1/2 ground rods

[don_resqcapt19]

mtnelectric,

Ground Rods are installed to provide a path between the Electrical Service and the Utility's power pole when the Service Lateral Neutral is interrupted.

That is not the indended purpose and it would be a rare ground rod that could serve in place of the service grounded conductor.
Don

 

[mtnelect]

Grounding - "The Great Myth"

Grounding - "The Great Myth"

Grounding has become less important since the introduction of plastic water pipes in new construction. Most of the water companies routinely install plastic pipes from their water mains to the water meters. So there has been less emphasis on grounding. What is there to ground ?

This has been discussed by the National Association of Electrical Inspectors. I will find the articles and post them latter.

 

[LJSMITH1]

Cowboyjwc,

Your comment brings up a good point. If that is true, then there is no reason for anything to be listed in the first place. If all AHJ's potentially have the authority to make a determination of application, performance, or functionality for a product, then why do manufacturers need to bother to have a listing on product?

This was the subject of one of my previous threads in which there was a rumor that some AHJ's were insisting on UL only listing. They would not accept ETL, CSA or any other - equivalent - third party listing. Since I have studied 110.2 & 110.3 A & B, I cannot imagine that any state or local AHJ would think that they have the authority to pick and choose whether or not products need to be listed and by whom.

There has to be some rule or guideline, somewhere, that prohibits an AHJ from making unqualified judgements as to the validity of a product used in a certain application. As a manufacturer of electrical products (and in this particular instance), I could not imagine trying to make the determination if a ground rod type/construction/size is suitable for the installed application. As an AHJ, my only frame of reference would be a third party listing and the ability to see the details of the listing to help make a determination.

In any case, barring any cited section from the NEC, the AHJ would have no evidence to back up his rejection of the rods.

 

[cowboyjwc]

Cowboyjwc,

Your comment brings up a good point. If that is true, then there is no reason for anything to be listed in the first place. If all AHJ's potentially have the authority to make a determination of application, performance, or functionality for a product, then why do manufacturers need to bother to have a listing on product?

This was the subject of one of my previous threads in which there was a rumor that some AHJ's were insisting on UL only listing. They would not accept ETL, CSA or any other - equivalent - third party listing. Since I have studied 110.2 & 110.3 A & B, I cannot imagine that any state or local AHJ would think that they have the authority to pick and choose whether or not products need to be listed and by whom.

There has to be some rule or guideline, somewhere, that prohibits an AHJ from making unqualified judgements as to the validity of a product used in a certain application. As a manufacturer of electrical products (and in this particular instance), I could not imagine trying to make the determination if a ground rod type/construction/size is suitable for the installed application. As an AHJ, my only frame of reference would be a third party listing and the ability to see the details of the listing to help make a determination.

In any case, barring any cited section from the NEC, the AHJ would have no evidence to back up his rejection of the rods.

First I would like to say this and I hope others agree. I like to use this forum for open and frank discussion among people like myself that have been in the trades and to help those that are starting out and being able to play the devil once in awhile.

I rely on 3rd party testing labs as a part of my daily inspections and would have to be very sure of my self in order to pass something that was not listed and labeled.

That being said, since I can drive a piece of pipe in the ground and us it as an electrode, is it really that much different than having a nonlisted ground rod, for the sake of argument of course. :smile:

Jump in any time Don.

 

[quogueelectric]

surface area is simple geometry

surface area is simple geometry

The mathmatical equations to figure out surface area gives you the electrical equations or ncommon sence that the more surface area equals the more parallell paths thus lowering the ground rod resistance to the earth. A 5/8 rod is the minimum I can use here. !/2 " rods are also sold I just dont know where you can use them.

 

[LJSMITH1]

Originally Posted by CowboyJC

That being said, since I can drive a piece of pipe in the ground and us it as an electrode, is it really that much different than having a non-listed ground rod, for the sake of argument of course.

I think that's a fantastic analogy! Again, this is where the performance and technical aspect comes into play with regards to the manufacturer of the product. They are the experts (so to speak), and they should know if their product will perform as advertised. The only way to validate that independently is through third party testing and listing.

-Larry

 

[lpelectric]

Cowboyjwc,

Your comment brings up a good point. If that is true, then there is no reason for anything to be listed in the first place. If all AHJ's potentially have the authority to make a determination of application, performance, or functionality for a product, then why do manufacturers need to bother to have a listing on product?

This was the subject of one of my previous threads in which there was a rumor that some AHJ's were insisting on UL only listing. .

For an AHJ to arbitrarily opt to only allow U.L. and not ETL or CSA (US), is a great way for these aggrieved companies to launch a "Restraint of Fair Trade" suit. I think that an AHJ who is so limited in knowledge of NRTL's, etc., would be well advised to cut down on the arrogance and minimize the exposure for his/her community to lawsuits. :smile:

 

[infinity]

The mathmatical equations to figure out surface area gives you the electrical equations or ncommon sence that the more surface area equals the more parallell paths thus lowering the ground rod resistance to the earth. A 5/8 rod is the minimum I can use here. !/2 " rods are also sold I just dont know where you can use them.

Is the 5/8" minimum a local requirement? The NEC says that you can use a 1/2" copper clad rod if it's listed.

 

[quogueelectric]

poco requirement

poco requirement

Is the 5/8" minimum a local requirement? The NEC says that you can use a 1/2" copper clad rod if it's listed.

I think I dont have time to look it up for a few months lots of sand here I dont think sandy soil is a good conductor. just remember what they taught me 30 yrs ago and have seen one or two guys get knocked down for HD groundrods they carry both sizes . Lots of open neutral problems around here salt air and sandy soil and lots of old resort type cottages that are becoming main households for those who cant afford much as house prices skyrocket near the ocean. Old ground conductors were A single 12 or less and half of them are not attatched anymore as city water comes in.

 

[iwire]

Lots of open neutral problems

A ground rod, no matter how large can not make up for open neutral problems.

 

[mtnelect]

Grounding has become less important since the introduction of plastic water pipes in new construction. Most of the water companies routinely install plastic pipes from their water mains to the water meters. So there has been less emphasis on grounding. What is there to ground ?

This has been discussed by the International Association of Electrical Inspectors. I will find the articles and post them latter.

http://www.iaei.org/subscriber/magazine/00_c/grounding.htm

 

[mtnelect]

Grounding

Grounding

mtnelectric,

That is not the indended purpose and it would be a rare ground rod that could serve in place of the service grounded conductor.
Don

Thank you for your response ... You are correct ... Please refer to this link: http://www.iaei.org/subscriber/magazine/00_c/grounding.htm

This is a great forum to learn from !

Michael

 

[infinity]

That article lacks the information that a 1/2" copper clad ground rod is permitted if it's listed.

 

[mtnelect]

Ground Rods & And Anything You Wanted To Know On The NEC

Ground Rods & And Anything You Wanted To Know On The NEC

Thank you for your response.

The International Association of Electrical Inspectors have a news magazine section with a archive search engine. You will find answers to most of the questions posed on this forum. And they also have a forum for their members.

Michael

http://www.iaei.org/

 

[George Stolz]

Grounding has become less important since the introduction of plastic water pipes in new construction. Most of the water companies routinely install plastic pipes from their water mains to the water meters. So there has been less emphasis on grounding. What is there to ground ?

Michael, IMO, this statement reflects the disorder of Article 250 - nothing has changed, as far as "what's left to ground?" The electrical service is required to be grounded (earthed), and nothing has changed by a shift in what electrodes are available or common in structures. It's still required to be earthed as much today as yesterday.

All the references I saw in the article you linked to over at IAEI (which admittedly, I only skimmed halfway through) were related to getting the service connected to earth.

The critical change that comes about by the shift to more non-conductive piping being used for water piping is that there's "nothing left to bond." Bonding is different, in that the service couldn't care less about the water piping, it receives no benefit from the connection - the bonding is solely for the operation of OCPDs in the event that the water piping becomes accidentally energized.

This can be a valuable, lifesaving connection - but the text in 250.104(A) is so poor that it's really hard to determine just how far we must go in the name of bonding water pipes. There have been some pretty good discussions about this here in the past, you might have seen them.

I don't understand why your responses keep centering around the IAEI site. I don't care what they know or have, to be brutally honest.

I do care about the people that come here (because this is where I am) and that may benefit from a discussion about this, that, or the other. If you (or Quoque) still feel that grounding electrodes are to compensate for open neutrals, by all means, speak up and let's discuss it - don't be bashful.

 

[tallguy]

The critical change that comes about by the shift to more non-conductive piping being used for water piping is that there's "nothing left to bond." Bonding is different, in that the service couldn't care less about the water piping, it receives no benefit from the connection - the bonding is solely for the operation of OCPDs in the event that the water piping becomes accidentally energized.

I'm still fuzzy on this... let's say I have the #4 jumper between the copper pipe and the neutral bar of the panel. Pipe becomes energized... What exactly happens with the OCPD and how would it be different if the jumper was not there?

These discussions seem to go round and round about bonding, lightning protection, dropped neutrals, and so on -- seems like everyone has a different idea and its difficult to make any headway. I, for one, could use some fundamental explanation of an OCPD works during such a fault. On a GFCI it's obvious, since the grounded conductor is actually attached to the CB. For a "normal" MCCB, I'm missing it...

 

[mtnelect]

Grounding - Bonding

Grounding - Bonding

Thank you George on your comments !

I was wrong on the ground rods ...

But on the International Association of Electrical Inspectors web site you will find allot of articles on every subject that has been discussed on this forum.

Particularly on the subject of ground rods ... They have a 11 year study going on in different parts of the country on the effect of soils on ground rods ... Check it out.

http://www.iaei.org/

Michael

 

[JohnJ0906]

I'm still fuzzy on this... let's say I have the #4 jumper between the copper pipe and the neutral bar of the panel. Pipe becomes energized... What exactly happens with the OCPD and how would it be different if the jumper was not there?

These discussions seem to go round and round about bonding, lightning protection, dropped neutrals, and so on -- seems like everyone has a different idea and its difficult to make any headway. I, for one, could use some fundamental explanation of an OCPD works during such a fault. On a GFCI it's obvious, since the grounded conductor is actually attached to the CB. For a "normal" MCCB, I'm missing it...

Tallguy, for an OCPD to operate, it needs to see a current larger than it's rating. Therefore we want a low resistance path back to the SOURSE - the transformer. That is the purpose of the EGC and the bond to the grounded conductor (neutral) at the service entrance or the SDS.

If, say, a 20 amp circuit feeds a receptacle. The hot conductor contacts the metal box, which is connected to the EGC. The current would flow on the EGC all the way back to the service or SDS, through the bond to neutral, back to the transformer, through the coils, and back to the OCPD.

We now have a circuit with a low resistance. If its, say, 2 ohms on a 120v circuit, we have a current of 60 amps. (120v/2ohms) That will trip the 20 amp breaker.

 

[don_resqcapt19]

Michael,

You will find answers to most of the questions posed on this forum. And they also have a forum for their members.

Take a look at their forum....this one gets more posts on many single days than theirs does in a month.
As far as the IAEI site I would expect that most of the users of this forum are aware of that site. Many of us are members of that organization. They have some good information, but no better than what can be found here.
Don

 

[George Stolz]

I'm still fuzzy on this... let's say I have the #4 jumper between the copper pipe and the neutral bar of the panel. Pipe becomes energized... What exactly happens with the OCPD and how would it be different if the jumper was not there?

To further elaborate on John's good explanation, if the bonding jumper were not there then in the event of a ground fault to the pipe, the pipe would be energized to 120V, and nothing else would happen. It's just another "hot" conductor awaiting a load. That load could be a person.

With the bonding in place, then if the pipe becomes energized, then current travels along the circuit conductors to the point where the fault is taking place. Then the current travels along the piping to the bonding jumper, and through the jumper to the Main Bonding Jumper that connects the EGCs to the service (or system) neutral. From there, back to the source.

The circuit is very low resistance (because we intentionally constructed it to be) so the OCPD opens quickly; hopefully before someone comes along and touches the temporarily energized pipe.

The same concept goes for all normally-non-current-carrying metal pieces of electrical equipment. Read 250.4(A)(3-5). This is bonding.