NEUTRAL CONDUCTOR VS. GROUNDED CONDUCTOR

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SparkyMarky

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Rochester Joint Apprenticeship Training Committee-Instructor
I have recently started teaching at a union trade school and have stumbled on to a question I could not confidently answer. I am trying to understand the difference between a "neutral conductor" and a "grounded conductor" as it pertains to the NEC. The way I interpret it is, that if the conductor is the "grounded conductor" of a multiwire system connected to the neutral point of a system it is a "neutral conductor". I believe the "neutral conductor" is a "grounded conductor" in a multiwire system and the way I understand it is that the only time the "grounded conductor" is NOT a "neutral conductor" is in an installation where there is ONE ungrounded conductor and a "return" conductor(white/gray).

Would someone please help me understand this and perhaps provide me with a better explanation that I can pass on to my students?

Thank you,

M. Pratt
 
You are correct however, the NEC does incorrectly call it a neutral in a two wire circuit.

Roger
 
Here's the Article 100 definitions of neutral and grounded conductor. The neutral is by definition a grounded conductor but if you had a corner grounded delta system the grounded conductor would not be a neutral. The Article 100 definition for neutral was added in the 2008 NEC.

Neutral Conductor. The conductor connected to the neutral point of a system that is intended to carry current under normal conditions.
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Grounded Conductor. A system or circuit conductor that is intentionally grounded.
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All neutral conductors are grounded conductors, but the reverse is not true, In the NEC the only time you have a grounded conductor that is not a neutral conductor is where the supply system is a two wire system, with one conductor grounded, or where you have a corner grounded three phase system.
 
By the physics any single conductor of a system can be made the grounded conductor by intentionally connecting it to ground.

Like a 'bird on a wire' this single connection to earth doesn't create a closed circuit so current doesn't flow in it.

By the physics of the situation you can ground a neutral or a phase or a midpoint, and the system will work just fine.

Code generally requires that the conductor selected for grounding be the one closest to neutral. This is the true neutral in a wye or split single phase system, or a midpoint tn a high leg delta. But if only delta is required, code permits a 'corner grounded ' system where the grounded conductor is as far from neutral as they come.

Jon
 
don_resqcapt19 said:
All neutral conductors are grounded conductors, but the reverse is not true, In the NEC the only time you have a grounded conductor that is not a neutral conductor is where the supply system is a two wire system, with one conductor grounded, or where you have a corner grounded three phase system.
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I think you are incorrect in your first point, Don.
In an ungrounded wye supply there is still a neutral conductor. But under certain conditions the NEC requires a neutral conductor, if one exists, to be grounded.

Sent from my Pixel 4a using Tapatalk
 
infinity said:
How can you have an ungrounded Wye system?
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Classic example: PT cabinets. Usually not grounded at all. The most common arrangement is a broken delta since it saves one coil but a few use a wye connected system. Since it is for instrumentation and the intent is to measure the voltages including grounding it is typically ungrounded, although broken deltas typically ground the middle phase and use one leg for control power.
 
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