Offset Nipple between Meter and Disco

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George Stolz

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Windsor, CO NEC: 2017
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Service Manager
It's not fatigue, just utter disgust at failing to see absolutely any reason in just about anything you're saying.

We're told to bond something, which in a grounded system will eventually imply that it will be connected to the service neutral. This is such a basic concept that it bears no discussion - yet somehow, you have a problem with it.

It is plain that all service enclosures, one way or another, better wind up connected to the system neutral. You insist that "it's not that way here."

You're either not communicating very well, spouting nonsense for confusion's sake, or dangerous; you're far enough from my house I can safely not care which it is. So be it.
 

e57

Senior Member
It's not fatigue, just utter disgust at failing to see absolutely any reason in just about anything you're saying.
I have offered to agree to dis-agree a few times - we can leave it at that.

I have not claimed any victory - nor will I.
We're told to bond something, which in a grounded system will eventually imply that it will be connected to the service neutral. This is such a basic concept that it bears no discussion - yet somehow, you have a problem with it.

It is plain that all service enclosures, one way or another, better wind up connected to the system neutral. You insist that "it's not that way here."
It is not that way here yet - I'm not on the '08 cycle yet. ;) The metering or any other enclosure prior to the main disconnect are not required to have a connection or be grounded by the grounded service conductor - yet. ;)

You're either not communicating very well, spouting nonsense for confusion's sake, or dangerous; you're far enough from my house I can safely not care which it is. So be it.
Lets play nice... I have not made any personal attacks on you... Nor will I.
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
It's not a personal attack, it's a fact. If you have exposed non-current-carrying metal housing service conductors that is not electrically connected to the service neutral, you have a shock hazard. It is dangerous and has been a code violation for many cycles. I have pointed out the code sections to you and you choose to ignore it.

In the 2005,
250.92 tells us to bond all the metal together.
250.24 tells us to connect the metal to the system neutral.
 

wwhitney

Senior Member
Location
Berkeley, CA
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Retired
An electrically conductive path from the point of a ground fault on a wiring systemthrough normally non-current-carrying conductors, equipment, or the earth to the electrical supply source.
If this quote (the Article 100 definition of ground fault current path) is intended to be language supporting your point of view that all paths must be low impedance, I don't follow you, because "An" is singular. So this definition says one path is adequate.

Wayne
 

e57

Senior Member
It's not a personal attack, it's a fact. If you have exposed non-current-carrying metal housing service conductors that is not electrically connected to the service neutral, you have a shock hazard. It is dangerous and has been a code violation for many cycles. I have pointed out the code sections to you and you choose to ignore it.

In the 2005,
250.92 tells us to bond all the metal together.
250.24 tells us to connect the metal to the system neutral.
Key words - bond together. (bond all the metal together)

(3) Bonding of Electrical Equipment.
Non-current carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected together and to the electrical supply source in a manner that establishes an effective ground-fault current path.

Thats what we want between the encloures - Right? What is that:
Ground-Fault Current Path.
An electrically conductive path from the point of a ground fault on a wiring system through normally non-current-carrying conductors, equipment, or the earth to the electrical supply source.
This is further qualified here:
(5) Effective Ground-Fault Current Path.
Electrical equipment and wiring and other electrically conductive material likely to become energized shall be installed in a manner that creates a permanent, LOW-impedance circuit facilitating the operation of the overcurrent device or ground detector for high-impedance grounded systems.
It shall be capable of safely carrying the maximum groundfault current likely to be imposed on it from any point on the wiring system where a ground fault may occur to the electrical supply source. The earth shall not be considered as an effective ground-fault current path.
Let me address another point here to someone else:
wwhitney said:
If this quote (the Article 100 definition of ground fault current path) is intended to be language supporting your point of view that all paths must be low impedance, I don't follow you, because "An" is singular. So this definition says one path is adequate.
Please pay close attention to the words in bold:
Ground-Fault Current Path.
An electrically conductive path from the point of a ground fault on a wiring system through normally non-current-carrying conductors, equipment, or the earth to the electrical supply source.
Does the neutral (AKA Grounded service conductor) fit the describtion in bold? Odds are it does not. Nor is it specifically listed by inclusion in the list under 250.92(B) 1~4, or through an FPN. That is my issue with the 'one end' that is not bonded. The other non-bonded end is bonded by the tuna sandwich. ;)
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
Please pay close attention to the words in bold:

Ground-Fault Current Path.
An electrically conductive path from the point of a ground fault on a wiring system through normally non-current-carrying conductors, equipment, or the earth to the electrical supply source.

Does the neutral (AKA Grounded service conductor) fit the describtion in bold? Odds are it does not.
No, it does not fit the description in bold. Instead, it fits the last part of the phrase, the "electrical supply source". The whole point of bonding is to provide a low impedance current path to the grounded service conductor, and hence back to the transformer.

Nor is it specifically listed by inclusion in the list under 250.92(B) 1~4, or through an FPN.
I don't understand this statement. The grounded service conductor is explicitly mentioned in 250.92(B)(1) "Bonding equipment to the grounded service conductor in a manner provided in 250.8"

Cheers, Wayne
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
That is my issue with the 'one end' that is not bonded.
It would be a shame, if that end were in danger of ever becoming detached from the end with the bonding bushing on it. :roll:

I think I'll get to work on a bonding device to attach to the center of the nipple; even with a bonding bushing in either end, it's no guarantee that the offset portion won't mutiny and detach itself from the ends...
 

e57

Senior Member
No, it does not fit the description in bold. Instead, it fits the last part of the phrase, the "electrical supply source". The whole point of bonding is to provide a low impedance current path to the grounded service conductor, and hence back to the transformer.


I don't understand this statement. The grounded service conductor is explicitly mentioned in 250.92(B)(1) "Bonding equipment to the grounded service conductor in a manner provided in 250.8"

Cheers, Wayne
Yes - it does not fit the description in bold. (Not trying to get sarcastic with you - but it is what has been referred to as the "tuna sandwich" earlier.) The electrical supply source is in two places, IF the grounded service conductor is connected in each enclosure. (Meter pan, and the main disconnecting means.) Current will not choose to take one path to the source over the other - it will take both. Correct? (Think about that objectively. Along one weaker path, fault current may even damage or destroy the other.)

One side of the nipples current paths fits the definition of "bonded" (an effective fault current path) - the other end merely fits the definition of "Grounded" as allowed by 250.142. And in this case - the "bonded" end is not even the path toward the source. The fact is it will take both paths. Correct?


IMO both sides should be a "bonded" effective fault current path. Or one end should be isolated electrically. My problem with this 'one end' interpretation is that the word "bonded" is used as a label - not an action with intent.
 

e57

Senior Member
It would be a shame, if that end were in danger of ever becoming detached from the end with the bonding bushing on it. :roll:
It just might - in the OP - my initial response mentioned that them things are not always acepted everywhere. Being mealy tin it just might turn into a Dali painting... :D
I think I'll get to work on a bonding device to attach to the center of the nipple; even with a bonding bushing in either end, it's no guarantee that the offset portion won't mutiny and detach itself from the ends...
You might get more of MY money from creating and listing a range of sizes of isolating fittings for use with RMC. Say 2" female to 2" male with insulation between them. Problem that I see would be over. You could even approach the NEC during ROP's and seek to mandate it's use. :D
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
Current will not choose to take one path to the source over the other - it will take both. Correct?
Yes. So what?

One side of the nipples current paths fits the definition of "bonded" (an effective fault current path) - the other end merely fits the definition of "Grounded" as allowed by 250.142.
Wrong, wrong, wrong. Both sides are bonded. One side is bonded more definitively as required by 250.92(B).

And in this case - the "bonded" end is not even the path toward the source. The fact is it will take both paths. Correct?

Think about this objectively.

Scenario #1: A ground fault occurs 200' downstream from the service. The fault current arrives at the service, and then splits between the neutral and the nipple. The current is halved on both paths. Explain the danger - and leave out the loose locknut bologna, I'm not interested. Tight locknuts installed per code.

Scenario #2: A fault occurs inside the nipple. It is connected to the neutral in the service disconnect. It is also bonded to a lesser degree to the meter socket can as well. Explain the danger.

Also think about the fact that your blessed bonding bushing creates a third, not a second path. The locknut on the bonding bushing side is also a path.

Multiple paths of bonding are not a bad thing. More paths equal lower resistance.

e57 said:
IMO both sides should be a "bonded" effective fault current path.
Then make a proposal. The NEC doesn't require it now.
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
Current will not choose to take one path to the source over the other - it will take both. Correct?
Sure. So why is that a problem?

(Think about that objectively. Along one weaker path, fault current may even damage or destroy the other.)
While a high impedance fault can over time cause damage from the heat dissipated, if it is parallel to a low impedance fault, the low impedance fault is going to get cleared first, one way or another (via the OCPD, or via burning up one of the service conductors).

So I don't see the problem with having two fault paths, one of low impedance and one of high impedance.

One side of the nipples current paths fits the definition of "bonded" (an effective fault current path) - the other end merely fits the definition of "Grounded" as allowed by 250.142.
In common usage, "bonded" is a term that applies to an object, not a path.

Cheers, Wayne
 

e57

Senior Member
My responses in red.
Quote:
Originally Posted by e57
Current will not choose to take one path to the source over the other - it will take both. Correct?

Yes. So what? You have two paths - both should provide effective continuity for fault current IMO. Otherwise you have applied a label as "bonded" but not in practice.


Quote:
One side of the nipples current paths fits the definition of "bonded" (an effective fault current path) - the other end merely fits the definition of "Grounded" as allowed by 250.142.
Wrong, wrong, wrong. Both sides are bonded. One side is bonded more definitively as required by 250.92(B). This is that label - but not in practice item again - 'Bonded in name only'


Quote:
And in this case - the "bonded" end is not even the path toward the source. The fact is it will take both paths. Correct?
Think about this objectively. OK...

Scenario #1: A ground fault occurs 200' downstream from the service. The fault current arrives at the service, and then splits between the neutral and the nipple. The current is halved on both paths. Explain the danger - and leave out the loose locknut bologna, I'm not interested. Tight locknuts installed per code. So per code I am allowed to also have concentric/eccentric/oversized knock outs and reducing washers - yep.... Looking at possibly ~10k AIC? Current takes both paths acing as a choke on the neutral - takes longer for the main OCP to trip.

Scenario #2: A fault occurs inside the nipple. It is connected to the neutral in the service disconnect. It is also bonded to a lesser degree to the meter socket can as well. Explain the danger. (As you well know I'm not going to call the "lesser degree" "bonded" - for the sake of discussion - lets call it "connected" ;)) So per code I am allowed to also have concentric/eccentric/oversized knock outs and reducing washers - yep.... Looking at possibly >10k AIC? Current takes both paths acing as a choke on the neutral - there is main OCP to trip. Damage occurs on the current path at the merely 'tightly connected' locknut - arcs - possibly causing damage to the ungrounded service conductors inside - this possible fault path will either blow open, causing further destruction to equipment, or it will hold until another connection opens. (Wow - sounds like fun.)


Also think about the fact that your blessed bonding bushing creates a third, not a second path. The locknut on the bonding bushing side is also a path. You know - you're right... But the locknuts are not required to be "bonded" - the raceway is. The locknuts are "grounded" to both the raceway, and the enclosure, both of those items are connected in a direct path by a conductor sized by 250.66, AND in a direct path to the item mentioned in 250.92(B)1 in that enclosure, reducing the danger explained in scenario #2 above.

Multiple paths of bonding are not a bad thing. More paths equal lower resistance. But not all paths are created equal - are they?


Quote:
Originally Posted by e57
IMO both sides should be a "bonded" effective fault current path.

Then make a proposal. The NEC doesn't require it now. I just might... If we were having this discussion last year and it was on top of my priorities when I submitted 2 other proposals - I might have.
 

e57

Senior Member
In common usage, "bonded" is a term that applies to an object, not a path.

Cheers, Wayne
That is what I see as a problem. It is used as a label - one that has been disconnected from its meaning.


Bonding (Bonded). The permanent joining of metallic
parts to form an electrically conductive path that ensures
electrical continuity and the capacity to conduct safely any​
current likely to be imposed.
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
My responses in red.
That makes responding harder. :)

My responses in red.
Current will not choose to take one path to the source over the other - it will take both. Correct?

Yes. So what?
You have two paths - both should provide effective continuity for fault current IMO.

You do not trust the continuity. That is a personal problem, a matter of perspective, and the CMP will expect you to technically substantiate that opinion to change the code.

One side of the nipples current paths fits the definition of "bonded" (an effective fault current path) - the other end merely fits the definition of "Grounded" as allowed by 250.142.
Wrong, wrong, wrong. Both sides are bonded. One side is bonded more definitively as required by 250.92(B).
This is that label - but not in practice item again - 'Bonded in name only'
Opinion.

Also, trying to tag it with the name "grounded" only serves to confuse the discussion, just as the lightning tangent, specific refusal to connect supply-side equipment tangent, and what ever rabbit trails we have taken to come to this point. You and I are both in agreement (I think) that an earthing connection has no bearing on our discussion.


Scenario #1: A ground fault occurs 200' downstream from the service. The fault current arrives at the service, and then splits between the neutral and the nipple. The current is halved on both paths. Explain the danger - and leave out the loose locknut bologna, I'm not interested. Tight locknuts installed per code.
So per code I am allowed to also have concentric/eccentric/oversized knock outs and reducing washers - yep.... Looking at possibly ~10k AIC? Current takes both paths acing as a choke on the neutral - takes longer for the main OCP to trip.
There is no choke on the neutral. All circuit conductors are in the same conduit, and that conduit is bonded. A parallel bonding path will only serve to clear the fault a touch faster, not slower.

Scenario #2: A fault occurs inside the nipple. It is connected to the neutral in the service disconnect. It is also bonded to a lesser degree to the meter socket can as well. Explain the danger.
This possible fault path will either blow open, causing further destruction to equipment, or it will hold until another connection opens.
You will have to find the service that this has occurred in to sway the CMP or myself. If the service conductors are faulting to the nipple, I do not expect the nipple to remain pristine, destruction will happen. With that bonding bushing connected to it, it will continue to dump it's fault current into the service neutral well past it's useful (reusable) life. That's about all we can ask of the nipple, no?


Also think about the fact that your blessed bonding bushing creates a third, not a second path. The locknut on the bonding bushing side is also a path.
You know - you're right... But the locknuts are not required to be "bonded" - the raceway is.
Quit acting stupid. You know damned well I was referring to the fact that the raceway is also bonded by the locknuts securing that raceway to the can.

The locknuts are "grounded" to both the raceway...
This is where I point to when I say that you are attempting to confuse the issue. Use proper terms. I'll let you call it "connected" when you want to communicate that you don't trust the bonding connection, but flopping over to "grounding" is useless.

Multiple paths of bonding are not a bad thing. More paths equal lower resistance.
But not all paths are created equal - are they?
No, and no two paths between anything have ever been required to be equal. Your issue is not the presence of two paths, so why keep harping on it? You're just confusing your case.

That is what I see as a problem. It is used as a label - one that has been disconnected from its meaning.
Only you have disconnected it from it's meaning.

I think it's time to lock you 2 in a room together and turn up the heat.
You, of all people, advocating inhumane treatment?!? :D
 

e57

Senior Member
Quit acting stupid. You know damned well I was referring to the fact that the raceway is also bonded by the locknuts securing that raceway to the can. (1)


This is where I point to when I say that you are attempting to confuse the issue. Use proper terms. I'll let you call it "connected" when you want to communicate that you don't trust the bonding connection, but flopping over to "grounding" is useless. (2)


~Your issue is not the presence of two paths, so why keep harping on it? You're just confusing your case. (3)


Only you have disconnected it from it's meaning. (4)
Look George, It is obvious that we (you and I) are not going to agree. But please knock of the 'stupid' type comments - they only serve to belittle yourself. Really whats next 'momma jokes'?

Back to the topic:

  1. "Standard locknuts or bushings shall not be the sole means for the bonding required by this section." The connection on one side has a bushing and jumper, the other side does not.
  2. Not flopping - anything... one side is grounded by definition, the other is bonded by definition. As a fault current path - it is not fitting the definition of "bonded".
  3. My issue IS the two paths, ALWAYS has been from the very beginning. One fits the definition of bonded, the other does not. (IMO it is '1/2 bonded', you and many others will say it is 'ALL bonded' - 'just a little bonded = BONDED'....)
  4. It's 'meaning' is there in black and white. IMO it's meaning has become a 'description', a 'label'. One word - removed from its definition.
So you don't have to look it up....

Bonding (Bonded). The permanent joining of metallic parts to form an electrically conductive path that ensures electrical continuity and the capacity to conduct safely any current likely to be imposed.​
Now ask yourself. Without the neutral, is the metallic conduit path "Bonded"?

Because with, or without the neutral - it needs to fit the definition IMO. It is still 'an electrically conductive path that needs to ensure electrical continuity and the capacity to conduct safely any current likely to be imposed.' ;)
 
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wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
[*]My issue IS the two paths, ALWAYS has been from the very beginning.
OK, good, your issue is the two paths. You obviously feel that the difference in requirements for the two ends of this service nipple presents a hazard. However, the NEC and the community does not see it that way. Do you have any evidence or examples of this hazard? Why is having a higher impedance fault path in parallel with a low impedance fault path a hazard?

One fits the definition of bonded, the other does not.
I think the discussion will be easier to follow if you adopt the common usage of "bonded" as refering to an object, not a path. I would suggest a different terminology for what you are advocating, like "I feel it is not enough for the nipple to be bonded, bonding should be required at both ends."

Bonding (Bonded). The permanent joining of metallic parts to form an electrically conductive path that ensures electrical continuity and the capacity to conduct safely any current likely to be imposed
As a definition of "bonded", this NEC definition leaves a lot to be desired. It is really only a definition of "bonding". The definition of "bonded" based on this is "having bonding to the common reference point", which would be the GEC or thereabouts.

Now ask yourself. Without the neutral, is the metallic conduit path "Bonded"?
This doesn't really matter, because the grounded service conductor is explicitly allowed to be used for bonding in 250.92(B)(1). This point has been raised by several people; do you have any response?

Cheers, Wayne
 

e57

Senior Member
OK, good, your issue is the two paths. You obviously feel that the difference in requirements for the two ends of this service nipple presents a hazard. However, the NEC and the community does not see it that way. Do you have any evidence or examples of this hazard? Why is having a higher impedance fault path in parallel with a low impedance fault path a hazard? (1)


I think the discussion will be easier to follow if you adopt the common usage of "bonded" as refering to an object, not a path. I would suggest a different terminology for what you are advocating, like "I feel it is not enough for the nipple to be bonded, bonding should be required at both ends." (2)


As a definition of "bonded", this NEC definition leaves a lot to be desired. It is really only a definition of "bonding". The definition of "bonded" based on this is "having bonding to the common reference point", which would be the GEC or thereabouts. (3)


This doesn't really matter, because the grounded service conductor is explicitly allowed to be used for bonding in 250.92(B)(1). This point has been raised by several people; do you have any response? (4)

Cheers, Wayne

  1. Yes - the issue has always been the two paths. I'm well aware of how it is seen. Evidence - yes - specific to a service no. Do I personally collect national and international data on equipment failure - NO. Do two current paths exist - yes. Is one capable of carrying the fault current safely without the other - no. Is one capable of carrying 1/2 of the fault current safely - no.
  2. I think I have put in as many different ways as necessary - maybe too many ways. If it is not clear by now....
  3. I have no idea where you get that? How would you apply that to an ungrounded system? "Bonding" still applies in that case - does it not?
  4. You may choose from any post on this thread - and the one on this topic before it. I do not see it as explicitly saying the grounded service conductor may be used eliminate the need to make the other path safely carry the fault current it will bear. This specific code does not take into account the arrangement of equipment or parallel connections. 250.142 allows equipment prior to the disconnecting means to be grounded by the grounded service conductor - it does not require it. But by doing so, and the use of a metallic raceway - a parallel path has been created, and should be capable of safely carrying that current - in whole or in part. IN MY OPINION.
 

iwire

Moderator
Staff member
Location
Massachusetts
Mark, is it that you refuse to believe what is written in the NEC or that you just do not agree with it?

Because it is very clear that a service raceway only has to be bonded to the neutral once. Nothing you have said ......... and God knows you have said a lot...... :grin: has shown that not to be true.

No matter how you like to do it or how you are used to seeing it done changes the basic NEC requirement of one bond required per raceway. It almost seems like you are trolling here. :confused:
 
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