Earth checking for grounding

[bernardgreen]

Unless the "bond" is non conductive then anything "bonded" to the main earth terminal ( MET ) is "earthed". Or are you saying the main earth terminal is not an earthing point ?

Silly me.......Of course on PME installs the MET is not earth as in ground but is the same as neutral ( incoming ) to which it is connected at the cut out.

So should the CPC "wire" be considered a "live" conductor ? It can get very "hot" when there is a problem in the supply network. This possibility of a "hot" CPC although rare, is probably the reason for the banning of the use of "earthed" equipment such as hedge trimmers by people who are standing on the real earth.

 

[RF Lighting]

Unless the "bond" is non conductive then anything "bonded" to the main earth terminal ( MET ) is "earthed". Or are you saying the main earth terminal is not an earthing point ?

Depends. I guess you've never seen an installation where the incomming earth has failed? I see loads of them, but that's not the point. You are not deliberately earthing the pipes, and to say you are is incorrect. You are bonding them.

Silly me.......Of course on PME installs the MET is not earth as in ground but is the same as neutral ( incoming ) to which it is connected at the cut out.

Makes no difference.

So should the CPC "wire" be considered a "live" conductor ?

No, because it isn't.

It can get very "hot" when there is a problem in the supply network.

What's heat got to do with anything?

This possibility of a "hot" CPC although rare, is probably the reason for the banning of the use of "earthed" equipment such as hedge trimmers by people who are standing on the real earth.

When was this ban introduced? Anyway that is earthing. Nothing to do with bonding at all.

I suggest you buy and read this:

 

[bernardgreen]

Depends. I guess you've never seen an installation where the incomming earth has failed? I see loads of them, but that's not the point. You are not deliberately earthing the pipes, and to say you are is incorrect. You are bonding them.

Yes I have seen two or three, one was an un-attended hilltop radio station. Considerable damage to equipement from burnt out "earth" ( or were they "bond" ) wires. Loss of the supply neutral half way up the hill meant the station's very low impedance earth mats were taking the return current back to the substation at the bottom of the hill. "earth" and neutral being joined at the cut out. IIRC the supply was changed to have 2 phases at 11 kV taken up the hill with a transformer located adjacent to the radio station to prevent a repeat.

Silly me.......Of course on PME installs the MET is not earth as in ground but is the same as neutral ( incoming ) to which it is connected at the cut out.

Makes no difference.

Not until the neutral from substation to house goes open circuit.

So should the CPC "wire" be considered a "live" conductor ?

But isn't the neutral conductor consider to require the same care and insulation as the live conductor.

It can get very "hot" when there is a problem in the supply network.

What's heat got to do with anything?

I meant "hot" as in being at some voltage above the safe (?) limit of 50 volts AC relative to true ground.

This possibility of a "hot" CPC although rare, is probably the reason for the banning of the use of "earthed" equipment such as hedge trimmers by people who are standing on the real earth.

When was this ban introduced? Anyway that is earthing. Nothing to do with bonding at all.

I do not know date and time but it was some years ago that I first heard that metal cased tools with an "earth" in the lead from the socket in the house were if not banned were highly frowned upon as being potentially more hazardous than a double insulated tool with no "earth" connection.

Relates to not exporting PME earths to outbuildings.

I suggest you buy and read this:

If it only clarifies the regulations and tries to say that a bond that has a galvanic connection to the MET cannot be considered as being "earthed" then I doubt it will convince me.

 

[RF Lighting]

Depends. I guess you've never seen an installation where the incomming earth has failed? I see loads of them, but that's not the point. You are not deliberately earthing the pipes, and to say you are is incorrect. You are bonding them.

Yes I have seen two or three, one was an un-attended hilltop radio station. Considerable damage to equipement from burnt out "earth" ( or were they "bond" ) wires. Loss of the supply neutral half way up the hill meant the station's very low impedance earth mats were taking the return current back to the substation at the bottom of the hill. "earth" and neutral being joined at the cut out. IIRC the supply was changed to have 2 phases at 11 kV taken up the hill with a transformer located adjacent to the radio station to prevent a repeat.

So you'll undestand that bonding still does it's job of keeping things safe whether it's earthed or not.

Silly me.......Of course on PME installs the MET is not earth as in ground but is the same as neutral ( incoming ) to which it is connected at the cut out.

Makes no difference.

Not until the neutral from substation to house goes open circuit.

Still makes no difference. Bonding will keep all extraneous parts at the same potential even a situation like that. That's the whole point of it.

So should the CPC "wire" be considered a "live" conductor ?

But isn't the neutral conductor consider to require the same care and insulation as the live conductor.

Yes, but that's because it's a live conductor. Earthing and bonding wires aren't.

It can get very "hot" when there is a problem in the supply network.

What's heat got to do with anything?

I meant "hot" as in being at some voltage above the safe (?) limit of 50 volts AC relative to true ground.

Please stick to using recognised terminology. If there is a problem with the supply and the incomming earth voltage is abouve true ground, then bonding will keep the installation safer by keeping all extraneous parts at the same potential. That's the whole point of it.

This possibility of a "hot" CPC although rare, is probably the reason for the banning of the use of "earthed" equipment such as hedge trimmers by people who are standing on the real earth.

When was this ban introduced? Anyway that is earthing. Nothing to do with bonding at all.

I do not know date and time but it was some years ago that I first heard that metal cased tools with an "earth" in the lead from the socket in the house were if not banned were highly frowned upon as being potentially more hazardous than a double insulated tool with no "earth" connection.

Relates to not exporting PME earths to outbuildings.

That is EARTHING!!!!! Nothing to do with bonding what-so-ever

I suggest you buy and read this:

If it only clarifies the regulations and tries to say that a bond that has a galvanic connection to the MET cannot be considered as being "earthed" then I doubt it will convince me.

Why don't you read it and find out.

 

[bernardgreen]

Relates to not exporting PME earths to outbuildings.

That is EARTHING!!!!! Nothing to do with bonding what-so-ever

I would prefer to see the bonding extended, but this requires a ≥10.0mm² earthing conductor from the house MET to the garage.

Read more: //www.diynot.com/forums/electrics/controlling-motor-surge.326322/#ixzz1x57e4mQr

So is this 10.0mm² conductor from the MET ( Main Earth Terminal ) an earth or a bond ?.

I am not trying to score points but just make the point that electrically there are [1] earth free bonds which have no connection of any kind to earth or ground and there are [2] bonds which are connecting the items together and at the same time connecting them to the earth or ground because a CPC or pipe is "importing" an earth to one of the bonded items.

 

[RF Lighting]

It is an EARTH to the garage consomer unit.

As there is now more than one extraneous part in the garage they need BONDING together.

As it happens this bonding will be earthed but that is not why it is installed and to say you are earthing the water supply would be incorrect. You could just as equally say you are water piping the earth.

If there was extraneous structural steel in there that would require bonding to the water pipe and the garage earth. If you remove the earth the steel and the water pipe would still be bonded together.

 

[EFLImpudence]

In 'normal' installations, only parts which are already earthed (extraneous) require main bonding -
because they are already earthed.

To equalise potential, NOT to ensure operation of the cpd.

I am not trying to score points but just make the point that electrically there are [1] earth free bonds which have no connection of any kind to earth or ground and there are

That is because you are bonding parts, to equalise potential, on an apparatus which is not earthed.

Bonding is bonding.

[2] bonds which are connecting the items together and at the same time connecting them to the earth or ground because a CPC or pipe is "importing" an earth to one of the bonded items.

They will already be connected to earth - either the MET or The Earth (planet).

They are being bonded to equalise potential.

 

[SimonH2]

One of the major problems in conducting research into what could be very subtle effects is the need to encorporate a massive number of variables into the data. If you were looking for sleep improvements by grounding then, to my mind, you'd need to also record a plethora of other variables - like diet, gender, age, genetic influences, occupation, stress levels, chemical exposures, whether you're getting it or not, the list goes on. Only then could you even hope to begin to isolate what could be effects due to grounding.

And of course, blind (or better still, double blind) tests.

Ie, you test people on these earthed mats - but some of the mats aren't actually earthed (the test subjects don't know if they are or not - hence it being a "blind" test). Often there are placebo effects which in the absence of properly blind tests will skew the results so show non-existant effects.
Ideally the tests need to be double blind - where the people administering the test don't know either. That's because the administrators may give subtle clues that the subjects pick up on.

 

[Peet]

And of course, blind (or better still, double blind) tests.

I agree. All part of trying to reduce the noise in the dataset to maybe see a correlation in the variable of interest.

 

[Peet]

The part of the thread discussing earthing and bonding I read with great interest. Mainly because when it's clear that the two or more parties clearly know their stuff, in the ensuing debate, an interesting one at that, I hope to learn something. I'm not sure if I've learned anything from it that I didn't already know, but that doesn't stop me reading. As they say 'you don't know what you don't know'. But do keep it clean, it makes for a much better debate

Part of the debate has been about semantics. Part of it has been about using terminology consistent with the current regs.

I always remember the first time I read about bonding and what the regs actually meant by it. Now maybe the name was new to me, but the idea wasn't. It's not unlike a Faraday cage at the end of the day. I come from a mixed up background of having done all kinds of stuff. And whilst I've always been involved in electrics and surrounded by electrical people, electrics has never been an income for me. Electronics design has. So while breaker curves, disconnection times and Z this, that, and the other, is second nature to me some of the really obvious stuff, like whose breakers fit what boards, isn't. Which can cause some weird looks in the wholesaler describing them stuff I can't name, but being able to tell them exactly what it does and why.

So for me, if the debate has done anything it's been a good reenforcement of the difference between earthing and bonding. Well, and the fact that in some instances the bonding is earthed.

I can still see it from both points of view.

Thankyou folks

Do we know if S87134 is still alive, or has he commited suicide?

 

[bernardgreen]

It's not unlike a Faraday cage at the end of the day.

The thing that worries me is that while everyone inside the Faraday cage is safe people who touch the outside will be at risk if the Faraday cage is not at a safe voltage relative to that person's "ground".

If I said I was connecting my outside water tap to the neutral bus bar in the consumer unit I guess a few people would think I was mad.

I come from a mixed up background of having done all kinds of stuff. And whilst I've always been involved in electrics and surrounded by electrical people, electrics has never been an income for me. Electronics design has.

We seem to have the same background.

Do we know if S87134 is still alive, or has he commited suicide?

Maybe gone to ground to un-earth the secrets of bondage.

 

[SimonH2]

So for me, if the debate has done anything it's been a good reenforcement of the difference between earthing and bonding. Well, and the fact that in some instances the bonding is earthed.

Personally, I think the biggest cause of confusion is even using the word "earth" in this context.

While "earthing something" does (almost) mean connecting it to earth where local earthing electrodes are used, for many of us, it means connecting stuff to something that is only indirectly connected to earth somewhere else

And of course, you also have to consider that "earth" isn't itself a nice conductive, homogenous, equipotential "thing". Something of particular concern where livestock is around.

I figure this is the reason for the distinct terms (in this context) - "earthing" meaning to provide a low impedance path for fault currents so as to ensure circuit protection triggers without creating excessively high voltages on anything exposed, while "bonding" means ensuring that everything conductive in an area is as the same potential even if that isn't exactly the same as local earth.

 

[Peet]

The thing that worries me is that while everyone inside the Faraday cage is safe people who touch the outside will be at risk if the Faraday cage is not at a safe voltage relative to that person's "ground".

And that in many electrical installations the equipotential zone doesn't have 'walls' so at some point must end. The zone needs consideration in the area use and building design, which the regs get hold of more and more.

 

[bernardgreen]

And that in many electrical installations the equipotential zone doesn't have 'walls' so at some point must end.

Where there are walls there are things like garden water taps, gas meters and exterior metal light fittings at the potential of the equipotential inside but outside the physical barriers ( walls ) that contain the zone.

 

[Peet]

Personally, I think the biggest cause of confusion is even using the word "earth" in this context.

While "earthing something" does (almost) mean connecting it to earth where local earthing electrodes are used, for many of us, it means connecting stuff to something that is only indirectly connected to earth somewhere else

And of course, you also have to consider that "earth" isn't itself a nice conductive, homogenous, equipotential "thing". Something of particular concern where livestock is around.

I figure this is the reason for the distinct terms (in this context) - "earthing" meaning to provide a low impedance path for fault currents so as to ensure circuit protection triggers without creating excessively high voltages on anything exposed, while "bonding" means ensuring that everything conductive in an area is as the same potential even if that isn't exactly the same as local earth.

I think you sum it up very well. Especially 'for many of us, it means connecting stuff to something that is only indirectly connected to earth somewhere else'.

On a bit of a sideline - Your link to the livestock electrocution. Many years ago I was talking to a chap who said that some of the more unscrupulous circus people used to use livestock as leakage detectors. Once the circus was setup, and transformers etc were on poles, an old horse would be driven round them to see if they leaked. Horses apparently are much more sensitive to leakage than humans are.