# Debate on over Flex as Grounding Conductor



## wildleg (Apr 12, 2009)

if the flex is good enough to be a suitable ground path, then why require the ground wire ?


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## Vintage Sounds (Oct 23, 2009)

wildleg said:


> if the flex is good enough to be a suitable ground path, then why require the ground wire ?


It's a hospital...maybe the EGC was spec'd ?


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## brother (Nov 25, 2008)

wildleg said:


> if the flex is good enough to be a suitable ground path, then why require the ground wire ?


 
Where in the code is not acceptable under the conditions I listed that its not an egc. And no, it was not spec this way.


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## RePhase277 (Feb 5, 2008)

Yes, the flex is your redundant grounding path, as required by 517. As long as you have a grounding conductor, and a second grounding path, in this case the flex, you are compliant.


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## codeone (Sep 15, 2008)

Your answer lies in the very article you cited. 517.13(B).

(B) Insulated Equipment Grounding Conductor. 
The
grounding terminals of all receptacles and all non-currentcarrying
conductive surfaces of fixed electrical equipment
likely to become energized that are subject to personal contact,
operating at over 100 volts, shall be connected to an
insulated copper equipment grounding conductor. The
equipment grounding conductor shall be sized in accordance
with Table 250.122 and installed in metal raceways
or as a part of listed cables having a metallic armor or
sheath assembly with the branch-circuit conductors supplying​these receptacles or fixed equipment.

Now you cited 250.18(6) which is for liquidtight flex if all conditions there are met it can be an equipment grounding conductor. so therefore it is your redundant path! Or if you are talking about steel flex 250.118(5).
You are required to have both in your circumstance.​


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## waco (Dec 10, 2007)

wherever I pull wires, I run an insulated EGC, period.


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## paul d. (Jul 13, 2008)

waco said:


> wherever I pull wires, I run an insulated EGC, period.


 what waco said. been that way since 1976 in comm & ind.


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## RIVETER (Sep 26, 2009)

*Debate*

The code is the minimnum requirement. As long as both the flex and the equipment ground are properly terminated, whoever decided to install the GREEN wire was not wrong.


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## Mountain Electrician (Jan 22, 2007)

codeone said:


> Your answer lies in the very article you cited. 517.13(B).
> 
> (B) Insulated Equipment Grounding Conductor.
> The
> ...


:thumbsup:


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## knowshorts (Jan 9, 2009)

brother said:


> If it was true, then the NEC would made that very clear.


That's one of the funniest things I heard all day. 

As far as I can tell, you are right. Just out of curiosity, why are you using flex, and not a scrap piece of HCF MC?


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## brother (Nov 25, 2008)

codeone said:


> Your answer lies in the very article you cited. 517.13(B).
> 
> (B) Insulated Equipment Grounding Conductor.
> ​​The​
> ...


 Yes it was s typo, I actually meant 250.118 5(d)., Not (6).


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## brother (Nov 25, 2008)

knowshorts said:


> That's one of the funniest things I heard all day.
> 
> As far as I can tell, you are right. Just out of curiosity, why are you using flex, and not a scrap piece of HCF MC?


 This is comming straight from the panel, Its just a personal preferrence but I do not like using mc or ac directly from the panel when going to a j-box that will feed other outlets. 

Its like you have forever 'limited' yourself from the panel, at least with the 3/4" flex you can still add circuits in there if you need to. Its only 3 wires of #12 in it, black white and green. plenty room from more.


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## brian john (Mar 11, 2007)

A better question is how are you going to stop fault current from traveling on the flex which is a parallel path with the EGC. Do you have insulating connectors or are you just going to rely on magic.


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## codeone (Sep 15, 2008)

brian john said:


> A better question is how are you going to stop fault current from traveling on the flex which is a parallel path with the EGC. Do you have insulating connectors or are you just going to rely on magic.


 Its called redundant grounding. The NEC does not prohibit parallel grounding paths in this instance it actually requires them. The NEC does prohibit parallel grounded conductor(neutral) paths.


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## RIVETER (Sep 26, 2009)

*Flex grounding*



codeone said:


> Its called redundant grounding. The NEC does not prohibit parallel grounding paths in this instance it actually requires them. The NEC does prohibit parallel grounded conductor(neutral) paths.


I agree with you. Tests have been done that prove that in an instance such as this reduncency, the conduit/flex could possibly carry up to 95% of the fault current, so it is very important for good mechanical connection...I will have to study up on the parallel neutral paths to see if I agree


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## RePhase277 (Feb 5, 2008)

brian john said:


> A better question is how are you going to stop fault current from traveling on the flex which is a parallel path with the EGC. Do you have insulating connectors or are you just going to rely on magic.


As others have said, it is a necessity in medical facilities. But, when using a metal raceway with an EGC installed, when isn't there parallel grounding paths? Or, when using cabling, we usually tie all the grounds in a box together, giving multiple paths. It seems like parallel grounds exist all over the place.


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## codeone (Sep 15, 2008)

RIVETER said:


> I agree with you. Tests have been done that prove that in an instance such as this reduncency, the conduit/flex could possibly carry up to 95% of the fault current, so it is very important for good mechanical connection...I will have to study up on the parallel neutral paths to see if I agree


You are right about parelling a neutral path you can do that if your conductors are the same,material,length, insulation and 1/0 or larger. You cannot bond the neutral and ground anywhere except the service otherwise you would have a paralell path that is not allowed or safe.

I did make a general miss statement the first time thanks Riveter for helping me get over my brain fade.:whistling2::laughing:


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## BuzzKill (Oct 27, 2008)

Glad you are not in my jurisdiction!


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## BuzzKill (Oct 27, 2008)

pull the extra Gwire and be done with it; now ay I would rely on flex alone.


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## codeone (Sep 15, 2008)

BuzzKill said:


> pull the extra Gwire and be done with it; now ay I would rely on flex alone.


just not in hospitals:thumbupatient care areas


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## JayH (Nov 13, 2009)

brother said:


> And no, it was not spec this way.


This sounds as if it were an addition or service in an existing facility. In that case a specification may not be provided.

OSHPD in California requires a redundant grounding condutor in almost all areas of health care facilities.


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## brian john (Mar 11, 2007)

codeone said:


> Its called redundant grounding. The NEC does not prohibit parallel grounding paths in this instance it actually requires them. The NEC does prohibit parallel grounded conductor(neutral) paths.


 
LIKE DUH! reread my post,or is the use of smilies with sarcasm neceassary!


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## codeone (Sep 15, 2008)

brian john said:


> LIKE DUH! reread my post,or is the use of smilies with sarcasm neceassary!


 May have taken your comment of sarcasm out of contex with the original posters comments. Or did not realize it was sarcasm. If so appologies to you.

LIKE DUH! If you look at my smile with sarcasm it was about my brain blip not your comment!:no:


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## brian john (Mar 11, 2007)

codeone said:


> May have taken your comment of sarcasm out of contex with the original posters comments. Or did not realize it was sarcasm. If so appologies to you.
> 
> LIKE DUH! If you look at my smile with sarcasm it was about my brain blip not your comment!:no:


 
No problem, It amazes me sometimes how some people (NOT YOU or any of the posters on this particular thread) think grounding with the EGC or grounded conductor operates. There is no magic and basically it is all common sense logical.

We see this across the board from electricians, master electricians, inspectors and engineers.

If I ever teach adult education again part of the course will be titled "Grounding it ain't magic, it is the 4th conductor in 240/120 and the 5th conductor in 480/277-208/120"


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## codeone (Sep 15, 2008)

brian john said:


> No problem, It amazes me sometimes how some people (NOT YOU or any of the posters on this particular thread) think grounding with the EGC or grounded conductor operates. There is no magic and basically it is all common sense logical.
> 
> We see this across the board from electricians, master electricians, inspectors and engineers.
> 
> If I ever teach adult education again part of the course will be titled "Grounding it ain't magic, it is the 4th conductor in 240/120 and the 5th conductor in 480/277-208/120"


Most likely 30-40+ years ago because they taught Electricity was trying to find Ground, and that electricity takes the path of least resistance. Instead of teaching that electricity is trying to get back to its source and it taks all paths available to it and you are trying to make sure there is one of less resistance than you. 
I Dont know it all, never will!


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## brian john (Mar 11, 2007)

codeone said:


> Most likely 30-40+ years ago because they taught Electricity was trying to find Ground, and that electricity takes the path of least resistance. Instead of teaching that electricity is trying to get back to its source and it taks all paths available to it and you are trying to make sure there is one of less resistance than you.
> I Dont know it all, never will!


I am not even close to knowing any of it, but the thought of all electricity sinking into some big hole in the earth is still prevalent in younger engineers and electricians.


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## RIVETER (Sep 26, 2009)

*Grounding*

I am glad we put that baby to bed. It is a very misunderstood subject.


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## codeone (Sep 15, 2008)

brian john said:


> I am not even close to knowing any of it, but the thought of all electricity sinking into some big hole in the earth is still prevalent in younger engineers and electricians.


 Sad but true!


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## RIVETER (Sep 26, 2009)

*flex*



brian john said:


> I am not even close to knowing any of it, but the thought of all electricity sinking into some big hole in the earth is still prevalent in younger engineers and electricians.


I have apprentices with me all the time and I have actually gone on line and some of the drawings indicate that the circuit current goes to earth. No wonder wrong info gets out.


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## BuzzKill (Oct 27, 2008)

engineering shorthand.


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## RePhase277 (Feb 5, 2008)

codeone said:


> Most likely 30-40+ years ago because they taught Electricity was trying to find Ground, and that electricity takes the path of least resistance. Instead of teaching that electricity is trying to get back to its source and it taks all paths available to it and you are trying to make sure there is one of less resistance than you.
> I Dont know it all, never will!


They never taught that electricity was trying to find ground, at least not in the sense of seeking the actual Earth. The word "ground" is often meant to denote the part of a circuit at the lower potential. For instance, in an automobile, "ground" means the negative pole of the battery. In electronics, what is called "ground" is often the midpoint between two voltages, like +5 V, 0 V, and -5 V.

Some older texts refer to the white wire of a two wire circuit as the "circuit ground". So in that respect ground is a part of the circuit and current does seek it. But since we have started using equipment grounding conductors, the term ground has taken on the meaning of the actual earth ground, or the nick name of the green bonding conductor ran with the circuit.


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## codeone (Sep 15, 2008)

InPhase277 said:


> They never taught that electricity was trying to find ground, at least not in the sense of seeking the actual Earth.
> .


 .I dont supposed you went to every school there was 30-40+ yrs ago?


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## RIVETER (Sep 26, 2009)

*flex*



InPhase277 said:


> They never taught that electricity was trying to find ground, at least not in the sense of seeking the actual Earth. The word "ground" is often meant to denote the part of a circuit at the lower potential. For instance, in an automobile, "ground" means the negative pole of the battery. In electronics, what is called "ground" is often the midpoint between two voltages, like +5 V, 0 V, and -5 V.
> 
> Some older texts refer to the white wire of a two wire circuit as the "circuit ground". So in that respect ground is a part of the circuit and current does seek it. But since we have started using equipment grounding conductors, the term ground has taken on the meaning of the actual earth ground, or the nick name of the green bonding conductor ran with the circuit.


I agree here but it is our responsibility to make sure that the people that we are explaining the concept to, understand it correctly. The NEUTRAL is NOT ground. It is a circuit conductor that is intentionally GROUNDED, but only at the service disconnect. We have to NOT perpetuate the misconception that because they are at the same potential...they are the same thing.


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## waco (Dec 10, 2007)

"Ground is ground the world around" is an old saying which is right -- in context, but I agree, ground and power ground neutral are not the same things, but we don't hear the latter very much.

In the wonderful world of electronics, "ground" merely denotes a reference point and still does. The side of a car battery that is tied to the chassis is the "grounded" pole and the car chassis is the "ground," but it only has meaning with respect to the other side of that battery.

In fact, the grounding electrode serves to ensure that all the exposed, conductive parts of a system are at the same voltage as the local ground and it works.

Ever had a thunderstorm approaching while you were handling the grounding electrode and the GEC? Can get exciting! "Twenty-mile lightning." Ex-service people might recognize that old saying.


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## codeone (Sep 15, 2008)

Still even alot of what you say is true, it has been taught in such a way that there is alot of misconception out there to this day. When I was in school the terms they used was that Electricity was trying to find Ground!

This is not a good way to teach the actual physics of electricity. They need to make the refference of trying to find its source, its trying to make a circle, not going to a referance point call ed ground. Out in a circuit there is a potential differance between the grounded conductor and the equipment grounding conductor. Otherwise you would be blasted when getting between a neutral conductor on 277v lighting and the equipment grounding conductor.

We do find enough of the missconception in the field that the ground rod is for the purpose to find ground which it is not. We only have the teaching field to blame and students who do not ask the right questions.


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## RIVETER (Sep 26, 2009)

codeone said:


> Still even alot of what you say is true, it has been taught in such a way that there is alot of misconception out there to this day. When I was in school the terms they used was that Electricity was trying to find Ground!
> 
> This is not a good way to teach the actual physics of electricity. They need to make the refference of trying to find its source, its trying to make a circle, not going to a referance point call ed ground. Out in a circuit there is a potential differance between the grounded conductor and the equipment grounding conductor. Otherwise you would be blasted when getting between a neutral conductor on 277v lighting.
> 
> We do find enough of the missconception in the field that the ground rod is for the purpose to find ground which it is not. We only have the teaching field to blame and students who do not ask the right questions.


Just when I thought we were getting close. Out in the circuit there is NOT a difference of potential between the grounded conductor and the equipment grounding conductor. Maybe we ought to call the equipment ground something else. Whether it is the conduit, the green wire, or the bare wire, the equipment ground only conducts current if there is a fault from an ungrounded conductor to ANY metal that is at ground potential.Am I misstating something...Anyone.


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## codeone (Sep 15, 2008)

RIVETER said:


> Just when I thought we were getting close. Out in the circuit there is NOT a difference of potential between the grounded conductor and the equipment grounding conductor. Maybe we ought to call the equipment ground something else. Whether it is the conduit, the green wire, or the bare wire, the equipment ground only conducts current if there is a fault from an ungrounded conductor to ANY metal that is at ground potential.Am I misstating something...Anyone.


If there wasnt ever a potential diff it would never trip a breaker when shorted.


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## RIVETER (Sep 26, 2009)

*flex*



codeone said:


> If there wasnt ever a potential diff it would never trip a breaker when shorted.


With all due respect, you probably know what you want to say but I don't believe you are saying what you know to be true, correctly. I am not trying to offend anyone but I will try to say it again, in a different way. If you have a conduit with a hot wire, (ungrounded circuit conductor), and a neutral wire, (intentionally grounded circuit conductor),as your branch circuit, and a joint in the HOT wire comes loose and makes contact with the conduit, which is BONDED to the neutral at the service, the hot wire has found a low resistance path back to its source; The large amount of FAULT current will break, or trip the overload device.


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## brian john (Mar 11, 2007)

With load on a circuit (single phase 2 wire for simplicity) and therefore current on the neutral/grounded conductor and current on the phase/hot/energized conductor, there is a difference of potential between the neutral and EGC (equipment grounding conductor) once you leave the point of the neutral ground bond.

And I am ignoring WACOS ground rod reference intentionally as it is off the mark once again.


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## brian john (Mar 11, 2007)

codeone said:


> Out in a circuit there is a potential differance between the grounded conductor and the equipment grounding conductor. Otherwise you would be blasted when getting between a neutral conductor on 277v lighting and the equipment grounding conductor.


If there is a difference of potential (which there is based on load and distance) You can in theory get shocked. I say theory because the voltage level seldom is high enough)



> We do find enough of the missconception in the field that the ground rod is for the purpose to find ground which it is not. We only have the teaching field to blame and students who do not ask the right questions.


In many cases the field electricians never went to school and assume incorrectly, other cases the teachers just SUCK.


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## RePhase277 (Feb 5, 2008)

I'm sure there was alot of confusion as to what the actual purpose of "ground" was. This stems from the vocabulary. How it was taught at least some of the time notwithstanding, in legit textbooks from the period, the idea of "circuit ground", "ground", "signal ground", etc. is well understood. How some people use it in the field, along with a lack of fundamental understanding, is quite another thing. When an engineer uses a term like "electricity goes to ground", it may actually have a legit meaning, that can be very easily misunderstood. 

Here's what I know about the Electrician's Ground:

1) 95% of the time, an electrician says "ground", but means "conductor bonded to neutral used to actuate the OCPD", AKA "bond", AKA "EGC"

2) 4.9% of the time "ground" means the actual connection to Terra Firma, be it a rod, plate, pipe, or Ufer electrode. AKA "GEC".

3) 0.1% of the time "ground" means "circuit conductor at lower potential".

4)The GEC doesn't actually bring the electrical system to the Earth's potential relative to the distribution system. It is really the opposite. The GEC ties the Earth to the local system voltage. It may seem like a play on words, but there is a difference.

5) The difference is that there are two circuits to consider, each with its own potential difference. One is the normal system circuit, and the other is a sky-Earth circuit that lightning travels. A lightning stroke is as real of a circuit as any, and obeys the same laws. It ain't magic.

6)As much as we love grounding today, the old timers had legit concerns against the practice of grounding, both in the Earth, and in bonding metal parts to a circuit conductor. These are all still real, and are interesting study to those truly interested in the Art of Grounding.


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## brian john (Mar 11, 2007)

In my experience most electricians do not know ground from grounded conductor to equipment grounding conductor. Many of the jobs I see with power quality issues the EC has first driven additional rods/electrodes in an misguided effort to improve the overall electrical system.

Some of the issues have to do with terminology when they think ground they think Mother Earth as noted. 

If most electricians would drop any thought of earth as actual important component of the electrical distribution system as this connection seldom to never comes into play and realize that adequate bonding leads to a 5th conductor that under normal operation carries no current, I THINK some of the issues will be minimized.

But in many cases I have seen electrical inspectors only check the ground rod and the GEC connection to the electrodes, which is one of the least important issues they should be checking.


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## Bob Badger (Apr 19, 2009)

brian john said:


> In my experience most electricians do not know ground from grounded conductor to equipment grounding conductor.


You are such an ass sometimes. :laughing:

I am pretty sure when you leave the trade the Govt will shut down the grid for our own safety.:laughing:


You are the guy that gets called in when things are wrong so IMPO your view gets distorted, you forget that on the way to these specific buildings with problems you pass 100s of buildings that do not have grounding or bonding issues.


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## paul d. (Jul 13, 2008)

i'm confused; can someone give an example of a real world grounding problem? :blink:


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## brian john (Mar 11, 2007)

paul d. said:


> i'm confused; can someone give an example of a real world grounding problem? :blink:


A system neutral grounded downstream from the main service resulting in the GFP tripping the main service switch at TSA headquarters?


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## brian john (Mar 11, 2007)

Bob Badger said:


> You are such an ass sometimes. :laughing:
> 
> I am pretty sure when you leave the trade the Govt will shut down the grid for our own safety.:laughing:
> 
> ...


Bob I have taken the Soares class 5 times, each time 2/3's to 3/4's of the class were basically lost in relation to grounding, once the instructor was misguided about the topic. When I go to jobs I ask electricians about grounding and most will say they cannot follow or understand The NEC rules on grounding, which is evident in the jobs we see.

In addition of the buildings we do maintenance in, better than 90% have grounding issues that can/will affect the operation of OCP devices, not a small issue.


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## paul d. (Jul 13, 2008)

brian john said:


> A system neutral grounded downstream from the main service resulting in the GFP tripping the main service switch at TSA headquarters?


 how did you find the problem and how did you fix it ?


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## brian john (Mar 11, 2007)

paul d. said:


> how did you find the problem and how did you fix it ?


This one was simple, the electrician that was tying in the 480/277 VAC panels in the electric closets on the floors installed bonding jumpers neutral to ground, We did a visual inspection and found this issue then we arranged an outage where we meggered the busway, panels and isolated all branch circuit neutrals and meggered them any that were shorted we traced out and cleared.


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## Bob Badger (Apr 19, 2009)

brian john said:


> Bob I have taken the Soares class 5 times, each time 2/3's to 3/4's of the class were basically lost in relation to grounding, once the instructor was misguided about the topic. When I go to jobs I ask electricians about grounding and most will say they cannot follow or understand The NEC rules on grounding, which is evident in the jobs we see.


OK you are right, everyone but you sucks.



> In addition of the buildings we do maintenance in, *better than 90% have grounding issues that can/will affect the operation of OCP devices, *not a small issue.


I think the BS is getting pretty deep. "better than 90%" give me a break.


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## paul d. (Jul 13, 2008)

brian john said:


> This one was simple, the electrician that was tying in the 480/277 VAC panels in the electric closets on the floors installed bonding jumpers neutral to ground, We did a visual inspection and found this issue then we arranged an outage where we meggered the busway, panels and isolated all branch circuit neutrals and meggered them any that were shorted we traced out and cleared.


 bet that could take some time on a big bldg. did you adjust the trip on the breaker GFP to get the customer back online ?


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## brian john (Mar 11, 2007)

Bob Badger said:


> OK you are right, everyone but you sucks.


No not at all, but I guess I am an ass for pointing out the obvious and trying to help. Of the electricians you work with give them a simple test on grounding and see how many have a basic understanding of this issue.



> I think the BS is getting pretty deep. "better than 90%" give me a break.


The next time you do a large facility remove the neutral ground bond and megger the neutral to ground. Somewhere in the distribution system I would bet there are branch circuit neutrals shorted, unless you or your firm does testing as you complete each panel, MDP and switchboard.


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## Bob Badger (Apr 19, 2009)

We will never see eye to eye on this one. 

This is really the issue in my mind



> that can/will affect the operation of OCP devices,


To me that is BS scare tactics, very few if any improper grounded to grounding conductor connections will adversely effect the operation of a OCPD. It may trip it earlier but not later.


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## waco (Dec 10, 2007)

"And I am ignoring WACOS ground rod reference intentionally as it is off the mark once again."

Of course you are because you really, really need to. Fragile egos are a bitch.

By the way, sh*thead, which "ground rod reference" is that?

I seldom use the term, since I prefer definitive discussion to hopeful shop talk. Grounded electrode works for me.

Fact is, we are technicians engaged in doing what others have determined should be done. That means "technique" more than theory. I know that is tough for the academics, but what the heck. I've long stopped paying much attention to them since they are very often more about talk than doing.

But why they feel they need be insulting is beyond me.

And by the way, earth grounding systems represent far different dynamics between places like El Paso, Texas and say, a North Carolina swamp.

We are technicians, but many of us have taught the theories we want to understand and many of us have forgotten more about electricity and electronics than some will ever know. 

So what?


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## waco (Dec 10, 2007)

Bob Badger said:


> We will never see eye to eye on this one.
> 
> This is really the issue in my mind
> 
> ...


I have to agree. An adequate "ground" path is defined by its ability to facilitate the operations of OCPDs, but the existence of GFI receptacles attest the the fact that dangerous voltage differences can exist without any awareness from the OCPD.

Bottom line (for me) is that flex is not a dependable path to prevent build up of voltage differences within systems. I think sometimes, we are talking apples and oranges, but it is aggravating to be insulted in such apples and oranges discussions.

Oh well.


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## brian john (Mar 11, 2007)

Bob Badger said:


> We will never see eye to eye on this one.
> 
> This is really the issue in my mind
> 
> ...


If you have ground fault protection and you have downstream grounds, current will normally be on the EGC, this current can result in nuisance tripping of the GFP. Under the same situation if a ground fault occurs the current will have multiple paths to the source including a portion of the current that should be on the EGC will return on the grounded conductor/neutral and can delay the operation of the GFP. Arcing Ground Faults are devastatingly fast and occur at very low currents, any delay in the operation of the GFP relay and tripping of the switch or CB this can lead to major damage.


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## Bob Badger (Apr 19, 2009)

brian john said:


> If you have ground fault protection and you have downstream grounds, current will normally be on the EGC, this current can result in nuisance tripping of the GFP.


No doubt, that would be why I said 'sooner'




> Under the same situation if a ground fault occurs the current will have multiple paths to the source including a portion of the current that should be on the EGC will return on the grounded conductor/neutral and can delay the operation of the GFP.


I say BS.

The more paths the lower the impedance the quicker the operation of the device.


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## waco (Dec 10, 2007)

How's that again? "current will normally be on the EGC..." How is that again?

Large systems suffer from having different "ground" potentials in different locations. Nothing new in that.

As I recall, procedures using precision measuring equipment (PME) usually (always) require isolation from power ground and direct "grounded" to the equipment it is used on. This is specifically to ensure it and the equipment are uneffected by "ground loops."


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## brian john (Mar 11, 2007)

Bob Badger said:


> No doubt, that would be why I said 'sooner'
> 
> 
> 
> ...


Bob not when you are dealing with GFP's and current sensors/CT's the current path is paramount in the fast operation.

In addition there are other major issues with downstream grounds EMF's and should you lose a neutral feeder the neutral current will try to travel over the neutral ground connection downstream, if this is a #12 the end user can have real issues.


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## Bob Badger (Apr 19, 2009)

brian john said:


> Bob not when you are dealing with GFP's and current sensors/CT's the current path is paramount in the fast operation.
> 
> In addition there are other major issues with downstream grounds EMF's and should you lose a neutral feeder the neutral current will try to travel over the neutral ground connection downstream, if this is a #12 the end user can have real issues.


OK you win.


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## brian john (Mar 11, 2007)

Actual I do not win I do not make the rules it is all about the nature of electricity and the OCPs we utilize to protect equipment in particular GFP's. I also try to post correct information in my post regarding technical data.

I tried to do a web search for some information on this there is some at IAEI has some excellent information and they do cover downstream grounds but not as to why there are negative effects with GFP's.


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## brian john (Mar 11, 2007)

paul d. said:


> bet that could take some time on a big bldg. did you adjust the trip on the breaker GFP to get the customer back online ?


The GFP was tripping occasionally they lessen load we lifted the obviously grounds they day they were found (after hours with a shut down). The job took 8 men 32 hours over two weekends.


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## Mike Guile (Jan 14, 2010)

*Grounding*

I was about to spend the next 15yrs devoted to grounding/bonding, but now,from your discussions, I think I'll quit now and work on how to seduce woman or something. 

I've lost it on this thread. What is verdict on using flex as primary grounding/bonding path??


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## brian john (Mar 11, 2007)

Mike Guile said:


> I was about to spend the next 15yrs devoted to grounding/bonding, but now,from your discussions, I think I'll quit now and work on how to seduce woman or something.
> 
> I've lost it on this thread. What is verdict on using flex as primary grounding/bonding path??


Was that what this was about?


----------



## 10492 (Jan 4, 2010)

Mike Guile said:


> I've lost it on this thread. What is verdict on using flex as primary grounding/bonding path??


Depends.


----------



## Mike Guile (Jan 14, 2010)

*?*



I thought science was Black or White??

I may just be sticking to Tom Henry, and not listen to anything else. I feel like my brain is getting poisoned with misinformation on here occasionally. 
:thumbup:


----------



## paul d. (Jul 13, 2008)

Mike Guile said:


> I was about to spend the next 15yrs devoted to grounding/bonding, but now,from your discussions, I think I'll quit now and work on how to seduce woman or something.
> 
> I've lost it on this thread. What is verdict on using flex as primary grounding/bonding path??


 on large comm/ind jobs its in the specs to install EGC in all conduits/flex. been that way for many years. so whats the fuss about ??:blink:


----------



## Mike Guile (Jan 14, 2010)

*Fuss*

No Fuss here. Just trying to get to the truth. Someone is right and someone is wrong. I was just at a place where they had the whole 10,000 ft of conduit with 2 wire.(No 3rd EGC). I asked for the blueprints and it was spec'd without the 3rd EGC. What's up with that? It was a few years ago though. What year did they start specing it on all jobs roughly? 70's 80's 90's??? Just curious


----------



## paul d. (Jul 13, 2008)

Mike Guile said:


> No Fuss here. Just trying to get to the truth. Someone is right and someone is wrong. I was just at a place where they had the whole 10,000 ft of conduit with 2 wire.(No 3rd EGC). I asked for the blueprints and it was spec'd without the 3rd EGC. What's up with that? It was a few years ago though. What year did they start specing it on all jobs roughly? 70's 80's 90's??? Just curious


we was installing EGC in 1976, when i started. what kind of job was it on the 10k with no EGC ??:blink:


----------



## Mike Guile (Jan 14, 2010)

*Indy*

It was a large dormitory in I.U. around 76' I think.


----------



## brian john (Mar 11, 2007)

If you are talking EMT or Rigid, there is no code requiring a copper EGC to be installed in EMT or rigid, specifications may require it.


----------



## Hertz Electric (Dec 20, 2009)

Originally Posted by *Bob Badger*  
_You are such an ass sometimes. :laughing:_

_I am pretty sure when you leave the trade the Govt will shut down the grid for our own safety.:laughing:_


_You are the guy that gets called in when things are wrong so IMPO your view gets distorted, you forget that on the way to these specific buildings with problems you pass 100s of buildings that do not have grounding or bonding issues._


brian john said:


> Bob I have taken the Soares class 5 times, each time 2/3's to 3/4's of the class were basically lost in relation to grounding, once the instructor was misguided about the topic. When I go to jobs I ask electricians about grounding and most will say they cannot follow or understand The NEC rules on grounding, which is evident in the jobs we see.
> 
> In addition of the buildings we do maintenance in, better than 90% have grounding issues that can/will affect the operation of OCP devices, not a small issue.


 
 Will you two girls knock it off, this is a professional electrical forum.


----------



## william1978 (Sep 21, 2008)

Hertz Electric said:


> Will you two girls knock it off, this is a professional electrical forum.


 :yawn::yawn:


----------



## B4T (Feb 10, 2009)

Hertz.. anyone ever call you a "girly man" :laughing:

Still waiting for you to post some pics of your electrical work.

Surely someone with your vast electrical knowledge has a couple of nuclear reactors that you wired in the last few months


----------



## RIVETER (Sep 26, 2009)

*flex as grounding*



brian john said:


> If there is a difference of potential (which there is based on load and distance) You can in theory get shocked. I say theory because the voltage level seldom is high enough)
> 
> 
> 
> In many cases the field electricians never went to school and assume incorrectly, other cases the teachers just SUCK.


If there is a difference of potential between the equipment ground and the neutral say, 100 feet away from the service which of the following cases would trip the breaker quicker? A hot to egc short or a hot to neutral short at that 100 foot distance.


----------



## william1978 (Sep 21, 2008)

Black4Truck said:


> Hertz.. anyone ever call you a "girly man" :laughing:
> 
> Still waiting for you to post some pics of your electrical work.
> 
> Surely someone with your vast electrical knowledge has a couple of nuclear reactors that you wired in the last few months


 I'm still waiting also. He would be the man if had wired a couple of nuclear reactors in the last few months.:laughing:


----------



## brother (Nov 25, 2008)

Hey, what happened to my thread??? you guys hijacked my thread!!


----------



## NolaTigaBait (Oct 19, 2008)

brother said:


> Hey, what happened to my thread??? you guys hijacked my thread!!


Let's start over. Ask me I will give the only correct answer.


----------



## RIVETER (Sep 26, 2009)

*Flex as grounding conductor*



brother said:


> Hey, what happened to my thread??? you guys hijacked my thread!!


Here it is back. Yes, you would still consider the flex as an equipment grounding conductor even if there were a green wire in it.


----------



## user4818 (Jan 15, 2009)

NolaTigaBait said:


> Let's start over. Ask me I will give the only correct answer.


:sleep1:


----------



## user4818 (Jan 15, 2009)

Hertz Electric said:


> Will you two girls knock it off, this is a professional electrical forum.


Aren't you actually a girl yourself? :whistling2:


----------



## brian john (Mar 11, 2007)

RIVETER said:


> If there is a difference of potential between the equipment ground and the neutral say, 100 feet away from the service which of the following cases would trip the breaker quicker? A hot to egc short or a hot to neutral short at that 100 foot distance.


Logially one would thing both would operate the same, the impedance of the circuit, phase to neutral or phase to ECG assuming the EGC and neutral are copper conductors. Though the parallel path for the EGC could have some effect depending on the material utilized?


----------



## RIVETER (Sep 26, 2009)

*Flex as a grounding conductor*



brian john said:


> Logially one would thing both would operate the same, the impedance of the circuit, phase to neutral or phase to ECG assuming the EGC and neutral are copper conductors. Though the parallel path for the EGC could have some effect depending on the material utilized?


I had not even considered the concept of there being a difference of potential between the neutral and the equipment ground at some distance from the service where they are are both connected PHYSICALLY. You mentioned that in one of your posts and I can kind of see that that may be true. The reason I asked the question that I did was that if it IS true, then with a tester,one would expected to read a difference. Then with that potential on the neutral, if it came in contact with the hot it would seem that the breaker may take longer to trip, in cycles per second. As you have said, it is kind of theoretical, but is interesting.


----------



## brian john (Mar 11, 2007)

RIVETER said:


> I had not even considered the concept of there being a difference of potential between the neutral and the equipment ground at some distance from the service where they are are both connected PHYSICALLY. You mentioned that in one of your posts and I can kind of see that that may be true. The reason I asked the question that I did was that if it IS true, then with a tester,one would expected to read a difference. Then with that potential on the neutral, if it came in contact with the hot it would seem that the breaker may take longer to trip, in cycles per second. As you have said, it is kind of theoretical, but is interesting.


The deal with the difference in potential has to do with voltage drop, there is voltage drop on the neutral due to the load, there is no load (hopefully) on the EGC and thus no VD.


----------



## JayH (Nov 13, 2009)

RIVETER said:


> Here it is back. Yes, you would still consider the flex as an equipment grounding conductor even if there were a green wire in it.


I don't know if it is still the same today, but in Los Angeles twenty years ago we were allowed to use flex as the equipment ground provided the flex was square cut and we used a compression connector, not a "jake" or screw in flex connector. There was a tool we used to cut the flex square.

I had never heard of this until I moved to LA so local jurisdictions will have different requirements for grounding equipment.


----------



## RIVETER (Sep 26, 2009)

*Debate over flex*



brian john said:


> The deal with the difference in potential has to do with voltage drop, there is voltage drop on the neutral due to the load, there is no load (hopefully) on the EGC and thus no VD.


That, to me seems to be negligible VD because of the negligible resistance of the conductor from one point to another. This is actually a question.


----------



## william1978 (Sep 21, 2008)

JayH said:


> I don't know if it is still the same today, but in Los Angeles twenty years ago we were allowed to use flex as the equipment ground provided the flex was square cut and we used a compression connector, not a "jake" or screw in flex connector. There was a tool we used to cut the flex square.
> 
> I had never heard of this until I moved to LA so local jurisdictions will have different requirements for grounding equipment.


 I had never heard of that either. Are you talking about a T&B tight bite flex conn.?


----------



## JayH (Nov 13, 2009)

william1978 said:


> I had never heard of that either. Are you talking about a T&B tight bite flex conn.?


 
They did not have to be specifically T&B, just the compression or "squeeze" type connector to qualify for the exemption from no EGC in the flex.

I tried to search for the tool we used but came up empty on Google, but you could not have the flex cut at an angle, it had to be cut so that the ends were flush to the stop in the connector all the way around.

The tool basically held the flex secure and had a slot that your hacksaw blade fit into to cut the flex square.

I've not seen one since I moved to NorCal in 1985.


----------



## RIVETER (Sep 26, 2009)

*Flex as grounding*



JayH said:


> I don't know if it is still the same today, but in Los Angeles twenty years ago we were allowed to use flex as the equipment ground provided the flex was square cut and we used a compression connector, not a "jake" or screw in flex connector. There was a tool we used to cut the flex square.
> 
> I had never heard of this until I moved to LA so local jurisdictions will have different requirements for grounding equipment.


I guess rules vary from place to place but the bottom line is that you have to have a good, tight mechanical fit on the flex. If you do it will be a pretty good conductor in the case of a fault. And if you do have a mechanical ground IN the flex, then the integrity of the flex and it's connections is very important.


----------



## brian john (Mar 11, 2007)

At 100 feet a 120 VAC #12 AWG circuit with 16 amps load will have a voltage drop of 6.1 volts. Depending on where in the circuit you measure neutral to ground will determine the difference of potential you read. Remember the EGC is at the same potential as the location of the neutral ground bond.


----------



## RIVETER (Sep 26, 2009)

*Debate over flex*



brian john said:


> At 100 feet a 120 VAC #12 AWG circuit with 16 amps load will have a voltage drop of 6.1 volts. Depending on where in the circuit you measure neutral to ground will determine the difference of potential you read. Remember the EGC is at the same potential as the location of the neutral ground bond.


Okay, bear with me. If you visualize placing one probe on the neutral and the other probe on the GEC with current ON the conductor, I just don't see much of a difference of potential...at least measurable. Are you talking only in theory?


----------



## brian john (Mar 11, 2007)

RIVETER said:


> Okay, bear with me. If you visualize placing one probe on the neutral and the other probe on the GEC with current ON the conductor, I just don't see much of a difference of potential...at least measurable. Are you talking only in theory?


No theory, in the circuit I noted you would measure between 0 and 3 VAC depending on where you measure voltage between the neutral and EGC.

If you measure 120 VAC at the circuit breaker between phase and neutral, 120 VAC between the Phase and EGC and between the neutral and EGC "0" VAC (this all assumes the neutral bond is at this location). Then you should read 114 VAC at the load due to VD, you should be reading 117 VAC between the phase conductor and EGC and 3 VAC between the neutral and EGC.

If all this is correct except the reading between neutral and EGC is "0" VAC you have a connection to the EGC on the neutral to close to the measurement point.

Try it with any measurements you take in the future.


----------



## RIVETER (Sep 26, 2009)

*debate over flex*

Brian, I will have to think about this. Thanks for the conversation. It sure beats worrying about what Hertz is doing. I hope he is okay. Maybe he will get in on some of these discussions. Grounding and bonding are my favorite subjects because they are misunderstood so often.


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## waco (Dec 10, 2007)

Seems to me, the NEC makes the discussion moot.


----------



## JayH (Nov 13, 2009)

waco said:


> Seems to me, the NEC makes the discussion moot.


Many local jurisdictions would say otherwise.


----------



## slickvic277 (Feb 5, 2009)

brother said:


> *Debate on over Flex as Grounding Conductor*
> I just want to be sure Im not reading it wrong, as there is a debate going on. A flex (less than 6ft) was installed in patient care area, hospital, and also a ground wire was installed. The circuit is on a 20 amp breaker. The debate is that the 'flex' no longer qualifies as an egc because of the flexibility was necessary, so therefore because of the redundant grounding requirment in 2008 NEC 517.13, its a violation.
> 
> I say it (THE FLEX) does qualify as an egc, and just because the 'flexibility' was necessary that code section only means that the ground wire must be installed, not that the flex itself is not longer a ground path. If it was true, then the NEC would made that very clear. This is my understanding of 2008 nec 250.118(6)e. Am I right??



This is interesting.I would say that since the flexibility is required then the fmc would not count as "ground" hence the need for the extra "egc" to be installed.Being that this is a HCF you are required to have redundant grounding,how do you now achieve this?Would the use of bonding bushings satisfy the requirement?What was the inspectors solution?
On a different note it was a piece of fmc that caused the mgm grand in Las Vegas to burn down and kill a bunch of people.For that alone I would always install an egc.


----------



## waco (Dec 10, 2007)

JayH said:


> Many local jurisdictions would say otherwise.


All the jurisdictions in my area go with the code, as do I. When the lawsuits start, see how fast a sovereign jurisdiction walks away.


----------



## codeone (Sep 15, 2008)

waco said:


> All the jurisdictions in my area go with the code, as do I. When the lawsuits start, see how fast a sovereign jurisdiction walks away.


LAWSUITS- Thats why its best to stick with the NEC no matter how small.
Its the Minimum. Minimum means you dont have much in alot of cases.:no:


----------



## user4818 (Jan 15, 2009)

slickvic277 said:


> On a different note it was a piece of fmc that caused the mgm grand in Las Vegas to burn down and kill a bunch of people.For that alone I would always install an egc.


The FMC caused the fire, allegedly. It was poor workmanship (a loose fitting) that was the issue.

Many people died because the building was not built to modern fire codes, allowing the fire to spread rapidly and the HVAC system carried the smoke throughout the building. It also did not have a full coverage fire alarm system.


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## brother (Nov 25, 2008)

Peter D said:


> The FMC caused the fire, allegedly. It was poor workmanship (a loose fitting) that was the issue.
> 
> Many people died because the building was not built to modern fire codes, allowing the fire to spread rapidly and the HVAC system carried the smoke throughout the building. It also did not have a full coverage fire alarm system.


 What fire was that?? when was it?? and How on EARTH did the fire marshall come up with a 'loose fitting' on a flex connector caused it?? Ive always been suspicious of soo called, 'the electrical caused the fire' judgements when everything gets burned up!!


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## brian john (Mar 11, 2007)

brother said:


> What fire was that?? when was it?? and How on EARTH did the fire marshall come up with a 'loose fitting' on a flex connector caused it?? Ive always been suspicious of soo called, 'the electrical caused the fire' judgements when everything gets burned up!!


I have read several fire reports about fires in hotels and night clubs, it is amazing, how someone not plugging a hole in a firewall can lead to massive destruction due to the nature of fire and oxygen.


----------



## slickvic277 (Feb 5, 2009)

brother said:


> What fire was that?? when was it?? and How on EARTH did the fire marshall come up with a 'loose fitting' on a flex connector caused it?? Ive always been suspicious of soo called, 'the electrical caused the fire' judgements when everything gets burned up!!



It was in L.V. in the early 80's I believe.The MGM Grand.The story goes that a piece of flex that was connected to an ice machine had wires that shorted to the flex(due to vibrations from the machine)the flex was relied on as the EGC but since the connection was poor and loose(due to vibration)the OCPD never opened and the flex became cherry red hot.Heating up inside a wall and starting the fire.Don't ask me how they knew it was the flex.


----------



## codeone (Sep 15, 2008)

Had to do an Inspection on a house that had a fire one day that the Fire Marshal determined was electrical. In about 10 min proved it was not. Electrical gets blamed for alot of fires it doesnt start. This paticular fire was never proved what started it however it was finally thought to be arson.:whistling2:


----------



## RIVETER (Sep 26, 2009)

*debate over flex*



slickvic277 said:


> It was in L.V. in the early 80's I believe.The MGM Grand.The story goes that a piece of flex that was connected to an ice machine had wires that shorted to the flex(due to vibrations from the machine)the flex was relied on as the EGC but since the connection was poor and loose(due to vibration)the OCPD never opened and the flex became cherry red hot.Heating up inside a wall and starting the fire.Don't ask me how they knew it was the flex.


 I can see how it would not trip the breaker...but if the flex was cherry red why didn't it melt the other conductor insulation? You would think that somewhere along the line the Hot would come in contact with a Neutral or other portion of the EGC to trip the breaker.


----------



## brother (Nov 25, 2008)

RIVETER said:


> I can see how it would not trip the breaker...but if the flex was cherry red why didn't it melt the other conductor insulation? You would think that somewhere along the line the Hot would come in contact with a Neutral or other portion of the EGC to trip the breaker.


I agree 100%!! So the statement 'fire was caused by electrical' stinks to high heaven to me!! if a flex got that hot its obvious that other conductors would melt their insulation. The breaker would have to be bad for it to not trip in my opinion.


----------



## RIVETER (Sep 26, 2009)

*Debate over flex*



brother said:


> I agree 100%!! So the 'fire was caused by electrical' stinks to high heaven to me!! if a flex got that hot its obvious that other other conductors would melt their insulation. The breaker would have to be bad for it to not trip in my opinion.


 We, as electricians, have to be knowlegable enough of our trade that we can offer plausible reasons as to why it was not an electrical fire. It is our premiums that go up...not the firefighters'.


----------



## slickvic277 (Feb 5, 2009)

RIVETER said:


> I can see how it would not trip the breaker...but if the flex was cherry red why didn't it melt the other conductor insulation? You would think that somewhere along the line the Hot would come in contact with a Neutral or other portion of the EGC to trip the breaker.



I agree 100% but I only know of the case on what little I read.I always felt that the information was always lacking accuracy.Perhaps the insulation failure was only on the "hot" conductor and made contact with the flex heating the flex up quicker then the other conductor insulation?I don't know,seems plausible just not very probable.


----------



## slickvic277 (Feb 5, 2009)

brother said:


> I agree 100%!! So the 'fire was caused by electrical' stinks to high heaven to me!! if a flex got that hot its obvious that other other conductors would melt their insulation. The breaker would have to be bad for it to not trip in my opinion.



I also think that the "electric caused the fire" is way over used and when the fire marshal can't figure out the cause there quick to jump to electrical as a scape goat.I don't feel it's really that obvious that the other conductors would have to melt and trip the breaker right away.The whole thing could have been slowly heating or arcing and could easily set surrounding drywall/plaster on fire well before the insulation melted enough to cause line to line fault.And I think we all seen breakers in poorly grounded systems not trip when they should have.Or breakers of bad design(Fed.Pacific for example) hold loads way beyond what there designed for.
I guess my point is although it doesn't seem likely,it's not impossible.


----------



## RIVETER (Sep 26, 2009)

*flex as grounding conductor*



slickvic277 said:


> I also think that the "electric caused the fire" is way over used and when the fire marshal can't figure out the cause there quick to jump to electrical as a scape goat.I don't feel it's really that obvious that the other conductors would have to melt and trip the breaker right away.The whole thing could have been slowly heating or arcing and could easily set surrounding drywall/plaster on fire well before the insulation melted enough to cause line to line fault.And I think we all seen breakers in poorly grounded systems not trip when they should have.Or breakers of bad design(Fed.Pacific for example) hold loads way beyond what there designed for.
> I guess my point is although it doesn't seem likely,it's not impossible.


 I CAN see where it could possibly cause a fire if it is arcing and the current never gets up to the breaker rating.However, CHERRY RED tells me that it should melt the other conductors. I'll bet that there are some electricians out there who are fire fighters,as well. Maybe they could tell how a fireman arrives at his conclusions.


----------



## slickvic277 (Feb 5, 2009)

RIVETER said:


> I CAN see where it could possibly cause a fire if it is arcing and the current never gets up to the breaker rating.However, CHERRY RED tells me that it should melt the other conductors. I'll bet that there are some electricians out there who are fire fighters,as well. Maybe they could tell how a fireman arrives at his conclusions.


Yae there are definitely electricians that are fire fighters but have you ever met a fire fighter who THINKS there an electrician?I see this a lot,they usually have positions of power,inspectors,fire marshals,stuff like that,and very few are qualified to be making educated determinations about the electrical industry.

I agree with your assessment of the conductors melting but I like to play devil's advocate just for the fun of it.


----------



## RIVETER (Sep 26, 2009)

*Flex as grounding conductor*

:whistling2:There is nothing wrong with being the devil's advocate. There is a lot of stuff that I pretend not to know about.


----------



## slickvic277 (Feb 5, 2009)

RIVETER said:


> I CAN see where it could possibly cause a fire if it is arcing and the current never gets up to the breaker rating.However, CHERRY RED tells me that it should melt the other conductors. I'll bet that there are some electricians out there who are fire fighters,as well. Maybe they could tell how a fireman arrives at his conclusions.



What if it was a 120v circuit? And the flex only contained a hot and a neutral wire and For the sake of argument what if the system wasn't properly grounded.If the neutral conductor melted but never caused the breaker to open,is that possible? I know it's asking for the perfect storm but do you think it's possible?
I don't know,seems like you would need a lot of things to go wrong for this "cause of fire" to be right.


----------



## JayH (Nov 13, 2009)

http://www.nfpa.org/assets/files/Press%20Room/LasVegasMGMGrand.pdf

Pages 46,47,& 48 have diagrams and description of the cause of the fire.


----------



## RIVETER (Sep 26, 2009)

*flex as grounding conductor*



slickvic277 said:


> What if it was a 120v circuit? And the flex only contained a hot and a neutral wire and For the sake of argument what if the system wasn't properly grounded.If the neutral conductor melted but never caused the breaker to open,is that possible? I know it's asking for the perfect storm but do you think it's possible?
> I don't know,seems like you would need a lot of things to go wrong for this "cause of fire" to be right.


Let's see if I can screw this up. If you have flexible conduit system that is not properly bonded and the HOT conductor comes in contact with it, the breaker would not necessarily trip because of the obvious. If you have a loose connector on the flexible conduit and the Hot wire comes in contact with the box that the connector is supposed to be attached, AND the rest of the flexible system is BONDED correctly, then you could possibly set up an arcing situation. And every time the waveform goes thru "Current Zero" the arc would extinguish for a small time and then re-ignite. To me, it would act kind of like a arc welder, only heating and damage would occur. If, by chance, the heat did not affect the Neutral insulation the arcing would continue until the metal was burned away enough so as not to satisfy the arc. The arcing current would not be enough to trip the overload device. That is where arc fault circuits come in. I changed the arc flash to arc fault...I knew I'd do that.


----------



## slickvic277 (Feb 5, 2009)

RIVETER said:


> Let's see if I can screw this up. If you have flexible conduit system that is not properly bonded and the HOT conductor comes in contact with it, the breaker would not necessarily trip because of the obvious. If you have a loose connector on the flexible conduit and the Hot wire comes in contact with the box that the connector is supposed to be attached, AND the rest of the flexible system is BONDED correctly, then you could possibly set up an arcing situation. And every time the waveform goes thru "Current Zero" the arc would extinguish for a small time and then re-ignite. To me, it would act kind of like a arc welder, only heating and damage would occur. If, by chance, the heat did not affect the Neutral insulation the arcing would continue until the metal was burned away enough so as not to satisfy the arc. The arcing current would not be enough to trip the overload device. That is where arc flash circuits come in.



This is great! we really dragged this theory through the ringer.Honestly,I'm over my head now.

I'll bet the fire marshal didn't go through this thorough of an investigation of the flex being the cause of the fire.Maybe under the exact situation you described would have been avoided if the arc fault breaker would have been invented in 1980 and used to protect this particular circuit.


----------



## RIVETER (Sep 26, 2009)

*flex*



slickvic277 said:


> This is great! we really dragged this theory through the ringer.Honestly,I'm over my head now.
> 
> I'll bet the fire marshal didn't go through this thorough of an investigation of the flex being the cause of the fire.Maybe under the exact situation you described would have been avoided if the arc fault breaker would have been invented in 1980 and used to protect this particular circuit.


You're right. By the way thanks for catching my error. I went back and changed it from arc flash to ARC fault.


----------



## slickvic277 (Feb 5, 2009)

JayH said:


> http://www.nfpa.org/assets/files/Press Room/LasVegasMGMGrand.pdf
> 
> Pages 46,47,& 48 have diagrams and description of the cause of the fire.


Interesting :thumbsup:


----------



## slickvic277 (Feb 5, 2009)

RIVETER said:


> You're right. By the way thanks for catching my error. I went back and changed it from arc flash to ARC fault.



I knew what you meant.


----------



## slickvic277 (Feb 5, 2009)

RIVETER said:


> Let's see if I can screw this up. If you have flexible conduit system that is not properly bonded and the HOT conductor comes in contact with it, the breaker would not necessarily trip because of the obvious. If you have a loose connector on the flexible conduit and the Hot wire comes in contact with the box that the connector is supposed to be attached, AND the rest of the flexible system is BONDED correctly, then you could possibly set up an arcing situation. And every time the waveform goes thru "Current Zero" the arc would extinguish for a small time and then re-ignite. To me, it would act kind of like a arc welder, only heating and damage would occur. If, by chance, the heat did not affect the Neutral insulation the arcing would continue until the metal was burned away enough so as not to satisfy the arc. The arcing current would not be enough to trip the overload device. That is where arc fault circuits come in. I changed the arc flash to arc fault...I knew I'd do that.


Check out page 47

http://www.nfpa.org/assets/files/Press Room/LasVegasMGMGrand.pdf 

I think you nailed it.


----------



## BuzzKill (Oct 27, 2008)

that's pretty cool.


----------



## RIVETER (Sep 26, 2009)

*Flex as ground*



slickvic277 said:


> Check out page 47
> 
> http://www.nfpa.org/assets/files/Press%20Room/LasVegasMGMGrand.pdf
> 
> I think you nailed it.


 I read a lot of it but I find page 36 and the top of 37 interesting. I will re-read it tonight. What I think I am reading ,based on their findings so far is that the point at which they discovered the loose connection in the flex is that that is where the arcing occurred. Hmmm. As I read it, that portion of the wall etc. did not appear burned. Doesn't make sense to me, but as I said I'll read it again tonight. I can tell you one thing for sure...it WAS written by an Electrician...not a firefighter.


----------



## vanvincent218 (Jan 8, 2010)

dont understand why you would want to use flex in the first place!!! havent seen a run yet that couldnt be piped!Too many electricians are running away from piping and taking the easy way out whenever they can! you can site whatever code you want to..its just wrong!!


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## JayH (Nov 13, 2009)

vanvincent218 said:


> dont understand why you would want to use flex in the first place!!! havent seen a run yet that couldnt be piped!Too many electricians are running away from piping and taking the easy way out whenever they can! you can site whatever code you want to..its just wrong!!


It makes sense to me to connect loads subject to vibration with a flexible connection.

It makes a lot less sense to connect that load with a rigid conduit.

The screw in flex connectors ("jakes" in my area) should be outlawed and EGC should be required in all conduits.


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## BuzzKill (Oct 27, 2008)

..either flex or sealtite, or possibly SO w/strain relief on motors for sure, and an EGC should always be pulled; I have scoffed at guys not running them religiously. Over build, dammit.


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## slickvic277 (Feb 5, 2009)

vanvincent218 said:


> dont understand why you would want to use flex in the first place!!! havent seen a run yet that couldnt be piped!Too many electricians are running away from piping and taking the easy way out whenever they can! you can site whatever code you want to..its just wrong!!



Equipment that vibrates require flex for obvious reasons(Transformers for example).Things like generators,transformers and refrigeration would be damaged if they were piped directly and suffered from heavy vibrations.But I will say one thing all flex should be of the "rigid" type not that cheap thin sh*t I see so often and the fittings should be of equal quality,I've seen lots of flex fittings crack from vibration or from over tightening.That should never happen.I also agree that all raceways should require to have an EGC installed.


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## RIVETER (Sep 26, 2009)

*flex as grounding*



slickvic277 said:


> Equipment that vibrates require flex for obvious reasons(Transformers for example).Things like generators,transformers and refrigeration would be damaged if they were piped directly and suffered from heavy vibrations.But I will say one thing all flex should be of the "rigid" type not that cheap thin sh*t I see so often and the fittings should be of equal quality,I've seen lots of flex fittings crack from vibration or from over tightening.That should never happen.I also agree that all raceways should require to have an EGC installed.


I am at another station and cannot open the file on the fire in Las Vegas. I did go to reports of the fire on that morning and have decided to not pursue it. As you have stated it is of utmost importance to have a Ground path for fault current and that that path be treated as important as the circuit conductors, both physically, and electrically. What do you think of using,say, MC-AL of the proper size for the flexible portion of the pipe run?At least, by code it seems as if it would be okay.


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## user4818 (Jan 15, 2009)

vanvincent218 said:


> dont understand why you would want to use flex in the first place!!! havent seen a run yet that couldnt be piped!Too many electricians are running away from piping and taking the easy way out whenever they can! you can site whatever code you want to..its just wrong!!


Says an ignorant man.


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## BuzzKill (Oct 27, 2008)

Peter D said:


> Says an ignorant man.


 ..is he from chicago?


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## B4T (Feb 10, 2009)

Peter D said:


> Says an ignorant man.


I bet he likes using AC to wire a house also :no:


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## user4818 (Jan 15, 2009)

Black4Truck said:


> I bet he likes using AC to wire a house also :no:


You have to watch out for those axe wielding maniacs who destroy all the romex and service cables.


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## slickvic277 (Feb 5, 2009)

RIVETER said:


> I am at another station and cannot open the file on the fire in Las Vegas. I did go to reports of the fire on that morning and have decided to not pursue it. As you have stated it is of utmost importance to have a Ground path for fault current and that that path be treated as important as the circuit conductors, both physically, and electrically. What do you think of using,say, MC-AL of the proper size for the flexible portion of the pipe run?At least, by code it seems as if it would be okay.



When you say MC-AL are you referring to metal clad cable constructed of an aluminum jacket and containing an EGC?Then I would say yes,according to code it's fine.Probably even a better method would be say a J-box on the end of the conduit with a piece of Mc-Al extending from the J-box to the load.With the EGC connected to the box and the equipment,that coupled with good solid fittings is probably a superior connection,in this situation any way.


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## B4T (Feb 10, 2009)

Peter D said:


> You have to watch out for those axe wielding maniacs who destroy all the romex and service cables.


I heard they were attacking NM Flex now :laughing:


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## user4818 (Jan 15, 2009)

BuzzKill said:


> ..is he from chicago?


Yes. However, I can't comprehend why some guys from or near Chicago seem completely unable to think outside the box.


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## RIVETER (Sep 26, 2009)

*flex*



slickvic277 said:


> When you say MC-AL are you referring to metal clad cable constructed of an aluminum jacket and containing an EGC?Then I would say yes,according to code it's fine.Probably even a better method would be say a J-box on the end of the conduit with a piece of Mc-Al extending from the J-box to the load.With the EGC connected to the box and the equipment,that coupled with good solid fittings is probably a superior connection,in this situation any way.


I've not run it myself, yet, but I've been there for the testing and the MC, and it's connectors seem very good.


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## BuzzKill (Oct 27, 2008)

Peter D said:


> Yes. However, I can't comprehend why some guys from or near Chicago seem completely unable to think outside the box.


 that's my point, I guess. Every sparkie from there seems to say the same thing.


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## brian john (Mar 11, 2007)

vanvincent218 said:


> dont understand why you would want to use flex in the first place!!! havent seen a run yet that couldnt be piped!Too many electricians are running away from piping and taking the easy way out whenever they can! you can site whatever code you want to..its just wrong!!


Do you comprehend or understand the necessity of utilizing flex?


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## codeone (Sep 15, 2008)

vanvincent218 said:


> dont understand why you would want to use flex in the first place!!! havent seen a run yet that couldnt be piped!Too many electricians are running away from piping and taking the easy way out whenever they can! you can site whatever code you want to..its just wrong!!


 You cant possibly understand the need for flex!:no:
There not saying using flex or MC everywhere, only where there is a need for flexability say at a disconnect and a machine the line side could be pipe or any other approved wiring method!


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## B4T (Feb 10, 2009)

brian john said:


> Do you comprehend or understand the necessity of utilizing flex?


I guess he has a magic system to dissipate the vibrations from motors


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## LGLS (Nov 10, 2007)

Peter D said:


> Yes. However, I can't comprehend why some guys from or near Chicago seem completely unable to think outside the box.


In order to comprehend the complexities of lowering one's standards, you have to at least start with some.

Perhaps you'd understand if you weren't already rockbottom.


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## user4818 (Jan 15, 2009)

LawnGuyLandSparky said:


> In order to comprehend the complexities of lowering one's standards, you have to at least start with some.
> 
> Perhaps you'd understand if you weren't already rockbottom.



:laughing::laughing:

What a troll. :laughing:


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## B4T (Feb 10, 2009)

LawnGuyLandSparky said:


> In order to comprehend the complexities of lowering one's standards, you have to at least start with some.
> 
> Perhaps you'd understand if you weren't already rockbottom.


:laughing:.. that got to sting


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## user4818 (Jan 15, 2009)

Black4Truck said:


> :laughing:.. that got to sting


Yes, I'm just devastated. :thumbup:


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## brian john (Mar 11, 2007)

Peter D said:


> :laughing::laughing:
> 
> What a troll. :laughing:


BUT a durn funny one!


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## user4818 (Jan 15, 2009)

brian john said:


> BUT a durn funny one!



Oh yes, hilarious. :w00t:

















:no:


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## Old Spark (Nov 18, 2008)

Veeder-root, a manufacturer of one of the best tank monitoring and leak detection system in the world, and they require two grounds from the panel supplying power to their console. They called one, chassis ground, the other system ground. They both attach to the chassis, so it's just redundant grounding. When asked, we were informed that they just want to be more assured that the system never is ungrounded.


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## brother (Nov 25, 2008)

vanvincent218 said:


> dont understand why you would want to use flex in the first place!!! havent seen a run yet that couldnt be piped!Too many electricians are running away from piping and taking the easy way out whenever they can! you can site whatever code you want to..its just wrong!!


 Like someone said, a TROLL!! Go away TROLL!!


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## BIGACE (Feb 4, 2010)

waco "green is ground around the world" is the proper quote!


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