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MMD > Archives > March 2001 > 2001.03.23 > 04Prev  Next


Neutral vs. Grounded Conductor
By Tom Lear

When is a neutral not a neutral?

Hi Robbie, By the way, are you from England or Australia?  I ask
because of an earlier reference to the power input of the Pianocorder
as "mains" which sounded an unusual description, i.e., not in common
usage in that context.

 [ I'm a California native.  I like to say "mains" because the
 [ British term unambiguously denotes _electric_ power.  -- Robbie

Not to beat a dead horse, but regarding the following:

>[ The term is confusing because "ground" can be either the green
>[ "ground wire" or it can mean "ground potential".  Since you didn't
>[ mention safety ground I assumed you spoke of the "neutral" wire
>[ which carries the return current of the motor.
>[ I believe that the U.S. electrical wiring recommendation reserves the
>[ term "ground" or "safety ground" to signify the earth connection via
>[ a water pipe or similar; normally no current flows through this wire.
>[ I believe that the U.S. electrical wiring recommendation reserves the
>[ term "ground" or "safety ground" to signify the earth connection via
>[ a water pipe or similar; normally no current flows through this wire.

The term "Ground", or "Grounded" is commonly understood to refer to
the ground wire, the grounded part of a service, etc., that does not
carry operating current.  It is there basically for safety.  (The
Dynavoice, being an old system is not grounded).

The more explicit term used, in the National Electric Code to refer to
conductors used for "Grounding", is "Grounding Conductors".  Green is
the required color, as you said.

Then there are the terms "Identified Conductor" or "Grounded Conductor"
which refers to a current carrying conductor which is also "Grounded"
at the service panel.  White is the correct color.

To recap:

  Grounding conductor: normally does not carry operating current;
  it is there for safety.

  Grounded Conductor: carries operating current; commonly the
  "white wire", or as per the code, "Identified Conductor".

>[ In single-phase wiring "neutral" is the conductor which carries the
>[ return current; it is at approximately earth potential.  The standard
>[ colors in USA are green for safety ground, white for neutral, and
>[ black for the "hot" wire.  -- Robbie

Let's see if I can shed a little more light on when a "neutral" is not
a "neutral".  From "Practical Electrical Wiring" by Richter, 10th edition:

  "Is It A Neutral Wire?  Where there are three service wires, the
grounded wire is definitely a neutral wire.  What about the wires that
begin at the service equipment and run to various circuits in the
building?

  "If the circuit is a 3-wire 120/240-volt circuit, the grounded wire
is definitely a neutral wire.  But if the circuit is a 2-wire 120-volt
circuit, the grounded wire, even if it does connect to the neutral wire
in the service equipment, is not a neutral wire; it is called just the
grounded wire.  Many people do call the grounded wire in a 2-wire
circuit a "neutral wire," but there can not be a neutral in a 2-wire
circuit.  All this will be explained in more detail in a later
chapter."

If more detail would be of interest, I can send it along.

Tom Lear
San Francisco, CA


(Message sent Fri 23 Mar 2001, 07:15:19 GMT, from time zone GMT-0500.)

Key Words in Subject:  Conductor, Grounded, Neutral, vs

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