If the electricity company's neutral gets disconnected at the meter or somewhere outside the house

[JohnW2]

Broken neutral, live earth ...

Yes, but as I keep writing, those potential issues surely only exist if it a PEN/CNE conductor is broken/lost - and not if a neutral conductor (just neutral) is broken "at the meter" (which was the first part of the OP question, and to which I responded)??
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[Ragnar_AT]

If the neutral happens to break somewhere in the three-phase part of the distribution you‘re in a world of pain because single-phase supplies or circuits end up effectively in series between two phases, with fairly unpredictable voltages depending on resistance.

 

[JohnW2]

If the neutral happens to break somewhere in the three-phase part of the distribution you‘re in a world of pain because single-phase supplies or circuits end up effectively in series between two phases, with fairly unpredictable voltages depending on resistance.

Again, agreed - but, as I keep saying,that is not relevant to what will happen if the neutral breaks "at the meter" within a (single-phase) installation.

 

[ebee]

Again, agreed - but, as I keep saying,that is not relevant to what will happen if the neutral breaks "at the meter" within a (single-phase) installation.

Correct - Sorry John but folks are missing your point here.
A break in N and only N will not result in a hazard without some other problem.
A break in a combined function N can result in a hazard though. That is the potential for danger of PME/CNE/TNC-S/PEN or what ever flavour you use to describe it, the combined conductor can, potentially, become a big problem.
We deliberately call a N cable "Live" for a good reason - it can bite you - the most obvious way to see that is the "Borrowed Neutral" scenario where the Neutral becomes anything up to Line Voltage if not properly strapped down to Earth along its whole route.

 

[ebee]

It may be just poor wording but...

Yes EFLI you are correct.
I was attempting to keep it simple rather than getting on with another of my rambles.

Analogy - Imagine a bathroom shaver socket, No matter what is on the supply input side of its isolating transformer the output side of that transformer has only one hazard of voltage, namely only by becoming connected to both of the output connections at the same time, any connection to E or anything else and only one of the output conductors will not cause a hazard.
If we decide to Earth/Ground one output conductor we create another possible hazard combination "The N only becomes N if it is Earth referenced somewhere along its length" otherwise it is just a floating voltage but opposite polarity of the other conductor (two Lines of opposite polarity and both of them floating therefore no voltage differential from anything else).

 

[plugwash]

Yes, but as I keep writing, those potential issues surely only exist if it a PEN/CNE conductor is broken/lost - and not if a neutral conductor (just neutral) is broken "at the meter" (which was the first part of the OP question, and to which I responded)??

I suspect some confusion is coming from the fact that probablly more than half of the people on the english speaking internet are americans.

In TN-C-S systems in the UK, then neutral and earth split at the service head, *before* the meter. So in the UK a lost neutral at the meter will not result in the earthing system becoming live.

In the USA on the other hand, the neutral and earth split at the customer's main panel. So a broken neutral at the meter will result in the grounding system becoming live.

 

[akist]

I suspect some confusion is coming from the fact that probablly more than half of the people on the english speaking internet are americans.

In TN-C-S systems in the UK, then neutral and earth split at the service head, *before* the meter. So in the UK a lost neutral at the meter will not result in the earthing system becoming live.

In the USA on the other hand, the neutral and earth split at the customer's main panel. So a broken neutral at the meter will result in the grounding system becoming live.

It was my bad description.

I was trying to describe that the supplier's N got disconnected away from the house (overhead cables).

I was also trying to describe that the supplier's N joins the house's N and the house's E "at the meter" (3-way connector inside the enclosure which houses the meter) and there, it can also "disconnect" (in my case, a very rusty connector).

The effect is the same: the supplier's N is disconnected from the house. The house's E now takes the full load of all appliances running in the house. The higher the load the higher the voltage on the E.

The house's RCD does not trip. People in and around the house are receiving shocks when they touch the shower tap where your feet are in water. Or when working outside with your feet in a puddle of water.

 

[JohnW2]

Correct - Sorry John but folks are missing your point here.

So it seems - despite the fact that I have made the point, I thought clearly, many times!

A break in N and only N will not result in a hazard without some other problem. .... A break in a combined function N can result in a hazard though. That is the potential for danger of PME/CNE/TNC-S/PEN or what ever flavour you use to describe it, the combined conductor can, potentially, become a big problem.

Exactly. Maybe people will understand what you have just written, even though they didn't seem to understand when I wrote (several times) essentially the same!

Kind Regards, John

 

[JohnW2]

I suspect some confusion is coming from the fact that probablly more than half of the people on the english speaking internet are americans. ... In TN-C-S systems in the UK, then neutral and earth split at the service head, *before* the meter. So in the UK a lost neutral at the meter will not result in the earthing system becoming live. ... In the USA on the other hand, the neutral and earth split at the customer's main panel. So a broken neutral at the meter will result in the grounding system becoming live.

Thanks. Whilst that is all very true,I am not aware (actually doubt) that any of the people who have seemingly not understand my point are American.

 

[JohnW2]

I was trying to describe that the supplier's N got disconnected away from the house (overhead cables). ... I was also trying to describe that the supplier's N joins the house's N and the house's E "at the meter" (3-way connector inside the enclosure which houses the meter) and there, it can also "disconnect" (in my case, a very rusty connector).

OK. That's essentially what I thought you will be describing.

The effect is the same: the supplier's N is disconnected from the house. The house's E now takes the full load of all appliances running in the house. The higher the load the higher the voltage on the E.

I suppose we need to know a bit more about what goes on at the "3-way connector". What you describe would only happen if the supplier's N became disconnected by your house's E remained connected to the house's N - is that what you are thinking of?

Even if that did happen, whilst it might possibly result in overheating (potentially fires) of bonding conductors (if the bonded parts had very low impedance paths to true earth), it should not present any risk of electric shock within the house - since, although the potential of the installation's 'earth' (hence potential of any touchable earthed metal - like the cases of appliances) could rise to considerably above true earth potential, the bonding should ensure that there is nothing within the house at true earth potential that one could touch simultaneously.

Kind Regards, John

 

[ebee]

Hah. So basically a PEN fault (The incoming E and incoming N have both been disconnected as they are one and the same conductor?

That was what John was trying to explain.

I am not aware (actually doubt) that any of the people who have seemingly not understand my point are American.

I would not accuse anyone of being "Americans" (Assuming you really mean USA ), that is an unfair slur on decent civilised people John!

 

[Scally-Ho]

My supply is from overhead and is polyphase. TP for my workshop and 1ph for my domestic via the star pointed pole mounted tranny, then underground. My domestic loading is negligible so everything is reasonably well balanced. If I lost a phase in my workshop, it would be instantly noticed.

 

[bernardgreen]

ensure that there is nothing within the house at true earth potential that one could touch simultaneously

The walls in some old cottages built with stone walls and no damp proofing can be slightly conductive.

In theory these walls are extraneous in that they "inport" the ground potential into the the house.

 

[akist]

OK. That's essentially what I thought you will be describing.

I suppose we need to know a bit more about what goes on at the "3-way connector". What you describe would only happen if the supplier's N became disconnected by your house's E remained connected to the house's N - is that what you are thinking of?

Yes exactly. The supplier's N gets disconnected away from the house. The house's N and E are intact and shorted together inside the meter's housing. The house's own E, in my case a rod in the ground, obviously has some resistance, which has not been noticed, not until the supply's N got disconnected. Now, all current consumed in the house goes through the house's E rather than the supply's N, and all the E in the house sits at some voltage higher than real E, because the house's earthing rod is a bit dry, or maybe even rusted away. In the garden, standing ankle deep in a puddle, or in the shower we get (mildly) electrocuted.

Even if that did happen, whilst it might possibly result in overheating (potentially fires) of bonding conductors (if the bonded parts had very low impedance paths to true earth), it should not present any risk of electric shock within the house - since, although the potential of the installation's 'earth' (hence potential of any touchable earthed metal - like the cases of appliances) could rise to considerably above true earth potential, the bonding should ensure that there is nothing within the house at true earth potential that one could touch simultaneously.

There are things in and outside the house that can have a much better E than the dedicated earthing rod, or the dodgy connector that bonds N + E + N together. You can have a very bad E, and never know, not until your supplier's N gets disconnected.

In my house in the UK (this is another house) I do not have a special earthing rod, would it not be a good idea to install one? I am thinking, if the supply's N gets disconnected, then I will also lose the house's E completely, save for random copper water pipes.

 

[JohnW2]

The walls in some old cottages built with stone walls and no damp proofing can be slightly conductive. ... In theory these walls are extraneous in that they "inport" the ground potential into the the house.

Yes, you're always reminding us of that.

I don't think you've ever quantified your view of what 'slightly conductive' may be. If you believe that it is such as to be a genuine concern, then the building should probably be condemned as not safe for habitation (unless the electricity supply were removed) unless/until extensive work were undertaken to either eliminate the damp walls or else somehow 'bond' them?