Neutral Question

[jumper]

What they do not use is a balanced single phase two wires with respect to that neutral.
One answer is that it gives us the ability to run both 120V and 240V loads from the same service without adding another transformer.

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Yeah, but since all the stuff in the house runs on one voltage there is no need for two voltages.

 

[Jraef]

A point missed here is that not all neutrals are grounded. Any Navy electrician will know that. I wasn't in the Navy but over the years I hired a couple as wiremen in my panel shop. I had a hard time convincing them that we (landlubbers) always ground the neutral someplace, they just were not used to that and it went against their training. When we built panels with transformers inside, they kept on leaving the neutrals floating. Everything worked fine, but it was a problem for electricians in the field who would test circuits by referencing to ground and find all kinds of odd voltages (because of capacitance), prompting trouble calls. After making these guys go out in the rain and snow to fix it, they would finally learn.

 

[ggunn]

Hello All- I am new to the forum and have a question that was asked of me and I am not sure exactly how to answer it. It came up in a discussion with a friend who is not an electrician. The question I was asked regards as to why the grounded conductor is referred to as the neutral. I found it difficult to explain why it is referred to as 'neutral'. Understanding that it is bonded to the ground at the service was not the issue, it was the use of the term neutral...because I couldn't define it is really bugging me. TIA!

The neutral can still be a neutral even if it isn't grounded. If the neutral in a split phase service is ungrounded, it's still the voltage midpoint between L1 and L2 and will still function as a neutral in unbalanced circuits. Whether it needs to be grounded to comply with the NEC is another question.

Note: I said ungrounded, not open, i.e., an ungrounded neutral connected to the center tap of the transformer. An open neutral is something else entirely.

 

[mbrooke]

A point missed here is that not all neutrals are grounded. Any Navy electrician will know that. I wasn't in the Navy but over the years I hired a couple as wiremen in my panel shop. I had a hard time convincing them that we (landlubbers) always ground the neutral someplace, they just were not used to that and it went against their training. When we built panels with transformers inside, they kept on leaving the neutrals floating. Everything worked fine, but it was a problem for electricians in the field who would test circuits by referencing to ground and find all kinds of odd voltages (because of capacitance), prompting trouble calls. After making these guys go out in the rain and snow to fix it, they would finally learn.

Not to side track- but what would be the point of that?

 

[jeremysterling]

Not to side track- but what would be the point of that?

Combat Readiness. Loss of propulsion or fire control due to an electrical fault casualty can be avoided by not allowing ground fault to trip critical circuits.

 

[MAC702]

A point missed here is that not all neutrals are grounded. Any Navy electrician will know that. ....

Perhaps, but it was outside the context of the OP, asking why the grounded conductor is often referred to as a "neutral" even when it is not functioning as one.

I was in the Navy, but that was before I became an electrician. I know anything electrical we brought on board had to be looked at by a Navy electrician so he could make sure it would work with the ship's electrical system, which I was told had two 55 V "hot" legs at the receptacle, for 110 V between the prongs that would normally be "hot" and "neutral."

 

[Ingenieur]

my wag
it has to do with charge/polarity
positive
negative
neutral

 

[jumper]

Perhaps, but it was outside the context of the OP, asking why the grounded conductor is often referred to as a "neutral" even when it is not functioning as one.

"

Actually what the OP wants to know to know is why we use the word “neutral” for the conductor.

What is the origin and meaning of the actuall word. We know how it is used in context of the NEC and such, but why was that word picked.

As Charlie B said, it really does not matter, someone at sometime somewhere chose it and it stuck. How or why it was chosen is unknown so far.

In short, what is the etymology of the word in an electrical context?

 

[ggunn]

Actually what the OP wants to know to know is why we use the word “neutral” for the conductor.

What is the origin and meaning of the actuall word. We know how it is used in context of the NEC and such, but why was that word picked.

As Charlie B said, it really does not matter, someone at sometime somewhere chose it and it stuck. How or why it was chosen is unknown so far.

In short, what is the etymology of the word in an electrical context?

It seems to me that it means a conductor that is neither L1 nor L2, or phase A, B, nor C but is at the voltage which is the sum of the voltages of the two or three others. If it is grounded it is at absolute zero, but if not it is at relative zero compared to the phase/line conductors. "Neutral" is, IMO, a good choice of terms.

 

[jumper]

It seems to me that it means a conductor that is neither L1 nor L2, or phase A, B, nor C but is at the voltage which is the sum of the voltages of the two or three others. If it is grounded it is at absolute zero, but if not it is at relative zero compared to the phase/line conductors. "Neutral" is, IMO, a good choice of terms.

No argument.

But who coined the term and why? Maxwell, Planck, Kirchhoff, etc?

Gotta be some egghead in the early stages of AC development or analysis.

 

[mbrooke]

my wag
it has to do with charge/polarity
positive
negative
neutral

A neutral still has a charge- otherwise you would not get current flow or 120 volts.

 

[jumper]

A neutral still has a charge- otherwise you would not get current flow or 120 volts.

Current does does not flow, it is a rate of flow.

Charge flows or rather a charge of so many columbs does.

 

[ggunn]

A neutral still has a charge- otherwise you would not get current flow or 120 volts.

I don't know what that means. Voltage on a single conductor is meaningless; it has to be referenced to something.

 

[Ingenieur]

A neutral still has a charge- otherwise you would not get current flow or 120 volts.

you have negative charge (excess electrons) or absence of electrons, holes or net positive protons
or no net charge, balanced or 'neutral', ie, protons=electrons natural state

 

[Ingenieur]

Current does does not flow, it is a rate of flow.

Charge flows or rather a charge of so many columbs does.

yep
ampere = coulomb / sec
a coulomb is a measure of 'charge' or electrons

[FONT=&quot]It is equivalent to the charge of approximately [/FONT][FONT=&quot]6.242×10¹⁸[/FONT][FONT=&quot] ([/FONT][FONT=&quot]1.036×10⁻⁵[/FONT][FONT=&quot] [/FONT]mol[FONT=&quot]) [/FONT]protons[FONT=&quot], and −1 C is equivalent to the charge of approximately [/FONT][FONT=&quot]6.242×10¹⁸[/FONT][FONT=&quot] [/FONT]electrons[FONT=&quot].[/FONT]

 

[mbrooke]

Current does does not flow, it is a rate of flow.

Charge flows or rather a charge of so many columbs does.

Which is caused by a potential between two points.

I don't know what that means. Voltage on a single conductor is meaningless; it has to be referenced to something.

That what I am saying. Voltage is a reference across two points. Between any phase and neutral you get voltage.

you have negative charge (excess electrons) or absence of electrons, holes or net positive protons
or no net charge, balanced or 'neutral', ie, protons=electrons natural state

Then why can you measure voltage L-N? There must be a charge difference on the neutral in order to get a voltage reading.

 

[jumper]

Which is caused by a potential between two points.

I am gonna give you the benefit of the doubt and believe that you are not saying that if there is a voltage potential between two points there will be “ current flow”, I think you mean that the voltage potential must exist for the possibllty of “ current flow” to occur.

 

[tom baker]

NEC knows the difference well. Historically the NEC has avoided the term neutral, choosing instead to use the term "grounded conductor" Reason being that not all conductors connected to earth are neutral. Two examples:

1. A corner grounded delta. Here a phase is grounded down. Its far from a center point, but code wants it to be treated like a neutral, ie unfused- and if run through a disconnect or OCPD, it must simultaneously open the hots.

2. A 120 volt only transformer. Technically there is no neutral, just two ends of a single winding. IF feeding outlets or light sockets, code wants one end grounded. Hence grounded conductor- treated and identified like you would with a typical neutral conductor.


Only recently has the NEC decided to use the term neutral, and when it does its only in applications where an actual center point is involved, ie sizing the grounded conductor on a 3 phase or split phase service, not counting the grounded conductor on a MWBC in derating ,ect- stuff that you know only applies to imbalance current.

Good answer. Thomas Edison may be the person who used neutral, referring the common conductor for a 120/240 V 3 wire system. The NEC did not use a grounded system until about 1920? There was much debate over grounding the secondary of an electrical system but eventually this became a code requirement.
The code used the term grounded conductor as in Art 200. Electricians used the term neutral, but not all grounded conductors are neutrals, IE a 2 wire 120 V circuit does not have a neutral. And I find nothing in the NEC that tells us a neutral is a grounded conductor, I submitted a code proposal to that effect which was rejected.

 

[mivey]

Current does does not flow, it is a rate of flow.

Charge flows or rather a charge of so many columbs does.

Well said. Spoken like an engineer. Now I know you have gone completely crazy.

 

[Ingenieur]

Then why can you measure voltage L-N? There must be a charge difference on the neutral in order to get a voltage reading.

????
open ckt
touch h-g
touch n-g
is the a difference?
is g/earth considered 0 potential?

Electric charge is the physical property of matter that causes it to experience a forcewhen placed in an electromagnetic field. There are two types of electric charges: positive and negative (commonly carried by protons and electrons respectively). Like charges repel and unlike attract. An object with an absence of net charge is referred to as neutral.