Definition of Ground Fault

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joebell

joebell

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I picked up a couple of MH's books as a Christmas present to myself. I am studying the Grounding Versus Bonding book and it is going over the definitions found in 250.2. I noticed that the definition of ground fault

An unintentional, electrically conducting connection between an ungrounded conductor of an electrical circuit and the normally non-current-carrying conductors , metallic enclosures, metallic raceways, metallic equipment or earth.


My question is this if the neutral conductor were to come into contact with normally non-current-carrying parts would this also be considered a ground fault condition? Wouldn't this cause objectionable current flow on these parts?

Joe
 
joebell said:
I picked up a couple of MH's books as a Christmas present to myself. I am studying the Grounding Versus Bonding book and it is going over the definitions found in 250.2. I noticed that the definition of ground fault

An unintentional, electrically conducting connection between an ungrounded conductor of an electrical circuit and the normally non-current-carrying conductors , metallic enclosures, metallic raceways, metallic equipment or earth.


My question is this if the neutral conductor were to come into contact with normally non-current-carrying parts would this also be considered a ground fault condition? Wouldn't this cause objectionable current flow on these parts?
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IMO, Even if the neutral is grounded correctly. The answer to your question is yes. It could,
It will make a gfci or an afci trip, too.
That's why we are required to use an insulated neutral, after the first disco. That's why we now use a 4-wire to ranges and dryers.
The electrons will take the quikest path back to the source. And mostly the neutral would be much quicker then the metal parts..
You might get some different answers.
 
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buckofdurham said:
IMO, Even if the neutral is grounded correctly. The answer to your question is yes. It could,
It will make a gfci or an afci trip, too.
That's why we are required to use an insulated neutral, after the first disco. That's why we now use a 4-wire to ranges and dryers.
The electrons will take the quikest path back to the source. And mostly the neutral would be much quicker then the metal parts..
You might get some different answers.
Click to expand...

I understand that is why we are required to install insulated neutrals and 4 wire receptacles for ranges and dryers. I'm wondering if the definition needs to be changed, instead of say an unintentional connection between an ungrounded conductor maybe it should say an unintentional connection between current carrying conductors.


Joe
 
buckofdurham said:
IMO, Even if the neutral is grounded correctly. The answer to your question is yes. It could,
It will make a gfci or an afci trip, too.
That's why we are required to use an insulated neutral, after the first disco. That's why we now use a 4-wire to ranges and dryers.
The electrons will take the quikest path back to the source. And mostly the neutral would be much quicker then the metal parts..
You might get some different answers.
Click to expand...


With a 4 wire range or dryer outlet or any feeder to a sub-panel for that matter the neutral isn't connected to the metal frame of the dryer or range or sub-panel. Only the EGC is, so there will not be any current flowing back on these parts if you keep ground and neutral seperate like you should.

I've also learned on this forum that the current doesn't just take the shortest or path of least resistance to ground but it takes all paths to ground. But the paths will have varying currents on them depending on their resistances, but still nonetheless if you have a 3 wire range or dryer then there is some current flowing through the grounded frame also.

I now understand how my wife got shocked from a range in an apartment we used to live in while she was touching the stainless steel sink at the same time as the range.
 
joebell said:
I'm wondering if the definition needs to be changed, instead of say an unintentional connection between an ungrounded conductor maybe it should say an unintentional connection between current carrying conductors.


Joe
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In my opinion, the definition is ok as it is. The neutral is a current carrying conductor and it is also a grounded conductor, so I think your suggestion would create confusion.
 
wirenut1980 said:
In my opinion, the definition is ok as it is. The neutral is a current carrying conductor and it is also a grounded conductor, so I think your suggestion would create confusion.
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I don't think it would create confussion, If the neutral is a current carrying conductor and makes contact with metal parts of the electrical system would this not also be a ground fault condition. I know enough current would not flow to trip the OCPD but you would be creating muliple paths for the neutral current to travel on. I don't understand why the definition only specifies that a ground fault condition happens with the ungrounded conductor?


Joe
 
joebell said:
My question is this if the neutral conductor were to come into contact with normally non-current-carrying parts would this also be considered a ground fault condition? Wouldn't this cause objectionable current flow on these parts?

Joe
Click to expand...

Look at the words that are being defined "ground fault".

What is the neutral? The grounded conductor as outlined in Article 200, Yes

If the neutral is in contact with the normally non-current-carrying metal parts would we then call this a ground ground fault? No
 
Line-to-ground = ground fault
line-to-line= short circuit
line-to-grounded conductor=short circuit

short circuit = fault from conductor to conductor
grounded conductor to ground= grounded ground fault?
 
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joebell said:
I don't think it would create confussion, If the neutral is a current carrying conductor and makes contact with metal parts of the electrical system would this not also be a ground fault condition. I know enough current would not flow to trip the OCPD but you would be creating muliple paths for the neutral current to travel on. I don't understand why the definition only specifies that a ground fault condition happens with the ungrounded conductor?


Joe
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I don't understand why you can't just be fine with the definition as it is. Leave well enough alone. :)
 
Pierre C Belarge said:
A fault condition in most instances will open an OCPD. A grounded conductor to equipment ground conductor connection/bond will not create a fault condition,opening an OCPD.
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I can live with that. I think the situation I am trying to define is found in 250.6 "Objectionable Current" and is not so much a Fault condition but can still pose a hazard.
 
joebell said:
I can live with that. I think the situation I am trying to define is found in 250.6 "Objectionable Current" and is not so much a Fault condition but can still pose a hazard.
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"250.6(C) Temporary Currents Not Classified as Objectionable Currents.

Temporary currents resulting from accidental conditions, such as ground-fault currents, that occur only while the grounding conductors are performing their intended protective functions shall not be classified as objectionable current for the purposes specified in 250.6(A)&(B)."




I do believe you are looking for something different than you originally were thinking.
 
Pierre C Belarge said:
"250.6(C) Temporary Currents Not Classified as Objectionable Currents.

Temporary currents resulting from accidental conditions, such as ground-fault currents, that occur only while the grounding conductors are performing their intended protective functions shall not be classified as objectionable current for the purposes specified in 250.6(A)&(B)."




I do believe you are looking for something different than you originally were thinking.
Click to expand...


Pierre,

I just want to make sure I've got this right. If a grounded (Neutral) conductor comes in contact, unintentionally , with a metal raceway or enclosure this condition can cause an objectionable current on those metal parts?



Joe
 
joebell said:
Pierre,

I just want to make sure I've got this right. If a grounded (Neutral) conductor comes in contact, unintentionally , with a metal raceway or enclosure this condition can cause an objectionable current on those metal parts?



Joe
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I'm not Pierre, but I know that the answer is yes it does cause objectionable current on those metal parts. That's why any new 240 volt circuits are 4 wire (seperate neutral and ground and not to be connected together at the load). Just like a sub-panel. So as to not create parallel neutrals and objectionable current on metal parts.

See my post #4 on first page.
 
If power is neither created or destroyed ( Newton ) ... What ever...

And, in the course of the use of using Power!

Where do you think the excess, overflow, noise (in-balance) goes? :roll:

There's nothing neutral about it, and never will be!

It is the continuation of a circuit to complete that circuit!

I should say as applied and where required!
 
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joebell said:
Pierre,

I just want to make sure I've got this right. If a grounded (Neutral) conductor comes in contact, unintentionally , with a metal raceway or enclosure this condition can cause an objectionable current on those metal parts?



Joe
Click to expand...

It will cause a parallel return path to source, current will flow on all common paths according to each paths level of resistance. It may not be a fault condition but the grounded conductor bonded past the service disconnect is a violation of 250.142(B) in your case.
 
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