erroneous post removed at OP request
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Supplementary Bonding Revisited
- Thread starter JohnW2
- Start date
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I do not wish to detract from your excellent work Studentspark.
However, whilst knowledge and understanding are themselves laudable pursuits, I cannot but think all these calculations are merely an academic exercise with many usually unknown variables.
As far as Main Bonding is concerned, no consideration of any of these touch voltages is ever considered. MB is just applied as a matter of course and is solely to equalise potential between the extraneous-c-p and the MET; that is, to remove the Ut2 without MB in the latest diagram.
Were the person in a kitchen, no thought is ever given to these values but if in a bathroom or similar then Supplementary Bonding comes in to play - although now not required if RCDs are fitted.
It is worth noting that the (by John) discredited R≤50/Ia would satisfy some of the above examples but this is purely fortuitous and is altered by different scenarios (e.g. different Ze) in other parts of the installation totally unconnected with the measurements needed to verify the equation. SB being the only way to ensure low touch voltage.
Whether this also applies to the situation of RCD and no SB, I am not sure.
However, whilst knowledge and understanding are themselves laudable pursuits, I cannot but think all these calculations are merely an academic exercise with many usually unknown variables.
As far as Main Bonding is concerned, no consideration of any of these touch voltages is ever considered. MB is just applied as a matter of course and is solely to equalise potential between the extraneous-c-p and the MET; that is, to remove the Ut2 without MB in the latest diagram.
Were the person in a kitchen, no thought is ever given to these values but if in a bathroom or similar then Supplementary Bonding comes in to play - although now not required if RCDs are fitted.
It is worth noting that the (by John) discredited R≤50/Ia would satisfy some of the above examples but this is purely fortuitous and is altered by different scenarios (e.g. different Ze) in other parts of the installation totally unconnected with the measurements needed to verify the equation. SB being the only way to ensure low touch voltage.
Whether this also applies to the situation of RCD and no SB, I am not sure.
Hi EFLI
Yes this is an academic exercise, I suppose. But if you don't get the theory clear in your mind, you are just going through the motions.
Installing MPB, is just something we get told to do. And I understand the need for it, but not the science behind it, well only in a basic way.
But if you get a good understanding of Earthing, earth paths, parallel and fault current and touch voltage, you can deal with the more complex earthing questions which may arise.
I do admit I should of cracked this years ago
Yes this is an academic exercise, I suppose. But if you don't get the theory clear in your mind, you are just going through the motions.
Installing MPB, is just something we get told to do. And I understand the need for it, but not the science behind it, well only in a basic way.
But if you get a good understanding of Earthing, earth paths, parallel and fault current and touch voltage, you can deal with the more complex earthing questions which may arise.
I do admit I should of cracked this years ago
OK. I've got a few other 'urgent' things on my plate at the moment, so can't respond immediately, but will do so as soon as I can - so you'll have to be a little patient
Kind Regards, John.
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OK. I've got a few other 'urgent' things on my plate at the moment, so can't respond immediately, but will do so as soon as I can - so you'll have to be a little patient
Kind Regards, John.
No worries at all John, I've been on and off with this for many years, so no rush.
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