theoretical question

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Old 05-21-06, 04:52 AM
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theoretical question

You "electrical guys" seemed pretty well versed in theory so let me ask a question or two that's been bugging me. Does alternating current (as opposed to direct current) mean electrons reverse direction as the sine wave moves from top to bottom? Secondly, why is neutral called neutral? Does the behavior of the electrons change after the load?
 
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Old 05-21-06, 07:01 AM
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1) yes
2) what would you call it? a rose is ..
neutral= center tap connection at the distribution transformer for residential houses, it is most commonly connected to earth by the grounding electrode (rod)
3) no
 
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Old 05-21-06, 07:13 AM
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It is called neutral because it is at zero potential but not necessarily at "earth" ground.
You can probably find some pretty sophisticated arguments when it comes to "electron flow" theory. IMO the most correct description is that electron displacement varies in amplitude and reverses in direction proportionate to the EMF.
 
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Old 05-21-06, 08:11 AM
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[QUOTE=Wayne Mitchell]It is called neutral because it is at zero potential but not necessarily at "earth" ground.
QUOTE]
OK, I know this will raise the ire of a few but I must.

What is it at zero potential in respect to?

Potential is a reference to the potential difference (voltage) of two points. If it is zero potential, it must be in reference to a second point. What second point?
 
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Old 05-21-06, 08:52 AM
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Here are a couple of possible definitions of neutral. For most transformer setups they are essentially the same.

1) A transformer can have multiple output terminals. The common transformers used to supply 120V in the US for power distribution generally have three or four output terminals. As nap mentions, when you measure voltage, you must measure it between two points. You could select _any_ of the transformer output terminals as your 'reference zero', and thus define the relative voltages of the other terminals. The neutral is that terminal which, if selected as the reference zero, results in the lowest total voltage relative to your reference zero.

2) Electrical potential is always defined between two points, however either or both of these points may be mathematical constructs rather than actual physical points. One can construct a point which is the _average_ potential of the transformer and call this the reference zero. The neutral point is the terminal whose potential is the average potential of the transformer. For certain asymmetric transformer arrangements, the neutral point is the terminal with the lowest potential relative to this average potential.

-Jon
 
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Old 05-21-06, 09:00 AM
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I like that Jon (winnie).

Now can you explain in terms of a single winding 2 tap only transformer . They would simply be referenced to each other and would (of course) be equal no matter which you measured them.

Now in addition, if you earth ground either of those points, you do make it a true neutral. The potential between this point and earth becomes 0 and the other terminal to earth becomes what was term to term.

Now maybe you can help me with this point though. If (in the transformer i described above) you do not have any earth ground, why will you read voltage from either terminal to earth ground? It will not be any exact voltage but often ends up ~1/2 of the term to term voltage.
 

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Old 05-21-06, 10:11 AM
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Hmm. I guess that by my definition 1 either terminal could be the neutral, which isn't correct. Though I would note that under the NEC, if such a secondary were to be grounded, either terminal could be used to supply the grounded conductor.

In a single coil secondary, the two output terminals will _not_ have the same potential; since they will have opposite polarity. There will be a coil in the center of the winding which is at the neutral potential, simply not connected to a terminal.

There really isn't a true 'ungrounded' system, since there are always leakage currents and _capacitive_ coupling. In the nominally ungrounded system that you describe, such leakage and capacitance will tend to make the terminal to ground voltages equal, unless there is something that upsets the balance, eg. a ground fault or some static discharge.

-Jon
 
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Old 05-21-06, 11:22 AM
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Hmm. I guess that by my definition 1 either terminal could be the neutral, which isn't correct. Though I would note that under the NEC, if such a secondary were to be grounded, either terminal could be used to supply the grounded conductor.
My point exactly; neither is a neutral, at this point. They are both merely "hot" terminals. One derives a neut (in this case) by grounding one term. After all, a neut, by specification (NEC) is a grounded conducter and by definition (NEC) a grounded conducter is one which is intentionally connected to an earth ground.

In a single coil secondary, the two output terminals will _not_ have the same potential; since they will have opposite polarity. There will be a coil in the center of the winding which is at the neutral potential, simply not connected to a terminal.
I think you may have misunderstood my statement. Basically, there is nothing to measure to other than each other. In that case, even if you revered your test leads, it will measure the same. Polarity would make a difference if you are using it as part of a buck-boost transformer but that would need an additional winding to happen.
The "coil" you speak of; what do you speak of. There is of course the core but other than the primary windings and the secondary windings, there is nothing else. Also, the "neutral" of a typical resi transformer uses a center tap brought out from the center point of the secondary windings to serve as the neut. Although any of the three terms would act as neut if grounded (earth) but would allow a 240 volt to ground and a 120 volt to ground term if any term other than the center tap used as neut.

There really isn't a true 'ungrounded' system, since there are always leakage currents and _capacitive_ coupling. In the nominally ungrounded system that you describe, such leakage and capacitance will tend to make the terminal to ground voltages equal, unless there is something that upsets the balance, eg. a ground fault or some static discharge.
That is probably as good as explanation as I have ever been given. Actual testing does show that they can be unequal.

Case in point.
I have a small transformer 2 term primary (120 v). 4 term secondary, hooked up as 24 volt secondary. (x2 -x3 tied, x1 and x4 as supply terms.)

with no ground connection but setting on a grounded metal table, voltage readings (secondary) were 26 volts term to term. x1 to an true earth ground ~5 volts ;x4 to ground ~12 volts
after grounding x1;
x1 to ground - 0 (of course)
x4 to ground or x1 26 volt

clearing x1 to ground and grounding x4; same readings but reversed, of course.

So is the odd voltage to ground (with no terms grounded) reading due to the capacitive coupling? But why the unequal reading to each term.

This is the similar as I have observed in actual situations in the field. Although with a 120 volt control transformer the voltages seem to be closer to a true 1/2 of term to term voltage but are usually not exactly equal.. The trans is mounted to a metal backplate which is actually grounded to earth via the EGC.

This entire post feeds back into the post of "bolides" with me.
Post by bolide

In a resi situation, if the "neut" is not actually earth grounded, there is no actual 0 reference. (true 0 volt reading) but by grounding the neut, it allows a 0 voltage reading on the neut at any point (barring open circuitry) and causing a 120 v to neut OR ground reading.

Where this is advantageous to the electrician is that if there is no actual earth ground, you could not reference hot or neut to ground for a test measurement. You would have either a 0 volt to ground from either hot or neut or somewhat less than 120 v.
depending to how your description of capacitive coupling or leakage explanation affects things.

So one practical application of a true earth ground would be:

observed 120v reading from a neut (in field) to ground.
cause; neut has lost connection somewhere between that point and panel connection (this is of course barring a short circuit and is taking into consideration that there is a device connected in that circuit (light switch on or such)
 
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Old 05-21-06, 12:25 PM
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In fact you can define polarity on a single coil secondary.

The potential difference between two points is the same no matter what path you follow between these two points.

If you take a voltage sensor and measure between both terminals of the transformer secondary and ground, then you will measure two separate voltages. These are AC voltages, and constantly changing. But when one terminal is most positive, the other terminal will be most negative, and vice-versa. If you graph the voltage difference between the two terminals, you will have a graph of the transformer secondary output. The graph of X2-X1 will be the inverse of X1-X2.

Remember that if you are using an RMS meter, that it is averaging the measured potential difference over time, and 'throwing away' any phase information. If you measure a 120V ungrounded control transformer, X2 might measure 60V RMS to ground, and X1 might measure 60V RMS to ground, but at any _instant_ in time, an oscilloscope might show X1 at -85V while X2 is at +85V, then a quarter cycle later they would both be at 0V, and then later at +85 and -85. The difference between the two (X2-X1) would vary from +170V to -170V.

The 'coil' that I mentioned was a slang term for the secondary winding of the transformer, which is composed of turns of wire wrapped around the core. Even with no actual terminal brought out, there will be a point on the transformer secondary that is always exactly halfway between the two terminals in potential. This is the neutral point of that secondary winding, even if there is no secondary terminal.

-Jon
 
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Old 05-21-06, 01:16 PM
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In fact you can define polarity on a single coil secondary.
agreed, did I state something contrary? I don't think so. I actually listed a use because of the polarity. The need for a second winding would be so there would be an additive or subtractive effect of the the voltage due to the relative polarity in a buck-boost transformer.

[QUOTE]
The potential difference between two points is the same no matter what path you follow between these two pointsQUOTE]
Not sure what you are relating this to. If it is the open neutral situation, you misunderstand the situation. If the neutral is not connected to ground, it is essentially a hot conductor. Since any neutral should read 0 volts to ground (or close, circuit resistance variances between any point on a neut and the refferencing ground can cause a reading >0), IF the electrician observes line voltage on the neutral (in reference to ground) it indicates that the connection to the neutral bar is open somewhere between that point and the neutral circuitry to the neutral bar.
If you take a voltage sensor and measure between both terminals of the transformer secondary and ground, then you will measure two separate voltages.
No, you should not. They are the opposite ends of the same windings and because of this, they should be equal to any equal reference point. The fact is, if you do not have a true reference point (grounded neutral) these readings are not dependable due to the lack of "connection" with the reference point. I am not dealing with instantaneous readings. Polarity would would also have no affect that I can see. I am simply reading from x1 or x4 to an un-associated ground. The only association there could be is via the EMF developed. With a small transformer setting on the table, the variance between the interaction read from the two terms would be so minimal I caould not read it with a basic meter.

Remember that if you are using an RMS meter, that it is averaging the measured potential difference over time, and 'throwing away' any phase information. If you measure a 120V ungrounded control transformer, X2 might measure 60V RMS to ground, and X1 might measure 60V RMS to ground, but at any _instant_ in time, an oscilloscope might show X1 at -85V while X2 is at +85V, then a quarter cycle later they would both be at 0V, and then later at +85 and -85. The difference between the two (X2-X1) would vary from +170V to -170V.
Not applicable. I am not using instantaneous readings. Just a run of the mill multi-meter. The comparitive measurements both would be averages.

The 'coil' that I mentioned was a slang term for the secondary winding of the transformer, which is composed of turns of wire wrapped around the core. Even with no actual terminal brought out, there will be a point on the transformer secondary that is always exactly halfway between the two terminals in potential. This is the neutral point of that secondary winding, even if there is no secondary terminal.
OK, this makes sense. The problem with this is it is not the same as a neutral as defined by the NEC. All neutral references in my posts are refferring to the NEC reference, not the mid-point definition. I posted the definition earlier.
You speak of A neutral point. I speak of THE neutral conductor. Two very different things.

Do you have a small transformer handy to check what I am reading?
 
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Old 05-21-06, 04:20 PM
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I don't think that I am clearly understanding what you are asking. I was just trying to describe what a transformer _neutral_ is.

While one might use 'neutral' as slang for the grounded conductor in a 120V secondary with one leg grounded, it is not the neutral of that transformer.

I belive that we are using the term polarity somewhat differently, and my use is probably less appropriate in the context of electrical installations.

Polarity is used both to mean the differentiation between grounded and ungrounded conductors or it is used to mean the positive versus negative phase relationship of a transformer winding. I was using the latter meaning, but the former meaning is much more common. You are quite correct that if you have an ungrounded 120V secondary, then polarity in the sense of hot versus grounded not defined.

Originally Posted by nap
If you take a voltage sensor and measure between both terminals of the transformer secondary and ground, then you will measure two separate voltages.
No, you should not. They are the opposite ends of the same windings and because of this, they should be equal to any equal reference point. The fact is, if you do not have a true reference point (grounded neutral) these readings are not dependable due to the lack of "connection" with the reference point. I am not dealing with instantaneous readings.
Average voltage readings (RMS average) throw away information. These readings are generally more useful because they let one see the forest rather than the trees, but are limited. If you want to understand what is happening in terms of the voltages in an ungrounded secondary, you need to deal with the physics definition of voltage, not the practical RMS average voltage that is usually used for electrical work.

Voltage can _always_ be defined in the physicists sense between _any_ two points, even if there isn't a conductive path between the two points. A satellite in space or a non conductive point on the surface of a sheet of glass (or a point inside the glass) can all have voltage relative to some other point. So called 'phantom voltage', seen with digital multimeters on unconnected wires, is a _real_ voltage measurement, but a measurement of voltage caused by very small amounts of charge, and a measurement of voltage that isn't backed up by much current. If you were to make the same measurement with a low impedance meter, the 'phantom voltage' all but disappears.

A transformer secondary, not connected to ground, still has voltage at each terminal. This voltage is not _stabilized_ in the sense of a nice low impedance source that holds it steady, but the voltage is well defined in the physics sense. With a suitable high impedance voltage sensor, one could measure the voltage of either terminal of this transformer secondary. When looked at in this fashion, a 'neutral point' for _any_ transformer can be defined; though there might be no electrical connection made to this point, and it might not be a grounded terminal (connected to a grounded conductor).

The RMS voltage to ground of either terminal of the transformer will be a composite of any voltage caused by DC charge on the coil, any AC leakage to the coil, any capacitive coupling between the coil and ground, and any current flowing through your voltmeter.

-Jon
 
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Old 05-21-06, 04:56 PM
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[QUOTE]
A transformer secondary, not connected to ground, still has voltage at each terminal. This voltage is not _stabilized_ in the sense of a nice low impedance source that holds it steady, but the voltage is well defined in the physics sense.
yes, yes, yes!!! that is what I have been after all this time. The readings a typical electrician takes in a typical electrical install are voltages that are referenced to ground. If this reference is not incorporated, the readings become confusing to those not aware of the reason. That is why it is important that an earth ground 0 point reference is established and maintained in a typical utility elecrtical system.

I have been trying to get others on this forum to understand this point but could not get it across to them. Maybe coming from you, they will accept it.
 
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Old 05-21-06, 05:31 PM
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Originally Posted by nap
yes, yes, yes!!! that is what I have been after all this time. The readings a typical electrician takes in a typical electrical install are voltages that are referenced to ground. If this reference is not incorporated, the readings become confusing to those not aware of the reason.
If the electrical system is not grounded, then all of the voltages _internal_ to the electrical system will still be perfectly normal. Electrical systems work perfectly well when ungrounded; this is sometimes intentionally done in industrial situations.

The typical readings that electricians take usually involved line-line, line-neutral, and various points to ground. The line-line and line-neutral voltages will remain _perfectly normal_ even if the system is entirely ungrounded. The line to ground voltages and neutral to ground voltages will become unstable if the system is ungrounded.

-Jon
 
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Old 05-21-06, 06:37 PM
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If the electrical system is not grounded, then all of the voltages _internal_ to the electrical system will still be perfectly normal. Electrical systems work perfectly well when ungrounded; this is sometimes intentionally done in industrial situations
.I know. I work with this on a regular basis.

The typical readings that electricians take usually involved line-line, line-neutral, and various points to ground. The line-line and line-neutral voltages will remain _perfectly normal_ even if the system is entirely ungrounded. The line to ground voltages and neutral to ground voltages will become unstable if the system is ungrounded.
resi systems are always grounded. It is a requirement. The bolded part is what I have been trying to get across to these guys for 3 days. The only addition I would like to make is that you will read some voltage from neutral to ground in this situation.

Please , please tell me you mean "earth ground" when you state ungrounded in the last line. and when you state "unstable" it is only when referenced to ground and not to another point on the transformer (terminals)
---------------------
Does this make sense to you then.

If a typical resi transformer is not grounded at any terminal, there will be no place where neutral (this ends up being the neutral in your definition because it is not grounded) will read 0 volts to any other point.

Inversely, if neutral (now it becomes a neutral in terms of the typical elec. install) is grounded, there will be a 0 volt diff from neut to ground.
--------------------
 
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Old 05-21-06, 06:41 PM
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practical

cem, wayne, nap, and winnie, you guys have made fascinating reading today on the subject of neutral. This site always amazes me on the depth of knowledge of the participants. But here's what I was really looking for: When I wire an outlet what is the difference between the hot(black) wire and the white (neutral) wire? After reading your posts is neutral grounded in the box? If electron behavior is the same why isn't neutral wire treated the same as hot wire? Touching neutral (white) wire doesn't seem to be as dangerous as touching black (hot) wire-why? Thanks for the great lessons so far!
 
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Old 05-21-06, 06:59 PM
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Originally Posted by rodf
cem, wayne, nap, and winnie, you guys have made fascinating reading today on the subject of neutral. This site always amazes me on the depth of knowledge of the participants. But here's what I was really looking for: When I wire an outlet what is the difference between the hot(black) wire and the white (neutral) wire? After reading your posts is neutral grounded in the box? If electron behavior is the same why isn't neutral wire treated the same as hot wire? Touching neutral (white) wire doesn't seem to be as dangerous as touching black (hot) wire-why? Thanks for the great lessons so far!
ok simple answers
When I wire an outlet what is the difference between the hot(black) wire and the white (neutral) wire?
120 volts. Oh that's not quite what you were looking for?
The whit (or grey is acceptable) wire is the neutral. It returns to the panel and is bonded to the ground at that point (service panel only) Befause of this it presents 0 volts (to ground reference)if everything is working correctly.

The black wire is the hot wire. It reads 120 volts to ground or neutral.

After reading your posts is neutral grounded in the box?
In the service panel (1st panel from meter if there is more than one panel) yes. but if you mean the junction box the recep or other things are mounted in, then a BIG no.

If electron behavior is the same why isn't neutral wire treated the same as hot wire?
It is safer this way. Well maybe I should n't really say that. It is because that is how we do it and it works
 
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Old 05-21-06, 07:55 PM
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Originally Posted by nap
If a typical resi transformer is not grounded at any terminal, there will be no place where neutral (this ends up being the neutral in your definition because it is not grounded) will read 0 volts to any other point.

Inversely, if neutral (now it becomes a neutral in terms of the typical elec. install) is grounded, there will be a 0 volt diff from neut to ground.
If a transformer is not grounded at any terminal, then the voltage between the transformer windings and ground becomes very unstable, and gets defined by the myriad of extremely small currents that flow. These include capacitive currents, leakage currents through insulation, ions moving through the air, etc. It would be possible that there are no points which are 0V to ground, or that some portion of the transformer is by chance at zero volts to ground.

Inversely, if any one terminal of the transformer is grounded, then there will be 0V between that terminal and ground. I would not call the grounded terminal a neutral; in a corner grounded delta the grounded conductor is clearly _not_ a neutral, and carries as much current as the ungrounded conductors.

Originally Posted by rodf
When I wire an outlet what is the difference between the hot(black) wire and the white (neutral) wire? After reading your posts is neutral grounded in the box? If electron behavior is the same why isn't neutral wire treated the same as hot wire? Touching neutral (white) wire doesn't seem to be as dangerous as touching black (hot) wire-why? Thanks for the great lessons so far!
To get a shock, you have to contact two points at _different_ voltage. Most shocks are between ground and some other voltage, because so much around us is either in contact with the ground, or electrically connected to the ground (say by water pipes or building structure). The other item is some energized wire or component.

Because the grounded (neutral) wire is electrically connected both to ground through a grounding electrode and to the bonded metal, there will be only very small voltage differences between the white wire and the bulk of conductive materials around. With little voltage, there is little shock hazard.

But the full circuit _current_ is flowing through the grounded conductor. This current is at low voltage (the voltage has been 'used up' if you will, supplying power to the load), and so won't shock you. But this is only true when the grounded conductor is intact and the current can flow freely. If the grounded conductor path is broken, current stops flowing through the load. The portion of the grounded conductor that is no longer connected back to the transformer will rise to full 'hot' voltage. People have been killed by electrocution when they've cut open neutral conductors that were carrying current.

-Jon
 
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Old 05-21-06, 08:16 PM
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Inversely, if any one terminal of the transformer is grounded, then there will be 0V between that terminal and ground. I would not call the grounded terminal a neutral; in a corner grounded delta the grounded conductor is clearly _not_ a neutral, and carries as much current as the ungrounded conductors.
You have to get on board with electricians terminology and defintions, Jon.

The grounded conductor is a neutral because it is grounded. We do not use the theoretical neutral you speak of. And yes, the corner grounded delta conductor is a neutral and is even indicated by a white marking on it. (NEC requirement for neut.)
A neutral is also defined as a current carrying conductor.
 
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Old 05-21-06, 10:05 PM
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The definition of a neutral is that it carries the imbalance of current in multiple hot wires from different taps of the transformer or generator, and is the common point of these. It does this whether it is grounded or not. The NEC makes this distinction by requiring the neutral to be grounded, implying a neutral is present in these circumstances, and they require you to ground it.

In a residential service, the neutral, as such, is present on the service side of the main disconnect and on the load side only in multiwire circuits (which include range and dryer loads) A neutral is not present on any 2 wire (120 volt) circuit, only a grounded conductor is.

Electrical systems are grounded for a number of reasons, not the least of which is preventing the shell of the equipment and associated wiring from rising to an excessive potential above ground due to influences from the voltages present on the supply side of transformers.

NAP, any good electrical site (not necessarily a DIY board, but an honest technical site that delves into the myriad ways of the electrical world) will explain a neutral is a neutral whether it is grounded or not, and it's definition and function is not based on its being grounded. The NEC requires that, not the laws of physics.

If you enjoy hijacking posts and making folks trying to help others look like they are playing the fool, there are a number of other forums on the WEB where they'd be more than happy to clean your clock for you. Much as it's a temptation, they don't condone or allow that here.
 
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Old 05-22-06, 04:15 AM
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Originally Posted by nap
You have to get on board with electricians terminology and defintions, Jon.

The grounded conductor is a neutral because it is grounded. We do not use the theoretical neutral you speak of. And yes, the corner grounded delta conductor is a neutral and is even indicated by a white marking on it. (NEC requirement for neut.)
A neutral is also defined as a current carrying conductor.
Before you start getting insulting, perhaps you should get on board with the terminology being used by the NEC.

Article 200 is titled 'Use and Identification of Grounded Conductors'. _Neutral_ is not mentioned anywhere in Article 200.

_Neutral_ is used in 310.15(B)(4) to figure out the effective number of current carrying conductors when 'multi-wire' circuits are used.

Neutral is also used in 250.26 for the selection of which conductor is to be grounded. 250.26 makes it pretty clear that if you are using a neutral conductor in your circuits, then it is the one to be grounded, but that the grounded conductor is _not_ necessarily neutral.

-Jon
 
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Old 05-22-06, 05:01 PM
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Originally Posted by rodf
Does the behavior of the electrons change after the load?
No. The difference is pressure. Like water that comes out the faucet, it can run only "downhill" from there and is limited in quantity.
 
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Old 05-22-06, 06:35 PM
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The definition of a neutral is that it carries the imbalance of current in multiple hot wires from different taps of the transformer or generator, and is the common point of these. It does this whether it is grounded or not. The NEC makes this distinction by requiring the neutral to be grounded, implying a neutral is present in these circumstances, and they require you to ground it.
So the neutral IS the GROUNDED conductor, by your own statement

In a residential service, the neutral, as such, is present on the service side of the main disconnect and on the load side only in multiwire circuits (which include range and dryer loads) A neutral is not present on any 2 wire (120 volt) circuit, only a grounded conductor is.
ok, I'll give. You tell the millions of electricians that the white wire on those receps is not a neutral. Actually you are wrong though. You see, a resi service is NOT a two wire system. It is a 3 wire system. The two hots at the panel make it such. Just because you only use one hot does not make it a two wire system. A control transformer would provide a 2 wire system.

Electrical systems are grounded for a number of reasons, not the least of which is preventing the shell of the equipment and associated wiring from rising to an excessive potential above ground due to influences from the voltages present on the supply side of transformers.
OK, nut what does this have to do with that white wire that isn't a neutral. That wire is intentionally not grounded anywhere except the service panel.

NAP, any good electrical site (not necessarily a DIY board, but an honest technical site that delves into the myriad ways of the electrical world) will explain a neutral is a neutral whether it is grounded or not, and it's definition and function is not based on its being grounded. The NEC requires that, not the laws of physics.
I never argued that fact. Since this is a DIY site and when somebody asks "what color screw does the nuetral go on on a recep" are you going to tell them it is not a neut? I doubt it. It is accepted terminology to condider that a neut.

If you enjoy hijacking posts and making folks trying to help others look like they are playing the fool, there are a number of other forums on the WEB where they'd be more than happy to clean your clock for you. Much as it's a temptation, they don't condone or allow that here.
Hijacking?? This was intentionally posted to address the theoretical actions of electricity. I did not deviate from that discussion.
 
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Old 05-22-06, 07:05 PM
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Before you start getting insulting, perhaps you should get on board with the terminology being used by the NEC.
I apologize if you took it as an insult. It was not meant as such. Obviously neutral is commonly accepted as a term for the white wire, even when it is not a true neutral. While I did not intend to infer that your use was wrong,(I know it is not) it's just that most electricians (including me up to this point) do not realize where neutral is actually derived. When most electricians speak of the neut, they are not intending to refer to the transformer neutral, they are refereing to the neutral conductor.

Article 200 is titled 'Use and Identification of Grounded Conductors'. _Neutral_ is not mentioned anywhere in Article 200
.That is part of the problem with the NEC. There are many references to the neutral CONDUCTOR. It states it is to be grounded. and yes, you are correct that although it is grounded it is not necessarily a neutral. (see apology )

_Neutral_ is used in 310.15(B)(4) to figure out the effective number of current carrying conductors when 'multi-wire' circuits are used.
ok

Neutral is also used in 250.26 for the selection of which conductor is to be grounded. 250.26 makes it pretty clear that if you are using a neutral conductor in your circuits, then it is the one to be grounded, but that the grounded conductor is _not_ necessarily neutral.
OK, I give. You are correct. after your points, I do see that the actual neutral of the transformer is what the NEC does describe as a neut. It is I (and millions of other electricians) that use the term neut not entirely correctly.

I will note this but you do know that electricians will still call the common conductor in a 3 phase wye system the neutral don't you?

but your statement several posts back is actually wrong and you showed me why.
While one might use 'neutral' as slang for the grounded conductor in a 120V secondary with one leg grounded, it is not the neutral of that transformer.
The grounded conductor is actually the neutral for that transformer. As I mentioned before, a resi system is not a 2 wire system, it is a 3 wire system, no matter how many wires of that system you use. The common (neutral) is the center tap of the windings therefore it is a neutral.
 
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Old 05-23-06, 05:01 AM
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I apologize for being too quick to take offense.

The fact of the matter is that language is not precise and is always changing.

Neutral and grounded have been confused for a very long time, and many electricians use and will continue to use 'neutral' to mean the grounded conductor. I understand that the NECs use of and distinction between Neutral and Grounded is an attempt to push the language, and make clear a distinction that is quite real in the physics of the matter.

I do not know the history of how the NEC code making panels decided on this particular use of the language. They could just as easily have come up with entirely new words to use in the code.

Later we can discuss using the term 'phase' for the two legs of a single phase panel, or the correct orientation of the ground pin on a receptacle

-Jon
 
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Old 05-23-06, 04:49 PM
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I apologize for being too quick to take offense.
No need, I have been a "bit" anal around here. I'm trying to mellow but it's hard for an old guy. You know the old dog, new tricks thing, right?


Later we can discuss using the term 'phase' for the two legs of a single phase panel, or the correct orientation of the ground pin on a receptacle
You are daring, I must say.

To all who I may have insulted. I truly apologize. There is another forum I spend some time on and at times members can be quite crass and adversarial (like myself apparently) . This forum is not as adversarial and I need to get with the program here when I am here.

You have a good forum here. There are members here with knowledge that is amazing and I need to learn to play nice with them.

Please accept my apologies.
 
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