Service Neutral

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websparky

Senior Member
Location
Cleveland, Ohio
Re: Service Neutral

OK..........What about the GEC? If you have a generator connected to an exsisting system through a 4 pole transfer switch, what do we do with the bonding connection of the service? We can't switch that also, right?

It seams that you are asking for something that is not available. Even with a generator, it needs to have a reference to ground when it is connected to a premise system, right?
 
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bennie

Esteemed Member
Re: Service Neutral

To revisit history; The origin of the AC systems without external connections Section 2526, later changed to; Isolated Systems, then Separately Derived Systems 250.26, was created due to many homes and farmhouses having light plants for lighting. These systems were often 120 volts and ungrounded.

The code section was adopted to spell out the grounding method required for the isolated systems, when they required grounding.

Generators do not require any special grounding, only the premises wiring system requires special attention.

Utility transformers using the MGN system will ground the isolated systems.

When the MGN is not connected to the isolated system, the code section is describing how the premises system is to be grounded. Most all domestic power systems are the MGN system, therefore no transformer is the power source for a separately derived system.
 
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bennie

Esteemed Member
Re: Service Neutral

I get challenged to supply documentation to validate my postings.

Proof of wrongdoing is up to the accuser not the accused. ;)

All documentation, for this topic, is on file at NFPA archives. I have communicated with the curator.

The title changes from AC Systems Without External Connections, to Isolated Systems, then to Separately Derived Systems, was all performed by a staff member. There was no official code panel action to change the title and definition.

The documented reason for changing the title was; "For technical accuracy of definition".

[ March 14, 2004, 09:48 AM: Message edited by: bennie ]
 
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bennie

Esteemed Member
Re: Service Neutral

Bob: I do not see a safety problem with the current methods, other than unneccessary EMF production.

Karl will have something to say about grounding a transformer at two earth locations.
 
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websparky

Senior Member
Location
Cleveland, Ohio
Re: Service Neutral

It is sad to think that this thread has turned into a typical Bennie thread. By that I mean;
Around and around we go, nothing resolved, nothing new, just the same old circle.

For me, I have better things to do than to play follow the "Bouncing Bennie".
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Re: Service Neutral

Joe?
confused-smiley-013.gif
 
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kiss

Senior Member
Re: Service Neutral

WOW: I take the weekend off and look what happens. Over 40 replies in 2 days. I appreciate all the responses,don't make this topic a subject of ANGER make it a learning venue. If you don't agree with a writer that ok, who is to say he is right or wrong. I believe most of the answers are given based on your belief and knowledge. If you can't agree after a few discussions move on. Thanks all for this lively discussion, I have learned a lot.
 
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websparky

Senior Member
Location
Cleveland, Ohio
Re: Service Neutral

Joe: I'm not insulted, I consider the source.
Click to expand...
Honestly Bennie!
Just answer questions that are asked about your statements.
Basic protocol when debating is to address the subject at hand.
That is why I said "Around and around we go, nothing resolved, nothing new, just the same old circle.
".

[ March 15, 2004, 05:14 PM: Message edited by: websparky ]
 
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karl riley

Senior Member
Re: Service Neutral

And no, Bennie, Karl has nothing to say here. The posted diagrams made everything clear as a bell. From clarity we then descend to muddied waters. Why would I want to take a bath in that? I've tried it many times.

Have a good night. On the East coast it's time for bed.

Karl
 
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bennie

Esteemed Member
Re: Service Neutral

Karl: Again, I apologize for my style of writing.
I am not good at describing my thinking pattern.

My reference, when I included your name, was pertaining to the earth grounding of the equipment ground wire at two locations. This connection will create a current flow. I was hoping you would validate my statement.

Maybe I am wrong.
 
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karl riley

Senior Member
Re: Service Neutral

Bennie, when studying the diagrams I saw no electrical reason for neutral to be flowing between generator and service panel on the equipment grounding conductor.

The posters (I forget who said what) were trying to get the point across that generator-produced neutral is trying to return to the generator source and has no reason to wander over to the service point; likewise, utility produced neutral is trying to return to the transformer, and has no reason to wander over to the generator.

When I say "trying" I use a human analogy. It is following voltage differentials. The source neutral return point is at a lower potential and causes the neutral to end up there.

Karl
 
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bennie

Esteemed Member
Re: Service Neutral

What happens when the service neutral is elevated to primary voltage?

What happens when the generator internally faults to the stator core?

I examined the drawings too. It appears to me there is a definite electrical connection between both neutrals regardless of the transfer switch position.
 
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Ed MacLaren

Senior Member
Re: Service Neutral

I examined the drawings too. It appears to me there is a definite electrical connection between both neutrals regardless of the transfer switch position.
Click to expand...
Of course there is. There is a single connection. No one disputes that.

On the first day of my electrical theory course in 1953 I learned that a complete circuit is required for current flow.

Only static charges can move from one location to another over a single path.

I'm pretty sure that you don't believe, as some people do, that all electrons are he*l bent on getting to the earth, over any available path.

I spent 36 years trying to remove that notion from my students minds.

Ed
 
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bennie

Esteemed Member
Re: Service Neutral

Should the service neutral elevate to 7.2 KV, above the ground, there is a problem with keeping an emergency generator operating on line.

If a generator has an internal fault, elevating the service neutral to 277 volts above ground, it can fry a lineman.

The neutrals should not be electrically connected.

As long as the earth is a common impedance, current will flow to and from the dirt.

Telling apprentices this does not happen, is confusing them.
 
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