Why "neutral"

[klrogers2]

Why do we use the term neutral for a grounded conductor? There is of course no definition of neutral in the NEC. The grounded conductor is sometimes at prefect zero potential voltage to ground so are we saying its "neutral" potential to ground. A directory type definition would be 'unbiased'.

Anyone have any ideas why and where we started using the term?


Kevin

 

[480sparky]

I see several uses of the word 'neutral' in the 1933 NEC in reference to what is called the identified conductor, what we call the grounded conductor today.

The term may go further back, but the numbering system was changed 'twixt the '31 and '33.

 

[iwire]

IMO the term neutral has nothing to do with it's potential to earth.

The neutral conductor is the conductor that carries only the imbalance between two or more other conductors.

If you have a two wire circuit say in a lamp cord you do not have a neutral you have a grounded and an ungrounded conductor.

On the other hand the supply to an electric dryer is two ungrounded and one grounded that s also a neutral conductor.

JMHO,

 

[Minuteman]

Neutral is a odd term. It does not really reflect the electrical condition of a conductor. I would guess, it is a grandfathered term representing the fact that a properly installed grounded conductor can be touched.

Another interesting term is "common". There's a word that can get confusing.

 

[wireguru]

neutral because its at zero volts and sits between the hots. (i have no idea, i just made this up)

 

[Minuteman]

neutral because its at zero volts and sits between the hots. (i have no idea, i just made this up)

Zero volts to ground, maybe.

 

[Smart $]

There is of course no definition of neutral in the NEC.

Perhaps not, but the 2008 NEC put something close in the definitions...

Neutral Conductor. The conductor connected to the neutral point of a system that is intended to carry current under normal conditions.

Neutral Point. The common point on a wye-connection in a polyphase system or midpoint on a single-phase, 3-wire system, or midpoint of a single-phase portion of a 3-phase delta system, or a midpoint of a 3-wire, direct-current system.

FPN: At the neutral point of the system, the vectorial sum of the nominal voltages from all other phases within the system that utilize the neutral, with respect to the neutral point, is zero potential.​

 

[Pierre C Belarge]

For once, I am going to take a neutral stance on this subject.

 

[PetrosA]

I think it's called a zero in most other languages, based on the L (line) and 0 (zero) markings on a lot of equipment overseas. I guess from a language point of view, zero and neutral are synonyms for the concept of the grounded conductor's potential to ground.

 

[Brian Oshman]

Neutral is a odd term. It does not really reflect the electrical condition of a conductor. I would guess, it is a grandfathered term representing the fact that a properly installed grounded conductor can be touched.

Another interesting term is "common". There's a word that can get confusing.

Neutral has nothing to do with its potential to ground or whether or not you can touch it without being shocked. Bonding the neutral to ground and all other metal components of a structure is what insures that. Neutral refers to the center tap, the mid point, the conductor able to simultaneously interact with all other phase conductors of a system.

 

[jim dungar]

I think it's called a zero in most other languages, based on the L (line) and 0 (zero) markings on a lot of equipment overseas. I guess from a language point of view, zero and neutral are synonyms for the concept of the grounded conductor's potential to ground.

The markings on equipment are 1 and 0 signifying on-off.

The presence or absence of a ground connection does not impact phase conductors or neutral conductors Would you call a corner-grounded phase conductor a neutral?

Neutral and phase are two adjectives that we have turned into nouns, by dropping words (like conductors). This is one reason they are hard to define.

 

[bob]

I believe the code use to define the neutral and a point in the circuit from which the voltage was the same when measured from that point to any other circuit conductors. A wye configuration has such a point. The delta configuration does not have this point. Conductor connected to this point in a delta configuration is termed the grounded conductor. Sometimes we mix the terms up but everyone seems to understand the terms when used.

 

[PetrosA]

The markings on equipment are 1 and 0 signifying on-off.

The presence or absence of a ground connection does not impact phase conductors or neutral conductors Would you call a corner-grounded phase conductor a neutral?

Neutral and phase are two adjectives that we have turned into nouns, by dropping words (like conductors). This is one reason they are hard to define.

I'm not referring to 1 and 0. In Europe most electrical devices that have screw terminals will have them marked with L and 0 or L and N

The corner grounded system does have a neutral point at the transformer, but it doesn't get used so no, I wouldn't call the grounded phase conductor a neutral.

I think I grasp the concept behind the neutral (or zero ) conductor. I imagine it sort of like a reversed fountain where there are three jets of water at the edge of the bowl spraying into the center (neutral point). I know this model is not accurate since AC flow isn't unidirectional like a spray of water, but the illustration helps me.

 

[jim dungar]

The corner grounded system does have a neutral point at the transformer, but it doesn't get used so no, I wouldn't call the grounded phase conductor a neutral.

A corner grounded delta connection does not have a 'neutral' connection point. A center-tapped delta has a point that is is neutral to two of the phase conductors, but not to the third.

0V would be a reference or common point, not necessarily a grounded point. As was previously discussed, if there are only two conductors in the circuit, one of them cannot be a neutral to the other, but it can be a reference.

 

[dbuckley]

I would guess, it is a grandfathered term representing the fact that a properly installed grounded conductor can be touched.

In Euroland the neutral is considered equivalent to a live (a/k/a hot) conductor, a stance that is exactly opposite to the NEC view. Same wire, same function, but different safety requirements.

 

[PetrosA]

A corner grounded delta connection does not have a 'neutral' connection point. A center-tapped delta has a point that is is neutral to two of the phase conductors, but not to the third.

0V would be a reference or common point, not necessarily a grounded point. As was previously discussed, if there are only two conductors in the circuit, one of them cannot be a neutral to the other, but it can be a reference.

I didn't say it had a neutral connection point, only a neutral point as any three phases do. It exists but isn't tapped... at least that's how it was explained to me.

In Euroland the neutral is considered equivalent to a live (a/k/a hot) conductor, a stance that is exactly opposite to the NEC view. Same wire, same function, but different safety requirements.

Is that because they don't use polarized plugs?

 

[brian john]

This should help clear it up?

IEEE 100-Dictionary

Neutral conductor

(Circuit consisting of three or more conductors). The conductor that is intended to be so energized, that, in the normal steady state, the voltages from every other conductor to the neutral conductor, at the terminals of entry of the circuit into a delimited region, are definitely related and usually equal in amplitude. NOTE: if the circuit is an alternating-current circuit, it is intended also that the voltages have the same period and phase difference between any two successive voltages, from each of the conductors to the neutral conductor, selected in a predetermined value usually equal to 2pi radians divided by the number of phase conductors m. SEE also network analysis center of distribution.

 

[jim dungar]

I didn't say it had a neutral connection point, only a neutral point as any three phases do. It exists but isn't tapped... at least that's how it was explained to me.

For the record, not all delta connected transformer banks have more than three output bushings, X1, X2, and X3. In a delta configuration it is not possible to have a 'neutral point' that is an equal voltage to all 3 phase conductors.

 

[Smart $]

For the record, not all delta connected transformer banks have more than three output bushings, X1, X2, and X3. In a delta configuration it is not possible to have a 'neutral point' that is an equal voltage to all 3 phase conductors.

Correct only when considering the source itself. However, a neutral voltage point can be derived by connecting a wye load having balanced impedance from each line to the common point—which is a "neutral point".

 

[Besoeker]

Is that because they don't use polarized plugs?

Some countries do an some don't.
The standard in UK is a three pin plug that can be inserted only one way.