C
chopper
were currently doing a job in massive old pub whats going to be a libary, my gaffer says put 10mm bonding to gas and water but how do you actually work out what size is required
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
By selection from BS7671
Section 544
By selection from BS7671
Section 544
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D
Deleted member 26818
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
It depends on the earthing system, the size of the main earth and the size of the supply neutral conductor.
With TT and TN-S, you determine the size required for the main earth using the adiabatic equation, then bonding conductors are half the CSA of the calculated main earth CSA, but no smaller than 6mm².
With TN-C-S, both the main earth and any bonding conductors are sized according to table 54.8 in BS7671, with the minimum being 10mm².
It depends on the earthing system, the size of the main earth and the size of the supply neutral conductor.
With TT and TN-S, you determine the size required for the main earth using the adiabatic equation, then bonding conductors are half the CSA of the calculated main earth CSA, but no smaller than 6mm².
With TN-C-S, both the main earth and any bonding conductors are sized according to table 54.8 in BS7671, with the minimum being 10mm².
C
chopper
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
just to add to this, i have just finished a apprentiship and i have never been taught about this, we do mainly houses so we allways install 10mm, but i just like to know for my own knoledge
just to add to this, i have just finished a apprentiship and i have never been taught about this, we do mainly houses so we allways install 10mm, but i just like to know for my own knoledge
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
Surely you would have covered sizing of protective bonding conductors at college?
If you havn't got any course notes or reference I am sure we can find something.
Surely you would have covered sizing of protective bonding conductors at college?
If you havn't got any course notes or reference I am sure we can find something.
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
Do you not have the On-Site Guide?
Page 27 onwards has it covered.
Do you not have the On-Site Guide?
Page 27 onwards has it covered.
C
chopper
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
after thinking about what i said, we did get a breif lesson i remember the tutor saying bonding should be half size of the neutral, after just looking in regs it does say this but if you have any notes or links that would be great
why is it half the neutral though and not half x a phase presume sometimes the neutral is different sizes on 3 phase some time, i not had much experience on 3 phse
after thinking about what i said, we did get a breif lesson i remember the tutor saying bonding should be half size of the neutral, after just looking in regs it does say this but if you have any notes or links that would be great
why is it half the neutral though and not half x a phase presume sometimes the neutral is different sizes on 3 phase some time, i not had much experience on 3 phse
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E
ezzzekiel
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
not sure what this guy is studying
not sure what this guy is studying
M
malcolmsanford
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
Read post 3 and Spinlondons excellent post, in a TNC-S the size of the Main Bonding conductor is proportional to the size of the incoming neutral and is explained in table 54.8 of the regs.
In a TT TN-S system the Main Bonding conductor is sized as minimum to be half the CSA of the Main Earthing Conductor, and must exceed 6mm.
The Main Bonding Conductor is sized for a TNC-S system on the Neutral conductor because it is the PEN conductor ( see the definitions in section 2 of the regs)
Read post 3 and Spinlondons excellent post, in a TNC-S the size of the Main Bonding conductor is proportional to the size of the incoming neutral and is explained in table 54.8 of the regs.
In a TT TN-S system the Main Bonding conductor is sized as minimum to be half the CSA of the Main Earthing Conductor, and must exceed 6mm.
The Main Bonding Conductor is sized for a TNC-S system on the Neutral conductor because it is the PEN conductor ( see the definitions in section 2 of the regs)
M
malcolmsanford
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
That is a totally inane post.
The lad is learning and asking questions on here after completing his training, and by posting that drivel as taught him absolutely nothing, except perhaps the merit of your help.
I have to assume you know everything by now and deem this lads question beneath you, if that is the case, perhaps you will refrain from posting such in-depth replies to subjects that are obviously beneath you.
As you have posted just 15 times in 3 years perhaps your best off as lurker status, and leave replies to peoples questions to those on here that wish to help them
That is a totally inane post.
The lad is learning and asking questions on here after completing his training, and by posting that drivel as taught him absolutely nothing, except perhaps the merit of your help.
I have to assume you know everything by now and deem this lads question beneath you, if that is the case, perhaps you will refrain from posting such in-depth replies to subjects that are obviously beneath you.
As you have posted just 15 times in 3 years perhaps your best off as lurker status, and leave replies to peoples questions to those on here that wish to help them
S
SPARTYKUS
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
Hi Chopper, another thing to watch is distance from MET; for example if you're up to 27/28 metres with your bonding 'run' then its at the limit of its required resistance ( <0.05 Ohms ). In this case (if it was,say,35 metres) then you should use 16mm2.
Is that right btw re: the 1/2 the neutral size just for TNCS? Isn't it for TN systems. Or am I wrong again!
Hi Chopper, another thing to watch is distance from MET; for example if you're up to 27/28 metres with your bonding 'run' then its at the limit of its required resistance ( <0.05 Ohms ). In this case (if it was,say,35 metres) then you should use 16mm2.
Is that right btw re: the 1/2 the neutral size just for TNCS? Isn't it for TN systems. Or am I wrong again!
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Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
Yes, a bit of confusion, it's sized in PROPORTION to the SUPPLIER'S neutral conductor (not the tails) on TN-C-S systems, and there isn't actually a 0.05 Ohm resistance limit on main protective bonding.
Yes, a bit of confusion, it's sized in PROPORTION to the SUPPLIER'S neutral conductor (not the tails) on TN-C-S systems, and there isn't actually a 0.05 Ohm resistance limit on main protective bonding.
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
and that's a new one on me. is the 0.05 only applicable to TN-S then, IQ?
and that's a new one on me. is the 0.05 only applicable to TN-S then, IQ?
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
No, it's only applicable between extraneous-conductive parts as in supplementary bonding, the figure does not apply to main protective bonding.
We had a good thread here around a year ago on this very thing.
Have a look at BS7671:2008 and Guidance Note 3 and you can see where the confusion comes from-the key word is between.
No, it's only applicable between extraneous-conductive parts as in supplementary bonding, the figure does not apply to main protective bonding.
We had a good thread here around a year ago on this very thing.
Have a look at BS7671:2008 and Guidance Note 3 and you can see where the confusion comes from-the key word is between.
M
malcolmsanford
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
If you look on the forms EIC and PIR forms the sections Main Protective Conductors just ask for a "verified connection" and not for a value. As our learned friend posts it is the terminology once again of our beloved regs that throws us.
If you look on the forms EIC and PIR forms the sections Main Protective Conductors just ask for a "verified connection" and not for a value. As our learned friend posts it is the terminology once again of our beloved regs that throws us.
E
ezzzekiel
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
new one on me any links to original thread?
my understanding was bonding should have a resistance upto 0.05ohms (10mm good for about 27metres)
just dug this up from quick search:
bonding serves the purpose of ensuring that no dangerous potential differences can occur. The resistance of such a bonding conductor must be low enough to ensure that its volt drop when carrying the operating current of the protective device never exceeds 50 V
which brings me back to what iq is saying as the above description fits the r<50/ia formula for supp bonding ?
new one on me any links to original thread?
my understanding was bonding should have a resistance upto 0.05ohms (10mm good for about 27metres)
just dug this up from quick search:
bonding serves the purpose of ensuring that no dangerous potential differences can occur. The resistance of such a bonding conductor must be low enough to ensure that its volt drop when carrying the operating current of the protective device never exceeds 50 V
which brings me back to what iq is saying as the above description fits the r<50/ia formula for supp bonding ?
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G
GLENNSPARK
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
NO...NO...NO...keep him posting please....as i have much to learn too (which is why i keep coming in here)...but i am sure his wisdom will soon baffle us all..............
D
Deleted member 26818
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
Damn, just not applying myself.
M
malcolmsanford
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
Oh don't ignore me TQ .........................please
Oh don't ignore me TQ .........................please
S
SPARTYKUS
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
HelloPage 74, GN3, 3.10.3 "detailed periodic inspecting". 4th para down :"When testing the effectiveness of main equipotential bonding conductors, the resistance value between a service pipe or other extraneous-conductive-part and the main earthing terminal should be of the order of 0.05 Ohms or less"Can't see the confusion there...? Am I missing something. Seems clear to me....
HelloPage 74, GN3, 3.10.3 "detailed periodic inspecting". 4th para down :"When testing the effectiveness of main equipotential bonding conductors, the resistance value between a service pipe or other extraneous-conductive-part and the main earthing terminal should be of the order of 0.05 Ohms or less"Can't see the confusion there...? Am I missing something. Seems clear to me....
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
Spartykus, I know what you are referring to here but read it again carefully, where does it say that the resistance of the bonding conductors should be defined?
The measurement is taken between the extraneous-conductive part and the main earthing terminal, you will not find any reference to a resistance limit of the bonding conductors in BS7671 or any of the Guidance Notes.
Spartykus, I know what you are referring to here but read it again carefully, where does it say that the resistance of the bonding conductors should be defined?
The measurement is taken between the extraneous-conductive part and the main earthing terminal, you will not find any reference to a resistance limit of the bonding conductors in BS7671 or any of the Guidance Notes.
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
however, the extraneous part ( say water pipe) is connected to the MET by means of it's bonding conductor, so by inference, that bonding conductor must have a resistance of 0.05ohms or less.
however, the extraneous part ( say water pipe) is connected to the MET by means of it's bonding conductor, so by inference, that bonding conductor must have a resistance of 0.05ohms or less.
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
But that's not allowing anything for a parallel path on the extraneous-conductive part....
But that's not allowing anything for a parallel path on the extraneous-conductive part....
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
It's a poorly written piece-I've got a meeting with Darrell Locke at the IET on 1st November for the Guidance Note 3 amendment-if he hasn't covered it already, I will certainly be drawing attention to it.
It's a poorly written piece-I've got a meeting with Darrell Locke at the IET on 1st November for the Guidance Note 3 amendment-if he hasn't covered it already, I will certainly be drawing attention to it.
brucelee
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Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
HI mate get them told wish someone would then there would be less confusion as far as I was aware its below 0.05 as this is what i was taught on 2391 last year and read but now you have said i will have another read properly lol for the umpteenth time
HI mate get them told wish someone would then there would be less confusion as far as I was aware its below 0.05 as this is what i was taught on 2391 last year and read but now you have said i will have another read properly lol for the umpteenth time
S
SPARTYKUS
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
:smile5:Morning:smile5:
IQ - Thanks for your patience. I hope you're not too jaded covering something you've clearly been over before, so thanks for bearing with me. I just wanted to understand why you said what you said, as, has been pointed out by several other (learned) members, and time served sparks I know, they all believe it to be so (the 0.05 Ohms or less for the main bond...etc etc). And also, recently, as BruceLee points out, on 2391 courses (was taught this on mine a few years ago too, and it was in all the text books I fervently acquired ....)
HOWEVER! I have stuck with it, re read it, re re read it, and I agree with you!
It is a very poorly written piece of English. Its a tricky language sometimes and to get to the bottom of it (what is written) requires a clear head and a freshly woken up mind.
I have it now. The text does as you say require 0.05 or less between the MET and the bonding conductor. Or other examples. It does not say (As I believed and have been led to believe by lecturers, text books, etc like Christopher Kitchers) that the, for example, disconnected (with a safely isolated installation of course) 88 metre run of 10mm2 main bond from one end to tuther has to be 0.05 or less. At last. I am with you!
You move in higher circles than me btw. I suspect you are a learned fellow. Again, thank you for your patience :mad2:
:smile5:Morning:smile5:
IQ - Thanks for your patience. I hope you're not too jaded covering something you've clearly been over before, so thanks for bearing with me. I just wanted to understand why you said what you said, as, has been pointed out by several other (learned) members, and time served sparks I know, they all believe it to be so (the 0.05 Ohms or less for the main bond...etc etc). And also, recently, as BruceLee points out, on 2391 courses (was taught this on mine a few years ago too, and it was in all the text books I fervently acquired ....)
HOWEVER! I have stuck with it, re read it, re re read it, and I agree with you!
It is a very poorly written piece of English. Its a tricky language sometimes and to get to the bottom of it (what is written) requires a clear head and a freshly woken up mind.
I have it now. The text does as you say require 0.05 or less between the MET and the bonding conductor. Or other examples. It does not say (As I believed and have been led to believe by lecturers, text books, etc like Christopher Kitchers) that the, for example, disconnected (with a safely isolated installation of course) 88 metre run of 10mm2 main bond from one end to tuther has to be 0.05 or less. At last. I am with you!
You move in higher circles than me btw. I suspect you are a learned fellow. Again, thank you for your patience :mad2:
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
It's a poor piece of text that divides opinion but it's one of the points that should really be black and white.
It's often a criticism that BS 7671 is open to interpretation and indeed it is but that is because it is written to be interpreted by competent persons on an infinite range of scenarios that could not possibly all be catered for.
I bet we move in the same circles, the IET just wanted a contractor's input for the Guidance Note amendments
It's a poor piece of text that divides opinion but it's one of the points that should really be black and white.
It's often a criticism that BS 7671 is open to interpretation and indeed it is but that is because it is written to be interpreted by competent persons on an infinite range of scenarios that could not possibly all be catered for.
I bet we move in the same circles, the IET just wanted a contractor's input for the Guidance Note amendments
E
Engineer54
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
The 14th edition managed it, ...but then that was the last Reg edition that was written in Plain English!! lol!!
Now, since the Reg's becoming a BS, a higher legal form of English has been applied, which can and often does confuse issues, ...ie, open to interpretation. There are quite a few areas where the IEE needs to go through and clean up passages. Many should have been sorted out ages ago, even if it was just as an on-line addendum/correction sheets, that could wait till the next revision issue to be included...
It's a poor piece of text that divides opinion but it's one of the points that should really be black and white.
It's often a criticism that BS 7671 is open to interpretation and indeed it is but that is because it is written to be interpreted by competent persons on an infinite range of scenarios that could not possibly all be catered for.
The 14th edition managed it, ...but then that was the last Reg edition that was written in Plain English!! lol!!
Now, since the Reg's becoming a BS, a higher legal form of English has been applied, which can and often does confuse issues, ...ie, open to interpretation. There are quite a few areas where the IEE needs to go through and clean up passages. Many should have been sorted out ages ago, even if it was just as an on-line addendum/correction sheets, that could wait till the next revision issue to be included...
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
Where the heck have you been lol?
That puts it to bed
Where the heck have you been lol?
That puts it to bed
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
Hello IQ, yes its been a while, not had much chance of late to post, hardly stopped for breath lol
There is a thread somewhere covering this issue, ill try and find it.
Hopefully GN3 will be a little clearer, its confused many, including a lot of 2391 lecturers who used the .05 figure when teaching students.
Regards Chris
Where the heck have you been lol?
That puts it to bed
Hello IQ, yes its been a while, not had much chance of late to post, hardly stopped for breath lol
There is a thread somewhere covering this issue, ill try and find it.
Hopefully GN3 will be a little clearer, its confused many, including a lot of 2391 lecturers who used the .05 figure when teaching students.
Regards Chris
Re: bonding gas and water how do you work out when to go up from 10mm to 16mm and so
The thread was "general testing questions" not sure how to place a proper link.
Pushrod had a reply from Richard from the IET, Richard has the job of updating GN3. His reply followed that of many, that of the 0.05.
Since then This has been clarified and the above reply from Paul is the approach which will be clarified in the new GN3.
Regards Chris
The thread was "general testing questions" not sure how to place a proper link.
Pushrod had a reply from Richard from the IET, Richard has the job of updating GN3. His reply followed that of many, that of the 0.05.
Since then This has been clarified and the above reply from Paul is the approach which will be clarified in the new GN3.
Regards Chris
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