Bonding gas/water yellow and blue

[Deleted member 26818]

Keeps reloading page

 

[LeeH]

I would expect you to if those legs are not connected together above ground.

Yes, obviously.

My confusion is the statement that you need to bond the same ‘pipe’ that ducks in and out of a floor.

2 extraneous parts I understand. The same extraneous part twice I do not.

 

[LeeH]

Still having problems with this site.

The kitty is running low, please click on the ropey adds to resume normal service.

 

[Deleted member 26818]

Problem with pipework that ducks under ground, is you don’t know what is happening with it.
Is it continuous?
Has it corroded?
Is it protected against corrosion?
Are there branches, or is it itself a branch?
Can you guarantee the pipe will never be disconnected?

The other problem is that the minimum CSA for an Earth conductor buried in the ground and not protected against corrosion by a sheath is 25mm2, 16mm2 if protected.

 

[Midwest]

Can someone reference the reg for testing an extraneous-conductive-part, in the examples given by 411.3.1.2. I only ask that, you would not need to test (those examples), as the reg says they have to be bonded, end of?

 

[telectrix]

re spinlondon's post:

The other problem is that the minimum CSA for an Earth conductor buried in the ground and not protected against corrosion by a sheath is 25mm2, 16mm2 if protected.

sureley that's for an earthing conductor, as in connected to a rod., not for a bonding conductor?

 

[Pete999]

re spinlondon's post:

The other problem is that the minimum CSA for an Earth conductor buried in the ground and not protected against corrosion by a sheath is 25mm2, 16mm2 if protected.

sureley that's for an earthing conductor, as in connected to a rod., not for a bonding conductor?

Agree that would make nonsense of the 4mm2 non protected and 2.5mm2 protected rules for supplementary bonding conductors, wouldn't it? Or has that been changed?

 

[HappyHippyDad]

When the 18th is published it looks like they have put it in black and white that if the incomer is plastic then doesn't need bonding.

That sounds promising Lee! Where did you see that, can you post a link please?

 

[Leesparkykent]

That sounds promising Lee! Where did you see that, can you post a link please?

The impact of the 18th Edition (BS 7671:2018) – Chapters 41, 46, 53 and Regulation 542.2.2 - IET Electrical - https://electrical.------.org/wiring-matters/66/impact-18th-cha-41-46-53/index.cfm

Look at 411.3.1.2 in the above link.

 

[ipf]

When the 18th is published it looks like they have put it in black and white that if the incomer is plastic then doesn't need bonding.

Bleedin' daft this 18th.....now they're telling us we have to change from green and yellow cable to black and white cable....if it's plastic.

 

[Midwest]

Lets also hope the earth rod & AFFD's also bite the dust, which some have suggested has.

 

[Deleted member 26818]

Can someone reference the reg for testing an extraneous-conductive-part, in the examples given by 411.3.1.2. I only ask that, you would not need to test (those examples), as the reg says they have to be bonded, end of?

There’s no Reg stating you have to test whether something is an extraneous conductive-Part.
There’s no need for one.
If it’s extraneous (i.e. comes into the building from outside), is conductive (i.e. can conduct electricity) and likely to introduce a difference in potential, then it needs bonding.

Determining whether something is extraneous is relatively easy, in the majority of instances you don’t even need to look, you just know.
Gas, water, electricity, cable TV, satalite TV, waste water, telephone, oil, etc. they’re all extraneous.

Determining whether something is a conductive-part however, seems to be problematic.
Plastic coated telephone cables, satellite and cable TV cables along with plastic waste pipes are all deemed as non-conductive.
For some reason, there’s confusion as to whether plastic gas pipes, plastic water pipes and plastic coated oil lines are conductive.
Because of this confusion, a lot of people are advising we test these supplies to determine whether there’s any connection to Earth.
Unfortunately there seems to be various views on what resistances indicate either a reliable connection to Earth or no connection to Earth.
Some say 0.05 Ohms, others say 20 Ohms indicate a reliable connection to Earth.
For whether there’s no connection to Earth the figures for resistance are 23 Mohms or 7.67 Kohms (22 Mohms and 6.67 Kohms when the 1 Mohm resistance of the human body is taken into account).

 

[Midwest]

There’s no Reg stating you have to test whether something is an extraneous conductive-Part.
There’s no need for one.
If it’s extraneous (i.e. comes into the building from outside), is conductive (i.e. can conduct electricity) and likely to introduce a difference in potential, then it needs bonding.

Determining whether something is extraneous is relatively easy, in the majority of instances you don’t even need to look, you just know.
Gas, water, electricity, cable TV, satalite TV, waste water, telephone, oil, etc. they’re all extraneous.

Tis what I've been saying for the best part of this thread. If its metal and comes out of the ground or into a building, then according to 411.3.1.2 it needs bonding. Some are suggesting testing it. Doesn't need testing, just bonding.

My rub is, with the plastic metal combo, unless your building the property yourself, how do you ensure that the metal part of the combo, isn't 'liable' to do the above.

 

[Deleted member 26818]

My rub is, with the plastic metal combo, unless your building the property yourself, how do you ensure that the metal part of the combo, isn't 'liable' to do the above.

Test.

 

[Midwest]

Test.

Why.

 

[Ian1981]

I did some students flats last year.
Plastic incoming water supply to each building then copper pipework.
From copper in the corridors it went to plastic entering each student room.
Showed the apprentice the testing procedure for testing extraneous parts using an insulation resistance tester.
The result was around 20Mohms.
Did I bond any copper pipes?
NOPE!

 

[Deleted member 26818]

Why.

Because, you want to verify that the extraneous conductive-parts are not likely to introduce a difference in potential.
Thus saving you from installing unnecessary bonding which may introduce a potential hazard.

 

[Deleted member 26818]

Here’s a link to an article which may help:
A guide to the determination of extraneous-conductive-parts - https://www.voltimum.co.uk/articles/guide-determination-extraneous

 

[Midwest]

Ok my last swipe at this; you don't test the pipes for 411.3.1.2, 544.1.2 says bond it after plastic.

I think this will just keep going around, until the 18th comes out.

This had an interesting discussion on such testing etc;

Bonding water services when plastic pipes are present - https://www.electriciansforums.co.uk/threads/bonding-water-services-when-plastic-pipes-are-present.61592/

Earthing water. Part plastic, part copper - https://www.electriciansforums.co.uk/threads/earthing-water-part-plastic-part-copper.30881/

 

[Deleted member 26818]

Agree that would make nonsense of the 4mm2 non protected and 2.5mm2 protected rules for supplementary bonding conductors, wouldn't it? Or has that been changed?

Why?

 

[Deleted member 26818]

re spinlondon's post:

The other problem is that the minimum CSA for an Earth conductor buried in the ground and not protected against corrosion by a sheath is 25mm2, 16mm2 if protected.

sureley that's for an earthing conductor, as in connected to a rod., not for a bonding conductor?

Alsways took it as applying to al Earth conductors.
Main earths, bonding, CPCs, etc.

 

[Simonslimline]

no.the 22k ohms is to prove whether or not a piece of copper /metal pipe is extraneous or not.

22k plus 1k for human body.

so 230volts/23K Ohms = 0.01Amps.

GN8 goes in to this.

 

[Deleted member 26818]

Just realised, I’ve been using Mohms instead of Kohms.

 

[Pete999]

Why?

Apologies spin misread the original post, my mistake

 

[Midwest]

Still not convinced.

However, having verified (by testing) that the internal metal pipework was extraneous and required bonding, would you bond it using a main protective bonding conductor or using a supplementary bonding conductor?

 

[Deleted member 26818]

If it’s extraneous, then it would be main bonding.
Supplementary bonding is for special locations and where Zs of a circuit is too high.

 

[Pete999]

If it’s extraneous, then it would be main bonding.
Supplementary bonding is for special locations and where Zs of a circuit is too high.

Thank you spinlondon

 

[mattg4321]

It's not a grey area. If it's an extraneous conductive part it needs bonding. If it's not an extraneous conductive part it doesn't need bonding. I always run a green and yellow in for gas and water on a new builds as I've had muppet meter fitters refusing to connect as no bonding, even though it didn't require bonding. If they moan I connect it then chop it off when the muppet has finished.

The other favourite of theirs is when they tell you the gas isn't bonded and they've only looked at the external meter box. They then insist it should be bonded at the external meter box even though we all know the regs say it should be at the point of entry into the building. Muppets

 

[Pete999]

The other favourite of theirs is when they tell you the gas isn't bonded and they've only looked at the external meter box. They then insist it should be bonded at the external meter box even though we all know the regs say it should be at the point of entry into the building. Muppets

Lets be fair the meter box IS the entry point to the building, albeit external, that's where the Gas and Electricity enter the building, it does in my house.

 

[Ian1981]

Let’s face it if you didn’t bond it at the meter box then the only other logical place is the likes of the boiler as take new builds the pipe enters the house and is buried in the wall.
Then it’s not bonded within 600mm of point of entry.

 

[mattg4321]

544. 1.2

“The main equipotential bonding connection to any gas, water or other service shall be made as near as practicable to the point of entry of that service into the premises. Where there is an insulating section or insert at that point, or there is a meter, the connection shall be made to the consumer's hard metal pipework and before any branch pipework. Where practicable the connection shall be made within 600mm of the meter outlet union or at the point of entry to the building if the meter is external”

Strongly implies that you shouldn’t bond at the meter box. However I do bond there if that’s the most practical place for it. Meter fitters hate it when I point out this regulation to them after I’ve bonded at the point of entry. Say where the pipe work comes out of a semi buried meter box and in through the wall to a cupboard housing the boiler.

A bit of common sense is all that’s needed

 

[willy fixit]

Common sense...
Muppet missed one out!

 

[charlie76]

Even with a plastic incoming water supply, if the installation is completely metallic (copper) it will almost definitely be introducing earth potential via the connection at the boiler. Where the plumber has bonded all the pipes together at the boiler as in the above picture, you can be sure all the metallic pipework will be introducing earth potential as the gas supply pipe to the boiler will be metallic and earthed at the boiler.

So unless you can confirm the pipework is not at earth potential (which it will be if it is an all metallic installation and the boiler supply is correctly earthed) then it will need bonding.

 

[Deleted member 26818]

Even with a plastic incoming water supply, if the installation is completely metallic (copper) it will almost definitely be introducing earth potential via the connection at the boiler. Where the plumber has bonded all the pipes together at the boiler as in the above picture, you can be sure all the metallic pipework will be introducing earth potential as the gas supply pipe to the boiler will be metallic and earthed at the boiler.

So unless you can confirm the pipework is not at earth potential (which it will be if it is an all metallic installation and the boiler supply is correctly earthed) then it will need bonding.

If the gas supply is metallic and bonded, and the water supply is plastic but the internal metallic water pipes are cross bonded with the metallic gas pipe, then it will all be at the same potential

 

[Deleted member 26818]

View attachment 40776 Common sense...
Muppet missed one out!

Waste of time cross bonding that lot, they’re all joined together by that bracket.

 

[Wilko]

Waste of time cross bonding that lot, they’re all joined together by that bracket.

Makes me laugh

 

[Pete999]

Makes me laugh

Taught at a Electrical Trainee course no doubt.

 

[charlie76]

If the gas supply is metallic and bonded, and the water supply is plastic but the internal metallic water pipes are cross bonded with the metallic gas pipe, then it will all be at the same potential

Agreed. But.... not relevant. If that was acceptable then you could say let’s only bond the gas even if the water is on a metallic supply pipe as it’s all at the same potential.

I’m only interpreting the regs.

 

[Midwest]

If it’s extraneous, then it would be main bonding.
Supplementary bonding is for special locations and where Zs of a circuit is too high.

Seems strange we are using a test for verifying the effectiveness of supplementary bonding, to establish if something needs to have main protective bonding conductor?

 

[Ian1981]

It’s not a test to verify supplementary bonding at all.
As bs 7671 states where doubt exists about the effectiveness of supplementary bonding conductors then the formula 50/Idelta N can be used in the case of an rcd or 50/Ia , if No rcd ,can be used to determine the effectiveness of the supplementary bonding to pipework

 

[Ian1981]

Agreed. But.... not relevant. If that was acceptable then you could say let’s only bond the gas even if the water is on a metallic supply pipe as it’s all at the same potential.

I’m only interpreting the regs.

no you couldn’t say that because the pipework could be altered or even disconnected which is why we provide bonding as close to the intake position as possible and before any branches or tee sections

 

[Midwest]

It’s not a test to verify supplementary bonding at all.
As bs 7671 states where doubt exists about the effectiveness of supplementary bonding conductors then the formula 50/Idelta N can be used in the case of an rcd or 50/Ia , if No rcd ,can be used to determine the effectiveness of the supplementary bonding to pipework

I don't how to respond to your post, isn't your first & second paragraph the same statement?

 

[Ian1981]

I’m saying testing a piece of metal to see if it’s an extraneous conductive part isn’t the same test to verify supplementary bonding conductors where doubt exists over there effectiveness.
I thought it was quite clear really.

 

[Midwest]

I’m saying testing a piece of metal to see if it’s an extraneous conductive part isn’t the same test to verify supplementary bonding conductors where doubt exists over there effectiveness.
I thought it was quite clear really.

I'm not trying to be confrontational, just trying to understand. I thought there was only one testing procedure, aka 415.2.2 and or Chris Kitcher video explanation.

 

[Ian1981]

I'm not trying to be confrontational, just trying to understand. I thought there was only one testing procedure, aka 415.2.2 and or Chris Kitcher video explanation.

No confrontation by me was meant it’s just the way the txt has come out I think.
I know the testing of extraneous parts comes from Gn8 and the 10mA “yeah I felt that “ approach.

 

[Midwest]

No confrontation by me was meant it’s just the way the txt has come out I think.
I know the testing of extraneous parts comes from Gn8 and the 10mA “yeah I felt that “ approach.

I'll have a read of GN8 & 3. Only asking as I come across a lot of existing PME installs, with existing bonding to plastic copper combo's in 6mm (16mm tails).

Edit; think I asked some advice from Elecsa Tech', see if I can dig up their response. I know the stance now with a metal service, is it must be upgraded to 10mm, whatever. Which is a nonsense, when doing some minor work!

 

[Deleted member 26818]

You don’t have to upgrade, unless there is evidence that the existing bonding is under stress.

 

[Ian1981]

I'll have a read of GN8 & 3. Only asking as I come across a lot of existing PME installs, with existing bonding to plastic copper combo's in 6mm (16mm tails).

Edit; think I asked some advice from Elecsa Tech', see if I can dig up their response. I know the stance now with a metal service, is it must be upgraded to 10mm, whatever. Which is a nonsense, when doing some minor work!

Well this is from the Electrical safety council website.
It’s down to the installer I guess and his interpretation of the requirements of bs 7671
Q1.67 When carrying out electrical work on an installation forming part of a TN-C-S system, is it necessary to upgrade existing 6 mm² protective equipotential bonding to 10 mm²?
Not necessarily. If the existing 6 mm² bonding connects all the extraneous-conductive-parts to the main earthing terminal, has been in place for a significant time and shows no signs of thermal damage, then it may not require to be upgraded.

Regulation number(s)

• 132.16
  
• 544.1.1

 

[Midwest]

There has been - Certsure wise - a change to that particular guidance. As its taken me about ten mins to post these few lines, I'll post tomorrow, when its less busy!

 

[Ian1981]

There has been - Certsure wise - a change to that particular guidance. As its taken me about ten mins to post these few lines, I'll post tomorrow, when its less busy!

Well I can’t see how say you move a light switch from one wall to another and you complete a minor works certificate PME earthing arrangement.
If the main protective bonding is in 6mm and has been there say all the installations life maybe 30 years, then to say you have to upgrade to 10mm which could be a pig of a job is ridiculous in my opinion