Neutral bar

Estiban · Apr 13, 2021

Hi
What’s the principle .
with a neutral not connected to the neutral bar will be 230v basically a line.
But when neutral is connected to neutral bar there is 0v.
Neutral and earth are connected further on with the same potential but I still don’t understand how the neutral bar and even the earth bar isn’t at 230v ?

Rockingit · Apr 14, 2021

I think I walked into a neutral bar in Singapore once, didn't stay long.

telectrix · Apr 14, 2021

Soi disant said:
No, it isn't. The supply neutral is still at a nominal 0V to earth, and the supply line is still at a nominal 230V to N & E.

What you have disconnected is no longer the neutral. It inherits its status as neutral by being connected to the neutral point in its frame of reference, i.e. the supply neutral. If you disconnect it from that it loses that status.

Most of the time that distinction doesn't matter, but it absolutely does when trying to understand that voltages are not singular, isolated things but are a difference in electrical potential between two points.

that's what i said.it's no longer a neutral as it's not referenced to 0v any more. you seem to have a penchant for twisting posts to suit your own ideas.

timhoward · Apr 14, 2021

Soi disant said:
Another thing which is not going to help anyone is loose, sloppy, terminology.

I think you are taking this a tad far!
It would appear from your logic that you'd like me to write "Broken line conductor which used to be a neutral conductor before it was broken and is insulated using black pvc according to pre-harmonised standards" on reports. I think I'd prefer to be loose and sloppy. You should try it too. The liberation feels amazing!
In fact I've just said "Neutral" to another sparky even though it isn't connected yet. Astoundingly they understood me. It felt great!

Soi disant · Apr 14, 2021

telectrix said:
that's what i said.it's no longer a neutral as it's not referenced to 0v any more.

Well, actually no, you didn't, you said this (with my emphasis):

telectrix said:
if you disconnect the neutral from the supply side, there is no current flow and hence no volt drop, sot the N is at a 230V potential.

And that's not me twisting things, and again, it's not me trying to start a fight. It's me trying, and failing, to get across what I think is a very important fundamental point.

If you had a 9V battery, with a bulb connected across it, and you disconnected, at the battery, the wire attached to the -ve terminal, it would no longer be a -ve wire. Were you to connect a voltmeter to it to measure what voltage it was at wrt battery - you would find that it was at +9V, and you would not be able to measure -9V between it and the battery +. It wouldn't be a -ve wire.

Of course this distinction doesn't matter most of the time when you're talking about the wires from the bulb holder, ditto the N conductor as per above, which is what I'd already said in #15, so in no way am I arguing with

timhoward said:
In fact I've just said "Neutral" to another sparky even though it isn't connected yet. Astoundingly they understood me. It felt great!

It's just that when someone is trying to get to grips with what is meant by "+9V", or "230V AC", about what potential differences exist between what points in a circuit, and when, and why, and why current flows, or does not flow, I think it is important to focus very precisely on what something actually is.

I'm sorry that I'm failing so badly to explain that people think I'm really trying to make trouble.

timhoward · Apr 14, 2021

Soi disant said:
I'm sorry that I'm failing so badly to explain that people think I'm really trying to make trouble.

I do think there has been some misunderstanding of intent. Trust me you have explained your point!
Sorry I was flippant. I just didn't want the poor chap to go off and become a plumber while we were arguing how best to describe a disconnected line conductor (and in fact his original post suggests he already understood this as a line conductor!)

(I also meant to say thank you for reminding me of the 325v peak waveform - it's been a long while since I did the x 1.414 maths for a WYE configuration)

ipf · Apr 14, 2021

So, with all this, 'neutral or not' talk, how do we test the RFC continuity of the 'neutral' (r n) on the circuit............. if it isn't connected to anything?
We've got to presume, sometimes.

It's like explaining a N fault (disconnected)

'There's a disconnected cable fault'
' What cable?'
'The blue one'.
'Is that the neutral?'
'No'.
'Well which one is it, then?'
'The one that's disconnected'.
Oh, fair enough, which one have you reconnected to clear the fault?
The neutral, of course'.

There's a hole in my bucket, dear Liza, dear Liza.

loz2754 · Apr 14, 2021

ipf said:
So, with all this, 'neutral or not' talk, how do we test the RFC continuity of the 'neutral' (r n) on the circuit............. if it isn't connected to anything?
We've got to presume, sometimes.

View attachment 84642

It's like explaining a N fault (disconnected)

'There's a disconnected cable fault'
' What cable?'
'The blue one'.
'Is that the neutral?'
'No'.
'Well which one is it, then?'
'The one that's disconnected'.
Oh, fair enough, which one have you reconnected to clear the fault?
The neutral, of course'.

There's a hole in my bucket, dear Liza, dear Liza.

Nice. Good argument there.

We're talking about a cable intended to be neutral. Only a severely afflicted pedant would attempt to argue otherwise.?

pc1966 · Apr 14, 2021

I think it was Lucian who pointed out a couple of months ago that the fact the N conductor is connected to earth, at some point, is what defines it as "neutral" compared to the line conductor(s).

The common earthing systems such as TN-S, TN-C-S and TT all revolve around how you connect to earth relative to the neutral conductor (separate, common PEN, or via the true Earth). Even IT systems usually have some high impedance means of referencing one conductor to the Earth's potential, for insulation monitoring if nothing else.

Even there, the choice of the Earth as 0V is simply a convention, certainly a reasonable one to justify, but it is still an arbitrary choice of what we mean when we say 0V in an absolute sense, rather than a voltage difference sense.

Mars is a bit for for an "earth rod" to get another opinion on 0V!

snowhead · Apr 15, 2021

I would imagine the O.P is sat in a corner quivering, wishing he'd never come on here and asked the question.

This thread needs deleting with the exception of the O.P and let it start again, without all the arguements over when is a Neutral not a Neutral.

It was a relatively simple question requiring a relatively basic answer.

UNG · Apr 15, 2021

Anyone for a floating neutral

snowhead · Apr 15, 2021

UNG said:
Anyone for a floating neutral

Ah, Yes But, No But, only if it actually exists.
I'm not having one if it's a phantom one.

ipf · Apr 17, 2021

snowhead said:
Ah, Yes But, No But, only if it actually exists.
I'm not having one if it's a phantom one.

So much for #24, then. ? ?

Micktw68 · Apr 17, 2021

Perfect example of just how argumentative and pedantic electricians are.

DJAndy · Apr 17, 2021

Micktw68 said:
Perfect example of just how argumentative and pedantic electricians are.

No they aren't

Neutral bar

Estiban

Rockingit

-

telectrix

-

timhoward

-

Soi disant

timhoward

-

ipf

-

loz2754

pc1966

snowhead

-

UNG

-

snowhead

-

ipf

-

Micktw68

DJAndy

News and Offers from Sponsors

Similar threads

OFFICIAL SPONSORS

YOUR Unread Posts