? Neutral ? Why do they call it that?

[mwilson87a]

Why?

Why?

Neutral and Ground differ in that one is a current carrying and one is not. They are both at 0V in reference to earth.

In your transformer, provided the secondary side is isolated from the primary (ie, not an autotransformer, etc...) you will have a voltage between your terminals that follows the waveform you put on the primary side (for the most part.)

You can hook things up to these terminals and run them just fine, but realize each terminal would be at some unknown voltage at all times. Saying ZERO volts would be somewhere in the middle of the secondary coil is SOMEWHAT accurate, but you'll never be able to find it.

You GROUND one of the terminals on the secondary side to set it to ZERO volts. Now you should branch from that terminal ONLY for your AC power on the secondary side, DO NOT try and use a ground elsewhere for your common. Neutral term is just a word to describe a zero potential line that is current carrying. There are a LOT of myths on what/how/why, but simply put, it comes from the need to keep people safe and stems from the light socket. The light socket is very unsafe. You screw a bulb in and the treads are live right away. This is where the POLARIZED plugs in homes came from. This helps keep the NEUTRAL, 0V, connection to the treaded portions. The 0V assignment came out of safety concerns.

Later on, the 3 wire system, with a HOT, NEUTRAL and then GROUND came into play. This was very ingenious. You have your hot, your 0V current carrying neutral for any exposed connections, then the ground is used to ensure any conductive surfaces will conduct current away should the HOT/NEUTRAL be hooked up wrong, the HOT comes loose, etc. Additionally, the flow of current in the neutral, though zero volts, can be cross compared to the ground and neutral-ground faults can also be detected.

So, WHY the names? HOT means OUCH, that's hot. NEUTRAL means safe, but what you use, and GROUND means earthed directly.

 

[kwired]

Neutral and Ground differ in that one is a current carrying and one is not. They are both at 0V in reference to earth.

In your transformer, provided the secondary side is isolated from the primary (ie, not an autotransformer, etc...) you will have a voltage between your terminals that follows the waveform you put on the primary side (for the most part.)

You can hook things up to these terminals and run them just fine, but realize each terminal would be at some unknown voltage at all times. Saying ZERO volts would be somewhere in the middle of the secondary coil is SOMEWHAT accurate, but you'll never be able to find it.

You GROUND one of the terminals on the secondary side to set it to ZERO volts. Now you should branch from that terminal ONLY for your AC power on the secondary side, DO NOT try and use a ground elsewhere for your common. Neutral term is just a word to describe a zero potential line that is current carrying. There are a LOT of myths on what/how/why, but simply put, it comes from the need to keep people safe and stems from the light socket. The light socket is very unsafe. You screw a bulb in and the treads are live right away. This is where the POLARIZED plugs in homes came from. This helps keep the NEUTRAL, 0V, connection to the treaded portions. The 0V assignment came out of safety concerns.

Later on, the 3 wire system, with a HOT, NEUTRAL and then GROUND came into play. This was very ingenious. You have your hot, your 0V current carrying neutral for any exposed connections, then the ground is used to ensure any conductive surfaces will conduct current away should the HOT/NEUTRAL be hooked up wrong, the HOT comes loose, etc. Additionally, the flow of current in the neutral, though zero volts, can be cross compared to the ground and neutral-ground faults can also be detected.

So, WHY the names? HOT means OUCH, that's hot. NEUTRAL means safe, but what you use, and GROUND means earthed directly.

Yes but also no. Most of what you said there is true but is slightly off topic of defining what is neutral. Neutral conductor does not have to be a grounded conductor, but most always is, but not all grounded conductors are/have to be a neutral conductor.

An equipment grounding conductor is electrically bonded to the grounded conductor (which may or may not be a neutral depending on the system) of a grounded system. We still have equipment grounding conductor requirements with non grounded systems as well, they bond non current carrying components together to help minimize voltage potential from developing in those items but are not bonded to any portion of the source if it is to be an ungrounded system.

 

[jaggedben]

You GROUND one of the terminals on the secondary side to set it to ZERO volts.

Grounding the neutral sets it to (roughly) zero volts to ground, nothing else. It's not zero volts to other conductors.

Neutral term is just a word to describe a zero potential line that is current carrying.

No, it means something more specific than that. If by zero potential you mean to ground, there are grounded conductors that are not neutrals.

So, WHY the names? HOT means OUCH, that's hot. NEUTRAL means safe, but what you use, and GROUND means earthed directly.

After all the good info offered in this thread you are now confusing things. The distinction you are making is properly between grounded conductors and equipment grounding conductors. Both are earthed. The grounded conductor is usually but not always a neutral.

 

[jaggedben]

How would a Venn diagram look to distinguish the definitions of neutrals and groundED conductors?

I thought it might be worth going back to this unanswered question. I believe the attached is correct. (There may be neutrals covered by the NEC that are not required to be grounded, but I'm not aware of them.)

 

[iwire]

You GROUND one of the terminals on the secondary side to set it to ZERO volts.

I have two issues with that.

1) We bond/ground one of the secondary side terminals to provide a fault path for operating the overcurrent device. Once we understand that need we than have a choice to make of which of the secondary conductors to bond. If one of the secondary conductors happens to be a neutral that is the one we are required to bond. It makes sense and it is code required.


2) The neutral will only be 'zero volts' to ground right at the bond. Downstream, with load on the conductors causing voltage drop the neutral voltage to earth will rise. Very common to have 2 to 4 volts between neutral and ground out at the outlets.

 

[romex jockey]

The vectoral sum would not be zero. It would be whatever the circuit voltage is. This goes to the heart of the original question. We call a conductor a neutral because of its midpoint characteristic (aka nominal vectoral sum) , not because of its lack of potential to ground.

Theoretically 'zero V' occurs with any secondary earthed , a vector is merely the mathematical sum of components . Where does the definition require said 'sum' to be plural?

In US power wiring we hardly ever have a neutral that isn't a grounded conductor. But we do occasionally have grounded conductors that aren't a neutral. Examples would be 120V systems, grounded (non-bipolar) DC systems, and corner grounded deltas.

As in every vehicle we drive, the computers we're typing this entire debate with, my local grange hall(vintage K&T 120 service) , my town pool's motor (open CG delta) , etc etc....

~RJ~

 

[romex jockey]

So, WHY the names? HOT means OUCH, that's hot. NEUTRAL means safe, but what you use, and GROUND means earthed directly.

Never messed up a noodle, eh?...:lol: ~RJ~

 

[kwired]

So, WHY the names? HOT means OUCH, that's hot. NEUTRAL means safe, but what you use, and GROUND means earthed directly.

I see some changes for 2020 NEC to come in art 100, or if it is urgent enough a TIA for 2017.

 

[jaggedben]

Theoretically 'zero V' occurs with any secondary earthed ,

'Zero V' to what? A voltage is always measured between two points. I don't think your statement actually makes sense, theoretically. :happyno: The neutral is not 'zero V' to everything.

a vector is merely the mathematical sum of components . Where does the definition require said 'sum' to be plural?

The Informational Note uses the words 'vectoral sum'. The definition doesn't actually use the words, but it accords with the note. I don't know what your trying to get at with the question about 'plural', but the NEC definition of neutral does not apply to any 2-wire systems, so the available nodes mean you'll always have 'plural' voltage measurements.

 

[jaggedben]

As in every vehicle we drive, ...
~RJ~

Technically the frames of vehicles with rubber tires are not grounded.

 

[mbrooke]

Theoretically 'zero V' occurs with any secondary earthed , a vector is merely the mathematical sum of components . Where does the definition require said 'sum' to be plural?





As in every vehicle we drive, the computers we're typing this entire debate with, my local grange hall(vintage K&T 120 service) , my town pool's motor (open CG delta) , etc etc....

~RJ~

It seems grounding alone calls for classification of a neutral conductor.

 

[mbrooke]

Not wrongly. Just differently. Except SI units. You really need to catch up with the rest of the world on that. Or get left behind in the Burmese jungles.

This is rather confusing

 

[romex jockey]

'Zero V' to what? A voltage is always measured between two points. I don't think your statement actually makes sense, theoretically. :happyno: The neutral is not 'zero V' to everything.

Point taken Jag, so how do we address isolation xformers....?

The Informational Note uses the words 'vectoral sum'. The definition doesn't actually use the words, but it accords with the note. I don't know what your trying to get at with the question about 'plural', but the NEC definition of neutral does not apply to any 2-wire systems, so the available nodes mean you'll always have 'plural' voltage measurements.

Is this same nec that defines 'earth' as dielectric Jag?

Just because the NEC creates a definition , it does not mean it is the all inclusive end all of what it intends to define.

That one can ground one side of a two wire system , meeting all requirements of 'neutral' in what constitutes the physics of electricity should be evidence enough

~RJ~

 

[romex jockey]

This is rather confusing

'by convention' ......?

meaning a job meeting?


~RJ~

 

[mbrooke]

'by convention' ......?

meaning a job meeting?


~RJ~

How its done.

I guess we now must define "energized"...

A PEN is not considered energized by convention, but a pure N is, even though both are close to earth potential even under load. Clear as mud, right?

 

[jaggedben]

Point taken Jag, so how do we address isolation xformers....?

Address what about them?

Is this same nec that defines 'earth' as dielectric Jag?

I guess I'm a fool for looking to see if the NEC defines 'earth', but if you were trying to make a point then you're the greater fool, because no, it is not the same NEC.

Just because the NEC creates a definition , it does not mean it is the all inclusive end all of what it intends to define.

True, but the NEC makes a sensible distinction between neutral and grounded conductor, and when that distinction is important one should not muddle terms. I see no reason we should drop the distinction.

That one can ground one side of a two wire system , meeting all requirements of 'neutral' in what constitutes the physics of electricity should be evidence enough
~RJ~

??? I don't think physics cares what we call things. That's a grounded conductor and not a neutral under the NEC. It doesn't meet the NEC requirements to be a neutral, and I don't know what alternative requirements you might have in mind.

It seems grounding alone calls for classification of a neutral conductor.

Is that an old NEC definition, or something else?

 

[mbrooke]

Is that an old NEC definition, or something else?

Definition in BS7671.

 

[jaggedben]

Definition in BS7671.

Well at least the NEC has no monopoly on bad logic and inconsistency.

 

[Besoeker]

'by convention' ......?

meaning a job meeting?


~RJ~

Yes. In a pub serving conventional ales.

 

[mbrooke]

Well at least the NEC has no monopoly on bad logic and inconsistency.

I know, right? :lol: