two grounding electrodes at services?

Status
Not open for further replies.

Electron_Sam78

Senior Member
Location
Palm Bay, FL
A friend of mine who's a general contractor and HVAC technician says that there is a new requirement for two ground rods to be installed at the sservices in new construction or remodel situations. Anyone heard of this requirement? The city is still using the 99 NEC here in my town and I haven't installed a service in three years so I'm not up on our power company requires these days.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Electron_Sam78 said:
A friend of mine who's a general contractor and HVAC technician says that there is a new requirement for two ground rods to be installed at the sservices in new construction or remodel situations. Anyone heard of this requirement? The city is still using the 99 NEC here in my town and I haven't installed a service in three years so I'm not up on our power company requires these days.

I am not sure about the 99 code but we have been installing 2 for years. The 2005 definitely requires two if you cannot get 25 ohms to ground with one. You are only required to add one more even if you don't get 25 ohms.
 

radiopet

Senior Member
Location
Spotsylvania, VA
Yep....the (2) rods is more over the local deputy BO saying...look..unless you have a megger and can show me 25 OHMS or less I want the augemented electrode....so rather than go out and buy a 3 point potential or a $ 1,000 megger......easier to spend the $ 25.00 and drive another rod 6' from the first one....

Then what I find funny is when an inspector turns if down when you add the second because he thinks it has to run continuous from the panel to the first rod and then to the second rod....while it is fine to do that....it is not required to be installed that way by the NEC.....I hear that one alot traveling around the country doing seminars...

The (1) is required....the 2nd one is required "if" you dont have 25 OHMS on the first rod....regardless if you do or not after the second one...no more are required after that....

Now...chances are you have OTHER electrodes "Present" which need to be bonded to the grounding electrode system per the NEC.
 

radiopet

Senior Member
Location
Spotsylvania, VA
and as Mike says all the time...they probably just pulled that number from...well who knows where.....just sounded like a good number to use...lol
 

crossman

Senior Member
Location
Southeast Texas
Of course, without further info from the OP, it just may be that we don't even need a ground rod, or perhaps we can use just one even if it is greater than 25 ohms, or of course you may need two.
 

Electron_Sam78

Senior Member
Location
Palm Bay, FL
Ok, so it's just the 25 ohms or an AHJ ruling that would cause us to need a 2nd electrode. That answers my question about it being a code requirement. I knew there was a resistance requirement for the grounding electrodes but I never had to worry about it here before. We just sunk a 5/8", 10' rod and that was it as far as the city and POCO were concerned. I'll have to do my homework the next time I do a service. Thanks for the inputs :smile:
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
abe72487 said:
Here in Idaho 2 rods are required and sometimes supplemental grounding such as ufer, or metal water pipe, or ground ring.


The CEE (ufer) and water pipe are required to be used if they qualify as an electrode. Ground rods or rings are never required by the NEC.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
don_resqcapt19 said:
That rule was in 250-84 as far back as the 1975 code.


You probably right. The 1999 NEC had a complete overhaul of Article 250 so it is possible that it was moved from another section within the article. Does anyone know why this was never really enforced back them?
 

wbalsam1

Senior Member
Location
Upper Jay, NY
In 1968 at 250-84 an extra rod was required when more than 25 ohms was a problem. 250-84 in 1959 required two or more made electrodes when one exceeded 25 ohms. 2584 of 1956 code required the same. :smile:
 

radiopet

Senior Member
Location
Spotsylvania, VA
det10c_20c.jpg


les.......this is the Megger ( manufacturer ) of Ground Resistance testers...in case my "Megger" comment confused anyone...lol
 

radiopet

Senior Member
Location
Spotsylvania, VA
lol...speaking of TWO rods....I did an inspection yesterday where I had the electrician pull on the ground rods ( because I had pulled on them in a previous failed inspection and had my doubts )....so I asked him..."so this ground looks hard....were the rods tough to drive"...his response was "Yes, they were quite tough "....then I pulled on one and it moved with only a pinky of a pull...so I made him finish.....Guess what,.....they were only 4' long...

He asked how I knew......well I said I could tell for the following reasons:

1.) Been doing this 22+ years...and they pulled up too easy if truly driven.
2.) No UL Markings within 12" of the end on one of the rods
3.) One end sticking up has the pointed end on it (not tapered...pointed )and the other one was flat on the top....which told me it was the same rod cut in half...

He blamed a helper and well........we know the rest of the story.
 
Status
Not open for further replies.
Top