second ground rod

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  #1  
Old 12-08-12, 06:53 AM
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second ground rod

I live in NY State and just got my serviced upgraded from 100 amps to 200amps. The one thing I noticed was attached to the original ground rod was another ground wire buried about an inch below ground. The wire ran away to about 6 ft and the was bent to a half loop facing back to the original ground. The was no second ground bar just buried an inch to an inch and a half below the ground. Is this normal or exceptable? I know you are suppose to have 2 ground rods for 200 amps but is this setup also allowed?
 
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Old 12-08-12, 07:42 AM
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This sounds unconventional. Can you straighten the conductor out and drive a second rod? Was this inspected?

Two rods are not always required. A Ufer ground is allowed to be the sole grounding means.
 
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Old 12-08-12, 02:10 PM
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Is your ground frozen? Your contractor may have just run the wire to the future rod and will be back in the spring to drive the 2nd rod.
 
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Old 12-09-12, 07:06 AM
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I know you are suppose to have 2 ground rods for 200 amps
2 ground rods is not a requirement.
 
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Old 12-09-12, 09:45 AM
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2 ground rods is not a requirement.

It is here in NJ....or at least my inspectors require two.
 
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Old 12-09-12, 09:58 AM
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If you only have one ground rod, you have to prove it is adequate by measuring the resistance. Having two ground rods removes that requirement. So everyone puts in two to make it easy.
 
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Old 12-09-12, 10:14 AM
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We only install one ground rod and have never been required to do a test. The only time we had to install two was when there was no water in the building and therefore the rod(s) were the primary grounding electrode.
 
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Old 12-09-12, 11:57 AM
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No the ground was not frozen and they are not coming back. Yes I could straighten it out and run a second ground rod but was more confused on why they did it. I am not sure if they did it to be sneaky and make it look like they ran a second or they did it that way because it was another way of running a second ground. I honestly just thought it was wierd and never saw that before. My mothers house in NJ has 200 amps and one ground rod but that was installed in 1970 and I know in NJ two are now required. I am not going to lose sleep over it but I just want to make sure that the way they did it was ok and not trying to bypass a code
 
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Old 12-09-12, 12:20 PM
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I wonder if they ran the wire and just forgot to drive the 2nd rod. I see no reason to run the wire without driving the rod. It is not like they saved tones of money. A rod is about $10 and the clamp is about $4. That is barely enough to buy lunch.
 
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Old 12-09-12, 04:30 PM
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I actually walked over to my neighbors who had an uprade from 100 to 200 amps 4 yrs ago. They only have one ground so perhaps 1 is only required in my county in NY. I just don't understand why they ran it to alone and did not attach it to a second ground. I guess if I get bored one day in the summer I could buy a ground rod and a clamp and drive it into the ground.
 
  #11  
Old 12-09-12, 05:04 PM
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You should see how they did my sister's house. They brought out a loop from the panel to the soil and back into the garage where it ran about ten feet through the studs and then exited the house. The loop was connected to nothing, just covered by the bark mulch and the far end was buried slightly and then arose a few feet away where it was cut. I scraped some of the bark away and found a short bent rod but no clamp.

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Old 12-09-12, 06:05 PM
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2 ground rods is not a requirement.
It is here in NJ....or at least my inspectors require two.
If a second rod is required it is a local amendment, the NEC only requires that one rod be installed measuring 25 ohms or less to earthen ground. I have never seen an inspector require a second rod, but in my area, resistance to ground with a new ground rod and new #6 copper ground wire is about 5 or 6 ohms. Yes, in many parts of the country driving a second rod negates the requirement to prove the resistance meets the rquirement. Smaller contractors many times don't have the equipment to measure the resistance.
 
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Old 12-09-12, 09:45 PM
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A second ground rod, per se, isn't required anywhere, so far as I know. It's just a quick and easy way to insure that the GEC will meet the resistance requirement.
 
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Old 12-10-12, 05:39 AM
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Actually the second rod does not guarantee the resistance is less than 25 ohms. Even if the resistance would test above 25 ohms the NEC does not require additional electrodes to get the resistance below 25 ohms.
 
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Old 12-10-12, 10:55 AM
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Actually the second rod does not guarantee the resistance is less than 25 ohms. Even if the resistance would test above 25 ohms the NEC does not require additional electrodes to get the resistance below 25 ohms.
That's true. I misspoke. Thank you, PC, for catching me on that.

The actual requirement is that the system
have a “good earth ground”... The generally accepted practice is to have the earth’s ground resistance not exceed 25 ohms.
In fact,
The NEC does not contain any requirement as to the maximum earth ground resistance permitted for a grounding electrode or the grounding electrode system.
However, the NEC does have specific requirements for the installation of the grounding electrode and the grounding electrode conductor. These rules are contained in Sections 250-50 through 250-70 and the following is a short summary of each.

Section 250-50 Grounding Electrode System

The earth ground resistance can be reduced by installing multiple grounding electrodes (see list below) and bonding them together so that they are in parallel to each other, Figure 12-4.

1. Metal underground water pipe in direct contact with the earth for 10 feet, supplemented by a “made electrode.”

2. Metal frame of the building or structure that is bonded to another electrode.

3. Electrically conductive foundation or footer steel not less than ˝-in. diameter and not less than a total of 20 feet in length.

4. A No. 2 conductor completely encircling the building or structure installed at a depth of not less than 2˝ feet.
To the point here, for a standard residential service,
Where none of the electrodes listed in Section 250-50 are available, then a “made electrode” consisting of ˝ inch copper clad or 5/8th inch galvanized (or larger) rod driven 8 feet vertically in the soil may be used. But if the ground resistance of a single “ground rod” is greater than 25 ohms, then a second “ground rod” must be installed so that [it] is no closer than 6 feet, and both ground rods must be bonded together with a No. 6 wire [250-56],[emphasis added]
So the short, quick answer is, if you're not prepared to test the resistance, and you don't know from experience that the soil in your area is typically not so resistive as to create an impedance greater than 25 ohms, then drive the second rod.

Really quick answer? "Do what the neighbors have done." I hope this clears this up a bit.

The source for the technical quotes above is Ground Resistance - It's Not What You Think, by Mike Holt. It's an interesting read, IMO.
 

Last edited by pcboss; 12-10-12 at 11:14 AM.
  #16  
Old 12-10-12, 04:51 PM
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These are all good points that promote checking for local amendments to NEC when undertaking a project. I remember a time when Madison County Illinois required a 5/8" X 10 foot ground rod for a residential 200 amp service. They had other specific requirements for that service too, but they didn't pertain to grounding. Today they just follow NEC.
 
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