I am upgrading an existing 150 amp service to a 200 amp service in Virginia Beach, VA. All the plumbing is plastic so there is no cold water ground. The inspector has told me that a second ground rod must be installed approximately 8' from the original one. I can't find this in the NEC. (I don't think he knows were it is)Can you tell me if this is code and if it is, what is the section so I can refer to it. I do understand that a second ground rod can't hurt, however there is an additional expense to the customer and I would like to justify it. Thanks.
Cold water ground
- Thread starter coastalhs
- Start date
- Status
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Re: Cold water ground
Even if you had a metal water pipe, some jurisdictions require two rods with the water pipe, to comply with 250.53(D)(2) and 250.56
Even if you had a metal water pipe, some jurisdictions require two rods with the water pipe, to comply with 250.53(D)(2) and 250.56
- Location
- Massachusetts
Re: Cold water ground
As the others have pointed out you have to look at 250.56 Resistance of Rod, Pipe, and Plate Electrodes. which requires a single rod to have a resistance to ground of 25 ohms or less shall be augmented by one additional electrode.
So if you can prove you have 25 ohms or less resistance you can stop with one rod or instead of testing you can just add a second rod.
250.56 goes on to say Where multiple rod, pipe, or plate electrodes are installed to meet the requirements of this section, they shall not be less than 1.8 m (6 ft) apart.
So your options are these IMO.
1)Use only one rod and prove 25 ohms or less resistance which requires specialized testing equipment.
2)Install 2 rods 6' or more apart from each other.
Bob
As the others have pointed out you have to look at 250.56 Resistance of Rod, Pipe, and Plate Electrodes. which requires a single rod to have a resistance to ground of 25 ohms or less shall be augmented by one additional electrode.
So if you can prove you have 25 ohms or less resistance you can stop with one rod or instead of testing you can just add a second rod.
250.56 goes on to say Where multiple rod, pipe, or plate electrodes are installed to meet the requirements of this section, they shall not be less than 1.8 m (6 ft) apart.
So your options are these IMO.
1)Use only one rod and prove 25 ohms or less resistance which requires specialized testing equipment.
2)Install 2 rods 6' or more apart from each other.
Bob
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Re: Cold water ground
I would agree with all of the responses and would add that as Bob had said, the grounds rods need only be a minimum of 6 feet apart, not the 8 feet that your inspector requested. Although spacing them farther than 6 feet will improve their efficacy.
I would agree with all of the responses and would add that as Bob had said, the grounds rods need only be a minimum of 6 feet apart, not the 8 feet that your inspector requested. Although spacing them farther than 6 feet will improve their efficacy.
johndeereman
Member
Re: Cold water ground
Iwould agree with all other responses.
Iwould agree with all other responses.
southernboys
Senior Member
Re: Cold water ground
working in gulf shores al we always drive two ground rods due to the 25 ohm requirement this on the beach so i would assume your on the beach as well?
working in gulf shores al we always drive two ground rods due to the 25 ohm requirement this on the beach so i would assume your on the beach as well?
Re: Cold water ground
I agree also, it's always 2 rods, who has the equipment or time to prove 25 ohms or less? Just curious, don't mean to hi-jack the thread, but does ANYBODY actually try to prove 25 or less?? Does anybody even own the equipment to do so other than maybe an engineering firm?
I agree also, it's always 2 rods, who has the equipment or time to prove 25 ohms or less? Just curious, don't mean to hi-jack the thread, but does ANYBODY actually try to prove 25 or less?? Does anybody even own the equipment to do so other than maybe an engineering firm?
southernboys
Senior Member
Re: Cold water ground
bruce in the past year I took a jman prep class and the insructor is the one who got the two ground rods initiated in my area so yes he did take us out there and proved that one ground rod would not decrease the resistancy to 25 ohms of course after driving 2nd rod we still did not have 25 thank God its only 2 rods as required and not 25 ohms
bruce in the past year I took a jman prep class and the insructor is the one who got the two ground rods initiated in my area so yes he did take us out there and proved that one ground rod would not decrease the resistancy to 25 ohms of course after driving 2nd rod we still did not have 25 thank God its only 2 rods as required and not 25 ohms
pierre
Senior Member
- Location
- Westchester County, New York
Re: Cold water ground
Bruce
I actually own the equipment
When I go to service inspections, I check the ground rod resistance, and generally in our area the resitance with 2 rods is anywhere from 40 to 300 ohms or more.
You should see the contractor's face when I test them - they usually think they are in trouble .
Bruce
I actually own the equipment
When I go to service inspections, I check the ground rod resistance, and generally in our area the resitance with 2 rods is anywhere from 40 to 300 ohms or more.
You should see the contractor's face when I test them - they usually think they are in trouble
.
busman
Senior Member
- Location
- Northern Virginia
- Occupation
- Master Electrician / Electrical Engineer
Re: Cold water ground
As another Virginia electrician, I was first red-tagged for this in Feb 2004. I then spent two hours driving a ground rod in the frozen ground. The inspector said it was brand new from that years inspector's conference. Their position was that no electricians ever measured to check the 25 ohms so it was more prudent to just require the second ground rod.
It's interesting to note that when doing separate building feeders, they are only requiring one ground rod.
As another Virginia electrician, I was first red-tagged for this in Feb 2004. I then spent two hours driving a ground rod in the frozen ground. The inspector said it was brand new from that years inspector's conference. Their position was that no electricians ever measured to check the 25 ohms so it was more prudent to just require the second ground rod.
It's interesting to note that when doing separate building feeders, they are only requiring one ground rod.
luke warmwater
Senior Member
Re: Cold water ground
So, Pierre, are you saying that it is the Electrician's responsibility to prove that one rod is <25 ohm, or is it the Inspector's responsibility to prove one rod is >25 ohm, before a second is driven?Originally posted by pierre:
Bruce
I actually own the equipment
When I go to service inspections, I check the ground rod resistance, and generally in our area the resitance with 2 rods is anywhere from 40 to 300 ohms or more.
You should see the contractor's face when I test them - they usually think they are in trouble
bradleyelectric
Senior Member
- Location
- forest hill, md
Re: Cold water ground
I spend the extra $12(they require cu in my county) and put the driver in my Hilti te76 and it takes about 2 minutes each rod. frozen or not.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: Cold water ground
Don't try this at home:
I have an US Army manual on grounding. It states that installing ground rods in frozen soil can be done with C-4 explosive and then backfilling the hole around the ground rod.
Don't try this at home:
I have an US Army manual on grounding. It states that installing ground rods in frozen soil can be done with C-4 explosive and then backfilling the hole around the ground rod.
Re: Cold water ground
In actuality you do need a grounding electrode that is as close to the service AND the meter socket as possible to provide a path for lightning current. If the service switch is not close to the meter some electrical utilities require another rod at the meter. This is vital for the newer electronic and older semielectronic meters.
If you are going to drive 2 ground rods you are better off to use a threadless or threaded rod coupling and drive the rod 16 feet deep. A Colorado electrical utility says that on the portions of their system that have 17 foot ground rods they have ZERO lightning damage. Maybe in 10 years they might have a big enough lightning strike to toast a 17 foot ground rod.
One of the top inspectors in northeast Ohio says that the top 6 feet of a rod that is driven from the surface does not do anything. He got to be a little infamous when he was a contractor because he liked to drive a ground rod beneath the basement floor before the floor was poured, what is known as a Labriola Loop. This required an extra trip from the inspector.
In actuality you do need a grounding electrode that is as close to the service AND the meter socket as possible to provide a path for lightning current. If the service switch is not close to the meter some electrical utilities require another rod at the meter. This is vital for the newer electronic and older semielectronic meters.
If you are going to drive 2 ground rods you are better off to use a threadless or threaded rod coupling and drive the rod 16 feet deep. A Colorado electrical utility says that on the portions of their system that have 17 foot ground rods they have ZERO lightning damage. Maybe in 10 years they might have a big enough lightning strike to toast a 17 foot ground rod.
One of the top inspectors in northeast Ohio says that the top 6 feet of a rod that is driven from the surface does not do anything. He got to be a little infamous when he was a contractor because he liked to drive a ground rod beneath the basement floor before the floor was poured, what is known as a Labriola Loop. This required an extra trip from the inspector.
busman
Senior Member
- Location
- Northern Virginia
- Occupation
- Master Electrician / Electrical Engineer
Re: Cold water ground
Thanks for the tips on ground rod driving. In fact, I bought a Driver attachment for my Bosch Combination Hammer right after that experience. Never thought to try C-4.
Thanks for the tips on ground rod driving. In fact, I bought a Driver attachment for my Bosch Combination Hammer right after that experience. Never thought to try C-4.
electricmanscott
Senior Member
- Location
- Boston, MA
- Occupation
- Massachusetts Master Electrician, one man show.
Re: Cold water ground
I don't see how this would satisfy the NEC requirements.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Hospital Master Electrician
Re: Cold water ground
I'd imagine a behemoth like that would have an installed resistance of less than 25 ohms.
250.56.
I'd imagine a behemoth like that would have an installed resistance of less than 25 ohms.
250.56.
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