Ground rod ohms
- Thread starter D.Rater
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peter d
Senior Member
- Location
- New England
Re: Ground rod ohms
Drive 2 rods and forget about it. A ground impedance tester is very expensive.
Drive 2 rods and forget about it. A ground impedance tester is very expensive.
southernboys#2
Member
Re: Ground rod ohms
the code requres proof of I believe 25 ohms or less if you cant prove it were required to drive two ground rods.About time the code starts getting enforced. jmho.
the code requres proof of I believe 25 ohms or less if you cant prove it were required to drive two ground rods.About time the code starts getting enforced. jmho.
physis
Senior Member
Re: Ground rod ohms
I don't have 2005, cause we're still on 99 in Ca. unless somethings's finally happened and I havn't heard about it yet.
Does the "code" say that the contractor has to "prove" the 25 or less ohms?
If not, I beleive it's a valid debate as to who has to "prove" anything. Why shouln't it be assumed that the AHJ has the burden instead?
What's easier aside. I don't consider what's easier to be a valid answer to a legitamate question.
I don't have 2005, cause we're still on 99 in Ca. unless somethings's finally happened and I havn't heard about it yet.
Does the "code" say that the contractor has to "prove" the 25 or less ohms?
If not, I beleive it's a valid debate as to who has to "prove" anything. Why shouln't it be assumed that the AHJ has the burden instead?
What's easier aside. I don't consider what's easier to be a valid answer to a legitamate question.
- Location
- New Jersey
- Occupation
- Journeyman Electrician (retired)
Re: Ground rod ohms
If this is a new building put in a #4 copper CEE before the footing is poured and forget about the rods altogether.
If this is a new building put in a #4 copper CEE before the footing is poured and forget about the rods altogether.
electricmanscott
Senior Member
- Location
- Boston, MA
- Occupation
- Massachusetts Master Electrician, one man show.
Re: Ground rod ohms
Sam you are right. The contactor does not have to prove anything per se. The contractors installation must meet the 25 ohm standard. How is the contractor to know that it does or does not meet the standard without testing it? Options are contractor buys test equipment to ensure installations are compliant or install two rods.
Sam you are right. The contactor does not have to prove anything per se. The contractors installation must meet the 25 ohm standard. How is the contractor to know that it does or does not meet the standard without testing it? Options are contractor buys test equipment to ensure installations are compliant or install two rods.
southernboys#2
Member
Re: Ground rod ohms
the article is 250.56 and it states that if the resistance is not less than 25 ohms it should be supplemented by a second ground rod thus the burden is on us imho.
the article is 250.56 and it states that if the resistance is not less than 25 ohms it should be supplemented by a second ground rod thus the burden is on us imho.
paul
Senior Member
- Location
- Snohomish, WA
Re: Ground rod ohms
Several years ago, the state of WA went around the state and tested several ground rods. Out of all of those tested, not one met 25Ω or less. Now, unless we can prove to the inspector that we have met that threshold, we must pound two rods. It's easier and cheaper to pound the 2nd rod in the ground.
Several years ago, the state of WA went around the state and tested several ground rods. Out of all of those tested, not one met 25Ω or less. Now, unless we can prove to the inspector that we have met that threshold, we must pound two rods. It's easier and cheaper to pound the 2nd rod in the ground.
busman
Senior Member
- Location
- Northern Virginia
- Occupation
- Master Electrician / Electrical Engineer
Re: Ground rod ohms
Speaking of ground rods and inspections, my friend showed me a neat trick the other day. He had a jar of those flourescent zip ties and no real use for them so he started placing one on each ground rod when they are buried in mulch. The inspector really liked that he didn't have to hunt for the connections. Never hurts to grease the skids a little.
Mark
Speaking of ground rods and inspections, my friend showed me a neat trick the other day. He had a jar of those flourescent zip ties and no real use for them so he started placing one on each ground rod when they are buried in mulch. The inspector really liked that he didn't have to hunt for the connections. Never hurts to grease the skids a little.
Mark
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: Ground rod ohms
The NEC does not place the burden of proof on anyone. It just states the requirement that southerboys#2 cited. Therefore, nothing prevents the inspector from seeing only one rod and asking a question about the ground resistance of that one rod. Also, nothing prevents an inspector from declining to approve an installation without first getting a satisfactory answer to that question.
My only problem would be if a single rod was tested and did show a resistance of 25 ohms or less, and if the test results were to be shown to the inspector, but the inspector says he wants to witness the test and tells the installer to do the test again. I don't know if that ever happens, but I would say that that would be an example of the abuse of authority.
The NEC does not place the burden of proof on anyone. It just states the requirement that southerboys#2 cited. Therefore, nothing prevents the inspector from seeing only one rod and asking a question about the ground resistance of that one rod. Also, nothing prevents an inspector from declining to approve an installation without first getting a satisfactory answer to that question.
My only problem would be if a single rod was tested and did show a resistance of 25 ohms or less, and if the test results were to be shown to the inspector, but the inspector says he wants to witness the test and tells the installer to do the test again. I don't know if that ever happens, but I would say that that would be an example of the abuse of authority.
- Location
- Massachusetts
Re: Ground rod ohms
IMO the inspector would be within their authority to see the test conducted.
The testers we have do not produce a report, they look like Digital or analog voltmeters.
I am sure there are meters that can produce a report but even at that I think I would be on shaky ground telling the inspector they must accept it.
I look at it the same way I do for a rough wall inspection.
The inspector must be called before the walls are closed so they can see the work, they do not have to take my word for it that I performed the work to code. If I take pictures and then the wall gets closed they may accept the pictures or may say no way.
I have had agreements with inspectors where I could close trenches without inspection if I kept pictures of the work.
IMO the inspector would be within their authority to see the test conducted.
The testers we have do not produce a report, they look like Digital or analog voltmeters.
I am sure there are meters that can produce a report but even at that I think I would be on shaky ground telling the inspector they must accept it.
I look at it the same way I do for a rough wall inspection.
The inspector must be called before the walls are closed so they can see the work, they do not have to take my word for it that I performed the work to code. If I take pictures and then the wall gets closed they may accept the pictures or may say no way.
I have had agreements with inspectors where I could close trenches without inspection if I kept pictures of the work.
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