number of ground rods

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romeo

Senior Member
I hope I don't get shut off for being off the original subject. The issue of how many ground rods are required at a building or structure supplied by a feeder has been a major issue with me.

Naturally we are assuming that there are no available electrodes at the building or structure and we will be using ground rods that do not meet the 25 ohms.

I maintain that 2 rods are required for any building or structure including a built support suppling a panel for an in ground pool if it is in a building or not

My reason: 250.32 requires that a GRS be installed in accordance with part III of Articale 250.

Part III of Articale 250: 250.56 requires a second rod.

I had that discussion with an instructor a a recent 15 hr class, He dropped the issue.

What do you say?
 

cmreschke

Senior Member
i drive one until i am proven that two is required and i dont meet the 25 ohms or less. we are in america and innocent until proven guilty.;)
 

Volta

Senior Member
Location
Columbus, Ohio
I also agree, prove that one is good, or put in two.

Funny thing is that we keep having inspectors tell us that we don't need the second one. :roll:

We keep putting them in, though. :cool:
 

romeo

Senior Member
number of ground rods

I also agree, prove that one is good, or put in two.

Funny thing is that we keep having inspectors tell us that we don't need the second one. :roll:

We keep putting them in, though. :cool:

That is why I have so much trouble, it is not only inspectors but also some instructors.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
i drive one until i am proven that two is required and i dont meet the 25 ohms or less. we are in america and innocent until proven guilty.;)

So inspectors are allowing you to only install one rod and the installation passes? Do they test for 25 ohms or less?
 

cpal

Senior Member
Location
MA
Naturally we are assuming that there are no available electrodes at the building or structure and we will be using ground rods that do not meet the 25 ohms.

I maintain that 2 rods are required

I do not read 250 as requiring a second rod. 250.56 states in part,
"A single electrode consisting of a rod, pipe, or plate that does not have a resistance to ground of 25 ohms or less shall be augmented by one additional electrode"

The resistance of a single rod may be reduced by means other than driving a second rod or adding an augmented electrode listed in 250.52.
If that course is pursued then a second electrode may not be necessary.


Part III of Articale 250: 250.56 requires a second rod.



I don't see the language as requiring a second rod, I see it as giving permission to use a second rod (etc).

granted the second rod is usually the most economical method of achieving the 25 ohms or less, but there are options.


I had that discussion with an instructor a a recent 15 hr class, He dropped the issue.
What do you say?

I would give the instructor the benefit of the doubt and question if you were pressing the issue without considering the alternatives??
it can be difficult to handle a contentious conversation within the format of a code update.

Were You??
 
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infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I do not read 250 as requiring a second rod. 250.56 states in part,
"A single electrode consisting of a rod, pipe, or plate that does not have a resistance to ground of 25 ohms or less shall be augmented by one additional electrode"

The resistance of a single rod may be reduced by means other than driving a second rod or adding an augmented electrode listed in 250.52.
If that course is pursued then a second electrode may not be necessary.




I don't see the language as requiring a second rod, I see it as giving permission to use a second rod (etc).

granted the second rod is usually the most economical method of achieving the 25 ohms or less, but there are options.




I would give the instructor the benefit of the doubt and question if you were pressing the issue without considering the alternatives??
it can be difficult to handle a contentious conversation within the format of a code update.

Were You??

A second rod is not required, but one rod is required to have a resistance of 25 ohms or less. In almost every jurisdiction the onus is on the installer to prove that the one rod complies with the requirement. You are correct that there are other electrodes permitted to be used to augment the single rod.
 

romeo

Senior Member
number of ground rods

I do not read 250 as requiring a second rod. 250.56 states in part,
"A single electrode consisting of a rod, pipe, or plate that does not have a resistance to ground of 25 ohms or less shall be augmented by one additional electrode"

The resistance of a single rod may be reduced by means other than driving a second rod or adding an augmented electrode listed in 250.52.
If that course is pursued then a second electrode may not be necessary.




I don't see the language as requiring a second rod, I see it as giving permission to use a second rod (etc).

granted the second rod is usually the most economical method of achieving the 25 ohms or less, but there are options.




I would give the instructor the benefit of the doubt and question if you were pressing the issue without considering the alternatives??
it can be difficult to handle a contentious conversation within the format of a code update.

Were You??

I am in Massachusetts, You are correct there are alternatives, as I mentioned we are assuming there are no other electrodes present,and we are using ground rods for the ges.I have never seen any other method used other than an additional ground rod,as you mentioned it is the most economical way.
 

hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
Another misconception is that you always have to drive a ground rod, even though other grounding electrodes are available and meet the resistance requirements. Also have had inspectors want a 3/0 to a single ground rod. I did have one inspector want to turn me down on a 2000 amp 480 volt service, where I had a #4 to the ground rod (which I didn't need anyway) He said show me where the code allowed it, when I did, he totally agreed and said he learned something today.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Two rods required or prove one is 25 ohms or less.

Why is it that an inspector is required to prove you are wrong for everything else but in the case of something as insignificant as whether there is 25 ohms or less, somehow the electrician has to prove that?

I think the issue is mostly going away as a CEE is now virtually a requirement.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I wish that were the case around here and certainly it will never affect the service change so rods will be around for some time.

if you do a service change what forces you to change the GES? especially if it is rods. You disconnect the old service and hook up the new, and the GEC remains in place.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
if you do a service change what forces you to change the GES? especially if it is rods. You disconnect the old service and hook up the new, and the GEC remains in place.
If there is a rod. If there is generally only one is driven so another is added. Since rods have a definite life span I usually will dive 2 new ones.

Also, for some unknown reason, the state has determined that the CEE does not have to be used because the EC is not on the job during that time. I hate that rule. I have my builders trained now and I must do constant reminding of them to call me when they get ready for a pour. I wish the state would mandate it be done so the builders won't need reminding. They tear up one footing if the forget may help them remember the next time.
 

romeo

Senior Member
number of ground ros

number of ground ros

Another misconception is that you always have to drive a ground rod, even though other grounding electrodes are available and meet the resistance requirements. Also have had inspectors want a 3/0 to a single ground rod. I did have one inspector want to turn me down on a 2000 amp 480 volt service, where I had a #4 to the ground rod (which I didn't need anyway) He said show me where the code allowed it, when I did, he totally agreed and said he learned something today.

Wow #6 gec for rods has been in the code for a long time, but it sounds like the inspector was reasonable enough to admit his mistake. Show me someone that doesn't make a mistake and I will show you someone that isn't doing anything.

However I have seen over sized conductors to ground rods many times, so some ec are confused also.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
If there is a rod. If there is generally only one is driven so another is added. Since rods have a definite life span I usually will dive 2 new ones.

Just how does the inspector have any way to know the rod is at the end of it's life span, even if that were a real issue.

I think a lot of people in the electrical industry fixate on grounding like it is something that really matters, when in reality it is not that big of a deal.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Just how does the inspector have any way to know the rod is at the end of it's life span, even if that were a real issue.

I think a lot of people in the electrical industry fixate on grounding like it is something that really matters, when in reality it is not that big of a deal.
It is not a matter of the inspector knowing or not. If a rod has been 20 years or so depending on conditions it could be compromised. I agree ground rods don't do much but I do believe it is better than nothing so why not make it right when you upgrade. It seems like the right thing to do.
 
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