Grounding Electrodes

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dahualin

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NEC 250.52 says that (1) Metal Undeground Water Pipe (2) Metal Frame of the Building or Structure (3) Concrete-Encased Electrode (4) Ground Ring (5) Rod and Pipe Electrodes (6) Plate Electrodes (7) Other Local Metal Underground Systems are electrodes permitted for grounding.
My question is how many electrodes mentioned above are required for a grounding electrode system? Do I need get all of them? If I have (1) (2) (3) available, do I need get the rest especially (4), (5) and (6)? Normally I will do (5) Rod Electrodes.

Thanks in advance.

David
 
250.50 Grounding Electrode System.
If available on the premises at each building or structure served, each item in 250.52(A)(1) through (A)(6) shall be bonded together to form the grounding electrode system. Where none of these electrodes are available, one or more of the electrodes specified in 250.52(A)(4) through (A)(7) shall be installed and used.
 
As Bob said, if they are all available then you must use all of them. Typically if it's a building with a metallic water pipe you will need that and one to supplement it. Since most new buildings have rebar in the footings that would be the supplemental electrode. Basically if you have a metal water pipe you'll need at least two. If you have a plastic water pipe you'll need only one which will usually be the CEE.
 
Thanks for the comments.

What I am concerning is the (4) Ground ring (5) Rod Electrodes and (6) Plate Electrodes, because they are not part of the building, in othe words, they are almost always available. My question is those three electrods should be used or could be used as grounding electrodes no matter the building is a new or existing one?

For example, I am designing a building with (1) Metal Water Pipe and (2) Steel Structure available. My approach to the design is that the grounding electrode system will comprise of (1), (2) and (5)Rod. Is that enough? Do I have to add (4) Ground Ring and (6) Plate Electrodes? Thanks.

David
 
dahualin said:
For example, I am designing a building with (1) Metal Water Pipe and (2) Steel Structure available. My approach to the design is that the grounding electrode system will comprise of (1), (2) and (5)Rod. Is that enough? Do I have to add (4) Ground Ring and (6) Plate Electrodes? Thanks.

David
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NO. The metal water pipe and structural steel is sufficent. Don't even bother with the ground rods. No concrete encased electrode present?
 
dahualin said:
What I am concerning is the (4) Ground ring (5) Rod Electrodes and (6) Plate Electrodes, because they are not part of the building, in othe words, they are almost always available.
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I don't agree that these grounding electrodes are always available. You must install them for them to become available IMO.

bphgravity said:
NO. The metal water pipe and structural steel is sufficent. Don't even bother with the ground rods.
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I agree with what Bryan said.

Chris
 
Chris,

They are almost always available I mentioned before means they are not depended on the building. If we need them, we almost always can install them. Not like (1) Metal Water Pipe (2) Steel Structure (3) Concrete Encased rebar, they are not always available depending on what kind of building it is. If the building has no water service, (1) is not available and we are not going to install a metal water pipe for grounding electrode system; if the building is not steel structure building, (2) is not available; if the building is an exisitng building, (3) is not available.

Basically, (4), (5) and (6) are always available if you need them and install them. My question is 1). Do we have to use (4), (5) and (6) for all projects? 2)If not, what is the minimum amount of electrodes NEC require to install for new construction and existing building renovation?

Thanks.

David
 
iwire said:
250.50 Grounding Electrode System.
If available on the premises at each building or structure served, each item in 250.52(A)(1) through (A)(6) shall be bonded together to form the grounding electrode system. Where none of these electrodes are available, one or more of the electrodes specified in 250.52(A)(4) through (A)(7) shall be installed and used.
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Bob,

Is the (A)(6) supposed to be (A)(3)? If it is, that will make more sense to me. Thanks.

David
 
dahualin said:
Basically, (4), (5) and (6) are always available if you need them and install them.
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My point is that you must install them to be available. 250.50 states that "All grounding electrodes as described in 250.52(A)(1) through (A)(6) that are present at each building or structure served shall be bonded together to form the grounding electrode system." So again (4),(5), and (6) aren't present unless we install them.

dahualin said:
My question is 1). Do we have to use (4), (5) and (6) for all projects? 2)If not, what is the minimum amount of electrodes NEC require to install for new construction and existing building renovation?
Click to expand...

1) You do not need use (4), (5), and (6) unless they are present.

2) One, unless you use (2) then you must supplement the water pipe with another electrode.

Chris
 
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