Why Do We Not Get A Shock From The Neutral Conductor?

[SPECIAL LOCATION]

Just for the record Neutral IS a LIVE conductor...

The conductor you are calling Live is now called the LINE conductor.. previously PHASE conductor..

but whichever way you look at it LINE & NEUTRAL are BOTH Live conductors.

:coat

{sorry if that point has already been made further back.. only skip read the thread.}

 

[andrewedwardjudd]

errr no - TNCS has a linked neutral in the service head. In NZ the link is within the consumer unit and the earth is provided with a rod. In NZ you are also not allowed to break the neutral, so no DP switches on anything either.

The fact is there is no difference of substance that i am aware of between the UK house i had and my nz house as it is now connected. The External metal earth pole was only recently connected because after being away i was required to get a certificate of compliance before reconnection. I would still have had an earth connection to the copper water pipe, and i dont now have bonding going between the sinks and so forth.

There is no big deal about the earth wiring that I can see so far that makes for any fundamental difference just because the connection is inside the CU or outside of it.

In Finland I have no internal earth wiring. But since earth and neutral in the house are effectively different branches of the same thing the system is in practice very similar.

As far as i can tell so far I can get a shock from live in the UK, Finland and NZ because the designed regulated electrical system provides the means whereby a circuit can easily be formed back to the substation and if this was not in place I would not easily get a shock touching the live. I wonder how many people are killed each year because of this practice?

I am not saying it can be improved upon but it appears to be a fact this regulated practice does kill people.

 

[andrewedwardjudd]

Just for the record Neutral IS a LIVE conductor...

The conductor you are calling Live is now called the LINE conductor.. previously PHASE conductor..

but whichever way you look at it LINE & NEUTRAL are BOTH Live conductors.

{sorry if that point has already been made further back.. only skip read the thread.}

Thanks for the clarification, I am not sure the point was made earlier although several people said that considerable danger could originate because of the neutral. I have at times been refering to the neutral as the so called neutral.

It seems to me that it is only a properly created earthing system that forces the neutral to be safe relative to earth and if that failed and the live leaked to earth then neutral would enable a person to get a shock. In our current system neutral is required to be part of the earth so touching any live is very likely to make a dangerous connection back to the substation.

Is my understanding correct on that or way out?

 

[sellers]

How about this,

if electricity takes the path of least resistance, why does it flow through the human body when it could quite happily continue on its circuit through the load and back down the neutral (if that is less resistance)

 

[SLIPSHOD & SLAPDASH]

Thanks for the reply.

As you agree, in reality the current is not flowing from L to N, and it is reversing,

That is not correct. The current is flowing from live to neutral but it sinewave is alternating +/- 50hz.

 

[andrewedwardjudd]

How about this,

if electricity takes the path of least resistance, why does it flow through the human body when it could quite happily continue on its circuit through the load and back down the neutral (if that is less resistance)

Electricity does not take the path of least resistance. Unless the mains circuit is so heavily loaded that the voltage falls to a very low voltage, a dangerous voltage is always available to enable a lethal current to flow thru your body via the various supplied routes back to the source of power. It does not matter how the circuit is made if you are part of the circuit and there is sufficient potential difference across you to enable the shocking current to flow.

 

[SLIPSHOD & SLAPDASH]

Unless the mains circuit is so heavily loaded that the voltage falls to a very low voltage, a dangerous voltage is always available to enable a lethal current to flow thru your body via the various supplied routes back to the source of power. It does not matter how the circuit is made if you are part of the circuit and there is sufficient potential difference across you to enable the shocking current to flow.

That may be correct but electricity still does take the least resistive path.

 

[andrewedwardjudd]

That may be correct but electricity still does take the least resistive path.

What does the expression mean? Electricity has no knowledge of the resistances thru which it flows. If there is a potential difference then there will be *many* current flows proportional to the impedance/resistance, wherever it is experienced.

It can only be correct to say most electricity flows via the least resistive path. You cannot say what you are saying in the absolute manner you have said.

 

[andrewedwardjudd]

That is not correct. The current is flowing from live to neutral but it sinewave is alternating +/- 50hz.

It is called alternating current.

 

[revjames]

well you learn something new everyday.... it goes +ve then -ve 50 times a second..... wow Thats what them ozzy rockers were on about all this time....

 

[safedepth]

By that token are you seriously suggesting direct current only travels in one direction and ac reverses direction?

Ac reverses polarity not direction.

 

[andrewedwardjudd]

By that token are you seriously suggesting direct current only travels in one direction and ac reverses direction?

Ac reverses polarity not direction.

The concept is as you suggest. Direct current is a single direction of current flow where the polarity of for example a battery is constant, even if the voltage produced by the battery is variable. Therefore if you connect a speaker with the appropriate in series resistance, the speaker makes a thud sound as the diaphragm is pulled in or out one single time, and thereafter you hear nothing.

With an alternating current the speaker hums as the diaphragm goes in and out at the alternating current rate of for example 50 cycles.

 

[Sidewinder]

Can I ask what it the aim of this thread please?

Comparing international systems is not easy, especially when they are based on differing standards.

The UK, Finland & NZ all are based on different concepts, there can be no direct comparison.

Apart from one certain fact, that electricity is lethal.

 

[andrewedwardjudd]

Can I ask what it the aim of this thread please?

Comparing international systems is not easy, especially when they are based on differing standards.

The UK, Finland & NZ all are based on different concepts, there can be no direct comparison.

Apart from one certain fact, that electricity is lethal.

The beginning idea of the thread was to resolve the nature of the neutral and find out why we get shocked by a live so that unquestionably I know the answer. My theory about the shock pathway going via air seems to have been debunked, but i was still wanting to know why the live was hot

In my own mind i am beginning to be satisfied i know what is happening

The variations on wiring a house are not important.

In the UK NZ and Finland, neutral is grounded and thus there is an easily available potential circuit which can be completed via your body if you touch 'live' even if you do not directly touch neutral to form a circuit.

In either country if you touch neutral there is no easily available circuit that be completed to form a circuit back to the substation.

 

[NozSpark]

Right,,,,,

When we state a voltage it is ALWAYS "with respect to" (wrt)...

230V in the UK wrt earth, this is because the neutral is tied to earth in the power stations and sub stations so no matter what if you have a reasonable connection to earth you will get an electric shock off the Line conductor, it is unlikely that you will get a shock off a Neutral conductor because in broad terms it is connected to earth and therefore you will not have a potential difference.

Now, the reason that birds perching on un insulated distribution cables don't get electrocuted is because they are not in any way connected to earth (i.e. complete the circuit back to the power/sub station).... So going by that principle if you were stood on a completley insulating surface (isolated from earth) and touched a Line conductor you wouldn't receive a shock.

Batteries and earth Isolated generators are also "safe" to touch as they are not referenced to earth (if installed correctly) so you could touch their Line conductors and not receive a shock also.

 

[revjames]

Right,,,,,

When we state a voltage it is ALWAYS "with respect to" (wrt)...

Batteries and earth Isolated generators are also "safe" to touch as they are not referenced to earth (if installed correctly) so you could touch their Line conductors and not receive a shock also.

what about telephone exchanges and +48VDC grounded to earth? you definitely can get a belt of the -ve there

 

[NozSpark]

Just thought though are you on about a +48V DC / 0V DC (earth tied) / -48V DC system there???

In which case the -48V DC is wrt Earth and you'll therefore have a PD anyhow

TBH I was trying to keep it simple or this guy'll tie himself up in knots (unless he's a troll that is)

 

[revjames]

have tried sensible replies and sarcasm and he still goes on and on and on..... just thought I'd throw my 2p worth (and thats all its worth) in. I remember installing a massive battery and generator system in an exchange and no I didnt try it but reckoned I would have felt something uncomfortable had I touched the -ve at the battery. But don't lets go off at a tangent this thread is bad enough as it is!

 

[NozSpark]

TBH I don't know anything about telephone exchanges except that some of my calls are routed through them ; )

Like I said if it's referenced to earth then you could get a shock, but if it isn't you won't (well not to earth anyhow )

 

[revjames]

Mind you that was a telephone exchange in NZ, maybe theyre different here or Finland.... lets not go there