1. Metal underground water pipe as grounding electrode. In order to qualify as a grounding electrode, it has to be at least 10ft in direct contact with earth. Question: If the pipe emerges from ground 1 foot before it enters the periphery of the building (in other words, it emerges just outside the building), does it qualify as a grounding electrode, assuming that it meets all the other requirements? If it does, how about 2 feet before the building? If it does, what is the maximum distance the pipe has to emerge from the periphery of the building to qualify as a grounding electrode? Or has to positively emerge INSIDE the building to qualify and not an inch outside the periphery?
Metal Underground Water Pipe
- Thread starter corvalan
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Re: Metal Underground Water Pipe
This question is really out there. IMO, the code would require the connection to be made within 5 feet of where the water pipe emerges from the ground, even if it's 20 feet away from the building. The fact that the pipe does eventually enter the building makes it an accessible grounding electrode, and must be bonded. No matter how far away. All interior water piping systems must be bonded anyway, you know. Why would anyone want the water pipe to emerge outside the building? It's like building your garage to open onto the back yard instead of on the road. You would have to drive your car through the backyard to park it. Dumb!
This question is really out there. IMO, the code would require the connection to be made within 5 feet of where the water pipe emerges from the ground, even if it's 20 feet away from the building. The fact that the pipe does eventually enter the building makes it an accessible grounding electrode, and must be bonded. No matter how far away. All interior water piping systems must be bonded anyway, you know. Why would anyone want the water pipe to emerge outside the building? It's like building your garage to open onto the back yard instead of on the road. You would have to drive your car through the backyard to park it. Dumb!
Re: Metal Underground Water Pipe
Thanks for the anwswer. I add the following comments:
1. You are right, this might be a dumb situation for residential applications. But this situation is very common in industrial applications. In many plants, there is an underground metal water pipe that emerges before the plant building (sometimes several hundred feet) and then penetrates the structure.
2. I understand that if the pipe does not qualify as a grounding electrode, I still have to connect it to the grounding system.
3. I want to know the maximum distance from the building that the underground pipe can emerge to be considered a grounding electrode. The whole purpose of a grounding electrode is to have a LOCAL ground reference, not a remote ground reference. I feel unconfortable with the idea of considering a pipe that emerges 100 feet away from the structure (and then penetrates the building)as a NEC grounding electrode. I believe that the whole concept of the grounding electrode system is to create a LOCAL ground reference, like a local an equipotential (if this word exists, I am not shure ) system.
Thanks.
Ruben
Thanks for the anwswer. I add the following comments:
1. You are right, this might be a dumb situation for residential applications. But this situation is very common in industrial applications. In many plants, there is an underground metal water pipe that emerges before the plant building (sometimes several hundred feet) and then penetrates the structure.
2. I understand that if the pipe does not qualify as a grounding electrode, I still have to connect it to the grounding system.
3. I want to know the maximum distance from the building that the underground pipe can emerge to be considered a grounding electrode. The whole purpose of a grounding electrode is to have a LOCAL ground reference, not a remote ground reference. I feel unconfortable with the idea of considering a pipe that emerges 100 feet away from the structure (and then penetrates the building)as a NEC grounding electrode. I believe that the whole concept of the grounding electrode system is to create a LOCAL ground reference, like a local an equipotential (if this word exists, I am not shure ) system.
Thanks.
Ruben
tonyi
Senior Member
Re: Metal Underground Water Pipe
Aside from the commercial aspect already mentioned, some older residences have 3' thick field stone foundations. Not the sort of thing you casually punch a masonry drill through. People get real creative about routing when faced with that stuff
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- Bremerton, Washington
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- Master Electrician
Re: Metal Underground Water Pipe
Its done commonly in warmer parts of the country.
My dads apartment in Florida has the water pipe entering on the outside. I have see it here on older buildings where the water line enters under a porch, and of course freezes.
Its done commonly in warmer parts of the country.
My dads apartment in Florida has the water pipe entering on the outside. I have see it here on older buildings where the water line enters under a porch, and of course freezes.
websparky
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- Cleveland, Ohio
Re: Metal Underground Water Pipe
Hi corvalan,
IMO:
If you are concerned that the pipe may travel hundreds of feet above grade before it travels 10 feet below grade, please consider this; A transformer may very well be located hundreds of feet away from the structure and it is grounded where it sits. Yet, at the premises, there are at least two (local) grounding electrodes. Your statement "The purpose of a grounding electrode is to have a LOCAL ground reference..." may be true but it has nothing to do with the situation you are describing. The water pipe you are describing needs to be bonded whether or not it is considered a grounding electrode for the premises in question. The premises does however need two grounding electrodes and if you are concerned that the water pipe does not qualify, then by all means, add the proper additional electrode(s)!
Your concern of where the pipe emerges from the ground is interesting and has most likely been considered before by others here at this forum. I believe the result would be the same as to whether to bond it or not!
Hi corvalan,
IMO:
If you are concerned that the pipe may travel hundreds of feet above grade before it travels 10 feet below grade, please consider this; A transformer may very well be located hundreds of feet away from the structure and it is grounded where it sits. Yet, at the premises, there are at least two (local) grounding electrodes. Your statement "The purpose of a grounding electrode is to have a LOCAL ground reference..." may be true but it has nothing to do with the situation you are describing. The water pipe you are describing needs to be bonded whether or not it is considered a grounding electrode for the premises in question. The premises does however need two grounding electrodes and if you are concerned that the water pipe does not qualify, then by all means, add the proper additional electrode(s)!
Your concern of where the pipe emerges from the ground is interesting and has most likely been considered before by others here at this forum. I believe the result would be the same as to whether to bond it or not!
Re: Metal Underground Water Pipe
Ok, thanks for all the answers, but the main issue is still not solved.
Situation: A totally continuous metal water pipe, that run underground for more than 10 feet and that emerges from ground 100 feet before the building, and then goes the 100 feet above ground until it enters the building.
Question: According to the NEC, does the pipe qualify as a grounding electrode or not?
I know that independently of being a grounding electrode or not, it should be bonded to ground. But that is not the issue. Again, the question is very simple; does this pipe qualify as a grounding electrode?
Ok, thanks for all the answers, but the main issue is still not solved.
Situation: A totally continuous metal water pipe, that run underground for more than 10 feet and that emerges from ground 100 feet before the building, and then goes the 100 feet above ground until it enters the building.
Question: According to the NEC, does the pipe qualify as a grounding electrode or not?
I know that independently of being a grounding electrode or not, it should be bonded to ground. But that is not the issue. Again, the question is very simple; does this pipe qualify as a grounding electrode?
ryan_618
Senior Member
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- Salt Lake City, Utah
Re: Metal Underground Water Pipe
In my opinion, there are only two things that must be met to have an electrode:
1) pipe must be buried for 10 feet, and
2) pipe must be electrically continuos to the connection of the grounding electrode conductor.
You have both of these and therefore you have an electrode.
[ November 10, 2003, 03:39 PM: Message edited by: ryan_618 ]
Thats enough information. You have an electrode.
In my opinion, there are only two things that must be met to have an electrode:
1) pipe must be buried for 10 feet, and
2) pipe must be electrically continuos to the connection of the grounding electrode conductor.
You have both of these and therefore you have an electrode.
[ November 10, 2003, 03:39 PM: Message edited by: ryan_618 ]
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- Illinois
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- retired electrician
Re: Metal Underground Water Pipe
I don't think that a water pipe that emerges from the ground 100' from the building is a "required" grounding electrode. Look at 250.50. "... If available on the premises at each building or structure served, ... ". In my opinion 100' away is not "at each building served". Also the intent of the "5' rule" is that the GEC be connected within 5' of where the underground water pipe emerges from the ground. In normal building applications the point of emergence from the ground and the point of entry into the building is the same place.
Don
I don't think that a water pipe that emerges from the ground 100' from the building is a "required" grounding electrode. Look at 250.50. "... If available on the premises at each building or structure served, ... ". In my opinion 100' away is not "at each building served". Also the intent of the "5' rule" is that the GEC be connected within 5' of where the underground water pipe emerges from the ground. In normal building applications the point of emergence from the ground and the point of entry into the building is the same place.
Don
ryan_618
Senior Member
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- Salt Lake City, Utah
Re: Metal Underground Water Pipe
Is there any danger in using it?
Is there any danger in using it?
- Location
- Illinois
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- retired electrician
Re: Metal Underground Water Pipe
Ryan,
I see no problem in using it as a grounding electrode. It is just my opinion that it is not a "required grounding electrode". In any case, as long as the joints are conductive, it will be a grounding electrode because 250.104 requires the interior piping to be bonded.
Don
Ryan,
I see no problem in using it as a grounding electrode. It is just my opinion that it is not a "required grounding electrode". In any case, as long as the joints are conductive, it will be a grounding electrode because 250.104 requires the interior piping to be bonded.
Don
Re: Metal Underground Water Pipe
Don:
I appreciate your input. I feel confortable with your point of view. I believe that is important what you established that if the pipe emerges a long distance outside the building, only the connection point is availble in the building, not the electrode itself. Therefore, since the electrode is NOT available on the premise, the pipe cannot be considered a "required" grounding electrode.
Don:
I appreciate your input. I feel confortable with your point of view. I believe that is important what you established that if the pipe emerges a long distance outside the building, only the connection point is availble in the building, not the electrode itself. Therefore, since the electrode is NOT available on the premise, the pipe cannot be considered a "required" grounding electrode.
dana1028
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- San Francisco Bay area
Re: Metal Underground Water Pipe
Don - I have the utmost respect for you but would like to disagree and make the following argument.
There is nothing in the code that even suggests the GEC must be connected within 5 ft. of the water pipe emerging from the ground. The 5 ft. 'intent' of the code deals with making the GEC connection to interior piping; this was new to the code in 1993.
In Corvalan's example his exterior piping does in fact service the building directly (he said the water pipe penetrates the building)...it just so happens to be above ground for 100 ft. before entering the building.
NEC official interpretation No. 212, (May 26, 1941) states that "available" means within the building served.
IMO - this GE is available and it is in the ground for more than 10 ft., therefore it is a mandatory GE.
Don - I have the utmost respect for you but would like to disagree and make the following argument.
There is nothing in the code that even suggests the GEC must be connected within 5 ft. of the water pipe emerging from the ground. The 5 ft. 'intent' of the code deals with making the GEC connection to interior piping; this was new to the code in 1993.
In Corvalan's example his exterior piping does in fact service the building directly (he said the water pipe penetrates the building)...it just so happens to be above ground for 100 ft. before entering the building.
NEC official interpretation No. 212, (May 26, 1941) states that "available" means within the building served.
IMO - this GE is available and it is in the ground for more than 10 ft., therefore it is a mandatory GE.
pierre
Senior Member
- Location
- Westchester County, New York
Re: Metal Underground Water Pipe
I agree with Don in as much as it can or should not be used as a GEC. Connecting the GEC past 5 feet is generally prohibited, and that is because the integrity of the piping cannot be assured. For the same reason outside is why I would not want it used, bond it to the system yes.
Pierre
I agree with Don in as much as it can or should not be used as a GEC. Connecting the GEC past 5 feet is generally prohibited, and that is because the integrity of the piping cannot be assured. For the same reason outside is why I would not want it used, bond it to the system yes.
Pierre
Re: Metal Underground Water Pipe
How about the wording IF AVAILABLE ON THE PREMISES. Does it refer to the electrode itself or to a connection point to the electrode?
If it is to the electrode itself, I belive that it is not available on the premises because it is far away outside of the premises.
How about the wording IF AVAILABLE ON THE PREMISES. Does it refer to the electrode itself or to a connection point to the electrode?
If it is to the electrode itself, I belive that it is not available on the premises because it is far away outside of the premises.
ryan_618
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- Salt Lake City, Utah
Re: Metal Underground Water Pipe
Pierre, you make a very valid point, but I still disagree with it. If for some reason the pipe is broken or coupled with a non-conductive fitting, you will still have a supplement ground, as required. If this were to happen there is no danger because the piping is bonded to GEC system.
I think it is an available electrode, but I'm not the AHJ on this job.
Pierre, you make a very valid point, but I still disagree with it. If for some reason the pipe is broken or coupled with a non-conductive fitting, you will still have a supplement ground, as required. If this were to happen there is no danger because the piping is bonded to GEC system.
I think it is an available electrode, but I'm not the AHJ on this job.
dana1028
Senior Member
- Location
- San Francisco Bay area
Re: Metal Underground Water Pipe
Corvalan - the electrode is the entire metal water piping system (up to the 5 ft.limit within a building)...it does not stop being a component of the electrode system just because it emerges from the ground.
[ November 10, 2003, 07:19 PM: Message edited by: dana1028 ]
Corvalan - the electrode is the entire metal water piping system (up to the 5 ft.limit within a building)...it does not stop being a component of the electrode system just because it emerges from the ground.
[ November 10, 2003, 07:19 PM: Message edited by: dana1028 ]
- Location
- Illinois
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- retired electrician
Re: Metal Underground Water Pipe
dana,
The purpose of the "5'rule" is to place the GEC connection to the pipe in a location that will make it less likely that a nonmetallic repair will be made between the GEC connection and the point where the water pipe enters the earth. The 100' above grade section makes a nonmetallic repair much more likely. The pipe beyond the point where it emerges from the ground is not a grounding electrode so therefor the metal underground water pipe electrode is not available at the building. The metal pipe between the building and the point where it emerges from the earth would be a grounding electrode conductor. I don't see water pipe listed in 250.62 as material to be used as a grounding electrode conductor.
However this whole thread is actually meaningless. The metal water pipe must be bonded to the electrical system with a conductor sized per Table 250.66. If the piping is electrically continuous, then the underground part will be used as an electrode.
Don
dana,
The purpose of the "5'rule" is to place the GEC connection to the pipe in a location that will make it less likely that a nonmetallic repair will be made between the GEC connection and the point where the water pipe enters the earth. The 100' above grade section makes a nonmetallic repair much more likely. The pipe beyond the point where it emerges from the ground is not a grounding electrode so therefor the metal underground water pipe electrode is not available at the building. The metal pipe between the building and the point where it emerges from the earth would be a grounding electrode conductor. I don't see water pipe listed in 250.62 as material to be used as a grounding electrode conductor.
However this whole thread is actually meaningless. The metal water pipe must be bonded to the electrical system with a conductor sized per Table 250.66. If the piping is electrically continuous, then the underground part will be used as an electrode.
Don
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