Service grounding with well water

[Jim Makara]

I have a question regarding grounding 2 200amp service panels. Since the main water supply to the home is plastic poly piping from the well, is only grounding the service panels to 1 ground rod acceptable or does there need to be 2 ground rods installed?

Thank you for your responces,

Jim

[Wayne Carlisle]

Depends! Did they use a concrete encased electrode or was the ground rod the only means of grounding. If a ground rod is the only electrode, then they may need to be supplemented if the resistance is 25 ohms or less.

[Todd Johnson]

Depends! Did they use a concrete encased electrode or was the ground rod the only means of grounding. If a ground rod is the only electrode, then they may need to be supplemented if the resistance is 25 ohms or less.

I know you meant to say "it may need to be supplemented if the resistance is NOT 25 ohms or less"
250.50 says all present electrodes at each building or structure shall be bonded together.
250.56 states that a single electrode that does not have 25 ohms or less to ground shall be augmented by one of the other electrodes listed in 250.52(A)(4) through (A)(8)

All it says is one additional electrode, then you are done.

[Wayne Carlisle]

Depends! Did they use a concrete encased electrode or was the ground rod the only means of grounding. If a ground rod is the only electrode, then they may need to be supplemented if the resistance is 25 ohms or less.

they meaning them....the people owning the structure.

Sorry if I was a little confusing.

[Jerry Peck]

I know you meant to say "it may need to be supplemented if the resistance is NOT 25 ohms or less"

*IF* the ground rod is "the only electrode, the it MUST HAVE a supplemental electrode:
- 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.
- - - FPN: The paralleling efficiency of rods longer than 2.5 m (8 ft) is improved by spacing greater than 1.8 m (6 ft).

UNLESS it is proven that the resistence is 25 ohms or less.

Now, as Wayne stated, if there is a concrete encased electrode then the ground rod can have any resistance to ground that happens to be there.

And as you stated, "it says is one additional electrode, then you are done.", it does not matter what the resistance to ground is after the second made electrode has been installed ... AT LEAST 6 feet from the other electrode.

[Speedy Petey]

If there is a CCE and a plastic water pipe feeding the house NO other electrodes are required.
A CCE does not require a supplemental electrode.

Don't forget the water bond if there is copper piping in the house.

[Todd Johnson]

*IF* the ground rod is "the only electrode, then it MUST HAVE a supplemental electrode:

JP; Your first statment will mislead. "if" it is the only electode and "IF" the resistance is not 25 ohms or less, 250.56 says it SHALL be augmented by an addition electode. Only then does it require "MUST HAVE" an additional electrode. "IF" other electrodes are present then 250.50 states they shall be bonded together, DONE!
I am trying to agree with you butg there are other variables, senarios, arguments that come into play as you have mentioned in other posts. Is this an existing installation or new? Did it meet the code when it was installed? In this instance I think it SHOULD be addressed but does it HAVE to be? It should deffinately be noted.

We do have existing building codes, depending on the location you are in. What year was the house built and soforth. JM does not specify a location so we dont know.

Did I confuse everybody yet? Fix it JP :D

[Jerry Peck]

Todd,

*IF* you read my post and DO NOT STOP before reading it, then my statement is correct.

On the other hand, your statement is incorrect as stated.


JP; Your first statment will mislead. "if" it is the only electode and "IF" the resistance is not 25 ohms or less,

Incorrect as stated, but you are almost there.


"IF" other electrodes are present then 250.50 states they shall be bonded together, DONE!

That is what I said, not sure why you are trying to confuse people throwing that back in there when it does not pertain to what you are stating.

*IF* there is a concrete encased electrode, then the driven rod IS NOT THE ONLY ELECTRODE, is it? Moot point when talking about a single driven rod only.


*IF* the ground rod is "the only electrode, the it MUST HAVE a supplemental electrode:
...
UNLESS it is proven that the resistence is 25 ohms or less.

You need to learn to read the entire post, I simply replaced the code section with "..." so you could read it easier.

The code does not state a ground rod is okay if it has 25 ohms or less, the code states that the ground rod needs to be supplemented with another rod if it "does not have a resistance to ground of 25 ohms or less".

See the difference?

In one you are stating that a driven rod is okay by itself, and that to call for a supplemental rod one must measure the resistance as being greater than 25 ohms to ground.

In the other the code is stating that a driven rod which does not have 25 ohms to ground or less SHALL BE augmented with a supplemental rod, meaning that one must measure the resistance to show that it has 25 ohms or less to ground ... or install a second rod and not worry about measuring it.

A small difference in the way the code is worded makes a big difference in what it is saying.

[Todd Johnson]

I knew you could fix it! Thanks JP

[Fred Hughes]

OK folks, make it simple for me. If I inspect a house with well water brought in (apparently) by black plastic, how do I know what the resistance is?

[Speedy Petey]

OK folks, make it simple for me. If I inspect a house with well water brought in (apparently) by black plastic, how do I know what the resistance is?
You shouldn't need to know.
With a plastic water feed you need:
- At least one grounding electrode. This can be one Ufer (concrete encased electrode) or ground rod. A single ground rod need to be supplemented by another ONE if the 25 ohms cannot be met. It is easier to simply sink the second one than bother with testing or having the inspector question it. VERY few field electrician have the $1000+ tester required to check grounding electrode resistance.

- A water bond attached to the cold water pipe IF the piping systems in the house is metallic. May homes these days are piped with Pex so no water bond is required, but, metallic items on the water system may need bonding.