Main bondage

[Jonny66]

Can you see professor Boff, how a simple piece of writing can be miss understood, so therefore someone with your capacity to soak up information at such an incredible rate should in all probability probably be a lot more humble.

 

[Jonny66]

Or in all probability be a plumber.

 

[Marvo]

Stop the bickering and keep the thread on topic.

You were warned.

 

[Guest55]

banstick for jenny66 ?
;-)

xmas came early thanks to the santa known as Marvo.
Salut !

 

[Geoffsd]

The 0.05 value is the value below which potential difference should be, between simultaneously accessible extraneous conductive parts. Example of which is a gas pipe and a water pipe next to each other. Test between the two.

Even if both are 10mm bonded individually back to MET, if the difference between the two is greater than 0.05 then they need to be bonded to each other.

If that is the case then that would be supplementary bonding which, unless in a bathroom or similar location, is not required.

The 0.05 figure is not a value to be achieved between MET and bonding point taking into account the value of resistance of the cable.

But that is, indeed, what is required in my old copy of GN3 (has it changed?).

So - if still required, it must be agreed that it is not possible to achieve this with a conductor whose own resistance is greater than 0.05Ω.


It also states that supplementary bonding conductors must have a resistance of 0.05Ω or less.

 

[KAS1]

The 0.05 ohms has nothing to do with the value of the bonding conductor at all, it or any other measurement you will be able to work out the length of any size cable, so once again nothing to do with the bonding conductor max value.

 

[Guest55]

stuff........

yawn....

 

[Guest55]

If that is the case then that would be supplementary bonding which, unless in a bathroom or similar location, is not required.


But that is, indeed, what is required in my old copy of GN3 (has it changed?).

So - if still required, it must be agreed that it is not possible to achieve this with a conductor whose own resistance is greater than 0.05Ω.


It also states that supplementary bonding conductors must have a resistance of 0.05Ω or less.

i wouldnt consider anything written in the guidance notes as regulations that need to complied with to be honest Geoff.

 

[Guest55]

10 , 9 , 8 , 7 ,...........

 

[Swicade]

First time i've read this thread but the most amusing point of it for me is the fact post #14 explained the 0.05 value and it seems to have taken a day for many others to catch up....

 

[VoltzElectrical]

I am perfectly willing to accept thanks for the information given in Voltz's posts if you think it is valuable, after all I missed much of the Wales Vs France game to explain it to him in detail!

sorry bud, I did not take credit for your valuable input, but perhaps i should have given you more direct credit for your enlightenment. I remembered something along the lines of which you were trying to explain to me a while go and this brang it all home to me while i was perusing the forum and keeping half an eye on a stalemate game at the time.

Thanks for the chat and at least the boys done good after we finished talking!

xx

 

[VoltzElectrical]

First time i've read this thread but the most amusing point of it for me is the fact post #14 explained the 0.05 value and it seems to have taken a day for many others to catch up....

Really! I fail to see how post no.14 sheds any light on the understanding of this issue.

 

[GLENNSPARK]

it is an existing bonding cable, was gonna change the board for an assessment but now i'll need this to be sorted. p.s. the cowboy who installed this bodged quite alot so dunno what is going on

well then always keep an open mind. as soon as you see turd at an install....

 

[VoltzElectrical]

well then always keep an open mind. as soon as you see turd at an install....

come on Glenn, don't be a slow starter, you are well up on the regs, let's have your input on this issue.

Only READ ALL THE POSTS FIRST AND HOLD OFF THE FULL STOPS!!!

xx

 

[capitolltd]

The 0.05 relates to the bonding connection, not the conductor length. This is to conform the clamp is connected to the conductive part with a low resistance joint. (i.e. paint removed from pipe). This relates over to the 0.1 + R of lead used in the COP for portable appliance testing, as there are 2 points of connection (0.05+0.05=0.1)
The purpose of the main protective bonding conductor is to equalise the potential, so we only see the volt drop (touch voltage) of the R2 conductor, between conductive parts under fault conditions. If no bonding is present, we will see the volt drop of the R2 conductor, plus the volt drop of the external earth. Obviously this will be greater in TT installations, due to the higher resistance in the earth electrodes.

 

[netblindpaul]

The 0.05 relates to the bonding connection, not the conductor length. This is to conform the clamp is connected to the conductive part with a low resistance joint. (i.e. paint removed from pipe). This relates over to the 0.1 + R of lead used in the COP for portable appliance testing, as there are 2 points of connection (0.05+0.05=0.1)
The purpose of the main protective bonding conductor is to equalise the potential, so we only see the volt drop (touch voltage) of the R2 conductor, between conductive parts under fault conditions. If no bonding is present, we will see the volt drop of the R2 conductor, plus the volt drop of the external earth. Obviously this will be greater in TT installations, due to the higher resistance in the earth electrodes.

Quite, think about the clamp and the pipe, simultaneously accessible conductive parts...

 

[ezzzekiel]

Seems to me a few varied explanations yet not one definitive answer, 0.05 appears to be a standard value used with no understanding of the reason.

Be nice to know the correct theory

 

[Guest55]

this value of 0.05 ohms is irrelevent regardless of how its measured , you size the bonds as per the requirements of section 544 bs7671.
no mention of maximum resistance or length is even mentioned in the regs.
when push comes to shove , the numbers suggested in the guidance notes dont mean jack , theyre just suggestions for the many different ways of compliance.

 

[Guitarist]

As a few of us have already stated, the fact that it's over 0.05 on a relatively short run is indicating that it's not continuous and needs investigating.

 

[KAS1]

"Does main bonding in every circumstance always need to be under 0.05. main bonding in a house where the main water was moved has 10mm cable but resistance of 0.25 ohms"

a few of us have already stated, the fact that it's over 0.05 on a relatively short run is indicating that it's not continuous and needs investigating.

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Noooooooooooooooooooooooooooooooooooo it does not have to be so