

 

[Des 56]

I would also agree with your last post Malcolm

But for many, new to absorbing the straight and narrow unclouded guidlines that are found in our industry :blush5: it is a daunting task to come to a decision themselves, when reliance on those guidlines is so crucial to them,especially when confronted with perhaps an assessor who may have regimented thoughts on the matter and an unbending opinion on what should or should not be done

 

[Deleted member 9648]

The only reason for main bonding is to tie services introducing an external earth potential to the electrical earthing system....
The only reason for supplementary bonding is to tie services introducing an earth potential into a special location (as defined in bs7671) to the electrical earthing within that location.
Thats all you need to know....not brain surgery....so why do so many fail to get it?

 

[malcolmsanford]

Totally agree Des, but if we start bonding bits of metal that don't need it, surely we are in danger of making that piece of metal "live" during a fault.

Ok it will be for milli-seconds if the protection device is correct, and what are the chances during those milli-seconds the wife is touching a bonded non extraneous part, soaking wet, believe me Des I've tried to get all those in place, but she won't stand still long enough.

But still I can't see how bonding a non extraneous part, is making the installation safer.

 

[malcolmsanford]

The only reason for main bonding is to tie services introducing an external earth potential to the electrical earthing system....
The only reason for supplementary bonding is to tie services introducing an earth potential into a special location (as defined in bs7671) to the electrical earthing within that location.
Thats all you need to know....not brain surgery....so why do so many fail to get it?

Address to Mr Cook care of the IE..................................