Do Two Rods Need to Run Continuous Ground Rods
- #1
250.56 Resistance of Rod, Pipe, and Plate Electrodes. 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 of any of the types specified by 250.52(A)(4) through (A)(8). 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.
How does your jurisdiction treat that code section? Do they require a second rod whenever a single rod is required?
When I write the correction, I always spell out the word "feet" as in "a minimum 6 feet away from the first rod"
I still get these:
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jar546
Chief Cook & Bottlewasher
- #4
For service changes and upgrades or new installations that don't have rebar in the footer, we always see 2 ground rods because of the same reasons stated above. 1) Not many have the equipment necessary to test and 2) Those that do have a hard time getting 25 ohms or less with our soils.
Here is a short story that I will make long.
I was always under the impression that if you had a water pipe that qualified as a grounding electrode, then if you added a rod outside, that was the 2nd electrode IF you could not prove the 25 ohm rule. In my little head, we had 2 grounding electrodes and since the water pipe was larger and longer and tied into a system underground, it was the main grounding electrode and the single rod added as the supplemental for the 25 ohm rule. I was corrected in person by Michael Johnston who sits on a few CMPs.
Of course, me being me, I had to question him and I asked: "So let me get this straight. If I have a house that has a plastic water main coming in and plastic pipe through out, I have to have 2 ground rods and agree. But, you are telling me that if I have a metallic water pipe that is considered a grounding electrode, I have to add 2 rods (if I don't meter the one) in addition to the water pipe?". His answer was "Yes, that is the intent."
I love to learn right from the source when possible. It make the humbling experience more bearable.
- #6
ICE said:
Each and every time. At a temp pole, remote building, service, or any place that a rod, pipe, or plate electrode is installed except as outlined in 250.54. The 2011 cycle cleared this up quite a bit by requiring two rods plain and simple (250.53(A)(2).
ICE said:
Bonding of metal water pipes comes from a different part of Article 250 than the installation of electrodes. The bonding of cold to hot metal water pipes is not found in the NEC.
- #10
It doesn't take much to get a license in California. Most of what I see is some guy passing himself off as a licensed electrician. A lot of it is a general contractor that hires anybody that doesn't have burnt fingers to do electrical work.
This was presented as a water pipe bond. They were serious.
This had a general contractor behind it.
I had nothing to do with this job until they requested a final inspection. The job card had approvals through lath. All that was left was a final.
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jar546
Chief Cook & Bottlewasher
- #14
Here in Pueblo Colorado we have very dry soil with poor conductivity. By default the inspectors out here require two 8' rods driven a minimum of 6' apart.
Source: https://www.thebuildingcodeforum.com/forum/threads/2-ground-rods.8993/
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