number of ground rods

[petersonra]

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.

What else are you going to "make right" while you are at it?

The NM insulation that has been in the attic for 20 years at elevated temperatures could be compromised too. Did you replace all that too?

 

[Dennis Alwon]

What else are you going to "make right" while you are at it?

The NM insulation that has been in the attic for 20 years at elevated temperatures could be compromised too. Did you replace all that too?

If I am working on the service and do a service change I feel that upgrading the rods is part of it. I believe you would fail inspection around here if you didn't. Why does it bother you that I add a rod- it isn't a big deal and it needs to be done to be compliant, IMO.

If you upgrade from 100 amp to 200 amps do you leave the existing #6 going to the water pipes? IMO, if you did you would be in violation. If I do a service change then it is going to get done to meet todays code.

 

[cpal]

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.

I agree and thought that was indicated in my first post. Did I mess something??

 

[cpal]

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.

So am I!!!

My point was , There are options in the MEC as well as the NEC.

You could choose to chemically treat the area or install a deep driven rod, or default to 250.56. I was trying to give another perspective of why your course instructor apparently did not address your question. You never gave a full account as to why the instructor dropped the subject.

How many people where in the class
was the question brought up during a grounding presentation
did you press the issue
did the instructor appear un-prepaired
was the subject addressed as a side bar??????????


I thought it might be an intersting subject but the thread has taken another direction.

 

[cpal]

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.

I disagree that CEE are making the 25 ohm issue moot, but thats my opinion.

I also disagree that the 25 ohms is insignificant, maybe it is!! maybe it isn't, but it is the minimum requirment set out in art 250.

I also beleive that it is the responibility of the installing professional to present evidence that the 25 ohms to ground or less is achieved. i also think the installer should present the method of determing this and the recorded data to support his claim.

Cell towers require a lower resistance to ground than the minmum requirments of the NEC.

Also part of the certification requires documentation, Ground Res Tester, Fall of potential, Clamp on probe.

The inspectors usually do not have these instruments at their disposal.

 

[cmreschke]

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

yes i only install one rod and have yet to be proven wrong on it because the inspectors around here claim that they do not have the funds available for the testing equipment so they choose to just let it go. if i am proven wrong i would gladly drive the second ground rod
i have driven a second rod when there is no metal water piping coming into residence and have been violated because i have run two sep. gec from panel to rods 1 for each rod. inspector says must be continuous panel to rod to rod which are 6 ' apart. i think not. i feel i am installing second rod to comply with two paths to ground per service and feel that panel to rod to rod is only one ground path. one time inspector had me take second gec out and drive rod below grade to eliminate it.
comercially normally two to four rods per print spec.

 

[cmreschke]

and as far as inspectors not having the equipment maybe they should take some of the exhorbitant permit fees and buy the equipment. we as contractors and electricians alike are expected to have all tools required for the task at hand why not the inspectors as well. it is part of their jobs to be able to prove us wrong. we do not have to prove ourselves right.

 

[don_resqcapt19]

I disagree that CEE are making the 25 ohm issue moot, but thats my opinion.

They are per the NEC. The 25 ohm rule does not apply to the CEE.

I also disagree that the 25 ohms is insignificant, maybe it is!! maybe it isn't, but it is the minimum requirment set out in art 250.

This is a subject of debate so as you said, maybe it is, maybe it isn't.

I also beleive that it is the responibility of the installing professional to present evidence that the 25 ohms to ground or less is achieved. i also think the installer should present the method of determing this and the recorded data to support his claim.

Yes, I believe it is the installer's responsibility to provide evidence of compliance with the 25 ohm rule when a single ground rod or ground plate is installed.

Cell towers require a lower resistance to ground than the minmum requirments of the NEC.

That is a design issue related to radio performance and lightning protection and really has nothing to do with the rules in the NEC.

Also part of the certification requires documentation, Ground Res Tester, Fall of potential, Clamp on probe.
The inspectors usually do not have these instruments at their disposal.

The cost of the testing equipment and doing the testing and documentation is exactly why most installers, when using ground rods, find it cost effective to install a second rod and call it a day.

 

[cpal]

They are per the NEC. The 25 ohm rule does not apply to the CEE.
This is a subject of debate so as you said, maybe it is, maybe it isn't.
Yes, I believe it is the installer's responsibility to provide evidence of compliance with the 25 ohm rule when a single ground rod or ground plate is installed.
That is a design issue related to radio performance and lightning protection and really has nothing to do with the rules in the NEC.
The cost of the testing equipment and doing the testing and documentation is exactly why most installers, when using ground rods, find it cost effective to install a second rod and call it a day.

Thanks for agreeing with me.

I was not citing the cell towers to reinforce a code requirment per say. I used that example to illustrate that the 25 ohms is not that useless, as stated in a previous post.

 

[cpal]

and as far as inspectors not having the equipment maybe they should take some of the exhorbitant permit fees and buy the equipment. we as contractors and electricians alike are expected to have all tools required for the task at hand why not the inspectors as well. it is part of their jobs to be able to prove us wrong. we do not have to prove ourselves right.

The Ec can deduct the cost of equipment as a business expense. In some parts of the country the E I works for the municipality and the costy of such eq is directly charged to the tax payer. Guess whos not going to buy a ground resistance tester.

 

[tortuga]

Here is the $345 question

Here is the $345 question

What does the parts and labor of the 2nd ground rod cost on average?
$7.50 for the rod, $ .9 for the clamp, $5 in wire, labor cost $~30? or about 45 bucks.
now I don't think you would need a real fancy cell tower grounding impedance tester, I found this one for $345 (with NIST Calibration Certificate)
Now what is a "recognized method" of testing? How long does it take? and does one ground rod pass?
If one ground rod is always around 10 - 20 Ohms perhaps it would be a worthy investment. If you charge $34.5 for the test and it will pay for itself in 10 service changes.
OR if you don't have 25 ohms after 2 groundrods you will have paid $345 to know you probably need 3 in your area, however that seems not required?
Here in Oregon we have the following amendments:

(3) Section 250.52 Grounding Electrodes. Amended as follows:
(a) Amend 250.52(A)(3) by inserting the following: "In new construction with steel reinforced concrete footings, a concrete-encased grounding electrode connected to the grounding electrode system is required. The installation shall meet the requirements of Section 250.50. When a concrete encased electrode system is used, a minimum size of 1/2-inch reinforcing bar or rod shall be stubbed up at least 12 inches above the floor plate line or floor level, whichever is the highest, near the service entrance panel location."
(b) Amend 250.52(B)(2) by inserting the following: "(3) In existing electrical installations, when a service change or upgrade occurs, an existing metal underground water pipe shall not be used unless the metal underground water pipe has been verified as suitable for continued use as a grounding electrode. An existing metal underground water pipe shall be bonded to the new grounding electrode system as required by 250.104(A)."
(4) Section 250.56 Resistance of Rod, Pipe, and Plate Electrodes. Amend by inserting the following at the end of the first sentence of 250.56: "For permanent installations where the only grounding electrode is a single ground rod, pipe or plate, documented verification of 25 ohms or less shall be provided. Documented verification shall be done by a recognized method, provided by the installer, and made available for the electrical inspector."

 

[infinity]

i have driven a second rod when there is no metal water piping coming into residence and have been violated because i have run two sep. gec from panel to rods 1 for each rod. inspector says must be continuous panel to rod to rod which are 6 ' apart. i think not. i feel i am installing second rod to comply with two paths to ground per service and feel that panel to rod to rod is only one ground path. one time inspector had me take second gec out and drive rod below grade to eliminate it.
comercially normally two to four rods per print spec.

Your inspectors don't seem to know much about Article 250 if this is what they're enforcing. And there is no two paths to ground per service requirement in the NEC.

Here's a graphic, if the water pipe doesn't exist the ground rods with one GEC and a bonding jumper is all that's required.

 

[brian john]

now I don't think you would need a real fancy cell tower grounding impedance tester, I found this one for $345 (with NIST Calibration Certificate)

A GOOD TESTER runs around $1,200.00, calibration is good for a year so re-calabration is required (runs us around $4,500.00 a year for around 300 pieces of equipment)

Now what is a "recognized method" of testing? How long does it take? and does one ground rod pass?

3-point test as described in the AEMC site (AEMC.COM), per IEEE, ANSI and NETA.

If one ground rod is always around 10 - 20 Ohms perhaps it would be a worthy investment. If you charge $34.5 for the test and it will pay for itself in 10 service changes.

for a single rod around 30-60 minutes, plus report processing.

:

OR if you don't have 25 ohms after 2 groundrods you will have paid $345 to know you probably need 3 in your area, however that seems not required?
Here in Oregon we have the following amendments

At $345.00 a test I am losing money, QUIT driving the rates down!

What is almost funny (BUT ISN'T), is the amount of time and effort many electricians and inspectors put in to the electrode we drive into the earth, yet overlook simple EGC and bonding at the service and throughout the facility.

 

[JohnE]

Romeo if you had just taken Charlie's (cpal) code review with me a few years ago we wouldn't have this discussion. :grin: Mike will probably set one up with him and Bill for this winter.

For the record I agree with you and everyone else, a 2nd electrode is required.

 

[brian john]

For the record I agree with you and everyone else, a 2nd electrode is required.

Not required, an alternative to testing.

 

[tortuga]

3-point test as described in the AEMC site (AEMC.COM), per IEEE, ANSI and NETA.

It seems like you are in the testing business I have never even seen a groundrod test can you (or anyone) tell us if on average (in your area) 1 groundrod is around 25 Ohms?

 

[romeo]

number of ground rods

If I am working on the service and do a service change I feel that upgrading the rods is part of it. I believe you would fail inspection around here if you didn't. Why does it bother you that I add a rod- it isn't a big deal and it needs to be done to be compliant, IMO.

If you upgrade from 100 amp to 200 amps do you leave the existing #6 going to the water pipes? IMO, if you did you would be in violation. If I do a service change then it is going to get done to meet todays code.

I agree and think that it is well said. Not only change the gec to the water pipe but add, a code compliant ges, which would most likely be ground rod or rods.

 

[charlie b]

I will only take a moment to mention that a Washington State code states that if a ground resistance test is not performed, then a second ground rod is required.

 

[romeo]

number of ground rods

Romeo if you had just taken Charlie's (cpal) code review with me a few years ago we wouldn't have this discussion. :grin: Mike will probably set one up with him and Bill for this winter.

For the record I agree with you and everyone else, a 2nd electrode is required.

Hi John.Nice to see you here. I am glad you agree.

Please let me know if if that code review happens.

I did Crownshield Ave this AM

 

[electricmanscott]

Romeo if you had just taken Charlie's (cpal) code review with me a few years ago we wouldn't have this discussion. :grin: Mike will probably set one up with him and Bill for this winter.

For the record I agree with you and everyone else, a 2nd electrode is required.

I always take their class. Bill's view on this might surprise some. It did me.

I also agree, the 2nd electrode is required in Romeo's example.