Water Ground versus Grounding Electrodes

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aelectricalman

aelectricalman

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When is water grounding not necessary? Is it always required in new construction? I have one inspector that requires both 1 ground rod and one water ground or 2 ground rods and no water is needed. The other says that 2 ground rods must me driven and also a water ground is needed.

My question is this. If the plumbing is leaving the home in plastic or PVC or whatever else it is that they use, can I just have the 2 ground rods seried 6 feet apart, or do I need to add a third ground rod seperate from the other two seried electrodes to accomidate for the lack of water ground.

Secondly, if the lightning is going to ground the fastest way possible, won't one of the systems be useless. Why is the water ground mandated if only one system will truely carry the load to ground. Am i wrong in my assumption or is it so it picks the bast of the two.

Editted because I have not passed hooked on phonics course.

[ February 22, 2005, 07:03 PM: Message edited by: aelectricalman ]
 
Re: Water Ground versus Grounding Electrodes

If a METALIC underground water line is present then it must be used. If its PVC then you don't use it. However, if the pipes inside the house are metalic, then you must bond them to the grounding system. An underground metalic water line is one of your best grounding systems available.

Now if you use the underground water line then you MUST suppliment it with another listed grounding electrode.....ROD, UFER, ETC.
 
Re: Water Ground versus Grounding Electrodes

I just looked at your post again, since you have a PVC line you can use two ground rods separated by at least 6 feet............more separation is better. No need to place a separate or third electrode as you asked.
 
Re: Water Ground versus Grounding Electrodes

Originally posted by stud696981:
If a METALIC underground water line is present then it must be used.
Click to expand...
Is this still correct. If you do have a Metallic grounding system and just don't want to use it, can you use 2 ground rods only w/ no water grounding.

[ February 22, 2005, 06:21 PM: Message edited by: aelectricalman ]
 
Re: Water Ground versus Grounding Electrodes

If it is there, you must use it. 250.50. A ground rod does not come into the picture until you discover that none of the items in 250.52(A)(1) through (A)(6) are available. A ground rod is a supplemental electrode; the other six are the primary electrodes, when any or all are available. Then, if you do use a ground rod, you come under the "25 ohms or two rods" rule.

[ February 22, 2005, 06:45 PM: Message edited by: charlie b ]
 
Re: Water Ground versus Grounding Electrodes

Under Art.250.50,250.52 If available at leaste (10ft.) of burried metal water pipe you need to use it as part of the grounding system. But of course if the above is not there than under Art.250.104 you still need to bond the interior metal water pipe if any.
 
Re: Water Ground versus Grounding Electrodes

Here is the procedure as I see it:

1. Ground all of the following that is available:
a. metal water pipes
b. Metal frame of building, where grounded.
c. Concrete encased electrodes

(I assume ground rods and plate electrodes and ground rings won't just happen to be available on site.)

2. If you have grounded anything other than the water pipe, you may stop. Otherwise, goto #3.

3. Provide a single ground rod. Either test and verify its resistance is less than 25 ohms, or provide another ground rod at least 6' away.

Steve
 
Re: Water Ground versus Grounding Electrodes

You stated that this is a new building. When the 2005 NEC is adopted the concrete encased electrode will have to be included as a grounding electrode. They changed the wording from if available on the premises, to, all grounding electrodes that are present. This is going to suck in areas where it wasn't required previously (such as here) because you have to be there when the footers are poured. Before it just wasn't available when you got there!
 
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