Definition of a Circuit.

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bennie

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The following text is the official accepted definition by the World Scientific and Engineering community.

Circuit; A closed path followed or capable of being followed by an electrical current.

The NEC CMP's do not have the authority to rule otherwise. If they do, please give me the source delegating this permission.
 
Re: Definition of a Circuit.

My understanding is that if a term is defined in the NEC you have to go by the NEC definition. Mike Holt states in his texts when a item is not defined, then the IEEE dictonary is used. If the term is still not defined the pecking order goes to Webster's Dictionary.

Bennie: Please don't take this as negative or confrontational. I pay close attention to everything you say. I have big ears and an open mind.

Thanks for all your postings!

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[ October 11, 2003, 09:35 PM: Message edited by: awwt ]
 
Re: Definition of a Circuit.

The NEC doesn't define "circuit" so websters or other definitions are it.

Roger
 
Re: Definition of a Circuit.

Wayne: A long time ago, I did some technical writing for the Federal Government, namely the DOD. The strict rule was to only use words that make sense in a common understanding of the meaning. The phrase, "common sense", originated from this statement.

The NEC is a legal document of technical material, when adopted by a government agency.

It could be a problem in litigation when words are used that are not common sense.
 
Re: Definition of a Circuit.

You have to be an insider with a magic decoder ring to get the intended meaning of many NEC citations.

Even here on mikeholt.com there are a lot of misunderstandings because we are all not on the same page when it comes to lingo definitions.

A phrase like "multi-wire branch circuit" does not seem very special until you get under the hood and find out that it's different than a branch circuit. All ciruits have more than one wire so aren't all circuits multi-wire? Nope, not when it comes to the NEC. And so forth.

../Wayne C.

PS: sub-panel, load-center, grounding conductor, grounded conductor, and so forth...

[ October 06, 2003, 04:05 PM: Message edited by: awwt ]
 
Re: Definition of a Circuit.

Bennie can you explain how the NEC is changing the definition of circuit conductor in this article.

250.142 Use of Grounded Circuit Conductor for Grounding Equipment.
(B) Load-Side Equipment. Except as permitted in 250.30(A)(1) and 250.32(B), a grounded circuit conductor shall not be used for grounding non?current-carrying metal parts of equipment on the load side of the service disconnecting means or on the load side of a separately derived system disconnecting means or the overcurrent devices for a separately derived system not having a main disconnecting means.
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If we where talking about a DC circuit using Red for positive and Black for negative and I was to say the "Remove the black circuit conductor"

Would you say I was changing the definition of circuit conductor?

Just because one conductor is not a total circuit does not mean it is not a "circuit conductor"

Your have mentioned a couple of times that you are an "outcast" and that you got "trashed" but you are setting yourself up for this, your take on the use of the Neutral as ground goes against everything we have been taught.

Is it possible you are mistaken? :)

Not electrically, but in your interpretation of the NEC.

Bob
 
Re: Definition of a Circuit.

Bob: It is possible I am mistaken, it is also possible the interpretations of the code are mistaken.

When the maximum elevation for a circuit breaker handle was changed from 6'6" to 6'7", one of the respected code experts wrote the reason was due to the human being taller at present time in relation to the past.

This mentality has created a lot of false instructions for procedures.

The only problem I have with the code is there is too much room for guesswork and speculation on many issues.

The 6'7 issue should have stated the change was to make the dimension closer to 2 meters. This would have eliminated a lot of garbage talk.
 
Re: Definition of a Circuit.

How's this definition?

"Electrical Circuit:
An electrical circuit has at least four basic parts: (1) a source of electromotive force,
(2) conductors, (3) load or loads, and (4) some means of control."
 
Re: Definition of a Circuit.

My main reason for this thread is to point out the contradiction of the definition of a circuit conductor in the CMP statement. The Soares Grounding Book also quotes this statement for the justification of re-grounding the neutral.

Both are implying that an equipment ground conductor, to the neutral of a transformer, is not a circuit conductor.

Talk about making rules to fit anything that can not be understood.
 
Re: Definition of a Circuit.

Bennie,
The position of the NEC is that only a conductor that is expected to carry current under normal operating conditions is a "circuit conductor".
Don
 
Re: Definition of a Circuit.

We have had this discussion enough to have worn out many monitors and keyboards and I have done my best to stay neutral (pun intended :) ) but,
The position of the NEC is that only a conductor that is expected to carry current under normal operating conditions is a "circuit conductor".
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is so lame and the fact that they use it to suit their needs is rediculous.

I'll ask again, is a automobile not an automobile when it is parked.

I'm not saying there is a need to change how things are done, but to say white is not white for our purpose in this conversation, and we will tell you when you can recognize it as white is kind of BOGUS :D

UH sorry, don't mind me. ;)

Roger

[ October 06, 2003, 08:01 PM: Message edited by: roger ]
 
Re: Definition of a Circuit.

Originally posted by roger:
is a automobile not an automobile when it is parked.
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Depends on where its parked I'd imagine...

Parked on the Cross Bronx Expressway, it won't be an auto for long :D
 
Re: Definition of a Circuit.

OH NO, you mean the guys with the NEC have contacts there too. :D

Just kidding, contrary to my criticizing some parts of the NEC I think the people involved overall do a good job. It's a big job


Roger
 
Re: Definition of a Circuit.

Careful guys, we don't want the Do-It-Yourself crowd getting a chuckle out of the professionals arguing about what a circuit is. :D

Ed
 
Re: Definition of a Circuit.

200.3 says it all. An equipment ground conductor is a circuit conductor.

Anyone who can prove otherwise please do.
 
Re: Definition of a Circuit.

My scientific side does not completely understand the N-G separation science. It seems to be a bit of Voodoo logic. Mechanically there is not a lot of difference between the neutral (grounded conductor) and the ground. The difference is what they are bonded to in the electrical system.

The neutrals are bonded together within a circuit only. The grounds (GEC) are all bonded together (except in an IG situation) regardless of which circuit they are on.

The neutrals are not bonded to the outlet boxes, appliance chassis', and the subpanels. The grounds are bonded to the outlet boxes, appliance chassis', and subpanels.

The neutral is a focused "return" path for the hot. The ground is a web.

The neutral is sized to match the OCPD of the circuit (plus any known harmonics). The ground is typically undersized and it is assumed that it will not carry as much load.

The neutral is expected to do its job properly day in and day out. The ground is only called upon in an aberrant situation.

The ground is not intended to be a parallel system but because the ground & neutral are bonded at the service end their individuality is subject to becoming muddy.

Feel free to pick this apart or bootstrap onto it. That's the only way I can take it out of the Voodoo category and into the totally scientific category.
 
Re: Definition of a Circuit.

My scientific side does not completely understand the N-G separation science. It seems to be a bit of Voodoo logic.
Click to expand...
Because this is a very important topic and there may be readers here that are new at this, I think it is important that we do our best to explain it.

Let's try these statements one by one, and see if we are in agreement.

1. The grounded (sometimes neutral) conductor is one of the load circuit conductors. It must be sized to carry load current, which can be continuous.

2. The equipment "grounding" conductor (EGC), (which isn't actually a grounding conductor at all, but that's another story,) is sized to operate the circuit overcurrent device, and is only required to carry the fault current for a few seconds.

3. It (the EGC) is not sized to carry circuit load current, and therefor must be prevented from being in parallel with the grounded load circuit conductor.

4. Because the system grounded (sometimes neutral) conductor, and the equipment enclosures, are permitted to be grounded to the same grounding electrode, they are bonded together at the supply end by the main bonding jumper, so they must be kept isolated from one another thereafter, within the same building.

How are we doing so far? Wayne C, I think you said basically the same thing, in different words.

Ed

[ October 07, 2003, 12:08 AM: Message edited by: Ed MacLaren ]
 
Re: Definition of a Circuit.

Yes. We're on the same page so far. Thanks for doing this. It is VERY important! Maybe we should take this to a new thread in the grounding forum? If your thesis makes sense it could be made into an FAQ.

../Wayne C.

[ October 07, 2003, 12:14 AM: Message edited by: awwt ]
 
Re: Definition of a Circuit.

To continue our discussion regarding the reason behind this rule -

"250.142 Use of Grounded Circuit Conductor for Grounding Equipment.
(B) Load-Side Equipment. Except as permitted in 250.30(A)(1) and 250.32(B), a grounded circuit conductor shall not be used for grounding non?current-carrying metal parts of equipment on the load side of the service disconnecting means or on the load side of a separately derived system disconnecting means or the overcurrent devices for a separately derived system not having a main disconnecting means."

In addition to the reasons given by others in the thread "Objectionable current" this might help explain the shock hazard.
This is my reasoning. (Please check to see if I've made an error.)

With an unbalanced load, if the grounded (sometimes neutral) conductor is used to ground equipment enclosures, and the grounded conductor was to become open, the voltage-to-ground on equipment enclosures could approach 120 volts, with no other fault existing. Sketch B

3wire5.gif


Ed

[ October 07, 2003, 11:13 AM: Message edited by: Ed MacLaren ]
 
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