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Posted by Jamie on November 21, 2007, 9:24 pm
Dennis wrote:
>>Neutral wires are present in 120V circuits as well, yes neutral and ground
>>busses are bonded together in the panel, but the white wire is still
>>called neutral though it carries the full return current. A white wire can
>>be hot if used in a switch drop or to a 240v appliance receptacle but in
>>that case there should be a band of black or red tape around it to mark it
>>as such, though in most houses I've worked on they've skipped that.
>
>
> A lot of people refer to the white as a neutral, but offically in the NEC is
> referred to as an "identified" conductor.
>
> A neutral is only present in a 240 v or higher branch circuit or feeder. (I
> think that's where a lot of confusion comes in as the potential between a
> 240 volt leg and the neutral is 120 volts, however that's not a branch
> circuit in and of itself). Because a neutral carries only an unbalanced
> load, it's allowed to be reduced in size from the ungrounded phase
> conductors. See 220.61 where the NEC talks about how to calculate the
> unbalanced load on a neutral. A grounded white wire in a 120 volt circuit
> always carries the full load of the circuit and is sized the same as an
> ungrounded conductor.
>
> I pulled this off of Mike Holt's website (read carefully, the 2-wire circuit
> in the 2nd para is a standard 120 volt circuit):
> Neutral Conductor. The IEEE dictionary defines a neutral conductor as the
> conductor with an equal potential difference between it and
>
> the other output conductors of a 3- or 4-wire system. Therefore, a neutral
> conductor is the white/gray wire of a 3-wire single-phase
>
> 120/240V system, or of a 4-wire three-phase 120/208V or 277/480V system.
>
> Since a neutral conductor must have equal potential between it and all
> ungrounded conductors in a 3- or 4-wire system, the white wire
>
> of a 2-wire circuit, and the white wire from a 4-wire three-phase 120/240V
> delta-connected system are not neutral conductors-they're
>
> grounded conductors.
>
>
> Anyway, I believe that the white IS called a neutral in the UK, but not here
> in the US (not by the NEC anyways).
>
>
in 120 volt outlet circuits its white.
Even in side of industrial panels for 120 volt control wire the
neutral is white or though, it really does not have to be white in
side of panels but it sure make's life much easier. Gray and yellow
isn't used much any more..
The neutral is always equal in load capacity and length of the high
side.
It's tied to ground only in the service panel where the earth
electrode is bonded near by. THe neutral shall never make an earth
connection else where.
All runs of H/N to each outlet needs to be of equal length. This is
very important especially when it comes to CFCI and arc breakers.
--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5
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